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Question 1
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A high school football player comes to the emergency department after a hard tackle. He complains of pain in the front of his shoulder, limited movement in his affected arm, and notices that his collarbone is protruding outward. An X-ray shows that his clavicle is displaced, particularly at the lateral end, but still intact. The medial end of the clavicle is still in contact with the sternum, and there are no other bone abnormalities. Given the extent of the dislocation, you suspect that multiple ligaments have been torn. Which of the following ligaments is the least likely to be affected?
Your Answer: Coracoacromial ligament
Explanation:The coracoacromial ligament is not likely to be damaged in a clavicle dislocation, as it does not connect to the clavicle. The ligaments that attach to the lateral end of the clavicle include the acromioclavicular ligament, trapezoid ligament, and conoid ligament (collectively known as the coracoclavicular ligament). In the case of an acromioclavicular joint dislocation, the severity of the injury depends on which ligaments are damaged. Mild cases may involve only a sprain or rupture of the acromioclavicular ligament, while more severe cases may involve rupture of all ligaments attaching to the lateral end of the clavicle.
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 2
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A 43-year-old man presents to his doctor with complaints of struggling to use the twist throttle on his motorcycle with his right hand. He sustained a mid-shaft fracture of his right humerus in a car accident 10 weeks ago, which was successfully treated with surgery. What is the most frequent nerve injury resulting from this type of fracture?
Your Answer: Radial nerve injury
Explanation:The most common nerve injury that occurs with a mid-shaft fracture of the humerus is radial nerve injury. This type of injury can cause a dropped wrist presentation, which is characterized by weakness in wrist extension and difficulty making a fist. The patient in the scenario describes difficulty accelerating on their motorcycle, which requires normal wrist extension and the ability to make a fist.
Other nerve injuries that can occur include axillary nerve injury, which affects shoulder abduction and external rotation and is usually caused by anterior shoulder dislocation. Median nerve injury can result in weakness of forearm pronation, wrist flexion, and thumb flexion, and is associated with carpal tunnel syndrome. Musculocutaneous nerve injury, on the other hand, does not typically affect wrist movements and is responsible for elbow flexion and certain shoulder movements.
The humerus is a long bone that runs from the shoulder blade to the elbow joint. It is mostly covered by muscle but can be felt throughout its length. The head of the humerus is a smooth, rounded surface that connects to the body of the bone through the anatomical neck. The surgical neck, located below the head and tubercles, is the most common site of fracture. The greater and lesser tubercles are prominences on the upper end of the bone, with the supraspinatus and infraspinatus tendons inserted into the greater tubercle. The intertubercular groove runs between the two tubercles and holds the biceps tendon. The posterior surface of the body has a spiral groove for the radial nerve and brachial vessels. The lower end of the humerus is wide and flattened, with the trochlea, coronoid fossa, and olecranon fossa located on the distal edge. The medial epicondyle is prominent and has a sulcus for the ulnar nerve and collateral vessels.
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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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Oliver, a 6-year-old boy, arrives at the emergency department with his mother after falling from a swing and landing on his outstretched hand. He is experiencing intense pain in his left arm. An X-ray is conducted.
He has a weak radial pulse.
What is the frequently occurring fracture in children that raises the likelihood of Volkmaan's ischemic contractures?Your Answer: Supracondylar fracture of the humerus
Explanation:Volkmaan’s ischemic contractures can be caused by a supracondylar fracture of the humerus, which poses a risk of damage to the brachial artery and subsequent ischemia distal to the fracture. This type of fracture is more common in children, while a Colles fracture, which can also lead to Volkmaan’s ischemic contractures, is more common in adults. Another fracture that can result in Volkmaan’s ischemic contractures is a Monteggia fracture, which involves a fracture of the proximal third of the ulna and dislocation of the proximal head of the radius.
