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Question 1
Correct
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A 12-year-old boy with sickle cell anaemia arrives at the emergency department with a hot, swollen, erythematous and painful knee. The symptoms developed over a few hours and he is unable to bear weight on the affected leg. Upon joint aspiration, cloudy synovial fluid with neutrophilia is observed. What is the primary mode of transmission for this condition?
Your Answer: Hematogenous spread
Explanation:Septic arthritis is often characterized by sudden joint pain, swelling, and warmth, and is typically caused by hematogenous spread of bacteria. Staphylococcus aureus is the most common causative organism, except in individuals with sickle cell anemia, where Salmonella is more common. While direct introduction or extension from a nearby infection can also cause septic arthritis, hematogenous spread is the most frequent cause. Unlike respiratory diseases, septic arthritis is not spread through respiratory droplets. In sexually active patients, gonococcal arthritis caused by Neisseria gonorrhoeae should be considered as a potential cause.
Septic Arthritis in Adults: Causes, Symptoms, and Treatment
Septic arthritis is a condition that occurs when bacteria infect a joint, leading to inflammation and swelling. The most common organism that causes septic arthritis in adults is Staphylococcus aureus, while Neisseria gonorrhoeae is the most common organism in sexually active young adults. The infection is usually spread through the bloodstream, often from distant bacterial infections such as abscesses. The knee is the most commonly affected joint in adults.
Symptoms of septic arthritis include acute joint swelling, restricted movement, warmth to the touch, and fever. To diagnose the condition, synovial fluid sampling is necessary and should be done before administering antibiotics if needed. Blood cultures and joint imaging may also be necessary.
Treatment for septic arthritis involves intravenous antibiotics that cover Gram-positive cocci, such as flucloxacillin or clindamycin if the patient is allergic to penicillin. Antibiotics are typically given for several weeks, and patients may be switched to oral antibiotics after two weeks. Needle aspiration is used to decompress the joint, and arthroscopic lavage may be required. Overall, prompt diagnosis and treatment are essential to prevent joint damage and other complications.
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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 70-year-old man with a history of untreated hypertension and diabetes mellitus presents to the clinic with worsening bone and joint pain. Upon examination, diffuse muscular tenderness is noted but is otherwise unremarkable. The following blood test results are obtained:
Calcium 1.9 mmol/L (2.1-2.6)
Phosphate 2.0 mmol/L (0.8-1.4)
ALP 170 IU/L (44-147)
Parathyroid Hormone 70 pg/mL (15-65)
What is the most likely diagnosis?Your Answer: Secondary hyperparathyroidism
Explanation:The patient’s low serum calcium, high serum phosphate, high ALP, and high PTH levels suggest that they have chronic kidney disease leading to secondary hyperparathyroidism. This occurs when the kidneys are unable to synthesize enough vitamin D, resulting in low calcium levels. Additionally, poor kidney function leads to high phosphate levels. As a compensatory mechanism, the parathyroid hormone levels increase, causing lytic bone lesions and high ALP, which explains the patient’s diffuse musculoskeletal tenderness.
Humoral hypercalcemia of malignancy is a condition where parathyroid hormone-related peptide acts similarly to parathyroid hormone, leading to high calcium levels. However, phosphate levels would be low or normal due to the effect of this hormone. In contrast, this patient’s parathyroid hormone levels are high, indicating secondary hyperparathyroidism.
Liver disease alone does not typically cause disturbances in calcium metabolism.
Primary hyperparathyroidism is characterized by excess secretion of parathyroid hormone, resulting in high serum calcium and parathyroid hormone levels. However, in this condition, phosphate levels are low due to the effect of high parathyroid hormone. This patient’s blood work does not suggest primary hyperparathyroidism.
Tertiary hyperparathyroidism occurs in end-stage renal disease, where longstanding secondary hyperparathyroidism leads to excess production of parathyroid hormone and eventual hypercalcemia, rather than hypocalcemia.
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 3
Incorrect
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A 25-year-old female patient visits her GP with concerns about her work performance. She reports experiencing painful episodes in her fingers for the past month, which turn white and then red. As a gardener, she requires a high level of manual dexterity for her job. The symptoms subside after she finishes her shift.
What is the underlying pathophysiological mechanism responsible for the patient's symptoms?Your Answer: Chronic increase in pressure within the carpal tunnel
Correct Answer: Exaggerated vasoconstriction
Explanation:The patient’s symptoms suggest Raynaud’s disease, which is characterized by an exaggerated vasoconstrictive response to the cold in the digital and cutaneous arteries. As the patient is young and has no history or features of an underlying rheumatological disease, it is more likely to be primary Raynaud’s disease rather than Raynaud’s phenomenon. While a blood clot or rheumatoid arthritis can also cause similar symptoms, the patient’s age and lack of relevant history make these less likely. Carpal tunnel syndrome and Cushing’s disease are unlikely to be the cause of the patient’s hand pain.
Raynaud’s phenomenon is a condition where the arteries in the fingers and toes constrict excessively in response to cold or emotional stress. It can be classified as primary (Raynaud’s disease) or secondary (Raynaud’s phenomenon) depending on the underlying cause. Raynaud’s disease is more common in young women and typically affects both sides of the body. Secondary Raynaud’s phenomenon is often associated with connective tissue disorders such as scleroderma, rheumatoid arthritis, or systemic lupus erythematosus. Other causes include leukaemia, cryoglobulinaemia, use of vibrating tools, and certain medications.
