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Question 1
Incorrect
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As a medical student on wards in the endocrinology department, you come across a patient suffering from syndrome of inappropriate antidiuretic hormone secretion. During the ward round, the consultant leading the team decides to test your knowledge and asks about the normal release of antidiuretic hormone (ADH) in the brain.
Can you explain the pathway that leads to the release of this hormone causing the patient's condition?Your Answer: ADH is released from the posterior pituitary gland via hormonal stimulation from the hypothalamus
Correct Answer: ADH is released from the posterior pituitary gland via neural cells which extend from the hypothalamus
Explanation:The posterior pituitary gland is formed by neural cells’ axons that extend directly from the hypothalamus.
In contrast to the anterior pituitary gland, which has separate hormone-secreting cells controlled by hormonal stimulation, the posterior pituitary gland only contains neural cells that extend from the hypothalamus. Therefore, the hormones (ADH and oxytocin) released from the posterior pituitary gland are released from the axons of cells extending from the hypothalamus.
All anterior pituitary hormone release is controlled through hormonal stimulation from the hypothalamus.
The adrenal medulla directly releases epinephrine, norepinephrine, and small amounts of dopamine from sympathetic neural cells.
The pituitary gland is a small gland located within the sella turcica in the sphenoid bone of the middle cranial fossa. It weighs approximately 0.5g and is covered by a dural fold. The gland is attached to the hypothalamus by the infundibulum and receives hormonal stimuli from the hypothalamus through the hypothalamo-pituitary portal system. The anterior pituitary, which develops from a depression in the wall of the pharynx known as Rathkes pouch, secretes hormones such as ACTH, TSH, FSH, LH, GH, and prolactin. GH and prolactin are secreted by acidophilic cells, while ACTH, TSH, FSH, and LH are secreted by basophilic cells. On the other hand, the posterior pituitary, which is derived from neuroectoderm, secretes ADH and oxytocin. Both hormones are produced in the hypothalamus before being transported by the hypothalamo-hypophyseal portal system.
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This question is part of the following fields:
- Neurological System
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Question 2
Incorrect
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A 61-year-old man is being evaluated during the ward round in the ICU. The patient was admitted through the emergency department with his wife who reported that he had lost consciousness.
During the examination, the patient is able to move his eyes spontaneously and can perform different eye movements as instructed. However, the patient seems incapable of responding verbally and has 0/5 power in all four limbs.
Which artery occlusion is probable to result in this clinical presentation?Your Answer: Anterior cerebral artery
Correct Answer: Basilar artery
Explanation:Locked-in syndrome is a rare condition that can be caused by a stroke, particularly of the basilar artery. This can result in quadriplegia and bulbar palsy, while cognition and eye movements may remain intact. Other potential causes of locked-in syndrome include trauma, brain tumours, infection, and demyelination.
If the anterior cerebral artery is affected by a stroke, the patient may experience contralateral hemiparesis and sensory loss, with the lower extremity being more severely affected than the upper extremity. Additional symptoms may include behavioural abnormalities and incontinence.
A stroke affecting the middle cerebral artery can cause contralateral hemiparesis and sensory loss, with the face and arm being more severely affected than the lower extremity. Speech and visual deficits are also common.
Strokes affecting the posterior cerebral artery often result in visual deficits, as the occipital lobe is responsible for vision. This can manifest as contralateral homonymous hemianopia.
Cerebellar infarcts, such as those affecting the superior cerebellar artery, can be difficult to diagnose as they often present with non-specific symptoms like nausea/vomiting, headache, and dizziness.
Stroke can affect different parts of the brain depending on which artery is affected. If the anterior cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the lower extremities being more affected than the upper. If the middle cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the upper extremities being more affected than the lower. They may also experience vision loss and difficulty with language. If the posterior cerebral artery is affected, the person may experience vision loss and difficulty recognizing objects.
Lacunar strokes are a type of stroke that are strongly associated with hypertension. They typically present with isolated weakness or loss of sensation on one side of the body, or weakness with difficulty coordinating movements. They often occur in the basal ganglia, thalamus, or internal capsule.
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This question is part of the following fields:
- Neurological System
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Question 3
Incorrect
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A 65-year-old man presents to the emergency department with a sudden onset of weakness and sensory loss on the right side of his body that started 2 hours ago. He reports difficulty walking due to more pronounced leg weakness than arm weakness, but denies any changes in vision or speech. The patient has a medical history of type 2 diabetes and hypertension and is currently taking metformin and ramipril for these conditions.
Imaging is immediately performed, and treatment for his condition is initiated.
What is the likely location of the lesion based on the given information?Your Answer: Left middle cerebral artery
Correct Answer: Left anterior cerebral artery
Explanation:The correct answer is the left anterior cerebral artery. The patient is experiencing a stroke on the right side of their body, with the lower extremity being more affected than the upper. This indicates that the anterior cerebral artery is affected, specifically on the left side as the symptoms are affecting the right side of the body.
The other options are incorrect. If the middle cerebral artery was affected, the upper extremities would be more affected than the lower. If the right anterior cerebral artery was affected, the left side of the brain would be affected. If the right middle cerebral artery was affected, there would be more weakness in the upper extremities and the left side of the body would be affected.
Stroke can affect different parts of the brain depending on which artery is affected. If the anterior cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the lower extremities being more affected than the upper. If the middle cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the upper extremities being more affected than the lower. They may also experience vision loss and difficulty with language. If the posterior cerebral artery is affected, the person may experience vision loss and difficulty recognizing objects.
Lacunar strokes are a type of stroke that are strongly associated with hypertension. They typically present with isolated weakness or loss of sensation on one side of the body, or weakness with difficulty coordinating movements. They often occur in the basal ganglia, thalamus, or internal capsule.
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This question is part of the following fields:
- Neurological System
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Question 4
Incorrect
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A 6-year-old child has been in a car accident and has a fracture of the floor of the orbit. The surgeon you consulted is worried that one of the extra-ocular muscles may be trapped in the fracture site. Which muscle is most vulnerable?
Your Answer: Medial rectus
Correct Answer: Inferior rectus
Explanation:The correct muscle that is most at risk in a fracture of the floor of the orbit, also known as an orbital blowout fracture, is the inferior rectus muscle. This muscle is located above the thin plate of the maxillary bone that makes up the floor of the orbit, and is therefore more susceptible to being trapped in these types of fractures.
When the inferior rectus muscle becomes trapped in a blowout fracture, it can result in restricted eye movements and affect extra-orbital soft tissue. This type of fracture is known as a trapdoor fracture and is often associated with the oculocardiac reflex or Aschner phenomenon, which can cause symptoms such as bradycardia, nausea and vomiting, vertigo, and syncope.
It is important to note that the inferior oblique muscle is also commonly affected in these types of fractures, but it was not an option in this question. Additionally, levator palpebrae inferioris is not an actual muscle and is therefore a dummy answer. The muscle that raises the upper eyelid is actually called the levator palpebrae superioris.