The humerus is a long bone that runs from the shoulder blade to the elbow joint. It is mostly covered by muscle but can be felt throughout its length. The head of the humerus is a smooth, rounded surface that connects to the body of the bone through the anatomical neck. The surgical neck, located below the head and tubercles, is the most common site of fracture. The greater and lesser tubercles are prominences on the upper end of the bone, with the supraspinatus and infraspinatus tendons inserted into the greater tubercle. The intertubercular groove runs between the two tubercles and holds the biceps tendon. The posterior surface of the body has a spiral groove for the radial nerve and brachial vessels. The lower end of the humerus is wide and flattened, with the trochlea, coronoid fossa, and olecranon fossa located on the distal edge. The medial epicondyle is prominent and has a sulcus for the ulnar nerve and collateral vessels.
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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 30-year-old construction worker presents to the GP with a complaint of right forearm pain that started 2 days ago. He reports that the pain began suddenly after lifting heavy equipment and has been progressively worsening. Upon examination, there is noticeable swelling in the forearm, and the pain intensifies with flexion of the elbow. The GP suspects a possible injury to the brachioradialis muscle.
Which nerve could have been impacted by this injury?Your Answer: Radial nerve
Explanation:The correct nerve that supplies innervation to the brachioradialis muscle is the radial nerve.
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
Correct
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A 50-year-old man presents to the emergency department with a 24-hour history of left knee pain and swelling. He has difficulty bearing weight on the left leg and reports no recent trauma, fevers, or chills. The patient has also been experiencing constipation, excessive urination, and fatigue for several months. He has a history of passing a kidney stone with hydration. He does not take prescription medications or use tobacco, alcohol, or illicit drugs.
During examination, the patient's temperature is 37.2 ºC (98.9ºF) and blood pressure is 130/76 mmHg. The right knee is tender, erythematous, and swollen. Arthrocentesis reveals a white blood cell count of 30,000/mm3, with a predominance of neutrophils and numerous rhomboid-shaped crystals.
What substance is most likely the composition of the crystals?Your Answer: Calcium pyrophosphate
Explanation:The patient is experiencing acute inflammatory arthritis, which is likely caused by pseudogout. This condition occurs when calcium pyrophosphate dihydrate crystals are deposited in the synovial fluid, and it is often associated with chronic hypercalcemia resulting from primary hyperparathyroidism. Pseudogout typically affects the knee joint, and the presence of rhomboid-shaped calcium pyrophosphate crystals in the synovial fluid is diagnostic. Calcium hydroxyapatite crystals are typically found in tendons, while calcium oxalate is the most common component of renal calculi. Xanthomas refer to the deposition of cholesterol and other lipids in soft tissues, while gout is characterized by the deposition of monosodium urate in joints and soft tissues.
Understanding Pseudogout
Pseudogout, also known as acute calcium pyrophosphate crystal deposition disease, is a type of microcrystal synovitis that occurs when calcium pyrophosphate dihydrate crystals are deposited in the synovium. This condition is commonly associated with increasing age, but younger patients who develop pseudogout usually have an underlying risk factor such as haemochromatosis, hyperparathyroidism, low magnesium or phosphate levels, acromegaly, or Wilson’s disease.
The knee, wrist, and shoulders are the most commonly affected joints in pseudogout. Diagnosis is made through joint aspiration, which reveals weakly-positively birefringent rhomboid-shaped crystals, and x-rays, which show chondrocalcinosis. In the knee, linear calcifications of the meniscus and articular cartilage can be seen.
Management of pseudogout involves joint fluid aspiration to rule out septic arthritis, followed by treatment with NSAIDs or intra-articular, intra-muscular, or oral steroids, similar to the treatment for gout. Understanding the risk factors and symptoms of pseudogout can help with early diagnosis and effective management of this condition.