If there is suspicion of secondary Raynaud’s phenomenon, patients should be referred to a specialist for further evaluation. Treatment options include calcium channel blockers such as nifedipine as a first-line therapy. In severe cases, intravenous prostacyclin (epoprostenol) infusions may be used, which can provide relief for several weeks or months. It is important to identify and treat any underlying conditions that may be contributing to the development of Raynaud’s phenomenon. Factors that suggest an underlying connective tissue disease include onset after 40 years, unilateral symptoms, rashes, presence of autoantibodies, and digital ulcers or calcinosis. In rare cases, chilblains may also be present.
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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 79-year-old man comes to your clinic with a protruding lump in his upper arm that he noticed while gardening last week. He experienced a dull ache in the front of his shoulder at the time, but he is now pain-free and has full use of his arm. During the examination, you observe an asymmetry in the patient's arms, with a circular mass on the lower portion of his left arm. When you ask him to flex his biceps muscles, you notice that the affected arm displays the 'popeye sign.' Based on the patient's history and physical examination, it appears that he has a rupture of the long head of biceps brachii tendon. What is the origin of the long head of biceps brachii tendon?
Your Answer: Supraglenoid tubercle of the scapula
Explanation:The long head of biceps tendon runs from the supraglenoid tubercle of the scapula. A ruptured tendon of the long head of biceps brachii is more common in older individuals and may present with the ‘Popeye’ sign. Management is dependent on the patient, with surgical repair for younger patients or those with co-existing rotator cuff tears, and a conservative approach for most patients.
The shoulder joint is a shallow synovial ball and socket joint that is inherently unstable but capable of a wide range of movement. Stability is provided by the muscles of the rotator cuff. The glenoid labrum is a fibrocartilaginous rim attached to the free edge of the glenoid cavity. The fibrous capsule attaches to the scapula, humerus, and tendons of various muscles. Movements of the shoulder joint are controlled by different muscles. The joint is closely related to important anatomical structures such as the brachial plexus, axillary artery and vein, and various nerves and vessels.
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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 78-year-old man complains of heartburn and indigestion for the past 3 weeks, which he attributes to a new medication he started taking a few days ago. He has a medical history of hypertension, diabetes mellitus, osteoarthritis, right hip replacement, and recurrent falls. Which of the following medications could be causing his symptoms?
Your Answer: Bisoprolol
Correct Answer: Alendronic acid
Explanation:Oesophageal problems can be caused by bisphosphonates, which are commonly used to prevent and treat osteoporosis. These drugs can lead to gastrointestinal issues, including oesophagitis, which should prompt discontinuation of the medication. Long-term use of bisphosphonates can also result in atypical femoral fractures and osteonecrosis of the jaw. Therefore, patients should be periodically re-evaluated to assess the benefits and risks of continuing treatment, especially after five or more years of use. Before starting bisphosphonate treatment, patients should have a dental check-up and any necessary dental work should be performed.
Gliclazide, a sulfonylurea drug, can cause hypoglycemia symptoms such as dizziness, lack of energy, drowsiness, headache, and sweating.
Metformin is associated with lactic acidosis and gastrointestinal problems.
Bisoprolol can cause erectile dysfunction, cold hands and feet, bradycardia, and hypotension.
Paracetamol, unlike NSAIDs, is not known to cause indigestion.
Bisphosphonates: Uses, Adverse Effects, and Patient Counselling
Bisphosphonates are drugs that mimic the action of pyrophosphate, a molecule that helps prevent bone demineralization. They work by inhibiting osteoclasts, the cells responsible for breaking down bone tissue. Bisphosphonates are commonly used to prevent and treat osteoporosis, hypercalcemia, Paget’s disease, and pain from bone metastases.
However, bisphosphonates can cause adverse effects such as oesophageal reactions, osteonecrosis of the jaw, and an increased risk of atypical stress fractures of the proximal femoral shaft in patients taking alendronate. Patients may also experience an acute phase response, which includes fever, myalgia, and arthralgia following administration. Hypocalcemia may also occur due to reduced calcium efflux from bone, but this is usually clinically unimportant.
To minimize the risk of adverse effects, patients taking oral bisphosphonates should swallow the tablets whole with plenty of water while sitting or standing. They should take the medication on an empty stomach at least 30 minutes before breakfast or another oral medication and remain upright for at least 30 minutes after taking the tablet. Hypocalcemia and vitamin D deficiency should be corrected before starting bisphosphonate treatment. However, calcium supplements should only be prescribed if dietary intake is inadequate when starting bisphosphonate treatment for osteoporosis. Vitamin D supplements are usually given.
The duration of bisphosphonate treatment varies depending on the level of risk. Some experts recommend stopping bisphosphonates after five years if the patient is under 75 years old, has a femoral neck T-score of more than -2.5, and is at low risk according to FRAX/NOGG.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 6
Incorrect
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A 50-year-old male presents to the emergency department after sustaining a high-impact golf ball injury to his foot while playing golf. Upon examination, there is bruising around the lateral malleolus and loss of sensation to the lateral foot. Palpation reveals tenderness in the lateral malleolus. An X-ray confirms a posteriorly displaced fracture of the lateral malleolus. What structure is likely to have been affected by this displacement?
