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Question 1
Incorrect
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Which muscle initiates abduction of the shoulder at an early age?
Your Answer: Latissimus dorsi
Correct Answer: Supraspinatus
Explanation:The primary function of the intermediate deltoid muscle is to abduct the humerus, but it relies on the supraspinatus muscle to initiate this movement. Rotator cuff disease often involves damage to the supraspinatus tendon.
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 2
Correct
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A young adult is started on a novel medication for managing their Crohn's disease. They are advised that the medication is to be taken once a week and may elevate their susceptibility to infections. Additionally, folic acid is prescribed alongside the new medication to mitigate other potential adverse effects.
What is the mode of action of this drug?Your Answer: Inhibits dihydrofolate reductase
Explanation:Methotrexate inhibits dihydrofolate reductase to suppress the immune system and manage Crohn’s disease. This medication is taken once weekly and prescribed with folic acid. Methotrexate blocks the production of nucleotides, which impairs cell replication, particularly in rapidly replicating immune cells, leading to a reduced autoimmune response. Binding to steroid receptors, inhibiting dihydropteroate synthetase, and mimicking the shape of purines are incorrect answers. These mechanisms of action belong to other medications used to manage different conditions.
Methotrexate is an antimetabolite that hinders the activity of dihydrofolate reductase, an enzyme that is crucial for the synthesis of purines and pyrimidines. It is a significant drug that can effectively control diseases, but its side-effects can be life-threatening. Therefore, careful prescribing and close monitoring are essential. Methotrexate is commonly used to treat inflammatory arthritis, especially rheumatoid arthritis, psoriasis, and acute lymphoblastic leukaemia. However, it can cause adverse effects such as mucositis, myelosuppression, pneumonitis, pulmonary fibrosis, and liver fibrosis.
Women should avoid pregnancy for at least six months after stopping methotrexate treatment, and men using methotrexate should use effective contraception for at least six months after treatment. Prescribing methotrexate requires familiarity with guidelines relating to its use. It is taken weekly, and FBC, U&E, and LFTs need to be regularly monitored. Folic acid 5 mg once weekly should be co-prescribed, taken more than 24 hours after methotrexate dose. The starting dose of methotrexate is 7.5 mg weekly, and only one strength of methotrexate tablet should be prescribed.
It is important to avoid prescribing trimethoprim or co-trimoxazole concurrently as it increases the risk of marrow aplasia. High-dose aspirin also increases the risk of methotrexate toxicity due to reduced excretion. In case of methotrexate toxicity, the treatment of choice is folinic acid. Overall, methotrexate is a potent drug that requires careful prescribing and monitoring to ensure its effectiveness and safety.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 3
Correct
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A 25-year-old man is stabbed in the neck, in the area between the omohyoid and digastric muscles. During surgery to explore the injury, a nerve injury is discovered just above the lingual artery where it branches off from the external carotid artery. What is the most probable outcome of this injury?
Your Answer: Paralysis of the ipsilateral side of the tongue
Explanation:The external carotid artery is located posterior to the hypoglossal nerve, while the lingual arterial branch is situated below it. In case of damage to the nerve, the genioglossus, hyoglossus, and styloglossus muscles on the same side will become paralyzed. When the patient is instructed to stick out their tongue, it will deviate towards the affected side.
The Anterior Triangle of the Neck: Boundaries and Contents
The anterior triangle of the neck is a region that is bounded by the anterior border of the sternocleidomastoid muscle, the lower border of the mandible, and the anterior midline. It is further divided into three sub-triangles by the digastric muscle and the omohyoid muscle. The muscular triangle contains the neck strap muscles, while the carotid triangle contains the carotid sheath, which houses the common carotid artery, the vagus nerve, and the internal jugular vein. The submandibular triangle, located below the digastric muscle, contains the submandibular gland, submandibular nodes, facial vessels, hypoglossal nerve, and other structures.
The digastric muscle, which separates the submandibular triangle from the muscular triangle, is innervated by two different nerves. The anterior belly of the digastric muscle is supplied by the mylohyoid nerve, while the posterior belly is supplied by the facial nerve.
Overall, the anterior triangle of the neck is an important anatomical region that contains many vital structures, including blood vessels, nerves, and glands. Understanding the boundaries and contents of this region is essential for medical professionals who work in this area.
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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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An 77-year-old woman visits her doctor complaining of loose teeth and mucosal ulcers that won't heal. She has a medical history of asthma, diabetes, and recurrent falls, as well as having undergone bilateral hip replacement surgery. Upon examination, the doctor notes periodontal disease, while radiology reports reveal sclerotic lesions in the mandible and maxilla that are indicative of osteonecrosis. Which medication could be responsible for her symptoms?