Cranial nerves are a set of 12 nerves that emerge from the brain and control various functions of the head and neck. Each nerve has a specific function, such as smell, sight, eye movement, facial sensation, and tongue movement. Some nerves are sensory, some are motor, and some are both. A useful mnemonic to remember the order of the nerves is Some Say Marry Money But My Brother Says Big Brains Matter Most, with S representing sensory, M representing motor, and B representing both.
In addition to their specific functions, cranial nerves also play a role in various reflexes. These reflexes involve an afferent limb, which carries sensory information to the brain, and an efferent limb, which carries motor information from the brain to the muscles. Examples of cranial nerve reflexes include the corneal reflex, jaw jerk, gag reflex, carotid sinus reflex, pupillary light reflex, and lacrimation reflex. Understanding the functions and reflexes of the cranial nerves is important in diagnosing and treating neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 5
Incorrect
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A 68-year-old male comes to the emergency department with hemiparesis. During your conversation with him, you discover that his speech is fluent but his repetition is poor. He is conscious of his inability to repeat words accurately but persists in trying. You suspect that a stroke may be the cause of this condition.
Which region of the brain has been impacted by the stroke?Your Answer: Occipital lobe
Correct Answer: Arcuate fasciculus
Explanation:The patient is exhibiting symptoms of conduction aphasia, which is typically caused by a stroke that affects the arcuate fasciculus.
If the lesion is in the parietal lobe, the patient may experience sensory inattention and inferior homonymous quadrantanopia.
Lesions in the inferior frontal gyrus can cause speech to become non-fluent, labored, and halting.
Occipital lobe lesions can result in visual changes.
If the lesion is in the superior temporal gyrus, the patient may produce sentences that don’t make sense, use word substitution, and create neologisms, but their speech will still be fluent.
Types of Aphasia: Understanding the Different Forms of Language Impairment
Aphasia is a language disorder that affects a person’s ability to communicate effectively. There are different types of aphasia, each with its own set of symptoms and underlying causes. Wernicke’s aphasia, also known as receptive aphasia, is caused by a lesion in the superior temporal gyrus. This area is responsible for forming speech before sending it to Broca’s area. People with Wernicke’s aphasia may speak fluently, but their sentences often make no sense, and they may use word substitutions and neologisms. Comprehension is impaired.
Broca’s aphasia, also known as expressive aphasia, is caused by a lesion in the inferior frontal gyrus. This area is responsible for speech production. People with Broca’s aphasia may speak in a non-fluent, labored, and halting manner. Repetition is impaired, but comprehension is normal.
Conduction aphasia is caused by a stroke affecting the arcuate fasciculus, the connection between Wernicke’s and Broca’s area. People with conduction aphasia may speak fluently, but their repetition is poor. They are aware of the errors they are making, but comprehension is normal.
Global aphasia is caused by a large lesion affecting all three areas mentioned above, resulting in severe expressive and receptive aphasia. People with global aphasia may still be able to communicate using gestures. Understanding the different types of aphasia is important for proper diagnosis and treatment.
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This question is part of the following fields:
- Neurological System
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Question 6
Incorrect
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A 55-year-old male presents to the neurology clinic with his wife. She reports noticing changes in his speech over the past six months. Specifically, she describes it as loud and jerky with pauses between syllables. However, he is still able to comprehend everything he hears. During your examination, you observe the same speech pattern but find no weakness or sensory changes in his limbs. Based on these findings, which area of the brain is most likely affected by a lesion?
Your Answer: Arcuate fasciculus
Correct Answer: Cerebellum
Explanation:Scanning dysarthria can be caused by cerebellar disease, which can result in jerky, loud speech with pauses between words and syllables. Other symptoms may include dysdiadochokinesia, nystagmus, and an intention tremor.
Wernicke’s (receptive) aphasia can be caused by a lesion in the superior temporal gyrus, which can lead to nonsensical sentences with word substitution and neologisms. It can also cause comprehension impairment, which is not present in this patient.
Parkinson’s disease can be caused by a lesion in the substantia nigra, which can result in monotonous speech. Other symptoms may include bradykinesia, rigidity, and a resting tremor, which are not observed in this patient.
A middle cerebral artery stroke can cause aphasia, contralateral hemiparesis, and sensory loss, with the upper extremity being more affected than the lower. However, this patient does not exhibit altered sensation on examination.
A lesion in the arcuate fasciculus, which connects Wernicke’s and Broca’s area, can cause poor speech repetition, but this is not evident in this patient.
Cerebellar syndrome is a condition that affects the cerebellum, a part of the brain responsible for coordinating movement and balance. When there is damage or injury to one side of the cerebellum, it can cause symptoms on the same side of the body. These symptoms can be remembered using the mnemonic DANISH, which stands for Dysdiadochokinesia, Dysmetria, Ataxia, Nystagmus, Intention tremour, Slurred staccato speech, and Hypotonia.
There are several possible causes of cerebellar syndrome, including genetic conditions like Friedreich’s ataxia and ataxic telangiectasia, neoplastic growths like cerebellar haemangioma, strokes, alcohol use, multiple sclerosis, hypothyroidism, and certain medications or toxins like phenytoin or lead poisoning. In some cases, cerebellar syndrome may be a paraneoplastic condition, meaning it is a secondary effect of an underlying cancer like lung cancer. It is important to identify the underlying cause of cerebellar syndrome in order to provide appropriate treatment and management.
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This question is part of the following fields:
- Neurological System
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Question 7
Incorrect
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Which one of the following does not pass through the inferior orbital fissure?
Your Answer: Trochlear nerve
Correct Answer: ophthalmic artery
Explanation:The ophthalmic artery originates from the internal carotid as soon as it penetrates the dura and arachnoid. It travels through the optic canal beneath the optic nerve and within its dural and arachnoid coverings. It ends as the supratrochlear and dorsal nasal arteries.
Foramina of the Base of the Skull
The base of the skull contains several openings called foramina, which allow for the passage of nerves, blood vessels, and other structures. The foramen ovale, located in the sphenoid bone, contains the mandibular nerve, otic ganglion, accessory meningeal artery, and emissary veins. The foramen spinosum, also in the sphenoid bone, contains the middle meningeal artery and meningeal branch of the mandibular nerve. The foramen rotundum, also in the sphenoid bone, contains the maxillary nerve.
The foramen lacerum, located in the sphenoid bone, is initially occluded by a cartilaginous plug and contains the internal carotid artery, nerve and artery of the pterygoid canal, and the base of the medial pterygoid plate. The jugular foramen, located in the temporal bone, contains the inferior petrosal sinus, glossopharyngeal, vagus, and accessory nerves, sigmoid sinus, and meningeal branches from the occipital and ascending pharyngeal arteries.
The foramen magnum, located in the occipital bone, contains the anterior and posterior spinal arteries, vertebral arteries, and medulla oblongata. The stylomastoid foramen, located in the temporal bone, contains the stylomastoid artery and facial nerve. Finally, the superior orbital fissure, located in the sphenoid bone, contains the oculomotor nerve, recurrent meningeal artery, trochlear nerve, lacrimal, frontal, and nasociliary branches of the ophthalmic nerve, and abducent nerve.