Your Answer: Anterior talofibular ligament
Correct Answer: Sural nerve
Explanation:The sural nerve is situated behind the lateral malleolus, which is commonly fractured due to direct trauma. In this patient, the lateral malleolus fracture is displaced posteriorly, posing a risk of direct compression and potential injury to the sural nerve. Other structures located behind the lateral malleolus include the short saphenous vein, peroneus longus tendon, and peroneus brevis tendon. The anterior talofibular ligament is a flat band that extends from the front edge of the lateral malleolus to the neck of the talus, just ahead of the fibular facet. The remaining options are incorrect.
Anatomy of the Lateral Malleolus
The lateral malleolus is a bony prominence on the outer side of the ankle joint. Posterior to the lateral malleolus and superficial to the superior peroneal retinaculum are the sural nerve and short saphenous vein. These structures are important for sensation and blood flow to the lower leg and foot.
On the other hand, posterior to the lateral malleolus and deep to the superior peroneal retinaculum are the peroneus longus and peroneus brevis tendons. These tendons are responsible for ankle stability and movement.
Additionally, the calcaneofibular ligament is attached at the lateral malleolus. This ligament is important for maintaining the stability of the ankle joint and preventing excessive lateral movement.
Understanding the anatomy of the lateral malleolus is crucial for diagnosing and treating ankle injuries and conditions. Proper care and management of these structures can help prevent long-term complications and improve overall ankle function.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 7
Incorrect
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A 25-year-old male is having a full anterior cruciate ligament reconstruction procedure in the primary orthopaedic operating room. While performing the surgery, the orthopaedic surgeon requests his assistant to locate the blood vessel that is being ligated to prevent bleeding and supplies oxygenated blood to the ACL.
Your Answer: Inferior medial geniculate arteries
Correct Answer: Middle genicular artery
Explanation:The middle genicular artery is responsible for providing blood supply to the anterior cruciate ligament, while the lateral femoral circumflex artery supplies certain muscles located on the lateral side of the thigh.
The knee joint is the largest and most complex synovial joint in the body, consisting of two condylar joints between the femur and tibia and a sellar joint between the patella and femur. The degree of congruence between the tibiofemoral articular surfaces is improved by the presence of the menisci, which compensate for the incongruence of the femoral and tibial condyles. The knee joint is divided into two compartments: the tibiofemoral and patellofemoral compartments. The fibrous capsule of the knee joint is a composite structure with contributions from adjacent tendons, and it contains several bursae and ligaments that provide stability to the joint. The knee joint is supplied by the femoral, tibial, and common peroneal divisions of the sciatic nerve and by a branch from the obturator nerve, while its blood supply comes from the genicular branches of the femoral artery, popliteal, and anterior tibial arteries.
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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 67-year-old man is being evaluated by a vascular specialist for poor diabetes control. His HbA1c is 7.8% and he has a medical history of type II diabetes, hypertension, hyperlipidaemia, and hypothyroidism. During the examination, the specialist observes diminished posterior tibial pulses. Which area is likely to experience compromised blood supply due to reduced blood flow through the posterior tibial artery?
Your Answer: Posterior compartment of the leg and plantar surface of the foot
Explanation:The posterior tibial artery is responsible for supplying oxygenated blood to the posterior compartment of the leg as well as the plantar surface of the foot.
Anatomy of the Posterior Tibial Artery
The posterior tibial artery is a major branch of the popliteal artery that terminates by dividing into the medial and lateral plantar arteries. It is accompanied by two veins throughout its length and its position corresponds to a line drawn from the lower angle of the popliteal fossa to a point midway between the medial malleolus and the most prominent part of the heel.
The artery is located anteriorly to the tibialis posterior and flexor digitorum longus muscles, and posteriorly to the surface of the tibia and ankle joint. The posterior tibial nerve is located 2.5 cm distal to its origin. The proximal part of the artery is covered by the gastrocnemius and soleus muscles, while the distal part is covered by skin and fascia. The artery is also covered by the fascia overlying the deep muscular layer.
Understanding the anatomy of the posterior tibial artery is important for medical professionals, as it plays a crucial role in the blood supply to the foot and ankle. Any damage or blockage to this artery can lead to serious complications, such as peripheral artery disease or even amputation.
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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 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: C3-C5
Correct 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 10
Correct
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A 32-year-old female patient visits the GP with a concern about her middle finger's inability to flex at the end. During the examination, it is observed that she cannot bend the distal interphalangeal joint of her middle finger.
Which muscle is accountable for this movement?Your Answer: Flexor digitorum profundus
Explanation:The correct answer is that the flexor digitorum profundus muscle is responsible for flexing the distal interphalangeal joint. The other options, such as the flexor digitorum superficialis and flexor pollicis longus, are responsible for different movements and are therefore incorrect. The palmar interossei are also not responsible for flexion at the distal interphalangeal joint. Lastly, there is no such muscle as the flexor digiti medius.
The forearm flexor muscles include the flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis, and flexor digitorum profundus. These muscles originate from the common flexor origin and surrounding fascia, and are innervated by the median and ulnar nerves. Their actions include flexion and abduction of the carpus, wrist flexion, adduction of the carpus, and flexion of the metacarpophalangeal and interphalangeal joints.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 11
Correct
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A 26-year-old medical student visits his doctor with a complaint of experiencing dry mouth, particularly at night, which has been affecting his sleep. He has a medical history of allergic rhinitis and is currently taking chlorphenamine for it.