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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 45-year-old woman from Afghanistan visits her GP complaining of weakness and bony pain in her legs. She denies experiencing any abdominal pain or changes in bowel habits and has no significant medical or surgical history. Upon conducting a blood test, the following results were obtained:
- Calcium: 1.8 mmol/L (normal range: 2.1-2.6)
- Phosphate: 0.5 mmol/L (normal range: 0.8-1.4)
- ALP: 240 u/L (normal range: 30-100)
- PTH: 78 pg/ml (normal range: 15-65)
What is the most probable diagnosis?Your Answer: Osteomalacia
Explanation:The correct diagnosis for this patient is osteomalacia, which is characterized by low serum calcium, low serum phosphate, raised ALP, and raised PTH. It is important to identify the risk factors for osteomalacia, such as decreased sunlight exposure, which can lead to vitamin D deficiency and subsequent hypocalcaemia. In response to hypocalcaemia, PTH levels increase, as seen in this case.
Acute pancreatitis is an incorrect diagnosis as it does not fit the patient’s clinical picture. Osteoarthritis is also an incorrect diagnosis as it would not cause changes in serum calcium, ALP, or PTH levels. Primary hyperparathyroidism is also an incorrect diagnosis as it is associated with high levels of PTH and calcium, which is not seen in this patient.
Lab Values for Bone Disorders
When it comes to bone disorders, certain lab values can provide important information about the condition. In cases of osteoporosis, calcium, phosphate, alkaline phosphatase (ALP), and parathyroid hormone (PTH) levels are typically normal. However, in osteomalacia, calcium and phosphate levels are decreased while ALP and PTH levels are increased. Primary hyperparathyroidism, which can lead to osteitis fibrosa cystica, is characterized by increased calcium and PTH levels but decreased phosphate levels. Chronic kidney disease can result in secondary hyperparathyroidism, which is marked by decreased calcium levels and increased phosphate and PTH levels. Paget’s disease, on the other hand, typically shows normal calcium and phosphate levels but increased ALP levels. Finally, osteopetrosis is associated with normal levels of calcium, phosphate, ALP, and PTH. By analyzing these lab values, healthcare professionals can better diagnose and treat bone disorders.
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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 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 8
Correct
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A 47-year-old man is undergoing a block dissection of the groin for a malignant melanoma. During the surgery, the femoral triangle is being explored to control intraoperative bleeding. What structure forms the medial border of the femoral triangle?
Your Answer: Adductor longus
Explanation:The adductor canal is bordered laterally by the vastus medialis and its roof is formed by the sartorius muscle. The adductor longus muscle forms the medial boundary of the femoral triangle.
The Adductor Canal: Anatomy and Contents
The adductor canal, also known as Hunter’s or the subsartorial canal, is a structure located in the middle third of the thigh, immediately distal to the apex of the femoral triangle. It is bordered laterally by the vastus medialis muscle and posteriorly by the adductor longus and adductor magnus muscles. The roof of the canal is formed by the sartorius muscle. The canal terminates at the adductor hiatus.
The adductor canal contains three important structures: the saphenous nerve, the superficial femoral artery, and the superficial femoral vein. The saphenous nerve is a sensory nerve that supplies the skin of the medial leg and foot. The superficial femoral artery is a major artery that supplies blood to the lower limb. The superficial femoral vein is a large vein that drains blood from the lower limb.
In order to expose the contents of the adductor canal, the sartorius muscle must be removed. Understanding the anatomy and contents of the adductor canal is important for medical professionals who perform procedures in this area, such as nerve blocks or vascular surgeries.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 9
Correct
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A 42-year-old man presents after a car accident. He has a posterior dislocation of his right knee but is in stable condition. During a neurological examination of his lower limbs, it is observed that he has a lack of plantarflexion and inversion in his right foot. Which nerve is likely affected?
Your Answer: Tibial nerve
Explanation:The tibial nerve is responsible for allowing a patient to plantarflex and invert their foot. Although it is rare for this nerve to be injured due to its location deep within soft tissue, it can be damaged in cases of posterior knee dislocations. When the tibial nerve is affected, the patient will experience a loss of these specific movements.
The common fibular nerve is not the correct answer. This nerve controls muscles in the anterior and lateral compartments of the lower limb, allowing for foot eversion and dorsiflexion. Therefore, if this nerve is damaged, the patient will experience the opposite symptoms of what is described in the scenario.