Your Answer: Alendronate
Explanation:Osteonecrosis of the jaw is a potential side effect of bisphosphonates, particularly alendronate, and the risk increases with prolonged use. However, the other options listed are not associated with this condition. While denosumab is also linked to osteonecrosis of the jaw, it is less common than with bisphosphonates. It is unlikely that the patient is taking denosumab as there is no mention of any contraindications to bisphosphonates, and alendronate is the first-line drug for bone protection. Additionally, denosumab is significantly more expensive than alendronate.
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 5
Incorrect
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During a hip examination, Sarah, a 65-year-old female, is found to have a positive trendelenburg's sign. When she stands on only her left leg, her right pelvis drops.
If the cause of her positive trendelenburg's sign is neurological, which nerve is affected in Sarah?Your Answer: Left inferior gluteal
Correct Answer: Right superior gluteal
Explanation:If the superior gluteal nerve is damaged, it can result in a positive Trendelenburg sign. This nerve is responsible for providing innervation to the gluteus minimus and gluteus medius muscles, which are important for abducting and medially rotating the lower limb, as well as preventing pelvic drop of the opposing limb. For example, when standing on only the right leg, the right gluteus minimus and gluteus medius muscles stabilize the pelvis. However, if the right superior gluteal nerve is damaged, the right gluteus minimus and gluteus medius muscles will not receive proper innervation, leading to instability and a drop in the left pelvis when standing on the right leg. On the other hand, the inferior gluteal nerve innervates the gluteus maximus muscles, which are responsible for extending the thigh and performing lateral rotation.
The Trendelenburg Test: Assessing Gluteal Nerve Function
The Trendelenburg test is a diagnostic tool used to assess the function of the superior gluteal nerve. This nerve is responsible for the contraction of the gluteus medius muscle, which is essential for maintaining balance and stability while standing on one leg.
When the superior gluteal nerve is injured or damaged, the gluteus medius muscle is weakened, resulting in a compensatory shift of the body towards the unaffected side. This shift is characterized by a gravitational shift, which causes the body to be supported on the unaffected limb.
To perform the Trendelenburg test, the patient is asked to stand on one leg while the physician observes the position of the pelvis. In a healthy individual, the gluteus medius muscle contracts as soon as the contralateral leg leaves the floor, preventing the pelvis from dipping towards the unsupported side. However, in a person with paralysis of the superior gluteal nerve, the pelvis on the unsupported side descends, indicating that the gluteus medius on the affected side is weak or non-functional. This is known as a positive Trendelenburg test.
It is important to note that the Trendelenburg test is also used in vascular investigations to determine the presence of saphenofemoral incompetence. In this case, tourniquets are placed around the upper thigh to assess blood flow. However, in the context of assessing gluteal nerve function, the Trendelenburg test is a valuable tool for diagnosing and treating motor deficits and gait abnormalities.
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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 28-year-old man presents to the emergency department with a wrist injury sustained from a fall. Upon examination, the physician notes tenderness in the anatomical snuffbox, as well as localized swelling and bruising. The physician suspects a fracture in one of the carpal bones and orders a series of plain x-rays to confirm the diagnosis. The physician is concerned about the potential consequences of leaving this fracture untreated due to its precarious blood supply.
Which blood supply could be compromised as a result of this injury?Your Answer: Retrograde blood supply to the trapezoid through the scaphoid
Correct Answer: Retrograde blood supply to the scaphoid through the tubercle
Explanation:Fractures to the scaphoid bone can result in avascular necrosis due to its sole blood supply through the tubercle. The healing process may be complicated by non-union as well. It is important to note that blood supply to the scaphoid is not anterograde and pain in the anatomical snuffbox is indicative of a scaphoid fracture, not a trapezium fracture. Additionally, the scaphoid bone receives blood supply through the tubercle, not the lunate surface.
The scaphoid bone has various articular surfaces for different bones in the wrist. It has a concave surface for the head of the capitate and a crescentic surface for the lunate. The proximal end has a wide convex surface for the radius, while the distal end has a tubercle that can be felt. The remaining articular surface faces laterally and is associated with the trapezium and trapezoid bones. The narrow strip between the radial and trapezial surfaces and the tubercle gives rise to the radial collateral carpal ligament. The tubercle also receives part of the flexor retinaculum and is the only part of the scaphoid bone that allows for the entry of blood vessels. However, this area is commonly fractured and can lead to avascular necrosis.