What is the correct explanation for the mechanism of action of chlorphenamine?Your Answer: H1 receptor antagonist
Explanation:Chlorphenamine is a medication.
Antihistamines for Allergic Rhinitis and Urticaria
Antihistamines, specifically H1 inhibitors, are effective in treating allergic rhinitis and urticaria. Sedating antihistamines like chlorpheniramine have antimuscarinic properties that can cause dry mouth and urinary retention. On the other hand, non-sedating antihistamines like loratadine and cetirizine are less likely to cause drowsiness. However, there is some evidence that cetirizine may still cause some level of drowsiness compared to other non-sedating antihistamines. Overall, antihistamines are a valuable treatment option for those suffering from allergic rhinitis and urticaria.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 12
Incorrect
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A 65-year-old woman is recuperating from a tibia fracture and has been wearing a snug cast over the proximal knee for three weeks. She reports numbness over the lateral two-thirds of the outer leg. During a lower limb neurological examination, the junior doctor suspects injury to the common fibular nerve. Which muscle is expected to be unaffected in this patient?
Your Answer: Extensor hallucis longus
Correct Answer: Biceps femoris
Explanation:The short head of the biceps femoris muscle is supplied by the common peroneal division of the sciatic nerve, while the long head is innervated by the tibial branch of the sciatic nerve. Despite this, the biceps femoris can still perform knee flexion. The extensor digitorum longus, extensor hallucis longus, and fibularis tertius muscles are all innervated by the deep fibular nerve, which is a branch of the common fibular nerve. Weakness in toe extension and big-toe extension may occur due to damage to these muscles, while the fibularis tertius muscle is important for eversion of the foot during walking.
The Biceps Femoris Muscle
The biceps femoris is a muscle located in the posterior upper thigh and is part of the hamstring group of muscles. It consists of two heads: the long head and the short head. The long head originates from the ischial tuberosity and inserts into the fibular head. Its actions include knee flexion, lateral rotation of the tibia, and extension of the hip. It is innervated by the tibial division of the sciatic nerve and supplied by the profunda femoris artery, inferior gluteal artery, and the superior muscular branches of the popliteal artery.
On the other hand, the short head originates from the lateral lip of the linea aspera and the lateral supracondylar ridge of the femur. It also inserts into the fibular head and is responsible for knee flexion and lateral rotation of the tibia. It is innervated by the common peroneal division of the sciatic nerve and supplied by the same arteries as the long head.
Understanding the anatomy and function of the biceps femoris muscle is important in the diagnosis and treatment of injuries and conditions affecting the posterior thigh.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 13
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 14
Incorrect
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Roughly what percentage of saliva production comes from the submandibular glands?
Your Answer: 40%
Correct Answer: 70%
Explanation:Anatomy of the Submandibular Gland
The submandibular gland is located beneath the mandible and is surrounded by the superficial platysma, deep fascia, and mandible. It is also in close proximity to various structures such as the submandibular lymph nodes, facial vein, marginal mandibular nerve, cervical branch of the facial nerve, deep facial artery, mylohyoid muscle, hyoglossus muscle, lingual nerve, submandibular ganglion, and hypoglossal nerve.
The submandibular duct, also known as Wharton’s duct, is responsible for draining saliva from the gland. It opens laterally to the lingual frenulum on the anterior floor of the mouth and is approximately 5 cm in length. The lingual nerve wraps around the duct, and as it passes forward, it crosses medial to the nerve to lie above it before crossing back, lateral to it, to reach a position below the nerve.
The submandibular gland receives sympathetic innervation from the superior cervical ganglion and parasympathetic innervation from the submandibular ganglion via the lingual nerve. Its arterial supply comes from a branch of the facial artery, which passes through the gland to groove its deep surface before emerging onto the face by passing between the gland and the mandible. The anterior facial vein provides venous drainage, and the gland’s lymphatic drainage goes to the deep cervical and jugular chains of nodes.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 15
Incorrect
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Which one of the following is a content of the adductor canal?
Your Answer: Femoral nerve
Correct Answer: Saphenous nerve
Explanation:The saphenous nerve and the superficial branch of the femoral artery are both present in this area.
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 16
Correct
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Sarah, a 67-year-old female, fell down some stairs and fractured her left calcaneus. Before starting the management, the doctors conducted a neurovascular examination of Sarah's lower limb and foot. They found that Sarah has palpable pulses, but she has reduced sensation in her lateral left foot. The doctor suspects that the fracture may have caused nerve damage, leading to the reduced sensation.
What nerve could be affected by the fracture, resulting in the reduced sensation in Sarah's lateral left foot?Your Answer: Sural nerve
Explanation:The lateral foot is innervated by the sural nerve, which is a branch of both the common fibular and tibial nerves. The medial aspect of the leg is innervated by the saphenous nerve, which arises from the femoral nerve. The sole of the foot is mainly innervated by branches of the tibial nerve, including the medial calcaneal, lateral, and medial plantar nerves. The dorsum of the foot is mainly innervated by the superficial fibular nerve, while the web space between the first and second toes is innervated by the deep fibular nerve.