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This question is part of the following fields:
- Neurological System
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Question 8
Incorrect
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A 67-year-old man comes to the clinic with persistent speech difficulties. He is concerned that he might have suffered a stroke. Which scoring system should be used to assess if he has had a stroke?
Your Answer: CHADS2-VASC score
Correct Answer: ROSIER score
Explanation:Stroke Assessment and Investigations
Whilst diagnosing a stroke may be straightforward in some cases, it can be challenging in others due to vague symptoms. The FAST screening tool, which stands for Face/Arms/Speech/Time, is a well-known tool used by the general public to identify stroke symptoms. However, medical professionals use a validated tool called the ROSIER score, recommended by the Royal College of Physicians. The ROSIER score assesses loss of consciousness or syncope, seizure activity, and new, acute onset of asymmetric facial, arm, or leg weakness, speech disturbance, or visual field defect. A score of more than zero indicates a likely stroke.
When investigating suspected stroke, a non-contrast CT head scan is the first line radiological investigation. The key question is whether the stroke is ischaemic or haemorrhagic, as this determines the appropriate treatment. Ischaemic strokes may show areas of low density in the grey and white matter of the territory, which may take time to develop. On the other hand, haemorrhagic strokes typically show areas of hyperdense material (blood) surrounded by low density (oedema). It is crucial to determine the type of stroke promptly, given the increasing role of thrombolysis and thrombectomy in acute stroke management. In rare cases, a third pathology such as a tumour may also be detected.
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This question is part of the following fields:
- Neurological System
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Question 9
Incorrect
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A 20-year-old man is admitted to the emergency department after being stabbed in the back. The knife has penetrated his spinal column at a perpendicular angle, causing damage to the termination of his spinal cord.
Which spinal level has been affected by the knife's penetration?Your Answer: L3
Correct Answer: L1
Explanation:In adults, the level of L1 is where the spinal cord usually ends.
Lumbar Puncture Procedure
Lumbar puncture is a medical procedure that involves obtaining cerebrospinal fluid. In adults, the procedure is typically performed at the L3/L4 or L4/5 interspace, which is located below the spinal cord’s terminates at L1.
During the procedure, the needle passes through several layers. First, it penetrates the supraspinous ligament, which connects the tips of spinous processes. Then, it passes through the interspinous ligaments between adjacent borders of spinous processes. Next, the needle penetrates the ligamentum flavum, which may cause a give. Finally, the needle passes through the dura mater into the subarachnoid space, which is marked by a second give. At this point, clear cerebrospinal fluid should be obtained.
Overall, the lumbar puncture procedure is a complex process that requires careful attention to detail. By following the proper steps and guidelines, medical professionals can obtain cerebrospinal fluid safely and effectively.
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This question is part of the following fields:
- Neurological System
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Question 10
Incorrect
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A 55-year-old male is seen in an outpatient neurology clinic after experiencing a stroke 3 weeks ago. He reports sudden, uncontrollable flailing movements in his right arm and leg. The movements are strong and involuntary, originating from the proximal sections of his limbs.
What area of the brain is likely to be impacted in this scenario?Your Answer: Substantia nigra of the basal ganglia
Correct Answer: Subthalamic nucleus of the basal ganglia
Explanation:Hemiballism is a rare hyperkinetic movement disorder that can be caused by a lesion to the subthalamic nucleus of the basal ganglia. This patient is exhibiting symptoms of hemiballism, including intense, flailing movements of the limbs that originate in the proximal area of the limb. It is important to distinguish hemiballism from chorea, which originates in the distal area of the limb.
Kluver-Bucy syndrome is associated with a lesion to the amygdala and presents with symptoms such as hypersexuality, hyperorality, hyperphagia, and visual agnosia.
Gait ataxia, characterized by an unsteady and uncoordinated gait, is associated with midline cerebellar lesions. However, this would not account for the hyperkinetic movements seen in this patient.
A stroke affecting the substantia nigra of the basal ganglia can cause Parkinson’s disease, which is characterized by bradykinesia, resting tremor, and shuffling gait.
A lesion to the temporal lobe can result in Wernicke’s aphasia, which is characterized by disorderly but fluent speech due to damage to Broca’s area.
Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.
In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.
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This question is part of the following fields:
- Neurological System
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Question 11
Incorrect
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Samantha is a 65-year-old alcoholic who has come to her doctor with worries about the feeling in her legs. She is experiencing decreased light-touch sensation and proprioception in both legs. Her blood work reveals a deficiency in vitamin B12.
What signs are most probable for you to observe in Samantha?Your Answer: Reduced temperature sensation bilaterally
Correct Answer: Positive Babinski sign
Explanation:The presence of a positive Babinski sign may indicate subacute degeneration of the spinal cord, which is typically caused by a deficiency in vitamin B12. This condition primarily affects the dorsal columns of the spinal cord, which are responsible for fine-touch, proprioception, and vibration sensation. In addition to the Babinski sign, patients may also experience spastic paresis. However, hypotonia is not typically observed, as this is a characteristic of lower motor neuron lesions. It is also important to note that temperature sensation is not affected by subacute degeneration of the spinal cord, as this function is mediated by the spinothalamic tract.
Subacute Combined Degeneration of Spinal Cord
Subacute combined degeneration of spinal cord is a condition that occurs due to a deficiency of vitamin B12. The dorsal columns and lateral corticospinal tracts are affected, leading to the loss of joint position and vibration sense. The first symptoms are usually distal paraesthesia, followed by the development of upper motor neuron signs in the legs, such as extensor plantars, brisk knee reflexes, and absent ankle jerks. If left untreated, stiffness and weakness may persist.
This condition is a serious concern and requires prompt medical attention. It is important to maintain a healthy diet that includes sufficient amounts of vitamin B12 to prevent the development of subacute combined degeneration of spinal cord.
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This question is part of the following fields:
- Neurological System
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Question 12
Incorrect
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A 25-year-old climber sustains a humerus fracture and requires surgery. The surgeons opt for a posterior approach to the middle third of the bone. Which nerve is most vulnerable in this procedure?
Your Answer: Ulnar
Correct Answer: Radial
Explanation:The humerus can cause damage to the radial nerve when approached from the back. To avoid the need for intricate bone exposure, an IM nail may be a better option.
The Radial Nerve: Anatomy, Innervation, and Patterns of Damage
The radial nerve is a continuation of the posterior cord of the brachial plexus, with root values ranging from C5 to T1. It travels through the axilla, posterior to the axillary artery, and enters the arm between the brachial artery and the long head of triceps. From there, it spirals around the posterior surface of the humerus in the groove for the radial nerve before piercing the intermuscular septum and descending in front of the lateral epicondyle. At the lateral epicondyle, it divides into a superficial and deep terminal branch, with the deep branch crossing the supinator to become the posterior interosseous nerve.