Similarly, the common peroneal nerve is not the correct answer. This nerve is responsible for foot drop, which is a loss of foot dorsiflexion and eversion. This is the opposite of what the patient in the scenario is experiencing. While it is possible for this nerve to be injured in a posterior knee dislocation, it is more commonly affected in cases of fibular neck fractures.
The femoral nerve is also not the correct answer. This nerve controls knee extension and thigh flexion, but it is not involved in foot movements. Additionally, the course of this nerve does not extend past the knee, so it cannot be damaged by a posterior knee dislocation.
Finally, the obturator nerve is not the correct answer. This nerve is located higher up in the limb and controls thigh adduction. Its course does not extend distally beyond the femoral head, so it cannot be affected by popliteal pathology.
Lower limb anatomy is an important topic that often appears in examinations. One aspect of this topic is the nerves that control motor and sensory functions in the lower limb. The femoral nerve controls knee extension and thigh flexion, and provides sensation to the anterior and medial aspect of the thigh and lower leg. It is commonly injured in cases of hip and pelvic fractures, as well as stab or gunshot wounds. The obturator nerve controls thigh adduction and provides sensation to the medial thigh. It can be injured in cases of anterior hip dislocation. The lateral cutaneous nerve of the thigh provides sensory function to the lateral and posterior surfaces of the thigh, and can be compressed near the ASIS, resulting in a condition called meralgia paraesthetica. The tibial nerve controls foot plantarflexion and inversion, and provides sensation to the sole of the foot. It is not commonly injured as it is deep and well protected, but can be affected by popliteral lacerations or posterior knee dislocation. The common peroneal nerve controls foot dorsiflexion and eversion, and can be injured at the neck of the fibula, resulting in foot drop. The superior gluteal nerve controls hip abduction and can be injured in cases of misplaced intramuscular injection, hip surgery, pelvic fracture, or posterior hip dislocation. Injury to this nerve can result in a positive Trendelenburg sign. The inferior gluteal nerve controls hip extension and lateral rotation, and is generally injured in association with the sciatic nerve. Injury to this nerve can result in difficulty rising from a seated position, as well as difficulty jumping or climbing stairs.
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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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A 6-year-old girl is brought to the clinic by her mother who is worried about her daughter's hearing loss. The girl has a history of frequent bone fractures. During the examination, the doctor observes that the external ear canal and tympanic membrane appear normal and there is no discharge or swelling. However, the girl's sclera has a bluish tint. What type of collagen is most likely affected in this case?
Your Answer: Type 1
Explanation:Osteogenesis imperfecta is caused by a defect in type 1 collagen, which is found in the skin, tendons, vasculature, and bones. This abnormality results in fragile bones, leading to multiple fractures, as seen in a child with deafness, blue sclera, and fractures. Type 2 collagen is present in cartilage and is not typically affected in osteogenesis imperfecta. Type 3 collagen is the primary component of reticular fibers, which are also not typically affected in this condition. Type 4 collagen makes up basement membranes, which are also not typically affected in osteogenesis imperfecta.
Understanding Osteogenesis Imperfecta
Osteogenesis imperfecta, also known as brittle bone disease, is a group of disorders that affect collagen metabolism, leading to bone fragility and fractures. The most common type of osteogenesis imperfecta is type 1, which is inherited in an autosomal dominant manner and is caused by decreased synthesis of pro-alpha 1 or pro-alpha 2 collagen polypeptides.
This condition typically presents in childhood, with individuals experiencing fractures following minor trauma. Other common features include blue sclera, deafness secondary to otosclerosis, and dental imperfections. Despite these symptoms, adjusted calcium, phosphate, parathyroid hormone, and ALP results are usually normal in individuals with osteogenesis imperfecta.
Overall, understanding the symptoms and underlying causes of osteogenesis imperfecta is crucial for proper diagnosis and management of this condition.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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