Anatomy of the Lateral Malleolus
The lateral malleolus is a bony prominence on the outer side of the ankle joint. Posterior to the lateral malleolus and superficial to the superior peroneal retinaculum are the sural nerve and short saphenous vein. These structures are important for sensation and blood flow to the lower leg and foot.
On the other hand, posterior to the lateral malleolus and deep to the superior peroneal retinaculum are the peroneus longus and peroneus brevis tendons. These tendons are responsible for ankle stability and movement.
Additionally, the calcaneofibular ligament is attached at the lateral malleolus. This ligament is important for maintaining the stability of the ankle joint and preventing excessive lateral movement.
Understanding the anatomy of the lateral malleolus is crucial for diagnosing and treating ankle injuries and conditions. Proper care and management of these structures can help prevent long-term complications and improve overall ankle function.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 17
Correct
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A 67-years-old man with a history of gout and seasonal allergies visits his primary care physician. He reports experiencing a burning sensation on the left side of his chest for the past three days, which has been disrupting his sleep. He has also had a fever for the last three days.
During the examination, the physician observes erythema and occasional vesicles on the left side of the patient's chest. The affected area extends from above his nipple to under his axilla.
What is the most probable diagnosis?Your Answer: Shingles
Explanation:Shingles is a painful blistering rash caused by reactivation of the varicella-zoster virus. It is more common in older individuals and those with immunosuppressive conditions. The diagnosis is usually clinical and management includes analgesia, antivirals, and reminding patients they are potentially infectious. Complications include post-herpetic neuralgia, herpes zoster ophthalmicus, and herpes zoster oticus. Antivirals should be used within 72 hours to reduce the incidence of post-herpetic neuralgia.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 18
Incorrect
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Which one of the following muscles does not attach to the radius?
Your Answer: Pronator quadratus
Correct Answer: Brachialis
Explanation:The ulna serves as the insertion point for the brachialis muscle, while the remaining muscles are inserted onto the radius.
Anatomy of the Radius Bone
The radius bone is one of the two long bones in the forearm that extends from the lateral side of the elbow to the thumb side of the wrist. It has two expanded ends, with the distal end being the larger one. The upper end of the radius bone has articular cartilage that covers the medial to lateral side and articulates with the radial notch of the ulna by the annular ligament. The biceps brachii muscle attaches to the tuberosity of the upper end.
The shaft of the radius bone has several muscle attachments. The upper third of the body has the supinator, flexor digitorum superficialis, and flexor pollicis longus muscles. The middle third of the body has the pronator teres muscle, while the lower quarter of the body has the pronator quadratus muscle and the tendon of supinator longus.
The lower end of the radius bone is quadrilateral in shape. The anterior surface is covered by the capsule of the wrist joint, while the medial surface has the head of the ulna. The lateral surface ends in the styloid process, and the posterior surface has three grooves that contain the tendons of extensor carpi radialis longus and brevis, extensor pollicis longus, and extensor indicis. Understanding the anatomy of the radius bone is crucial in diagnosing and treating injuries and conditions that affect this bone.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 19
Correct
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A 28-year-old man visits his GP with complaints of ongoing stiffness and pain in his lower back for the past 6 months. He reports no specific injury that could have caused his symptoms and mentions that he leads an active lifestyle. The pain is particularly severe in the morning but improves with physical activity. Following imaging tests, he is diagnosed with ankylosing spondylitis. What is the gene linked to this condition?
Your Answer: Human leucocyte antigen- B27
Explanation:Ankylosing spondylitis is associated with the HLA-B27 serotype, with approximately 90% of patients with the condition testing positive for it. Adrenal 21-hydroxylase deficiency is thought to be linked to HLA-B47, while HLA-DQ2 is associated with coeliac disease and the development of autoimmune diseases. HLA-DR4 is primarily linked to rheumatoid arthritis, while HLA-DR2 is associated with systemic lupus erythematosus, multiple sclerosis, and leprosy, but not ankylosing spondylitis.
Ankylosing spondylitis is a type of spondyloarthropathy that is associated with HLA-B27. It is more common in males aged 20-30 years old. Inflammatory markers such as ESR and CRP are often elevated, but normal levels do not rule out ankylosing spondylitis. HLA-B27 is not very useful in making the diagnosis as it is positive in 90% of patients with ankylosing spondylitis and 10% of normal patients. The most useful diagnostic tool is a plain x-ray of the sacroiliac joints, which may show subchondral erosions, sclerosis, squaring of lumbar vertebrae, bamboo spine, and syndesmophytes. If the x-ray is negative but suspicion for AS remains high, an MRI may be obtained to confirm the diagnosis. Spirometry may show a restrictive defect due to pulmonary fibrosis, kyphosis, and ankylosis of the costovertebral joints.
Management of ankylosing spondylitis includes regular exercise such as swimming, NSAIDs as first-line treatment, physiotherapy, and disease-modifying drugs such as sulphasalazine if there is peripheral joint involvement. Anti-TNF therapy such as etanercept and adalimumab may be given to patients with persistently high disease activity despite conventional treatments, according to the 2010 EULAR guidelines. Research is ongoing to determine whether anti-TNF therapies should be used earlier in the course of the disease.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 20
Correct
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An 80-year-old falls in the garden. She arrives at the emergency department with left leg pain and is unable to bear weight. Upon examination, her left leg is shortened and externally rotated. An x-ray is conducted in the emergency department, revealing an intracapsular fracture of the left neck of femur. The medical team reviews the imaging and expresses concern about osteonecrosis of the femoral head.