The radial nerve innervates several muscles, including triceps, anconeus, brachioradialis, and extensor carpi radialis. The posterior interosseous branch innervates supinator, extensor carpi ulnaris, extensor digitorum, and other muscles. Denervation of these muscles can lead to weakness or paralysis, with effects ranging from minor effects on shoulder stability to loss of elbow extension and weakening of supination of prone hand and elbow flexion in mid prone position.
Damage to the radial nerve can result in wrist drop and sensory loss to a small area between the dorsal aspect of the 1st and 2nd metacarpals. Axillary damage can also cause paralysis of triceps. Understanding the anatomy, innervation, and patterns of damage of the radial nerve is important for diagnosing and treating conditions that affect this nerve.
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This question is part of the following fields:
- Neurological System
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Question 13
Incorrect
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A woman in her early fifties comes in with sensory loss on the left side and sensory neglect on the same side. The physician suspects the presence of a space-occupying lesion. Where is the most probable location of this lesion?
Your Answer: Right temporal lobe
Correct Answer: Right parietal lobe
Explanation:The parietal lobe is linked to sensation and sensory attention, and damage to it results in contralateral deficits. Therefore, right parietal lobe damage leads to left-sided deficits.
Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.
In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.
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This question is part of the following fields:
- Neurological System
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Question 14
Incorrect
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A young intravenous drug user suffers from a false aneurysm and needs immediate surgery. During the procedure, the femoral nerve is accidentally cut, making the surgery more challenging. Which muscle is the least likely to be impacted by this injury?
Your Answer: Pectineus
Correct Answer: Adductor magnus
Explanation:R emember E very W ord I n T his E xercise
The femoral nerve is a nerve that originates from the spinal roots L2, L3, and L4. It provides innervation to several muscles in the thigh, including the pectineus, sartorius, quadriceps femoris, and vastus lateralis, medialis, and intermedius. Additionally, it branches off into the medial cutaneous nerve of the thigh, saphenous nerve, and intermediate cutaneous nerve of the thigh. The femoral nerve passes through the psoas major muscle and exits the pelvis by going under the inguinal ligament. It then enters the femoral triangle, which is located lateral to the femoral artery and vein.
To remember the femoral nerve’s supply, a helpful mnemonic is don’t MISVQ scan for PE. This stands for the medial cutaneous nerve of the thigh, intermediate cutaneous nerve of the thigh, saphenous nerve, vastus, quadriceps femoris, and sartorius, with the addition of the pectineus muscle. Overall, the femoral nerve plays an important role in the motor and sensory functions of the thigh.
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This question is part of the following fields:
- Neurological System
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Question 15
Correct
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A 63-year-old woman with a longstanding history of type 2 diabetes mellitus, hypertension, and hypercholesterolemia experienced sudden weakness in her right lower leg while preparing breakfast. She had a similar episode two days ago, which resolved after an hour. Her son brought her to the emergency department, where she reported her symptoms to the attending physician. The patient can speak well and fully comprehend what the doctor tells her. Upon examination, the doctor noted decreased touch sensation in her right leg. A non-contrast computed tomography (CT) scan was unremarkable, but a repeat CT scan after 12 hours revealed an area of hypo-attenuation in a region of the brain. Which artery of the cerebral circulation is most likely to be occluded in this patient?
Your Answer: Anterior cerebral artery
Explanation:The patient’s symptoms suggest a diagnosis of stroke, likely caused by their long history of diabetes, hypertension, and hypercholesterolemia, which are all risk factors for ischemic stroke. The absence of risk factors for hemorrhagic stroke, such as blood clotting disorders or warfarin use, supports this diagnosis. The CT scan performed upon admission may have been too early to detect the stroke, as ischemic strokes are typically visible on CT scans only after 6 hours. However, brain tissue swelling 12 hours later can produce an area of hypo-attenuation visible on CT scan.
The patient’s contralateral hemiparesis and sensory loss, with greater impact on the lower extremity than the upper, suggest an ischemic stroke affecting the anterior cerebral artery. If the posterior cerebral artery were obstructed, the patient would experience contralateral hemianopia with macular sparing. An ischemic stroke affecting the middle cerebral artery would more likely affect the upper limbs and face, and could also impact language centers or cause hemineglect. An ischemic stroke affecting the basilar artery could result in severe neurological impairment, such as locked-in syndrome or quadriplegia. An occlusion of the posterior inferior cerebellar artery would cause swallowing impairment, hoarseness, and loss of the gag reflex.
Stroke can affect different parts of the brain depending on which artery is affected. If the anterior cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the lower extremities being more affected than the upper. If the middle cerebral artery is affected, the person may experience weakness and loss of sensation on the opposite side of the body, with the upper extremities being more affected than the lower. They may also experience vision loss and difficulty with language. If the posterior cerebral artery is affected, the person may experience vision loss and difficulty recognizing objects.
Lacunar strokes are a type of stroke that are strongly associated with hypertension. They typically present with isolated weakness or loss of sensation on one side of the body, or weakness with difficulty coordinating movements. They often occur in the basal ganglia, thalamus, or internal capsule.
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This question is part of the following fields:
- Neurological System
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Question 16
Incorrect
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A 45-year-old female presents to the neurology clinic with diplopia and headache. Upon examination, her visual acuity is 6/6, and there is pupillary dilatation. An MRI of her head reveals a post-communicating artery aneurysm. What cranial nerve palsy is probable in this patient?
Your Answer: Second nerve palsy
Correct Answer: Third nerve palsy
Explanation:A third nerve palsy may be caused by an aneurysm in the posterior communicating artery.
Understanding Third Nerve Palsy: Causes and Features
Third nerve palsy is a neurological condition that affects the third cranial nerve, which controls the movement of the eye and eyelid. The condition is characterized by the eye being deviated ‘down and out’, ptosis, and a dilated pupil. In some cases, it may be referred to as a ‘surgical’ third nerve palsy due to the dilation of the pupil.
There are several possible causes of third nerve palsy, including diabetes mellitus, vasculitis (such as temporal arteritis or SLE), uncal herniation through tentorium if raised ICP, posterior communicating artery aneurysm, and cavernous sinus thrombosis. In some cases, it may also be a false localizing sign. Weber’s syndrome, which is characterized by an ipsilateral third nerve palsy with contralateral hemiplegia, is caused by midbrain strokes. Other possible causes include amyloid and multiple sclerosis.
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This question is part of the following fields:
- Neurological System
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Question 17
Correct
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A 22-year-old graduate student comes to you with concerns about abnormal muscle jerks and contractions while studying late for her upcoming exams. She is worried that she may be experiencing seizures. Upon further questioning, she denies any post-episode drowsiness, incontinence, or tongue biting, but admits that the muscle contractions occur just as she is about to fall asleep. She also denies any alcohol or illicit drug use.
If an EEG performed during these episodes showed theta waves, what diagnosis would be made?Your Answer: Hypnagogic jerks
Explanation:Non-REM stage 1 (N1) sleep is associated with hypnagogic jerks, also known as hypnic jerks, and is the lightest stage of sleep. During this phase, benign physiological muscular contractions occur and the EEG shows theta waves (3 to 8 Hz). Therefore, the correct answer is ‘hypnagogic jerks of stage N1 sleep’.
