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  • Question 1 - As it leaves the axilla, which muscle does the radial nerve pass over?...

    Correct

    • As it leaves the axilla, which muscle does the radial nerve pass over?

      Your Answer: Teres major

      Explanation:

      The triangular space serves as a pathway for the radial nerve to exit the axilla. Its upper boundary is defined by the teres major muscle, which has a close association with the radial nerve.

      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.

    • This question is part of the following fields:

      • Neurological System
      106
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  • Question 2 - An aging patient with Parkinson's disease is admitted to a neurology ward after...

    Incorrect

    • An aging patient with Parkinson's disease is admitted to a neurology ward after experiencing a fall. While conducting a cranial nerves examination, the physician observes that the patient is unable to gaze upward when their head is fixed in place. The physician begins to consider other potential diagnoses. What would be the most appropriate diagnosis?

      Your Answer: Corticobasal degeneration

      Correct Answer: Progressive supranuclear palsy

      Explanation:

      These are all syndromes that share the main symptoms of Parkinson’s disease, but also have additional specific symptoms:

      – Progressive supranuclear palsy affects the muscles used for looking upwards.
      – Vascular dementia is a type of dementia that usually occurs after several small strokes.
      – Dementia with Lewy bodies is characterized by the buildup of Lewy bodies, which are clumps of a protein called alpha-synuclein, and often includes visual hallucinations.
      – Multiple system atrophy often involves problems with the autonomic nervous system, such as low blood pressure when standing and difficulty emptying the bladder.

      Progressive supranuclear palsy, also known as Steele-Richardson-Olszewski syndrome, is a type of ‘Parkinson Plus’ syndrome. It is characterized by postural instability and falls, as well as a stiff, broad-based gait. Patients with this condition also experience impairment of vertical gaze, with down gaze being worse than up gaze. This can lead to difficulty reading or descending stairs. Parkinsonism is also present, with bradykinesia being a prominent feature. Cognitive impairment is also common, primarily due to frontal lobe dysfunction. Unfortunately, this condition has a poor response to L-dopa.

    • This question is part of the following fields:

      • Neurological System
      41.3
      Seconds
  • Question 3 - You are called to assess a 43-year-old woman in the emergency department who...

    Incorrect

    • You are called to assess a 43-year-old woman in the emergency department who was brought in by her partner after collapsing while attempting to get into a car. The patient has been experiencing generalised abdominal pain and diarrhoea for a few days and has recently complained of feeling weak and unsteady on her feet.

      Upon examination, the patient has intact lower limb sensation but struggles to perform movements against resistance. Both ankle and knee jerks are absent. You order bedside spirometry to assess respiratory function while awaiting further investigations.

      What is the most likely cause of the patient's symptoms?

      Your Answer: Clostridium botulinum infection

      Correct Answer: Infection with Campylobacter jejuni

      Explanation:

      The most probable diagnosis in this case is Guillain-Barre syndrome, which is a demyelinating ascending polyneuropathy that is typically triggered by a flu-like illness such as Epstein Barr virus or gastroenteritis caused by Campylobacter jejuni. The diagnosis is usually suspected based on clinical presentation, with nerve conduction studies and lumbar puncture sometimes used for confirmation. Bedside spirometry is also performed to assess respiratory function, as respiratory muscle weakness can lead to type 2 respiratory failure, which is a major complication of the condition. Supportive management is the initial approach, with ventilation considered if necessary. IVIG and plasma exchange are the main treatment options.

      Antibodies against acetylcholine receptors are associated with myasthenia gravis, which primarily affects the extra-ocular and bulbar muscles, causing diplopia and dysphagia. Involvement of the lower limbs is rare. Multiple sclerosis, on the other hand, is characterized by episodes of CNS damage that are separate in space and time, making it unlikely to be suspected in a single episode. Thrombotic thrombocytopenic purpura, which is caused by a deficiency in ADAMTS13, is a severe haematological disease that can lead to thrombocytopenia, haemolytic anaemia, renal impairment, and severe neurological deficit, but it is not the most likely cause in this case.

      Understanding Guillain-Barre Syndrome and Miller Fisher Syndrome

      Guillain-Barre syndrome is a condition that affects the peripheral nervous system and is often triggered by an infection, particularly Campylobacter jejuni. The immune system attacks the myelin sheath that surrounds nerve fibers, leading to demyelination. This results in symptoms such as muscle weakness, tingling sensations, and paralysis.

      The pathogenesis of Guillain-Barre syndrome involves the cross-reaction of antibodies with gangliosides in the peripheral nervous system. Studies have shown a correlation between the presence of anti-ganglioside antibodies, particularly anti-GM1 antibodies, and the clinical features of the syndrome. In fact, anti-GM1 antibodies are present in 25% of patients with Guillain-Barre syndrome.

      Miller Fisher syndrome is a variant of Guillain-Barre syndrome that is characterized by ophthalmoplegia, areflexia, and ataxia. This syndrome typically presents as a descending paralysis, unlike other forms of Guillain-Barre syndrome that present as an ascending paralysis. The eye muscles are usually affected first in Miller Fisher syndrome. Studies have shown that anti-GQ1b antibodies are present in 90% of cases of Miller Fisher syndrome.

      In summary, Guillain-Barre syndrome and Miller Fisher syndrome are conditions that affect the peripheral nervous system and are often triggered by infections. The pathogenesis of these syndromes involves the cross-reaction of antibodies with gangliosides in the peripheral nervous system. While Guillain-Barre syndrome is characterized by muscle weakness and paralysis, Miller Fisher syndrome is characterized by ophthalmoplegia, areflexia, and ataxia.

    • This question is part of the following fields:

      • Neurological System
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  • Question 4 - A 65-year-old man has recently undergone parotidectomy on his left side due to...

    Correct

    • A 65-year-old man has recently undergone parotidectomy on his left side due to a malignant parotid gland tumor. He has been back on the surgical ward for a few hours when he reports feeling weakness on the left side of his mouth. Upon examination, you observe facial asymmetry and weakness on the left side. He is unable to hold air under pressure in his mouth and cannot raise his left lip to show his teeth. This complication is likely due to damage to which nerve?