Which artery's damage is the most concerning in this case?Your Answer: Medial circumflex femoral artery
Explanation:The medial femoral circumflex artery is the primary supplier of blood to the femoral head. This artery wraps around the back of the femur to provide blood to the neck and head of the femur. In cases of femoral neck fractures, damage to this artery can occur, leading to a disruption of blood supply and resulting in osteonecrosis of the femoral head.
The deep femoral artery, also known as the profunda femoris, is a branch of the femoral artery that supplies the deep tissues of the thigh. It branches into the lateral and medial femoral circumflex arteries and the perforating arteries, but it does not directly supply the femoral head. It is not typically affected in cases of femoral neck fractures and is therefore not the correct answer.
The femoral artery is responsible for providing blood supply to the lower limb, but it does not directly supply the femoral head. It is not typically affected in cases of femoral neck fractures and is therefore not the correct answer.
The lateral femoral circumflex artery wraps around the front and side of the femur to supply the femoral neck and musculature on the lateral aspect of the thigh. While it does provide some blood supply to the femoral head, it is not the primary supplier and is therefore not the correct answer.
The popliteal artery is a continuation of the femoral artery at the adductor hiatus and supplies the knee, lower leg, and foot. It is not directly involved in the blood supply to the femoral head and is therefore not the correct answer.
Anatomy of the Femur: Structure and Blood Supply
The femur is the longest and strongest bone in the human body, extending from the hip joint to the knee joint. It consists of a rounded head that articulates with the acetabulum and two large condyles at its inferior aspect that articulate with the tibia. The superior aspect of the femur comprises a head and neck that pass inferolaterally to the body and the two trochanters. The neck meets the body of the femur at an angle of 125o and is demarcated from it by a wide rough intertrochanteric crest. The greater trochanter has discernible surfaces that form the site of attachment of the gluteal muscles, while the linea aspera forms part of the origin of the attachments of the thigh adductors.
The femur has a rich blood supply, with numerous vascular foramina existing throughout its length. The blood supply to the femoral head is clinically important and is provided by the medial circumflex femoral and lateral circumflex femoral arteries, which are branches of the profunda femoris. The inferior gluteal artery also contributes to the blood supply. These arteries form an anastomosis and travel up the femoral neck to supply the head. It is important to note that the neck is covered by synovial membrane up to the intertrochanteric line, and the posterior aspect of the neck is demarcated from the shaft by the intertrochanteric crest. Understanding the anatomy of the femur, including its structure and blood supply, is crucial for medical professionals in diagnosing and treating injuries and conditions related to this bone.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 21
Correct
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A 46-year-old woman arrives at the emergency department after falling while walking her dog. She explains that she stumbled on the pavement and landed on her left hand, with her hands taking the brunt of the fall.
During the examination, the doctor notices tenderness over the anatomical snuffbox and telescoping of the left thumb. What other structure is in danger of being harmed, considering the probable diagnosis?Your Answer: Radial artery
Explanation:The anatomical snuffbox contains the radial artery and is a common site for scaphoid fractures. The scaphoid bone forms the floor of the snuffbox and the radial artery provides its blood supply. Missing a scaphoid fracture can lead to avascular necrosis. Other structures such as the flexor pollicis longus tendon, median nerve, pisiform bone, and ulnar artery do not lie within the snuffbox.
The Anatomical Snuffbox: A Triangle on the Wrist
The anatomical snuffbox is a triangular depression located on the lateral aspect of the wrist. It is bordered by tendons of the extensor pollicis longus, extensor pollicis brevis, and abductor pollicis longus muscles, as well as the styloid process of the radius. The floor of the snuffbox is formed by the trapezium and scaphoid bones. The apex of the triangle is located distally, while the posterior border is formed by the tendon of the extensor pollicis longus. The radial artery runs through the snuffbox, making it an important landmark for medical professionals.
In summary, the anatomical snuffbox is a small triangular area on the wrist that is bordered by tendons and bones. It is an important landmark for medical professionals due to the presence of the radial artery.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 22
Incorrect
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A 28-year-old woman comes in with a pigmented lesion measuring 1.5cm on her back. The surgeon suspects it may be a melanoma. What would be the best course of action?
Your Answer: 2mm punch biopsy from the centre of the lesion
Correct Answer: Excisional biopsy of the lesion
Explanation:It is not recommended to partially sample suspicious naevi as this can greatly compromise the accuracy of histological interpretation. Complete excision is necessary for lesions that meet diagnostic criteria. However, it may be acceptable to delay wide excision for margins until definitive histology results are available.
When dealing with suspicious melanomas, it is important to excise them with complete margins. Radical excision is not typically performed for diagnostic purposes, so if subsequent histopathological analysis confirms the presence of melanoma, further excision of margins may be necessary. Incisional punch biopsies of potential melanomas can make histological interpretation challenging and should be avoided whenever possible.