Absence seizures, on the other hand, are short and frequent episodes of profound impairment of consciousness without loss of body tone, typically found in children. The EEG finding during an absence seizure is generalized 2.5 to 5 Herz (Hz) spike wave discharges, not theta waves.
Although alcohol withdrawal can cause seizures, isolated muscle contractions during the sleep-wake interphase are unlikely. Furthermore, the finding of theta waves makes stage N1 more likely.
Juvenile myoclonic epilepsy (JME) is characterized by myoclonic jerks, which are most frequent in the morning, within the first hour after awakening, though generalized tonic-clonic seizures (GTCS) and absence seizures can also occur. The EEG finding during episodes is 3 to 4 Hz polyspike-waves with frontocentral predominance, not theta waves.
Night terrors, which occur during non-REM stage N3 sleep, the deepest type of non-REM sleep, are a parasomnia during which there is a loss of motor tone, not muscle jerks. The EEG waveform during this stage of sleep are beta waves.
Understanding Sleep Stages: The Sleep Doctor’s Brain
Sleep is a complex process that involves different stages, each with its own unique characteristics. The Sleep Doctor’s Brain provides a simplified explanation of the four main sleep stages: N1, N2, N3, and REM.
N1 is the lightest stage of sleep, characterized by theta waves and often associated with hypnic jerks. N2 is a deeper stage of sleep, marked by sleep spindles and K-complexes. This stage represents around 50% of total sleep. N3 is the deepest stage of sleep, characterized by delta waves. Parasomnias such as night terrors, nocturnal enuresis, and sleepwalking can occur during this stage.
REM, or rapid eye movement, is the stage where dreaming occurs. It is characterized by beta-waves and a loss of muscle tone, including erections. The sleep cycle typically follows a pattern of N1 → N2 → N3 → REM, with each stage lasting for different durations throughout the night.
Understanding the different sleep stages is important for maintaining healthy sleep habits and identifying potential sleep disorders. By monitoring brain activity during sleep, the Sleep Doctor’s Brain can provide valuable insights into the complex process of sleep.
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This question is part of the following fields:
- Neurological System
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Question 18
Incorrect
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A 50-year-old woman presents to her primary care physician with complaints of fatigue and trouble staying alert while watching TV or reading, particularly in the evenings. Upon examination, she is diagnosed with myasthenia gravis. What is the underlying mechanism for this condition?
Your Answer: Partial inhibition of acetylcholine release from from the presynaptic membrane
Correct Answer: Antibodies are produced against acetylcholine receptors
Explanation:The accurate explanation is that myasthenia gravis involves the production of antibodies against acetylcholine receptors, leading to a decrease in the amount of available acetylcholine for use in the neuromuscular junction.
Myasthenia gravis is an autoimmune disorder that results in muscle weakness and fatigue, particularly in the eyes, face, neck, and limbs. It is more common in women and is associated with thymomas and other autoimmune disorders. Diagnosis is made through electromyography and testing for antibodies to acetylcholine receptors. Treatment includes acetylcholinesterase inhibitors and immunosuppression, and in severe cases, plasmapheresis or intravenous immunoglobulins may be necessary.
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This question is part of the following fields:
- Neurological System
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Question 19
Correct
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Which muscle is not innervated by the trigeminal nerve?
Your Answer: Stylohyoid
Explanation:The facial nerve provides innervation to the stylohyoid.
The trigeminal nerve is the main sensory nerve of the head and also innervates the muscles of mastication. It has sensory distribution to the scalp, face, oral cavity, nose and sinuses, and dura mater, and motor distribution to the muscles of mastication, mylohyoid, anterior belly of digastric, tensor tympani, and tensor palati. The nerve originates at the pons and has three branches: ophthalmic, maxillary, and mandibular. The ophthalmic and maxillary branches are sensory only, while the mandibular branch is both sensory and motor. The nerve innervates various muscles, including the masseter, temporalis, and pterygoids.
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This question is part of the following fields:
- Neurological System
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Question 20
Incorrect
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A 32-year-old woman who is a primigravida at 15 weeks gestation presents to the emergency department with drooped features on the left side of her face and a runny nose. She noticed this in the morning when washing her face. There is no limb weakness, visual disturbance, or dysphagia noted.
What other symptoms would be indicative of this diagnosis?Your Answer: Pins and needles in her right arm
Correct Answer: Loss of taste sensation
Explanation:The patient is exhibiting symptoms consistent with Bell’s palsy, which is an acute, unilateral, and idiopathic facial nerve paralysis. It is believed to be linked to the herpes simplex virus and is most commonly seen in individuals aged 20-40 years and pregnant women. The patient’s facial droop is unilateral with lower motor neuron involvement and hyperacusis in the ear on the affected side. Loss of taste sensation in the anterior two-thirds of the tongue on the same side may also be present.
Hyperlacrimation is not typically associated with Bell’s palsy, and patients may experience dry eyes due to reduced blinking on the affected side. Loss of smell sensation is not usually seen in Bell’s palsy and may indicate an alternative diagnosis, such as a neurodegenerative syndrome. Pins and needles in the limbs are not typically associated with Bell’s palsy, and if present, alternative diagnoses should be considered.
The presence of a vesicular rash around the ear strongly suggests Ramsay Hunt syndrome, which is caused by the reactivation of the varicella-zoster virus in the geniculate ganglion of the seventh cranial nerve. It presents with auricular pain, facial nerve palsy, a vesicular rash around the ear, and vertigo/tinnitus.
Bell’s palsy is a sudden, one-sided facial nerve paralysis of unknown cause. It typically affects individuals between the ages of 20 and 40, and is more common in pregnant women. The condition is characterized by a lower motor neuron facial nerve palsy that affects the forehead, while sparing the upper face. Patients may also experience postauricular pain, altered taste, dry eyes, and hyperacusis.
The management of Bell’s palsy has been a topic of debate, with various treatment options proposed in the past. However, there is now consensus that all patients should receive oral prednisolone within 72 hours of onset. The addition of antiviral medications is still a matter of discussion, with some experts recommending it for severe cases. Eye care is also crucial to prevent exposure keratopathy, and patients may need to use artificial tears and eye lubricants. If they are unable to close their eye at bedtime, they should tape it closed using microporous tape.
Follow-up is essential for patients who show no improvement after three weeks, as they may require urgent referral to ENT. Those with more long-standing weakness may benefit from a referral to plastic surgery. The prognosis for Bell’s palsy is generally good, with most patients making a full recovery within three to four months. However, untreated cases can result in permanent moderate to severe weakness in around 15% of patients.
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This question is part of the following fields:
- Neurological System
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Question 21
Incorrect
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A patient in their 50s presents with acute onset of slurred speech and weakness on the left side of their body. During examination, you observe weakness in their left arm and face. Despite the slurred speech, the patient is able to comprehend and respond to your questions. Which of the following sites is the most probable location of the lesion causing dysarthria?
