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Question 1
Incorrect
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A basketball enthusiast in his early twenties visits his GP complaining of discomfort in his right shoulder and neck, and also reports an unusual appearance on the right side of his upper back.
To assess the condition, the GP asks the patient to stand facing a wall and extend his arms straight in front of him, with his palms flat against the wall. The GP then instructs the patient to bend his arms and push away from the wall. During the movement, the patient's right shoulder blade protrudes from his back.
Based on the symptoms, which nerve is most likely to be affected?Your Answer: Spinal accessory nerve
Correct Answer: Long thoracic nerve
Explanation:The correct nerve that supplies the serratus anterior muscle is the long thoracic nerve. This muscle is responsible for pulling the scapula around the thorax, and damage to this nerve can cause medial winging of the scapula.
The axillary nerve is not the correct answer as it supplies the deltoid muscle, which is responsible for shoulder abduction. Damage to this nerve results in a flattened deltoid muscle, not winging of the scapula.
The musculocutaneous nerve supplies the biceps brachii muscle, which is responsible for elbow flexion. Damage to this nerve does not affect the scapulae.
The spinal accessory nerve supplies the sternocleidomastoid and trapezius muscles, and injury to this nerve may result in difficulty turning the head from side to side or shrugging the shoulders. It does not affect the scapulae.
Trauma to the thoracodorsal nerve may cause atrophy of the latissimus dorsi muscle and difficulty moving the affected shoulder, but it does not cause winging of the scapula.
Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 2
Correct
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A father brings his 4-year-old son to a dermatologist concerned about his dry skin. The child was also born via spontaneous vaginal delivery at term without any complications. He has always had dry skin, but it has become more severe lately. He has a past medical history of eczema.
What clinical feature could have aided in the diagnosis of ichthyosis based on the history and examination?Your Answer: 'fish-scale' skin
Explanation:Ichthyosis is characterized by the presence of dry, scaly skin resembling fish scales.
Understanding Acquired Ichthyosis
Acquired ichthyosis is a skin condition characterized by dry and scaly skin, often referred to as crocodile skin. Unlike congenital ichthyosis, which is present at birth, acquired ichthyosis develops later in life and can be caused by various factors. Some of the known causes of acquired ichthyosis include lymphoma, particularly Hodgkin’s lymphoma, other malignancies such as Kaposi’s sarcoma, leprosy, and malnutrition.
It is important to note that acquired ichthyosis is a rare condition and is often associated with underlying medical conditions.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 3
Correct
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A 35-year-old woman presents to your clinic complaining of increased joint pain and fatigue. She reports no significant medical history but mentions that her sister was recently diagnosed with systemic lupus erythematosus (SLE). On examination, there are no notable findings. Laboratory tests reveal the following results:
- Hemoglobin: 118 g/L (normal range for females: 115-160 g/L)
- Platelets: 260 * 109/L (normal range: 150-400 * 109/L)
- White blood cells: 7.5 * 109/L (normal range: 4.0-11.0 * 109/L)
- ANA: Negative
- ANCA: Negative
- Anti-La antibody: Negative
- Rheumatoid factor: Positive
Which blood test result is the most reliable indicator that SLE is unlikely in this patient?Your Answer: ANA (antinuclear antibodies)
Explanation:Systemic lupus erythematosus (SLE) can be investigated through various tests, including antibody tests. ANA testing is highly sensitive and useful for ruling out SLE, but it has low specificity. About 99% of SLE patients are ANA positive. Rheumatoid factor testing is positive in 20% of SLE patients. Anti-dsDNA testing is highly specific (>99%) but less sensitive (70%). Anti-Smith testing is also highly specific (>99%) but has a lower sensitivity (30%). Other antibody tests that can be used include anti-U1 RNP, SS-A (anti-Ro), and SS-B (anti-La).