Malignant melanoma is a type of skin cancer that has four main subtypes: superficial spreading, nodular, lentigo maligna, and acral lentiginous. Nodular melanoma is the most aggressive, while the other forms spread more slowly. Superficial spreading melanoma typically affects young people on sun-exposed areas such as the arms, legs, back, and chest. Nodular melanoma appears as a red or black lump that bleeds or oozes and affects middle-aged people. Lentigo maligna affects chronically sun-exposed skin in older people, while acral lentiginous melanoma appears on nails, palms, or soles in people with darker skin pigmentation. Other rare forms of melanoma include desmoplastic melanoma, amelanotic melanoma, and melanoma arising in other parts of the body such as ocular melanoma.
The main diagnostic features of melanoma are changes in size, shape, and color. Secondary features include a diameter of 7mm or more, inflammation, oozing or bleeding, and altered sensation. Suspicious lesions should undergo excision biopsy, and the lesion should be completely removed to facilitate subsequent histopathological assessment. Once the diagnosis is confirmed, the pathology report should be reviewed to determine whether further re-excision of margins is required. The margins of excision are related to Breslow thickness, with lesions 0-1mm thick requiring a margin of 1 cm, lesions 1-2mm thick requiring a margin of 1-2 cm (depending on site and pathological features), lesions 2-4mm thick requiring a margin of 2-3 cm (depending on site and pathological features), and lesions over 4mm thick requiring a margin of 3 cm. Further treatments such as sentinel lymph node mapping, isolated limb perfusion, and block dissection of regional lymph node groups should be selectively applied.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 23
Incorrect
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Which of the following is not found in the deep posterior compartment of the lower leg?
Your Answer: Flexor hallucis longus
Correct Answer: Sural nerve
Explanation:The deep posterior compartment is located in front of the soleus muscle, and the sural nerve is not enclosed within it due to its superficial position.
Muscular Compartments of the Lower Limb
The lower limb is composed of different muscular compartments that perform various actions. The anterior compartment includes the tibialis anterior, extensor digitorum longus, peroneus tertius, and extensor hallucis longus muscles. These muscles are innervated by the deep peroneal nerve and are responsible for dorsiflexing the ankle joint, inverting and evert the foot, and extending the toes.
The peroneal compartment, on the other hand, consists of the peroneus longus and peroneus brevis muscles, which are innervated by the superficial peroneal nerve. These muscles are responsible for eversion of the foot and plantar flexion of the ankle joint.
The superficial posterior compartment includes the gastrocnemius and soleus muscles, which are innervated by the tibial nerve. These muscles are responsible for plantar flexion of the foot and may also flex the knee.
Lastly, the deep posterior compartment includes the flexor digitorum longus, flexor hallucis longus, and tibialis posterior muscles, which are innervated by the tibial nerve. These muscles are responsible for flexing the toes, flexing the great toe, and plantar flexion and inversion of the foot, respectively.
Understanding the muscular compartments of the lower limb is important in diagnosing and treating injuries and conditions that affect these muscles. Proper identification and management of these conditions can help improve mobility and function of the lower limb.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 24
Incorrect
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A 25-year-old woman visits the clinic with a rash on her right ankle. She suspects it was triggered by a new anklet gifted by her friend. What category of hypersensitivity response does this fall under?
Your Answer: Type 1
Correct Answer: Type 4
Explanation:The Gell and Coombs classification divides hypersensitivity reactions into four types. Type 1 is immediate and IgE mediated, type 2 is mediated by IgG and IgM causing cell death, type 3 is mediated by immune complexes, and type 4 is delayed and mediated by T lymphocytes causing contact dermatitis. Examples of each type include allergic rhinitis, Goodpasture syndrome, and rheumatoid arthritis. Nickel is a common cause of contact dermatitis.
Understanding Contact Dermatitis
Contact dermatitis is a skin condition that can be caused by two main types of reactions. The first type is irritant contact dermatitis, which is a non-allergic reaction that occurs due to exposure to weak acids or alkalis, such as detergents. This type of dermatitis is commonly seen on the hands and is characterized by erythema, but crusting and vesicles are rare.
The second type of contact dermatitis is allergic contact dermatitis, which is a type IV hypersensitivity reaction. This type of dermatitis is uncommon and is often seen on the head following hair dyes. It presents as an acute weeping eczema that predominantly affects the margins of the hairline rather than the hairy scalp itself. Topical treatment with a potent steroid is indicated for this type of dermatitis.
Cement is a frequent cause of contact dermatitis. The alkaline nature of cement may cause an irritant contact dermatitis, while the dichromates in cement can also cause an allergic contact dermatitis. It is important to understand the different types of contact dermatitis and their causes to effectively manage and treat this condition.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 25
Incorrect
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A 67-year-old female presents to her primary healthcare provider with painful blisters on her gingival and buccal mucosa and skin that easily rupture and cause ulcers. The oral blisters began three months ago and the cutaneous lesions just a week ago. She has a medical history of hypertension, vitiligo, and type 2 diabetes mellitus. Upon examination of the oral cavity and skin, scattered shallow ulcerations ranging from 8 mm to 1 cm in diameter were observed. A biopsy of the lesions revealed acantholysis. The patient has been prescribed corticosteroids.