      Your Answer: Facial nerve

      Explanation:

      The facial nerve is the seventh cranial nerve and innervates the muscles of facial expression. It runs through the parotid gland and can be injured during parotidectomy. The maxillary nerve is the second division of the trigeminal nerve and carries sensory fibres from the lower eyelid, cheeks, upper teeth, palate, nasal cavity, and paranasal sinuses. The glossopharyngeal nerve is the ninth cranial nerve and has various functions, including carrying taste and sensation from the posterior third of the tongue and supplying parasympathetic innervation to the parotid gland. The mandibular nerve is the third division of the trigeminal nerve and carries sensory and motor fibres, supplying motor innervation to the muscles of mastication. The hypoglossal nerve is the twelfth cranial nerve and supplies the intrinsic muscles of the tongue.

      The facial nerve is responsible for supplying the muscles of facial expression, the digastric muscle, and various glandular structures. It also contains a few afferent fibers that originate in the genicular ganglion and are involved in taste. Bilateral facial nerve palsy can be caused by conditions such as sarcoidosis, Guillain-Barre syndrome, Lyme disease, and bilateral acoustic neuromas. Unilateral facial nerve palsy can be caused by these conditions as well as lower motor neuron issues like Bell’s palsy and upper motor neuron issues like stroke.

      The upper motor neuron lesion typically spares the upper face, specifically the forehead, while a lower motor neuron lesion affects all facial muscles. The facial nerve’s path includes the subarachnoid path, where it originates in the pons and passes through the petrous temporal bone into the internal auditory meatus with the vestibulocochlear nerve. The facial canal path passes superior to the vestibule of the inner ear and contains the geniculate ganglion at the medial aspect of the middle ear. The stylomastoid foramen is where the nerve passes through the tympanic cavity anteriorly and the mastoid antrum posteriorly, and it also includes the posterior auricular nerve and branch to the posterior belly of the digastric and stylohyoid muscle.

    • This question is part of the following fields:

      • Neurological System
      27.5
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  • Question 5 - A 55-year-old woman complains of discomfort and pain in her hand. She is...

    Correct

    • A 55-year-old woman complains of discomfort and pain in her hand. She is employed as a typist and experiences the most pain while working. She also experiences symptoms during the night. The pain is less severe in her little finger. Which nerve is most likely to be affected?

      Your Answer: Median

      Explanation:

      EIWRTREY

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 6 - A 65-year-old male comes to the head and neck clinic for his postoperative...

    Correct

    • A 65-year-old male comes to the head and neck clinic for his postoperative check-up following the removal of a tumour from his mouth. He reports experiencing numbness and tingling in the floor of his mouth after the surgery. It is suspected that the sensory nerve to the floor of his mouth may have been affected.

      What is the most probable nerve that has been damaged?

      Your Answer: Lingual nerve

      Explanation:

      The lingual nerve provides sensation to the floor of the mouth, a portion of the tongue, and the gingivae of the mandibular lingual. The mandibular nerve transmits sensory fibers to the submandibular glands, while the greater auricular nerve is responsible for sensation in the parotid gland. The hypoglossal nerve, the twelfth cranial nerve, controls tongue movement, and the facial nerve, the seventh cranial nerve, is responsible for salivation, lacrimation, facial movement, and taste in the anterior two-thirds of the tongue.

      Lingual Nerve: Sensory Nerve to the Tongue and Mouth

      The lingual nerve is a sensory nerve that provides sensation to the mucosa of the presulcal part of the tongue, floor of the mouth, and mandibular lingual gingivae. It arises from the posterior trunk of the mandibular nerve and runs past the tensor veli palatini and lateral pterygoid muscles. At this point, it is joined by the chorda tympani branch of the facial nerve.

      After emerging from the cover of the lateral pterygoid, the lingual nerve proceeds antero-inferiorly, lying on the surface of the medial pterygoid and close to the medial aspect of the mandibular ramus. At the junction of the vertical and horizontal rami of the mandible, it is anterior to the inferior alveolar nerve. The lingual nerve then passes below the mandibular attachment of the superior pharyngeal constrictor and lies on the periosteum of the root of the third molar tooth.

      Finally, the lingual nerve passes medial to the mandibular origin of mylohyoid and then passes forwards on the inferior surface of this muscle. Overall, the lingual nerve plays an important role in providing sensory information to the tongue and mouth.

    • This question is part of the following fields:

      • Neurological System
      42.1
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  • Question 7 - A pregnant woman at 14 weeks gestation arrives at the emergency department after...

    Correct

    • A pregnant woman at 14 weeks gestation arrives at the emergency department after experiencing an epileptiform seizure preceded by deja vu. Her blood pressure is 130/80 mmHg and 24-hour urine protein is 100 mg, but there is no indication of fetal growth restriction. What is the probable diagnosis?

      Your Answer: Temporal lobe epilepsy

      Explanation:

      Temporal lobe epilepsy is commonly associated with deja vu, as the hippocampus in the temporal lobe plays a role in memory. The only other possible condition is eclampsia, as pre-eclampsia does not involve seizures and absence seizures are more frequent in children. However, eclampsia is not the correct diagnosis in this case as the patient does not have hypertension, her proteinuria is not significant (which is typically over 300 mg/24 hours), and there is no evidence of fetal growth restriction. Although this last point is not always present in eclampsia, it is a potential indicator.

      Epilepsy Classification: Understanding Seizures

      Epilepsy is a neurological disorder that affects millions of people worldwide. The classification of epilepsy has undergone changes in recent years, with the new basic seizure classification based on three key features. The first feature is where seizures begin in the brain, followed by the level of awareness during a seizure, which is important as it can affect safety during a seizure. The third feature is other features of seizures.

      Focal seizures, previously known as partial seizures, start in a specific area on one side of the brain. The level of awareness can vary in focal seizures, and they can be further classified as focal aware, focal impaired awareness, and awareness unknown. Focal seizures can also be classified as motor or non-motor, or having other features such as aura.

      Generalized seizures involve networks on both sides of the brain at the onset, and consciousness is lost immediately. The level of awareness in the above classification is not needed, as all patients lose consciousness. Generalized seizures can be further subdivided into motor and non-motor, with specific types including tonic-clonic, tonic, clonic, typical absence, and atonic.

      Unknown onset is a term reserved for when the origin of the seizure is unknown. Focal to bilateral seizure starts on one side of the brain in a specific area before spreading to both lobes, previously known as secondary generalized seizures. Understanding the classification of epilepsy and the different types of seizures can help in the diagnosis and management of this condition.