Monitoring of SLE can be done through various markers, including inflammatory markers such as ESR. During active disease, CRP levels may be normal, and a raised CRP may indicate an underlying infection. Complement levels (C3, C4) are low during active disease due to the formation of complexes that lead to the consumption of complement. Anti-dsDNA titres can also be used for disease monitoring, but it is important to note that they are not present in all SLE patients. Overall, these investigations can help diagnose and monitor SLE, allowing for appropriate management and treatment.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 4
Correct
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A 17-year-old boy is out on a movie date with his girlfriend. During the film, he keeps his arm over her seat. However, when the movie ends, he realizes that he has limited wrist movement. Upon examination, he is unable to extend his wrist and has reduced sensation in his anatomical snuff box. Which nerve did he damage while at the cinema?
Your Answer: Radial
Explanation:Saturday night syndrome is a condition where the brachial plexus is compressed due to sleeping with the arm over the back of a chair. This can result in a radial nerve palsy, commonly known as wrist drop, where the patient is unable to extend their wrist and it hangs flaccidly.
Upper limb anatomy is a common topic in examinations, and it is important to know certain facts about the nerves and muscles involved. The musculocutaneous nerve is responsible for elbow flexion and supination, and typically only injured as part of a brachial plexus injury. The axillary nerve controls shoulder abduction and can be damaged in cases of humeral neck fracture or dislocation, resulting in a flattened deltoid. The radial nerve is responsible for extension in the forearm, wrist, fingers, and thumb, and can be damaged in cases of humeral midshaft fracture, resulting in wrist drop. The median nerve controls the LOAF muscles and can be damaged in cases of carpal tunnel syndrome or elbow injury. The ulnar nerve controls wrist flexion and can be damaged in cases of medial epicondyle fracture, resulting in a claw hand. The long thoracic nerve controls the serratus anterior and can be damaged during sports or as a complication of mastectomy, resulting in a winged scapula. The brachial plexus can also be damaged, resulting in Erb-Duchenne palsy or Klumpke injury, which can cause the arm to hang by the side and be internally rotated or associated with Horner’s syndrome, respectively.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 5
Incorrect
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A 29-year-old woman goes into labour following an uncomplicated pregnancy. During delivery, the baby is found to be in a breech position and there is insufficient time for a C-section. What is the condition that poses the greatest risk to the newborn?
Your Answer: Neonatal hypoglycaemia
Correct Answer: Developmental dysplasia of the hip
Explanation:Developmental dysplasia of the hip is more likely to occur in babies who were in a breech presentation during pregnancy. Neonatal hypoglycaemia can be a risk for babies born to mothers with gestational diabetes or those who are preterm or small for their gestational age. Asymmetrical growth restriction, where a baby’s head circumference is on a higher centile than their weight or abdominal circumference, is often caused by uteroplacental dysfunction, such as pre-eclampsia or maternal smoking.
Developmental dysplasia of the hip (DDH) is a condition that affects 1-3% of newborns and is more common in females, firstborn children, and those with a positive family history or breech presentation. It used to be called congenital dislocation of the hip (CDH). DDH is more often found in the left hip and can be screened for using ultrasound in infants with certain risk factors or through clinical examination using the Barlow and Ortolani tests. Other factors to consider include leg length symmetry, knee level when hips and knees are flexed, and restricted hip abduction in flexion. Ultrasound is typically used to confirm the diagnosis, but x-rays may be necessary for infants over 4.5 months old. Management options include the Pavlik harness for younger children and surgery for older ones. Most unstable hips will stabilize on their own within 3-6 weeks.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 6
Correct
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A man in his early 50s complains of experiencing numbness and pain in his right hand's thumb, index finger, and middle finger. Which nerve roots are most likely to be impacted?