Your Answer: Wernicke's area
Correct Answer: Corticobulbar tract
Explanation:The corticobulbar tract is responsible for motor innervation to the cranial nerves, including the hypoglossal nerve that controls the tongue. A lesion in this tract can cause dysarthria, which is the inability to articulate speech. Other cranial nerve signs, such as facial paralysis and difficulty swallowing, may also occur.
Wernicke’s area is involved in language comprehension and understanding, and lesions in this area can result in receptive dysphasia. Patients with receptive dysphasia may speak fluently but their sentences may not make sense.
The primary sensory cortex, located in the parietal lobe, receives sensory innervation. Lesions in this area can cause loss of sensation, proprioception, fine touch, and vibration sense on the contralateral side.
Broca’s area, found in the frontal lobe, is associated with expressive dysphasia. This type of dysphasia is characterized by difficulty producing language, resulting in labored and non-fluent speech.
The occipital lobe, responsible for visual processing, can be affected by lesions that cause homonymous hemianopia, agnosias, and cortical blindness.
Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.
In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.
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This question is part of the following fields:
- Neurological System
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Question 22
Incorrect
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A 5-year-old child is brought to the pediatric clinic by their mother. The child was born to a mother with gestational diabetes and had a difficult delivery due to shoulder dystocia. During the physical examination, the doctor observes paralysis of the intrinsic hand muscles. The doctor suspects the child has Klumpke's paralysis. What is commonly associated with this presentation?
Your Answer: Brown-Séquard syndrome
Correct Answer: Horner's syndrome
Explanation:Klumpke’s paralysis is not associated with Horner’s syndrome. It is caused by injury to the brachial plexus, specifically nerve roots C8-T1, and results in paralysis of the intrinsic hand muscles, weakness of wrist flexion, and movement of the fingers. When the T1 nerve root is affected, there may be an associated injury to the sympathetic chain, which can lead to symptoms of Horner’s syndrome such as partial ptosis, miosis, enophthalmos, and anhidrosis.
Anterior cord syndrome, Brown-Séquard syndrome, and central cord syndrome are all incorrect as they are not associated with Klumpke’s paralysis. Anterior cord syndrome causes motor paralysis and loss of pain and temperature sensation below the lesion, and is caused by ischaemia of the anterior spinal artery. Brown-Séquard syndrome is caused by a hemisection of the spinal cord due to traumatic injury, and central cord syndrome is the most common cervical cord injury that causes motor impairment of the upper limbs, usually due to trauma or osteoarthritis.
Horner’s syndrome is a condition characterized by several features, including a small pupil (miosis), drooping of the upper eyelid (ptosis), a sunken eye (enophthalmos), and loss of sweating on one side of the face (anhidrosis). The cause of Horner’s syndrome can be determined by examining additional symptoms. For example, congenital Horner’s syndrome may be identified by a difference in iris color (heterochromia), while anhidrosis may be present in central or preganglionic lesions. Pharmacologic tests, such as the use of apraclonidine drops, can also be helpful in confirming the diagnosis and identifying the location of the lesion. Central lesions may be caused by conditions such as stroke or multiple sclerosis, while postganglionic lesions may be due to factors like carotid artery dissection or cluster headaches. It is important to note that the appearance of enophthalmos in Horner’s syndrome is actually due to a narrow palpebral aperture rather than true enophthalmos.
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This question is part of the following fields:
- Neurological System
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Question 23
Incorrect
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A 41-year-old man is attacked with a knife outside a club. He experiences a severing of his median nerve as it exits the brachial plexus. Which of the following outcomes is the least probable?
Your Answer: Inability to oppose the thumb
Correct Answer: Complete loss of wrist flexion
Explanation:The flexor muscles will no longer function if the median nerve is lost. Nevertheless, the flexor carpi ulnaris will remain functional and cause ulnar deviation and some remaining wrist flexion. Total loss of flexion at the thumb joint occurs with high median nerve lesions.
Anatomy and Function of the Median Nerve
The median nerve is a nerve that originates from the lateral and medial cords of the brachial plexus. It descends lateral to the brachial artery and passes deep to the bicipital aponeurosis and the median cubital vein at the elbow. The nerve then passes between the two heads of the pronator teres muscle and runs on the deep surface of flexor digitorum superficialis. Near the wrist, it becomes superficial between the tendons of flexor digitorum superficialis and flexor carpi radialis, passing deep to the flexor retinaculum to enter the palm.
The median nerve has several branches that supply the upper arm, forearm, and hand. These branches include the pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, flexor pollicis longus, and palmar cutaneous branch. The nerve also provides motor supply to the lateral two lumbricals, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis muscles, as well as sensory supply to the palmar aspect of the lateral 2 ½ fingers.
Damage to the median nerve can occur at the wrist or elbow, resulting in various symptoms such as paralysis and wasting of thenar eminence muscles, weakness of wrist flexion, and sensory loss to the palmar aspect of the fingers. Additionally, damage to the anterior interosseous nerve, a branch of the median nerve, can result in loss of pronation of the forearm and weakness of long flexors of the thumb and index finger. Understanding the anatomy and function of the median nerve is important in diagnosing and treating conditions that affect this nerve.
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This question is part of the following fields:
- Neurological System
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Question 24
Incorrect
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An 80-year-old man comes to the emergency department after experiencing a fall. He reports a recent decline in his vision, including distortion of lines and loss of central vision, which was particularly noticeable tonight.
During the eye examination, you observe the presence of drusen and new vessel formation around the macula.
As part of his discharge plan, you schedule a follow-up appointment with an ophthalmologist, suspecting that monoclonal antibody treatment targeting vascular endothelial growth factor (VEGF) may be necessary.
What type of monoclonal antibody functions through this mechanism of action?Your Answer: Omalizumab
Correct Answer: Bevacizumab
Explanation:Bevacizumab is a monoclonal antibody that targets vascular endothelial growth factor (VEGF). It is used to slow down the progression of wet age-related macular degeneration (ARMD), which is the condition described in this case. Treatment with bevacizumab should begin within the first two months of diagnosis of wet ARMD.
Abciximab is a monoclonal antibody that targets platelet IIb/IIIa receptors, preventing platelet aggregation. It is used to prevent blood clots in unstable angina or after coronary artery stenting.
Adalimumab is a monoclonal antibody that targets tumor necrosis factor (TNF) and is primarily used to treat inflammatory arthritis.
Omalizumab is a monoclonal antibody that targets the IgE receptor, reducing the IgE response. It is used to treat severe allergic asthma.
Age-related macular degeneration (ARMD) is a common cause of blindness in the UK, characterized by degeneration of the central retina (macula) and the formation of drusen. The risk of ARMD increases with age, smoking, family history, and conditions associated with an increased risk of ischaemic cardiovascular disease. ARMD is classified into dry and wet forms, with the latter carrying the worst prognosis. Clinical features include subacute onset of visual loss, difficulties in dark adaptation, and visual hallucinations. Signs include distortion of line perception, the presence of drusen, and well-demarcated red patches in wet ARMD. Investigations include slit-lamp microscopy, colour fundus photography, fluorescein angiography, indocyanine green angiography, and ocular coherence tomography. Treatment options include a combination of zinc with anti-oxidant vitamins for dry ARMD and anti-VEGF agents for wet ARMD. Laser photocoagulation is also an option, but anti-VEGF therapies are usually preferred.