    • This question is part of the following fields:

      • Neurological System
      116.5
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  • Question 8 - A 70-year-old man experiences a fall resulting in a fractured neck of femur....

    Correct

    • A 70-year-old man experiences a fall resulting in a fractured neck of femur. He undergoes a left hip hemiarthroplasty and two months later presents with an abnormal gait. Upon standing on his left leg, his pelvis dips on the right side, but there is no evidence of foot drop. What could be the underlying cause of this presentation?

      Your Answer: Superior gluteal nerve damage

      Explanation:

      The cause of this patient’s trendelenburg gait is damage to the superior gluteal nerve, resulting in weakened abductor muscles. A common diagnostic test involves asking the patient to stand on one leg, which causes the pelvis to dip on the opposite side. The absence of a foot drop rules out the potential for polio or L5 radiculopathy.

      The gluteal region is composed of various muscles and nerves that play a crucial role in hip movement and stability. The gluteal muscles, including the gluteus maximus, medius, and minimis, extend and abduct the hip joint. Meanwhile, the deep lateral hip rotators, such as the piriformis, gemelli, obturator internus, and quadratus femoris, rotate the hip joint externally.

      The nerves that innervate the gluteal muscles are the superior and inferior gluteal nerves. The superior gluteal nerve controls the gluteus medius, gluteus minimis, and tensor fascia lata muscles, while the inferior gluteal nerve controls the gluteus maximus muscle.

      If the superior gluteal nerve is damaged, it can result in a Trendelenburg gait, where the patient is unable to abduct the thigh at the hip joint. This weakness causes the pelvis to tilt down on the opposite side during the stance phase, leading to compensatory movements such as trunk lurching to maintain a level pelvis throughout the gait cycle. As a result, the pelvis sags on the opposite side of the lesioned superior gluteal nerve.

    • This question is part of the following fields:

      • Neurological System
      33.6
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  • Question 9 - A pair of adolescents are fooling around with an airgun when one mistakenly...

    Incorrect

    • A pair of adolescents are fooling around with an airgun when one mistakenly shoots his buddy in the stomach. The injured friend is rushed to the ER where he is examined. The bullet has entered just to the right of the rectus sheath at the level of the 2nd lumbar vertebrae. Which of the following structures is the most probable to have been harmed by the bullet?

      Your Answer: Right adrenal gland

      Correct Answer: Fundus of the gallbladder

      Explanation:

      The most superficially located structure is the fundus of the gallbladder, which is found at this level.

      Anatomical Planes and Levels in the Human Body

      The human body can be divided into different planes and levels to aid in anatomical study and medical procedures. One such plane is the transpyloric plane, which runs horizontally through the body of L1 and intersects with various organs such as the pylorus of the stomach, left kidney hilum, and duodenojejunal flexure. Another way to identify planes is by using common level landmarks, such as the inferior mesenteric artery at L3 or the formation of the IVC at L5.

      In addition to planes and levels, there are also diaphragm apertures located at specific levels in the body. These include the vena cava at T8, the esophagus at T10, and the aortic hiatus at T12. By understanding these planes, levels, and apertures, medical professionals can better navigate the human body during procedures and accurately diagnose and treat various conditions.

    • This question is part of the following fields:

      • Neurological System
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  • Question 10 - A 25-year-old woman is being assessed in the delivery room for lack of...

    Correct

    • A 25-year-old woman is being assessed in the delivery room for lack of progress in labour. The release of oxytocin during labour and delivery is facilitated by a positive feedback loop. Which part of the brain is responsible for producing this hormone?

      Your Answer: Paraventricular nucleus of the hypothalamus

      Explanation:

      The paraventricular nucleus of the hypothalamus is responsible for producing oxytocin. This is achieved through the release of magnocellular neurosecretory neurons. Vasopressin (ADH) is also produced by these neurons.

      The mammillary bodies of the hypothalamus play a crucial role in recollective memory. Damage to these bodies, such as in cases of thiamine deficiency in Wernicke-Korsakoff syndrome, can result in memory impairment.

      Located at the lowest part of the brainstem and continuous with the spinal cord, the medulla oblongata contains the cardiac and respiratory groups, as well as vasomotor centers that regulate heart rate, blood pressure, and breathing.

      The substantia nigra is responsible for producing dopamine, which plays a role in regulating movement and emotion.

      The hypothalamus is a part of the brain that plays a crucial role in maintaining the body’s internal balance, or homeostasis. It is located in the diencephalon and is responsible for regulating various bodily functions. The hypothalamus is composed of several nuclei, each with its own specific function. The anterior nucleus, for example, is involved in cooling the body by stimulating the parasympathetic nervous system. The lateral nucleus, on the other hand, is responsible for stimulating appetite, while lesions in this area can lead to anorexia. The posterior nucleus is involved in heating the body and stimulating the sympathetic nervous system, and damage to this area can result in poikilothermia. Other nuclei include the septal nucleus, which regulates sexual desire, the suprachiasmatic nucleus, which regulates circadian rhythm, and the ventromedial nucleus, which is responsible for satiety. Lesions in the paraventricular nucleus can lead to diabetes insipidus, while lesions in the dorsomedial nucleus can result in savage behavior.

    • This question is part of the following fields:

      • Neurological System
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  • Question 11 - A 35 years old female presents to the emergency department with a mid-shaft...

    Correct

    • A 35 years old female presents to the emergency department with a mid-shaft humerus fracture. During the examination, the physician observes that she has lost the ability to extend her wrist, forearm, and fingers. Based on this, the doctor diagnoses a radial nerve injury.

      What other structure is most susceptible to damage in this scenario?

      Your Answer: Profunda brachii artery

      Explanation:

      The deep brachial artery, also known as the profunda brachii artery, arises from the brachial artery just below the teres major muscle. It runs closely alongside the radial nerve in the radial groove and provides blood supply to structures in the posterior aspect of the forearm. The brachial artery divides into the radial and ulnar arteries at the cubital fossa. It is important to note that the profunda femoris vein and great saphenous vein are located in the leg, not the arm.