What is the most likely cause of this condition in the patient?Your Answer: Antibodies against desmoplakin I
Correct Answer: Antibodies against desmoglein 3
Explanation:Pemphigus vulgaris is an autoimmune condition that occurs when the body’s immune system attacks desmoglein 3, a type of cell adhesion molecule found in epithelial cells. This disease is more prevalent in the Ashkenazi Jewish population. The most common symptom is mucosal ulceration, which can be the first sign of the disease. Oral involvement is seen in 50-70% of patients. Skin blistering is also a common symptom, with easily ruptured vesicles and bullae. These lesions are typically painful but not itchy and may appear months after the initial mucosal symptoms. Nikolsky’s sign is a characteristic feature of pemphigus vulgaris, where bullae spread following the application of horizontal, tangential pressure to the skin. Biopsy results often show acantholysis.
The first-line treatment for pemphigus vulgaris is steroids, which help to reduce inflammation and suppress the immune system. Immunosuppressants may also be used to manage the disease.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 26
Correct
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As a medical student on placement with a surgical team, you come across a patient who has developed foot drop in their right leg after surgery. You notice that the patient is dragging their right foot and experiencing weakness in dorsiflexion and eversion of their foot, as well as an inability to extend their toes. Which nerve is most likely to have been affected during the operation?
Your Answer: Common fibular nerve
Explanation:The common fibular nerve starts at the top of the popliteal fossa, passing medial to the biceps femoris and then crossing over the head of the gastrocnemius. It provides an articular branch to the knee before winding around the neck and passing under the Fibularis longus. At this point, it divides into superficial and deep branches. In the popliteal fossa, it also divides to give the lateral sural cutaneous nerve, which joins with a branch from the tibial nerve to form the sural nerve. If the nerve is damaged, it can result in foot drop, which can occur due to prolonged pressure on the nerve during an operation or other causes. Motor loss of other nerves, such as the tibial, sciatic, inferior gluteal, or femoral nerves, can result in weakness in other muscles.
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 27
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 28
Correct
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Which of the following nerves is responsible for innervating the triceps muscle?
Your Answer: Radial
Explanation:To memorize the nerve roots and their corresponding reflexes:
1-2: Ankle reflex (S1-S2)
3-4: Knee reflex (L3-L4)
5-6: Biceps reflex (C5-C6)
7-8: Triceps reflex (C7-C8)It’s important to note that the radial nerve provides innervation to all three heads of the triceps muscle, with a distinct branch to each head.
Anatomy of the Triceps Muscle
The triceps muscle is a large muscle located on the back of the upper arm. It is composed of three heads: the long head, lateral head, and medial head. The long head originates from the infraglenoid tubercle of the scapula, while the lateral head originates from the dorsal surface of the humerus, lateral and proximal to the groove of the radial nerve. The medial head originates from the posterior surface of the humerus on the inferomedial side of the radial groove and both of the intermuscular septae.
All three heads of the triceps muscle insert into the olecranon process of the ulna, with some fibers inserting into the deep fascia of the forearm and the posterior capsule of the elbow. The triceps muscle is innervated by the radial nerve and supplied with blood by the profunda brachii artery.
The primary action of the triceps muscle is elbow extension. The long head can also adduct the humerus and extend it from a flexed position. The radial nerve and profunda brachii vessels lie between the lateral and medial heads of the triceps muscle. Understanding the anatomy of the triceps muscle is important for proper diagnosis and treatment of injuries or conditions affecting this muscle.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 29
Correct
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Which of the following anatomical structures is located in the spiral groove of the humerus?
Your Answer: Radial nerve
Explanation:Fractures involving the shaft can compromise the radial nerve, which is located in this groove.
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 30
Correct
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A 75-year-old woman presents with a five-day history of difficulty initiating abduction of her right arm. She denies any pain or previous shoulder issues and has not experienced any trauma. During examination, her passive range of motion is normal, but she is unable to begin abduction from a neutral position. However, if she uses her left arm to lift her right arm to approximately 15 degrees, she is then able to continue abduction without difficulty. Which muscle is responsible for initiating shoulder abduction?
Your Answer: Supraspinatus
Explanation:The Supraspinatus muscle is responsible for starting the process of lifting the arm away from the body, up to a point of about 15 degrees. After this point, the Deltoid muscle takes over as the primary muscle responsible for continuing the arm’s upward movement. When the arm is lifted beyond 90 degrees, the Trapezius muscle comes into play, elevating the shoulder and rotating the scapula. Finally, the Infraspinatus muscle is responsible for producing lateral rotation of the arm at the shoulder.
Understanding the Rotator Cuff Muscles
The rotator cuff muscles are a group of four muscles that are responsible for the movement and stability of the shoulder joint. These muscles are known as the SItS muscles, which stands for Supraspinatus, Infraspinatus, teres minor, and Subscapularis. Each of these muscles has a specific function in the movement of the shoulder joint.
The Supraspinatus muscle is responsible for abducting the arm before the deltoid muscle. It is the most commonly injured muscle in the rotator cuff. The Infraspinatus muscle rotates the arm laterally, while the teres minor muscle adducts and rotates the arm laterally. Lastly, the Subscapularis muscle adducts and rotates the arm medially.
Understanding the functions of each of these muscles is important in diagnosing and treating rotator cuff injuries. By identifying which muscle is injured, healthcare professionals can develop a treatment plan that targets the specific muscle and promotes healing. Overall, the rotator cuff muscles play a crucial role in the movement and stability of the shoulder joint.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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