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This question is part of the following fields:
- Neurological System
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Question 25
Incorrect
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A 58-year-old male presents to the GP with back pain. He tells you the pain started three weeks ago after helping a friend move where he was lifting lots of heavy boxes. He says the pain radiates down the lateral aspect of his right thigh and often feels a tingling sensation in this area. On clinical examination you find reduced sensation below the right knee but the knee reflex is intact. You suspect he may have damaged his sciatic nerve.
Which other feature are you most likely to find?Your Answer: Positive trendelenburg sign
Correct Answer: Absent plantar reflex
Explanation:When a patient experiences a loss of ankle and plantar reflexes but retains their knee jerk reflex, it may indicate a sciatic nerve lesion. The sciatic nerve is responsible for innervating the hamstring and adductor muscles and is supplied by L4-5 and S1-3. Other symptoms of sciatic nerve damage include paralysis of knee flexion and sensory loss below the knee.
If a patient presents with a Trendelenburg sign, it may indicate an injury to the superior gluteal nerve. This nerve is responsible for thigh abduction by gluteus medius, and damage to it can cause weakness and a compensatory tilt of the body to the weakened gluteal side.
Tinel’s sign is a feature of carpel tunnel syndrome and occurs when the median nerve is tapped at the wrist, causing tingling or electric-like sensations over the distribution of the median nerve.
Damage to the obturator nerve can result in sensory loss at the medial thigh. This nerve is typically damaged in an anterior hip dislocation.
Understanding Sciatic Nerve Lesion
The sciatic nerve is a major nerve that is supplied by the L4-5, S1-3 vertebrae and divides into the tibial and common peroneal nerves. It is responsible for supplying the hamstring and adductor muscles. When the sciatic nerve is damaged, it can result in a range of symptoms that affect both motor and sensory functions.
Motor symptoms of sciatic nerve lesion include paralysis of knee flexion and all movements below the knee. Sensory symptoms include loss of sensation below the knee. Reflexes may also be affected, with ankle and plantar reflexes lost while the knee jerk reflex remains intact.
There are several causes of sciatic nerve lesion, including fractures of the neck of the femur, posterior hip dislocation, and trauma.
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This question is part of the following fields:
- Neurological System
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Question 26
Correct
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A 45-year-old woman had an attempted central line placement in her internal jugular vein, but the doctor accidentally damaged her carotid artery, requiring surgical exploration. During the procedure, a nerve was found between the carotid artery and internal jugular vein. What is the most likely identity of this nerve?
Your Answer: Vagus
Explanation:The carotid sheath contains the vagus nerve, while the hypoglossal nerve passes through it but is not situated inside it.
The common carotid artery is a major blood vessel that supplies the head and neck with oxygenated blood. It has two branches, the left and right common carotid arteries, which arise from different locations. The left common carotid artery originates from the arch of the aorta, while the right common carotid artery arises from the brachiocephalic trunk. Both arteries terminate at the upper border of the thyroid cartilage by dividing into the internal and external carotid arteries.
The left common carotid artery runs superolaterally to the sternoclavicular joint and is in contact with various structures in the thorax, including the trachea, left recurrent laryngeal nerve, and left margin of the esophagus. In the neck, it passes deep to the sternocleidomastoid muscle and enters the carotid sheath with the vagus nerve and internal jugular vein. The right common carotid artery has a similar path to the cervical portion of the left common carotid artery, but with fewer closely related structures.
Overall, the common carotid artery is an important blood vessel with complex anatomical relationships in both the thorax and neck. Understanding its path and relations is crucial for medical professionals to diagnose and treat various conditions related to this artery.
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This question is part of the following fields:
- Neurological System
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Question 27
Incorrect
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A 67-year-old male is referred to a neurologist for a complete evaluation of a 6-month history of anosmia. The patient denies any other symptoms except for anosmia and occasional headaches. An MRI scan reveals a small brain tumor, which is suspected to be the underlying cause of the symptoms.
What is the most probable location of this lesion?Your Answer: Temporal lobe
Correct Answer: Frontal lobe
Explanation:Anosmia, or loss of smell, can be caused by lesions in the frontal lobe of the brain. In addition to anosmia, frontal lobe lesions may also cause Broca’s aphasia, personality changes, and loss of motor function. Cerebellar lesions, on the other hand, may present with the DANISH symptoms, which include dysdiadochokinesia, ataxia, intention tremor, nystagmus, and hypotonia. Lesions in the occipital lobe can cause visual loss, while lesions in the parietal lobe may cause sensory problems, body awareness issues, and language development weakening. Finally, lesions in the temporal lobe may cause Wernicke’s aphasia, memory loss, emotional changes, and a superior quadrantanopia.
Brain lesions can be localized based on the neurological disorders or features that are present. The gross anatomy of the brain can provide clues to the location of the lesion. For example, lesions in the parietal lobe can result in sensory inattention, apraxias, astereognosis, inferior homonymous quadrantanopia, and Gerstmann’s syndrome. Lesions in the occipital lobe can cause homonymous hemianopia, cortical blindness, and visual agnosia. Temporal lobe lesions can result in Wernicke’s aphasia, superior homonymous quadrantanopia, auditory agnosia, and prosopagnosia. Lesions in the frontal lobes can cause expressive aphasia, disinhibition, perseveration, anosmia, and an inability to generate a list. Lesions in the cerebellum can result in gait and truncal ataxia, intention tremor, past pointing, dysdiadokinesis, and nystagmus.
In addition to the gross anatomy, specific areas of the brain can also provide clues to the location of a lesion. For example, lesions in the medial thalamus and mammillary bodies of the hypothalamus can result in Wernicke and Korsakoff syndrome. Lesions in the subthalamic nucleus of the basal ganglia can cause hemiballism, while lesions in the striatum (caudate nucleus) can result in Huntington chorea. Parkinson’s disease is associated with lesions in the substantia nigra of the basal ganglia, while lesions in the amygdala can cause Kluver-Bucy syndrome, which is characterized by hypersexuality, hyperorality, hyperphagia, and visual agnosia. By identifying these specific conditions, doctors can better localize brain lesions and provide appropriate treatment.
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This question is part of the following fields:
- Neurological System
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Question 28
Correct
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A 79-year-old man is brought to the emergency department after a witnessed fall from standing. He is complaining of severe pain at his left hip.
Examination of the lower limb reveals that he is unable to flex his left knee or mobilise his left ankle at all. His left knee reflex is present but he has an absent left-sided ankle jerk reflex. On the left side, sensation is lost below the knee. His right leg reveals no sensory or motor disturbance. An X-ray of both hips reveals a left-sided intracapsular neck of femur fracture.