      Anatomy of the Brachial Artery

      The brachial artery is a continuation of the axillary artery and runs from the lower border of teres major to the cubital fossa where it divides into the radial and ulnar arteries. It is located in the upper arm and has various relations with surrounding structures. Posteriorly, it is related to the long head of triceps with the radial nerve and profunda vessels in between. Anteriorly, it is overlapped by the medial border of biceps. The median nerve crosses the artery in the middle of the arm. In the cubital fossa, the brachial artery is separated from the median cubital vein by the bicipital aponeurosis. The basilic vein is in contact with the most proximal aspect of the cubital fossa and lies medially. Understanding the anatomy of the brachial artery is important for medical professionals when performing procedures such as blood pressure measurement or arterial line placement.

    • This question is part of the following fields:

      • Neurological System
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  • Question 12 - A 54-year-old factory worker gets his arm caught in a metal grinder and...

    Correct

    • A 54-year-old factory worker gets his arm caught in a metal grinder and is rushed to the ER. Upon examination, he displays an inability to extend his metacarpophalangeal joints and abduct his shoulder. Additionally, he experiences weakness in his elbow and wrist. What specific injury has occurred?

      Your Answer: Posterior cord of brachial plexus

      Explanation:

      Lesion of the posterior cord results in the impairment of the axillary and radial nerve, which are responsible for innervating various muscles such as the deltoid, triceps, brachioradialis, wrist extensors, finger extensors, subscapularis, teres minor, and latissimus dorsi.

      Brachial Plexus Cords and their Origins

      The brachial plexus cords are categorized based on their position in relation to the axillary artery. These cords pass over the first rib near the lung’s dome and under the clavicle, just behind the subclavian artery. The lateral cord is formed by the anterior divisions of the upper and middle trunks and gives rise to the lateral pectoral nerve, which originates from C5, C6, and C7. The medial cord is formed by the anterior division of the lower trunk and gives rise to the medial pectoral nerve, the medial brachial cutaneous nerve, and the medial antebrachial cutaneous nerve, which originate from C8, T1, and C8, T1, respectively. The posterior cord is formed by the posterior divisions of the three trunks (C5-T1) and gives rise to the upper and lower subscapular nerves, the thoracodorsal nerve to the latissimus dorsi (also known as the middle subscapular nerve), and the axillary and radial nerves.

    • This question is part of the following fields:

      • Neurological System
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  • Question 13 - A young woman comes in with a sudden and severe headache at the...

    Correct

    • A young woman comes in with a sudden and severe headache at the back of her head, which quickly leads to seizures. Upon examination, doctors discover an aneurysm. During the assessment, they observe that her right eye is displaced downwards and to the side. What could be the probable reason for this?

      Your Answer: Oculomotor nerve palsy

      Explanation:

      When someone has oculomotor nerve palsy, their medial rectus muscle is disabled, which causes the lateral rectus muscle to move the eye uncontrollably to the side. Additionally, the superior rectus, inferior rectus, and inferior oblique muscles are also affected, causing the eye to move downwards due to the unopposed action of the superior oblique muscle. This condition also results in ptosis, or drooping of the eyelid, due to paralysis of the levator palpebrae superioris muscle, and mydriasis, or dilation of the pupil, due to damage to the parasympathetic fibers.

      Disorders of the Oculomotor System: Nerve Path and Palsy Features

      The oculomotor system is responsible for controlling eye movements and pupil size. Disorders of this system can result in various nerve path and palsy features. The oculomotor nerve has a large nucleus at the midbrain and its fibers pass through the red nucleus and the pyramidal tract, as well as through the cavernous sinus into the orbit. When this nerve is affected, patients may experience ptosis, eye down and out, and an inability to move the eye superiorly, inferiorly, or medially. The pupil may also become fixed and dilated.

      The trochlear nerve has the longest intracranial course and is the only nerve to exit the dorsal aspect of the brainstem. Its nucleus is located at the midbrain and it passes between the posterior cerebral and superior cerebellar arteries, as well as through the cavernous sinus into the orbit. When this nerve is affected, patients may experience vertical diplopia (diplopia on descending the stairs) and an inability to look down and in.

      The abducens nerve has its nucleus in the mid pons and is responsible for the convergence of eyes in primary position. When this nerve is affected, patients may experience lateral diplopia towards the side of the lesion and the eye may deviate medially. Understanding the nerve path and palsy features of the oculomotor system can aid in the diagnosis and treatment of disorders affecting this important system.

    • This question is part of the following fields:

      • Neurological System
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  • Question 14 - A 35-year-old woman comes to the clinic complaining of worsening tingling sensation in...

    Incorrect

    • A 35-year-old woman comes to the clinic complaining of worsening tingling sensation in her legs and difficulty maintaining balance. She has no significant medical history.

      During the examination, it is observed that her lower limbs have significantly reduced proprioception and vibration sense. She also experiences distal paraesthesia. Additionally, her knee reflexes are brisk.

      A blood film is taken, which shows macrocytic anaemia and hypersegmented neutrophils.

      Based on the symptoms, what parts of the spinal cord are likely to be affected?

      Your Answer: Spinocerebellar tract and dorsal column

      Correct Answer: Dorsal column and lateral corticospinal tract

      Explanation:

      Subacute combined degeneration of the spinal cord affects the dorsal columns and lateral corticospinal tracts, as seen in this case with B12 deficiency. The loss of proprioception and vibration sense on examination, as well as brisk knee reflexes, are consistent with an upper motor neuron lesion finding. The anterior corticospinal tract, spinocerebellar tract, and spinothalamic tract are not typically affected in this condition. Therefore, the correct answer is the dorsal columns and lateral corticospinal tracts.

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 15 - At which of the following anatomical locations does the common peroneal nerve bifurcate...

    Correct

    • At which of the following anatomical locations does the common peroneal nerve bifurcate into the superficial and deep peroneal nerves?

      Your Answer: At the lateral aspect of the neck of the fibula

      Explanation:

      The point where the common peroneal nerve is most susceptible to injury is at the neck of the fibula, where it divides into two branches.