Your Answer: C5-T1
Explanation:Carpal tunnel syndrome is a condition that occurs when the median nerve in the carpal tunnel is compressed. This can cause pain and pins and needles sensations in the thumb, index, and middle fingers. In some cases, the symptoms may even travel up the arm. Patients may shake their hand to alleviate the discomfort, especially at night. During an examination, weakness in thumb abduction and wasting of the thenar eminence may be observed. Tapping on the affected area may also cause paraesthesia, and flexing the wrist can trigger symptoms.
There are several potential causes of carpal tunnel syndrome, including idiopathic factors, pregnancy, oedema, lunate fractures, and rheumatoid arthritis. Electrophysiology tests may reveal prolongation of the action potential in both motor and sensory nerves. Treatment options may include a six-week trial of conservative measures such as wrist splints at night or corticosteroid injections. If symptoms persist or are severe, surgical decompression may be necessary, which involves dividing the flexor retinaculum.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 7
Correct
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A 9-year-old child has been brought to the emergency department after falling onto their shoulder during a soccer game. They are experiencing pain across their shoulder and upper chest, which is most severe when the clavicular area is palpated. A visible bony deformity is present in the clavicular area. The physician suspects a fracture and orders an x-ray.
What is the most probable location of the fracture?Your Answer: Middle third of the clavicle
Explanation:The most frequent location for clavicle fractures is the middle third, which is the weakest part of the bone and lacks any ligaments or muscles. This is especially common in young children. Fractures in the proximal and distal thirds are less frequent and therefore incorrect answers. While sternum fractures can occur in high-force trauma, the mechanism of injury and visible bony deformity in this case suggest a clavicular fracture. Acromion fractures are rare and would not result in the observed bony injury.
Anatomy of the Clavicle
The clavicle is a bone that runs from the sternum to the acromion and plays a crucial role in preventing the shoulder from falling forwards and downwards. Its inferior surface is marked by ligaments at each end, including the trapezoid line and conoid tubercle, which provide attachment to the coracoclavicular ligament. The costoclavicular ligament attaches to the irregular surface on the medial part of the inferior surface, while the subclavius muscle attaches to the intermediate portion’s groove.
The superior part of the clavicle’s medial end has a raised surface that gives attachment to the clavicular head of sternocleidomastoid, while the posterior surface attaches to the sternohyoid. On the lateral end, there is an oval articular facet for the acromion, and a disk lies between the clavicle and acromion. The joint’s capsule attaches to the ridge on the margin of the facet.
In summary, the clavicle is a vital bone that helps stabilize the shoulder joint and provides attachment points for various ligaments and muscles. Its anatomy is marked by distinct features that allow for proper function and movement.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 8
Incorrect
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Which of these nerves passes through the greater and lesser sciatic foramina?
Your Answer: Sciatic nerve
Correct Answer: Pudendal nerve
Explanation:The structures passing through the lesser and greater sciatic foramina, from medial to lateral, are the pudendal nerve, internal pudendal artery, and nerve to obturator internus. The pudendal nerve originates from the ventral rami of the second, third, and fourth sacral nerves and passes through the greater sciatic foramen before crossing the spine of the ischium and reentering the pelvis through the lesser sciatic foramen. It gives off the inferior rectal nerves and terminates into the perineal nerve and the dorsal nerve of the penis or clitoris.
The Greater Sciatic Foramen and its Contents
The greater sciatic foramen is a space in the pelvis that is bounded by various ligaments and bones. It serves as a passageway for several important structures, including nerves and blood vessels. The piriformis muscle is a landmark for identifying these structures as they pass through the sciatic notch. Above the piriformis muscle, the superior gluteal vessels can be found, while below it are the inferior gluteal vessels, the sciatic nerve (which passes through it in only 10% of cases), and the posterior cutaneous nerve of the thigh.
The boundaries of the greater sciatic foramen include the greater sciatic notch of the ilium, the sacrotuberous ligament, the sacrospinous ligament, and the ischial spine. The anterior sacroiliac ligament forms the superior boundary. Structures passing through the greater sciatic foramen include the pudendal nerve, the internal pudendal artery, and the nerve to the obturator internus.