Based on the above information, what nerve is most likely to have been affected?Your Answer: Sciatic nerve
Explanation:When the sciatic nerve is damaged, the ankle and plantar reflexes become lost, but the knee jerk reflex remains intact. This type of nerve injury can cause weakness in knee flexion and all movements below the knee, as well as sensory loss below the knee and reduced ankle reflexes. A common cause of sciatic nerve damage is a neck of femur fracture.
It’s important to note that the common fibular nerve, which is a branch of the sciatic nerve, is located too low to be affected by a neck of femur fracture. If this nerve is injured, it will result in weakness in dorsiflexion and eversion at the ankle, as well as extension at the digits, but knee flexion will not be affected.
In contrast, damage to the femoral nerve will cause weakness in knee extension, not flexion. This type of nerve injury will also result in weakness in hip flexion and loss of sensation in the anteromedial thigh and medial leg and foot.
Obturator nerve damage can occur after abdominal or pelvic surgery, or in rare cases, from a posterior hip dislocation. This type of nerve injury will cause weakness in thigh adduction and sensory loss in the medial thigh.
Finally, a lesion in the superior gluteal nerve will result in the inability to abduct the hip, which will produce a positive Trendelenburg test.
Understanding Sciatic Nerve Lesion
The sciatic nerve is a major nerve that is supplied by the L4-5, S1-3 vertebrae and divides into the tibial and common peroneal nerves. It is responsible for supplying the hamstring and adductor muscles. When the sciatic nerve is damaged, it can result in a range of symptoms that affect both motor and sensory functions.
Motor symptoms of sciatic nerve lesion include paralysis of knee flexion and all movements below the knee. Sensory symptoms include loss of sensation below the knee. Reflexes may also be affected, with ankle and plantar reflexes lost while the knee jerk reflex remains intact.
There are several causes of sciatic nerve lesion, including fractures of the neck of the femur, posterior hip dislocation, and trauma.
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This question is part of the following fields:
- Neurological System
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Question 29
Incorrect
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A 39-year-old man comes to the emergency department with his wife who reports that he is exhibiting unusual behavior. According to her, he has been experiencing a progressively severe headache for the past three days. He vomited once this morning, and there is no history of head injury. Bilateral papilloedema is present on ophthalmoscopy. Although he scores a GCS of 15, his speech is sometimes slurred and confused. A CT scan of the head reveals a mass on the right side, near the midline in the anterior parietal lobe. The lateral and third ventricles are significantly dilated, indicating a blockage in the flow of cerebrospinal fluid (CSF). What structure does CSF from the third ventricle typically flow into the fourth ventricle through?
Your Answer: Lateral aperture (foramen of Luschka)
Correct Answer: Cerebral aqueduct
Explanation:The cerebral aqueduct is the correct answer.
The interventricular foramina allow the two lateral ventricles to drain into the third ventricle, which is located in the midline between the thalami of the two hemispheres. The third ventricle communicates with the fourth ventricle via the cerebral aqueduct (of Sylvius).
CSF flows from the third ventricle into the fourth ventricle through the cerebral aqueduct (of Sylvius). From the fourth ventricle, CSF can leave through one of four openings: the median aperture (foramen of Magendie), either of the two lateral apertures (foramina of Luschka), or the central canal at the obex.
The patient in the question is showing symptoms of raised intracranial pressure, which can be caused by various factors, including mass lesions and neoplasms. In this case, a mass is blocking the normal flow of CSF through the ventricular system, leading to an increase in intracranial pressure.
Cerebrospinal Fluid: Circulation and Composition
Cerebrospinal fluid (CSF) is a clear, colorless liquid that fills the space between the arachnoid mater and pia mater, covering the surface of the brain. The total volume of CSF in the brain is approximately 150ml, and it is produced by the ependymal cells in the choroid plexus or blood vessels. The majority of CSF is produced by the choroid plexus, accounting for 70% of the total volume. The remaining 30% is produced by blood vessels. The CSF is reabsorbed via the arachnoid granulations, which project into the venous sinuses.
The circulation of CSF starts from the lateral ventricles, which are connected to the third ventricle via the foramen of Munro. From the third ventricle, the CSF flows through the cerebral aqueduct (aqueduct of Sylvius) to reach the fourth ventricle via the foramina of Magendie and Luschka. The CSF then enters the subarachnoid space, where it circulates around the brain and spinal cord. Finally, the CSF is reabsorbed into the venous system via arachnoid granulations into the superior sagittal sinus.
The composition of CSF is essential for its proper functioning. The glucose level in CSF is between 50-80 mg/dl, while the protein level is between 15-40 mg/dl. Red blood cells are not present in CSF, and the white blood cell count is usually less than 3 cells/mm3. Understanding the circulation and composition of CSF is crucial for diagnosing and treating various neurological disorders.
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This question is part of the following fields:
- Neurological System
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Question 30
Correct
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A 43-year-old female comes to the ENT clinic with a history of constant vertigo and right-sided deafness for the past year. She has no significant medical history. Upon conducting an audiogram, it is discovered that her right ear has reduced hearing to both bone and air conduction. During a cranial nerve exam, an absent corneal reflex is observed on the right side, and she has poor balance. Otoscopy of both ears is normal. What is the probable underlying pathology responsible for this patient's symptoms and signs?
Your Answer: Vestibular schwannoma (acoustic neuroma)
Explanation:If a patient presents with loss of the corneal reflex, the likely diagnosis is vestibular schwannoma (acoustic neuroma). This is a noncancerous tumor that affects the vestibular portion of the 8th cranial nerve, leading to sensorineural deafness, tinnitus, and vertigo. As the tumor grows, it can also press on other cranial nerves. Loss of the corneal reflex is a classic sign of early trigeminal (cranial nerve 5) involvement, which is unlikely in any of the other listed conditions.
Meniere’s disease is not the correct answer. This is a disorder of the middle ear that causes episodic vertigo, sensorineural hearing loss, and a sensation of aural fullness or pressure.
Otosclerosis is also incorrect. This is an inherited condition that causes conductive deafness and tinnitus, typically presenting in patients aged 20-40 years.
Vestibular mononeuritis is not the correct answer either. This condition is caused by inflammation of the vestibular nerve following a recent viral infection and presents with vertigo, but hearing is not affected.
Vestibular schwannomas, also known as acoustic neuromas, make up about 5% of intracranial tumors and 90% of cerebellopontine angle tumors. These tumors typically present with a combination of vertigo, hearing loss, tinnitus, and an absent corneal reflex. The specific symptoms can be predicted based on which cranial nerves are affected. For example, cranial nerve VIII involvement can cause vertigo, unilateral sensorineural hearing loss, and unilateral tinnitus. Bilateral vestibular schwannomas are associated with neurofibromatosis type 2.
If a vestibular schwannoma is suspected, it is important to refer the patient to an ear, nose, and throat specialist urgently. However, it is worth noting that these tumors are often benign and slow-growing, so observation may be appropriate initially. The diagnosis is typically confirmed with an MRI of the cerebellopontine angle, and audiometry is also important as most patients will have some degree of hearing loss. Treatment options include surgery, radiotherapy, or continued observation.
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This question is part of the following fields:
- Neurological System
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