      The common peroneal nerve originates from the dorsal divisions of the sacral plexus, specifically from L4, L5, S1, and S2. This nerve provides sensation to the skin and fascia of the anterolateral surface of the leg and dorsum of the foot, as well as innervating the muscles of the anterior and peroneal compartments of the leg, extensor digitorum brevis, and the knee, ankle, and foot joints. It is located laterally within the sciatic nerve and passes through the lateral and proximal part of the popliteal fossa, under the cover of biceps femoris and its tendon, to reach the posterior aspect of the fibular head. The common peroneal nerve divides into the deep and superficial peroneal nerves at the point where it winds around the lateral surface of the neck of the fibula in the body of peroneus longus, approximately 2 cm distal to the apex of the head of the fibula. It is palpable posterior to the head of the fibula. The nerve has several branches, including the nerve to the short head of biceps, articular branch (knee), lateral cutaneous nerve of the calf, and superficial and deep peroneal nerves at the neck of the fibula.

    • This question is part of the following fields:

      • Neurological System
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  • Question 16 - A woman in her 50s with lung cancer and bone metastasis in the...

    Incorrect

    • A woman in her 50s with lung cancer and bone metastasis in the thoracic spinal vertebral bodies experiences a pathological fracture at the level of T4. The fracture is unstable and the spinal cord is severely compressed at this level. Which of the following findings will not be present six weeks after the injury?

      Your Answer: Sensory ataxia

      Correct Answer: Diminished patellar tendon reflex

      Explanation:

      When there is a lesion in the thoracic cord, it can lead to spastic paraparesis, hyperreflexia, and extensor plantar responses, which are all signs of an upper motor neuron (UMN) lesion. In addition, there may be incontinence, loss of sensation below the lesion, and a type of ataxia known as sensory ataxia. These symptoms usually appear a few weeks after the initial injury, once the spinal shock phase (characterized by areflexia) has passed.

      The spinal cord is a central structure located within the vertebral column that provides it with structural support. It extends rostrally to the medulla oblongata of the brain and tapers caudally at the L1-2 level, where it is anchored to the first coccygeal vertebrae by the filum terminale. The cord is characterised by cervico-lumbar enlargements that correspond to the brachial and lumbar plexuses. It is incompletely divided into two symmetrical halves by a dorsal median sulcus and ventral median fissure, with grey matter surrounding a central canal that is continuous with the ventricular system of the CNS. Afferent fibres entering through the dorsal roots usually terminate near their point of entry but may travel for varying distances in Lissauer’s tract. The key point to remember is that the anatomy of the cord will dictate the clinical presentation in cases of injury, which can be caused by trauma, neoplasia, inflammatory diseases, vascular issues, or infection.

      One important condition to remember is Brown-Sequard syndrome, which is caused by hemisection of the cord and produces ipsilateral loss of proprioception and upper motor neuron signs, as well as contralateral loss of pain and temperature sensation. Lesions below L1 tend to present with lower motor neuron signs. It is important to keep a clinical perspective in mind when revising CNS anatomy and to understand the ways in which the spinal cord can become injured, as this will help in diagnosing and treating patients with spinal cord injuries.

    • This question is part of the following fields:

      • Neurological System
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  • Question 17 - In what area is a lumbar puncture typically conducted? ...

    Correct

    • In what area is a lumbar puncture typically conducted?

      Your Answer: Subarachnoid space

      Explanation:

      To obtain samples of CSF, a needle is typically inserted between the third and fourth lumbar vertebrae, with the tip placed in the subarachnoid space. It is important to note that the spinal cord ends at L1 and is not at risk of harm during this procedure. However, if there is clinical evidence of increased intracranial pressure, lumbar puncture should not be performed.

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 18 - A 26-year-old female was admitted to the Emergency Department after a motorcycle accident....

    Correct

    • A 26-year-old female was admitted to the Emergency Department after a motorcycle accident. She reported experiencing intense pain in her left shoulder and a loss of strength in elbow flexion. The physician in the Emergency Department suspects that damage to the lateral cord of the brachial plexus may be responsible for the weakness.

      What are the end branches of this cord?

      Your Answer: The musculocutaneous nerve and the lateral root of the median nerve

      Explanation:

      The two end branches of the lateral cord of the brachial plexus are the lateral root of the median nerve and the musculocutaneous nerve. If the musculocutaneous nerve is damaged, it can result in weakened elbow flexion. The posterior cord has two end branches, the axillary nerve and radial nerve. The lateral pectoral nerve is a branch of the lateral cord but not an end branch. The medial cord has two end branches, the medial root of the median nerve and the ulnar nerve.

      Brachial Plexus Cords and their Origins

      The brachial plexus cords are categorized based on their position in relation to the axillary artery. These cords pass over the first rib near the lung’s dome and under the clavicle, just behind the subclavian artery. The lateral cord is formed by the anterior divisions of the upper and middle trunks and gives rise to the lateral pectoral nerve, which originates from C5, C6, and C7. The medial cord is formed by the anterior division of the lower trunk and gives rise to the medial pectoral nerve, the medial brachial cutaneous nerve, and the medial antebrachial cutaneous nerve, which originate from C8, T1, and C8, T1, respectively. The posterior cord is formed by the posterior divisions of the three trunks (C5-T1) and gives rise to the upper and lower subscapular nerves, the thoracodorsal nerve to the latissimus dorsi (also known as the middle subscapular nerve), and the axillary and radial nerves.

    • This question is part of the following fields:

      • Neurological System
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  • Question 19 - A patient visiting the neurology outpatient clinic presents with a motor deficit. The...

    Correct

    • A patient visiting the neurology outpatient clinic presents with a motor deficit. The neurologist observes muscle fasciculations, flaccid weakness, and decreased reflexes.

      What is the location of the lesion?

      Your Answer: Peripheral nerve

      Explanation:

      A lower motor neuron lesion can be identified by a decrease in reflex response.

      When a lower motor neuron lesion occurs, it can result in reduced tone, weakness, and muscle fasciculations. These neurons originate in the anterior horn of the spinal cord and connect with the neuromuscular junction.

      On the other hand, if the corticospinal tract is affected in the motor cortex, internal capsule, midbrain, or medulla, it would cause an upper motor neuron pattern of weakness. This would be characterized by hypertonia, brisk reflexes, and an upgoing plantar reflex response.

      Reflexes are automatic responses that our body makes in response to certain stimuli. These responses are controlled by the nervous system and do not require conscious thought. There are several common reflexes that are associated with specific roots in the spinal cord. For example, the ankle reflex is associated with the S1-S2 root, while the knee reflex is associated with the L3-L4 root. Similarly, the biceps reflex is associated with the C5-C6 root, and the triceps reflex is associated with the C7-C8 root. Understanding these reflexes can help healthcare professionals diagnose and treat certain conditions.