In contrast, the lesser sciatic foramen is a smaller space that contains the tendon of the obturator internus, the pudendal nerve, the internal pudendal artery and vein, and the nerve to the obturator internus. Understanding the contents and boundaries of these foramina is important for clinicians who may need to access or avoid these structures during surgical procedures or other interventions.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 9
Incorrect
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A 65-year-old man presents with a cough, headache, and fever. He has a medical history of hypertension and dyslipidemia and has taken ibuprofen for symptom relief. What is the mechanism of action for the antipyretic effect of the medication he took?
Your Answer: Reduction of prostaglandin I2
Correct Answer: Reduction of prostaglandin E2
Explanation:Non-steroidal anti-inflammatory drugs (NSAIDs) reduce the production of prostaglandin E2 (PGE2), which is responsible for their antipyretic effect. NSAIDs inhibit the enzyme cyclooxygenase (COX), which is required for the production of thromboxanes, prostaglandins, and prostacyclins. By reducing the production of PGE2, NSAIDs decrease fever by acting on the thermoregulation centre in the hypothalamus. However, NSAIDs can have side effects such as gastric ulcer, acute kidney injury, indigestion, and an increased risk of heart failure. It is important to note that insulin-like growth factor 1 (IGF-1) is not affected by NSAIDs, as it is stimulated by growth hormones.
Understanding Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) and COX-2 Selective NSAIDs
Non-steroidal anti-inflammatory drugs (NSAIDs) are medications that work by inhibiting the activity of cyclooxygenase enzymes, which are responsible for producing key mediators involved in inflammation such as prostaglandins. By reducing the production of these mediators, NSAIDs can help alleviate pain and reduce inflammation. Examples of NSAIDs include ibuprofen, diclofenac, naproxen, and aspirin.
However, NSAIDs can also have important and common side-effects, such as peptic ulceration and exacerbation of asthma. To address these concerns, COX-2 selective NSAIDs were developed. These medications were designed to reduce the incidence of side-effects seen with traditional NSAIDs, particularly peptic ulceration. Examples of COX-2 selective NSAIDs include celecoxib and etoricoxib.
Despite their potential benefits, COX-2 selective NSAIDs are not widely used due to ongoing concerns about cardiovascular safety. This led to the withdrawal of rofecoxib (‘Vioxx’) in 2004. As with any medication, it is important to discuss the potential risks and benefits of NSAIDs and COX-2 selective NSAIDs with a healthcare provider before use.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 10
Correct
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Which of the following nerves is responsible for the motor innervation of the sternocleidomastoid muscle?
Your Answer: Accessory nerve
Explanation:The accessory nerve provides the motor supply to the sternocleidomastoid, while the ansa cervicalis is responsible for supplying sensory information from the muscle.
The Sternocleidomastoid Muscle: Anatomy and Function
The sternocleidomastoid muscle is a large muscle located in the neck that plays an important role in head and neck movement. It is named after its origin and insertion points, which are the sternum, clavicle, mastoid process, and occipital bone. The muscle is innervated by the spinal part of the accessory nerve and the anterior rami of C2 and C3, which provide proprioceptive feedback.
The sternocleidomastoid muscle has several actions, including extending the head at the atlanto-occipital joint and flexing the cervical vertebral column. It also serves as an accessory muscle of inspiration. When only one side of the muscle contracts, it can laterally flex the neck and rotate the head so that the face looks upward to the opposite side.
The sternocleidomastoid muscle divides the neck into anterior and posterior triangles, which are important landmarks for medical professionals. The anterior triangle contains several important structures, including the carotid artery, jugular vein, and thyroid gland. The posterior triangle contains the brachial plexus, accessory nerve, and several lymph nodes.
Overall, the sternocleidomastoid muscle is a crucial muscle for head and neck movement and plays an important role in the anatomy of the neck.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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