    • This question is part of the following fields:

      • Neurological System
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  • Question 20 - A 28-year-old female experienced a crush injury while working, causing an air vent...

    Correct

    • A 28-year-old female experienced a crush injury while working, causing an air vent to fall and trap her arm. As a result, she developed fixed focal dystonia that led to flexion contracture of her right wrist and digits.

      During the examination, the doctor observed intrinsic hand muscle wasting. The patient's right forearm was supinated, her wrist was hyperextended, and her fingers were flexed. Additionally, there was a decrease in sensation along the medial aspect of her hand and arm, and a reduction in handgrip strength.

      Which nerve roots are affected in this case?

      Your Answer: C8/T1

      Explanation:

      T1 nerve root damage can result in Klumpke’s paralysis.

      Brachial Plexus Injuries: Erb-Duchenne and Klumpke’s Paralysis

      Erb-Duchenne paralysis is a type of brachial plexus injury that results from damage to the C5 and C6 roots. This can occur during a breech presentation, where the baby’s head and neck are pulled to the side during delivery. Symptoms of Erb-Duchenne paralysis include weakness or paralysis of the arm, shoulder, and hand, as well as a winged scapula.

      On the other hand, Klumpke’s paralysis is caused by damage to the T1 root of the brachial plexus. This type of injury typically occurs due to traction, such as when a baby’s arm is pulled during delivery. Klumpke’s paralysis can result in a loss of intrinsic hand muscles, which can affect fine motor skills and grip strength.

      It is important to note that brachial plexus injuries can have long-term effects on a person’s mobility and quality of life. Treatment options may include physical therapy, surgery, or a combination of both. Early intervention is key to improving outcomes and minimizing the impact of these injuries.

    • This question is part of the following fields:

      • Neurological System
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  • Question 21 - A 89-year-old man is brought to his primary care physician by his daughter...

    Incorrect

    • A 89-year-old man is brought to his primary care physician by his daughter who is worried about changes in his behavior following a stroke 10 weeks ago. The daughter reports that the man has gained 12 kg in the past 8 weeks and appears to be constantly putting household items in his mouth. He also struggles to identify familiar people and objects. During the appointment, the man mentions that his sex drive has significantly increased.

      Which specific area of the brain has been affected by the lesion?

      Your Answer: Frontal lobe

      Correct Answer: Amygdala

      Explanation:

      Kluver-Bucy syndrome is often caused by bilateral lesions in the medial temporal lobe, including the amygdala. This can lead to symptoms such as hyperorality, hypersexuality, hyperphagia, and visual agnosia. Lesions in the cingulate gyrus can result in poor decision-making and emotional dysfunction, while frontal lobe lesions can cause changes in behavior, anosmia, aphasia, and motor impairment. Hippocampus lesions can lead to memory impairment, and thalamic lesions can result in sensory and motor dysfunction.

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 22 - A 29-year-old female is being followed up in the epilepsy clinic after switching...

    Incorrect

    • A 29-year-old female is being followed up in the epilepsy clinic after switching from lamotrigine to carbamazepine for her generalised tonic-clonic seizures. What is the mechanism of action of her new medication?

      Your Answer: Binds to GABAA receptors allosterically to hyperpolarize neuronal cell membranes

      Correct Answer: Binds to sodium channels to increase their refractory period

      Explanation:

      Carbamazepine binds to voltage-gated sodium channels in the neuronal cell membrane, blocking their action in the inactive form. This results in a longer time for the neuron to depolarize, increasing the absolute refractory period and raising the threshold for seizure activity. It does not bind to potassium channels or GABA receptors. Blocking potassium efflux would increase the refractory period, while promoting potassium efflux would hyperpolarize the cell and also increase the refractory period. Benzodiazepines bind allosterically to GABAA receptors, hyperpolarizing the cell and increasing the refractory period.

      Understanding Carbamazepine: Uses, Mechanism of Action, and Adverse Effects

      Carbamazepine is a medication that is commonly used in the treatment of epilepsy, particularly partial seizures. It is also used to treat trigeminal neuralgia and bipolar disorder. Chemically similar to tricyclic antidepressant drugs, carbamazepine works by binding to sodium channels and increasing their refractory period.

      However, there are some adverse effects associated with carbamazepine use. It is known to be a P450 enzyme inducer, which can affect the metabolism of other medications. Patients may also experience dizziness, ataxia, drowsiness, headache, and visual disturbances, especially diplopia. In rare cases, carbamazepine can cause Steven-Johnson syndrome, leucopenia, agranulocytosis, and hyponatremia secondary to syndrome of inappropriate ADH secretion.

      It is important to note that carbamazepine exhibits autoinduction, which means that when patients start taking the medication, they may experience a return of seizures after 3-4 weeks of treatment. Therefore, it is crucial for patients to be closely monitored by their healthcare provider when starting carbamazepine.

    • This question is part of the following fields:

      • Neurological System
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  • Question 23 - A 15-year-old boy comes to your clinic complaining of feeling unsteady when walking...

    Correct

    • A 15-year-old boy comes to your clinic complaining of feeling unsteady when walking for the past 7 days. He mentions that he has been increasingly clumsy over the past month. During the examination, you notice a lack of coordination and an intention tremor on the left side, but no changes in tone, sensation, power, or reflexes. You urgently refer him to a neurologist and request an immediate MRI head scan. The scan reveals a mass in the left cerebellar hemisphere that is invading the fourth ventricle and potentially blocking the left lateral aperture. What is the name of the space into which cerebrospinal fluid (CSF) drains from the fourth ventricle through each lateral aperture (of Luschka)?

      Your Answer: Cerebellopontine angle cistern

      Explanation:

      The correct answer is the cerebellopontine cistern, which receives CSF from the fourth ventricle via one of four openings. CSF can leave the fourth ventricle through the lateral apertures (foramina of Luschka) or the median aperture (foramen of Magendie). The lateral apertures drain CSF into the cerebellopontine angle cistern, while the median aperture drains CSF into the cisterna magna. CSF is circulated throughout the subarachnoid space, but it is not present in the extradural or subdural spaces. The lateral ventricles are not directly connected to the fourth ventricle. The superior sagittal sinus is a large venous sinus that allows the absorption of CSF. The patient’s symptoms of clumsiness, intention tremor, and lack of coordination indicate a lesion of the ipsilateral cerebellar hemisphere, which can also cause gait ataxia, scanning speech, and dysdiadochokinesia.

      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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      • Neurological System
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  • Question 24 - A 45-year-old male patient presents with choreiform movements that he is unable to...

    Correct

    • A 45-year-old male patient presents with choreiform movements that he is unable to control or cease. During the consultation, you inquire about his family history and discover that his father experienced similar symptoms at a slightly later age. Based on this information, what genetic phenomenon is likely to have taken place between the patient and his father?

      Your Answer: Anticipation

      Explanation:

      Anticipation may be observed in Huntington’s disease due to its nature as a trinucleotide repeat disorder. The disease is caused by an autosomal dominant gene with CAG repeats in exon 1 of the Huntingtin gene. The number of CAG repeats is indicative of the severity of the disease, with individuals having 36 to 39 repeats potentially developing symptoms, while those with 40 or more repeats almost always develop the disorder. HD can occur in individuals with 36 to 120 CAG repeats.

      Anticipation is observed as the number of CAG repeats increases between generations. Offspring of individuals with 27 to 35 CAG repeats are at risk of developing HD, even though the parent does not suffer from the disease. Additionally, higher numbers of CAG repeats tend to cause HD to manifest at earlier ages, resulting in younger generations being affected by the disease.

      Huntington’s disease is a genetic disorder that causes progressive and incurable neurodegeneration. It is inherited in an autosomal dominant manner and is caused by a trinucleotide repeat expansion of CAG in the huntingtin gene on chromosome 4. This can result in the phenomenon of anticipation, where the disease presents at an earlier age in successive generations. The disease leads to the degeneration of cholinergic and GABAergic neurons in the striatum of the basal ganglia, which can cause a range of symptoms.

      Typically, symptoms of Huntington’s disease develop after the age of 35 and can include chorea, personality changes such as irritability, apathy, and depression, intellectual impairment, dystonia, and saccadic eye movements. Unfortunately, there is currently no cure for Huntington’s disease, and it usually results in death around 20 years after the initial symptoms develop.

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      • Neurological System
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  • Question 25 - A 36-year-old man has been referred to the sleep clinic by his GP...

    Incorrect

    • A 36-year-old man has been referred to the sleep clinic by his GP due to reports from his partner of sleepwalking and appearing frightened during the night. Additionally, he has been known to scream while sleeping and recently experienced an episode of bedwetting. At which stage of sleep do these symptoms typically occur?

      Your Answer: Rapid eye movement (REM) stage

      Correct Answer: Non-REM stage 3

      Explanation:

      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.

    • This question is part of the following fields:

      • Neurological System
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  • Question 26 - A 22-year-old man arrives at the emergency department with a stab wound on...

    Correct

    • A 22-year-old man arrives at the emergency department with a stab wound on the left side of his neck above the clavicle. Upon examination, there is no indication of damage to the pleura or any major blood vessels. However, a winged scapula is observed on the left side of his back, with the scapula protruding from the chest wall and the inferior angle pointing towards the midline. What nerve is responsible for this condition?

      Your Answer: Long thoracic nerve

      Explanation:

      The nerve responsible for a winged scapula is the long thoracic nerve, which originates from C5-7 and travels along the thorax to reach the serratus anterior muscle. Damage to this nerve can cause the scapula to lift off the thoracic wall and limit shoulder movement. Other nerves that can cause a winged scapula include the accessory nerve and dorsal scapular nerve. The transverse cervical nerve supplies the neck, the phrenic nerve supplies the diaphragm, the greater auricular nerve supplies the mandible and ear, and the suprascapular nerve supplies the shoulder muscles and joints.

      The Long Thoracic Nerve and its Role in Scapular Winging

      The long thoracic nerve is derived from the ventral rami of C5, C6, and C7, which are located close to their emergence from intervertebral foramina. It runs downward and passes either anterior or posterior to the middle scalene muscle before reaching the upper tip of the serratus anterior muscle. From there, it descends on the outer surface of this muscle, giving branches into it.

      One of the most common symptoms of long thoracic nerve injury is scapular winging, which occurs when the serratus anterior muscle is weakened or paralyzed. This can happen due to a variety of reasons, including trauma, surgery, or nerve damage. In addition to long thoracic nerve injury, scapular winging can also be caused by spinal accessory nerve injury (which denervates the trapezius) or a dorsal scapular nerve injury.

      Overall, the long thoracic nerve plays an important role in the function of the serratus anterior muscle and the stability of the scapula. Understanding its anatomy and function can help healthcare professionals diagnose and treat conditions that affect the nerve and its associated muscles.

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      • Neurological System
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  • Question 27 - Sarah is a 23-year-old female who is brought to the emergency department after...

    Correct

    • Sarah is a 23-year-old female who is brought to the emergency department after being stabbed multiple times in the back with a knife. After conducting a thorough neurological examination, you observe a loss of fine touch and vibration sensation on the right side, as well as a loss of pain and temperature sensation on the left side. Which tract has been affected to cause the loss of fine touch and vibration?

      Your Answer: Dorsal columns

      Explanation:

      The sensory ascending pathways are comprised of the gracile fasciculus and cuneate fasciculus, which together form the dorsal columns. When the back is stabbed, Brown-Sequard syndrome may occur, leading to the following symptoms:

      1. Spastic paresis on the same side as the injury, below the lesion
      2. Loss of proprioception and vibration sensation on the same side as the injury
      3. Loss of pain and temperature sensation on the opposite side of the injury.

      Spinal cord lesions can affect different tracts and result in various clinical symptoms. Motor lesions, such as amyotrophic lateral sclerosis and poliomyelitis, affect either upper or lower motor neurons, resulting in spastic paresis or lower motor neuron signs. Combined motor and sensory lesions, such as Brown-Sequard syndrome, subacute combined degeneration of the spinal cord, Friedrich’s ataxia, anterior spinal artery occlusion, and syringomyelia, affect multiple tracts and result in a combination of spastic paresis, loss of proprioception and vibration sensation, limb ataxia, and loss of pain and temperature sensation. Multiple sclerosis can involve asymmetrical and varying spinal tracts and result in a combination of motor, sensory, and ataxia symptoms. Sensory lesions, such as neurosyphilis, affect the dorsal columns and result in loss of proprioception and vibration sensation.

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      • Neurological System
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  • Question 28 - A 85-year-old man is brought to the emergency department after collapsing at home....

    Incorrect

    • A 85-year-old man is brought to the emergency department after collapsing at home. He has a history of hypertension and poorly controlled type 2 diabetes. During examination, he complains of right-sided facial pain and left-sided arm pain, and mentions that the room appears to be spinning. The patient also has reduced temperature sensation on the right side of his face and the left side of his body, an ataxic gait, and vomits during the examination. Which artery is the most likely to be affected?

      Your Answer: Basilar artery

      Correct Answer: Posterior inferior cerebellar artery

      Explanation:

      The correct diagnosis for a patient presenting with sudden onset vertigo and vomiting, dysphagia, ipsilateral facial pain and temperature loss, contralateral limb pain and temperature loss, and ataxia is posterior inferior cerebellar artery. This constellation of symptoms is consistent with lateral medullary syndrome, also known as Wallenberg syndrome, which is caused by ischemia of the lateral medulla. This condition is associated with involvement of the trigeminal nucleus, lateral spinothalamic tract, cerebellum, and nucleus ambiguus, resulting in the aforementioned symptoms.

      The anterior spinal artery, basilar artery, middle cerebral artery, and posterior cerebral artery are not associated with lateral medullary syndrome and would present with different symptoms.

      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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      • Neurological System
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  • Question 29 - A 59-year-old man arrives at the emergency department with a sudden onset of...

    Correct

    • A 59-year-old man arrives at the emergency department with a sudden onset of visual disturbance. He has a medical history of hypercholesterolemia and is currently taking atorvastatin. Additionally, he smokes 15 cigarettes daily, drinks half a bottle of wine each night, and works as a bond-trader.

      Upon examination of his eyes, a field defect is observed in the right upper quadrant of both his right and left eye. Other than that, the examination is unremarkable.

      What is the anatomical location of the lesion that is affecting his vision?

      Your Answer: Left inferior optic radiation

      Explanation:

      A right superior homonymous quadrantanopia in the patient is caused by a lesion in the left inferior optic radiation located in the temporal lobe. The sudden onset indicates a possible stroke or vascular event. A superior homonymous quadrantanopia occurs when the contralateral inferior optic radiation is affected.

      A lesion in the left superior optic radiation would result in a right inferior homonymous quadrantanopia, which is not the case here. Similarly, a lesion in the left optic tract would cause contralateral hemianopia, which is also not the diagnosis in this patient.

      Understanding Visual Field Defects

      Visual field defects can occur due to various reasons, including lesions in the optic tract, optic radiation, or occipital cortex. A left homonymous hemianopia indicates a visual field defect to the left, which is caused by a lesion in the right optic tract. On the other hand, homonymous quadrantanopias can be categorized into PITS (Parietal-Inferior, Temporal-Superior) and can be caused by lesions in the inferior or superior optic radiations in the temporal or parietal lobes.

      When it comes to congruous and incongruous defects, the former refers to complete or symmetrical visual field loss, while the latter indicates incomplete or asymmetric visual field loss. Incongruous defects are caused by optic tract lesions, while congruous defects are caused by optic radiation or occipital cortex lesions. In cases where there is macula sparing, it is indicative of a lesion in the occipital cortex.

      Bitemporal hemianopia, on the other hand, is caused by a lesion in the optic chiasm. The type of defect can indicate the location of the compression, with an upper quadrant defect being more common in inferior chiasmal compression, such as a pituitary tumor, and a lower quadrant defect being more common in superior chiasmal compression, such as a craniopharyngioma.

      Understanding visual field defects is crucial in diagnosing and treating various neurological conditions. By identifying the type and location of the defect, healthcare professionals can provide appropriate interventions to improve the patient’s quality of life.

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      • Neurological System
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  • Question 30 - A 82-year-old man arrives at the emergency department with complaints of severe flank...

    Incorrect

    • A 82-year-old man arrives at the emergency department with complaints of severe flank pain that extends to his groin. He reports experiencing bone pain for a few weeks and feeling down for the past month. His blood work reveals hypercalcemia.

      In response to his hypercalcemia, where would you anticipate increased activity?

      Your Answer: Parathyroid

      Correct Answer: C cells of the thyroid

      Explanation:

      The thyroid’s C cells secrete calcitonin, which plays a role in calcium homeostasis alongside PTH and vitamin D.

      If hypercalcaemia occurs, PTH and vitamin D levels decrease, and calcitonin is secreted by the thyroid’s C cells. This leads to a decrease in parathyroid activity.

      The renin-angiotensin-aldosterone system regulates the release of aldosterone from the zona glomerulosa.

      Insulin secretion from the pancreas’ beta cells is not affected by calcium levels.

      Maintaining Calcium Balance in the Body

      Calcium ions are essential for various physiological processes in the body, and the largest store of calcium is found in the skeleton. The levels of calcium in the body are regulated by three hormones: parathyroid hormone (PTH), vitamin D, and calcitonin.

      PTH increases calcium levels and decreases phosphate levels by increasing bone resorption and activating osteoclasts. It also stimulates osteoblasts to produce a protein signaling molecule that activates osteoclasts, leading to bone resorption. PTH increases renal tubular reabsorption of calcium and the synthesis of 1,25(OH)2D (active form of vitamin D) in the kidney, which increases bowel absorption of calcium. Additionally, PTH decreases renal phosphate reabsorption.

      Vitamin D, specifically the active form 1,25-dihydroxycholecalciferol, increases plasma calcium and plasma phosphate levels. It increases renal tubular reabsorption and gut absorption of calcium, as well as osteoclastic activity. Vitamin D also increases renal phosphate reabsorption in the proximal tubule.

      Calcitonin, secreted by C cells of the thyroid, inhibits osteoclast activity and renal tubular absorption of calcium.

      Although growth hormone and thyroxine play a small role in calcium metabolism, the primary regulation of calcium levels in the body is through PTH, vitamin D, and calcitonin. Maintaining proper calcium balance is crucial for overall health and well-being.

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      • Neurological System
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