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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 40-year-old male presents to the GP with fatigue and shortness of breath. He states that he is taking methotrexate for psoriasis. The GP takes some bloods, and finds the following results in his full blood count (FBC):
Hb 90 g/L
MCV 90 fL
Platelets 70 * 109/L
WBC 2.5 * 109/L
Neuts 1.5 * 109/L)
Lymphs 0.7 * 109/L
Mono 0.2 * 109/L
Eosin 0.1 * 109/L
The GP suspects this to be an adverse effect of methotrexate.
What adverse effect is indicated by these results?Your Answer: Thrombocytopenia
Correct Answer: Pancytopaenia
Explanation:The patient’s blood test indicates a decrease in red blood cells, white blood cells, and platelets, which is known as pancytopenia. This condition is caused by severe bone marrow suppression, which is a common side effect of methotrexate. Anemia, on the other hand, would only result in a low hemoglobin level and cannot account for the low platelet and white blood cell counts.
Methotrexate is an antimetabolite that hinders the activity of dihydrofolate reductase, an enzyme that is crucial for the synthesis of purines and pyrimidines. It is a significant drug that can effectively control diseases, but its side-effects can be life-threatening. Therefore, careful prescribing and close monitoring are essential. Methotrexate is commonly used to treat inflammatory arthritis, especially rheumatoid arthritis, psoriasis, and acute lymphoblastic leukaemia. However, it can cause adverse effects such as mucositis, myelosuppression, pneumonitis, pulmonary fibrosis, and liver fibrosis.
Women should avoid pregnancy for at least six months after stopping methotrexate treatment, and men using methotrexate should use effective contraception for at least six months after treatment. Prescribing methotrexate requires familiarity with guidelines relating to its use. It is taken weekly, and FBC, U&E, and LFTs need to be regularly monitored. Folic acid 5 mg once weekly should be co-prescribed, taken more than 24 hours after methotrexate dose. The starting dose of methotrexate is 7.5 mg weekly, and only one strength of methotrexate tablet should be prescribed.
It is important to avoid prescribing trimethoprim or co-trimoxazole concurrently as it increases the risk of marrow aplasia. High-dose aspirin also increases the risk of methotrexate toxicity due to reduced excretion. In case of methotrexate toxicity, the treatment of choice is folinic acid. Overall, methotrexate is a potent drug that requires careful prescribing and monitoring to ensure its effectiveness and safety.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 8
Incorrect
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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: Sartorius
Correct 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
Incorrect
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A teenage boy comes to the clinic with a winged scapula on his right side after sustaining an injury while playing rugby. The physician informs him that a nerve has been affected. Which specific nerve is responsible for this?
Your Answer: Accessory nerve
Correct Answer: Long thoracic nerve
Explanation:A mastectomy patient experiences winged scapula due to paralysis of the serratus anterior muscle, which is innervated by the long thoracic nerve. This nerve is often affected by rib injuries. The other nerves mentioned do not play a role in this disorder as they do not innervate this muscle. Damage to the musculocutaneous nerve would affect arm flexion, while damage to the axillary nerve would affect arm abduction. Damage to the thoracodorsal nerve would affect raising the trunk with the upper limb, and damage to the accessory nerve would affect neck movement.
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 10
Incorrect
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A 55-year-old man presents with a complaint of stiffness in his right shoulder for the past 8 months. Initially, he experienced severe pain, but now only stiffness persists. Upon examination, you observe that the right shoulder is stiff during both active and passive movements.
What is the probable underlying cause of this stiffness?Your Answer: Supraspinatus tear
Correct Answer: Adhesive capsulitis
Explanation:Adhesive capsulitis is identified by a decrease in shoulder mobility, both when moving the shoulder voluntarily and when it is moved by someone else. The ability to rotate the shoulder outward is more affected than the ability to rotate it inward or lift it away from the body.
On the other hand, a tear in the rotator cuff muscles will result in a reduction in active movement due to muscle weakness. Passive movement may also be restricted due to pain. However, we would not anticipate a rigid joint that opposes passive movement.
Adhesive capsulitis, also known as frozen shoulder, is a common cause of shoulder pain that is more prevalent in middle-aged women. The exact cause of this condition is not fully understood. It is associated with diabetes mellitus, with up to 20% of diabetics experiencing an episode of frozen shoulder. Symptoms typically develop over a few days and affect external rotation more than internal rotation or abduction. Both active and passive movement are affected, and patients usually experience a painful freezing phase, an adhesive phase, and a recovery phase. Bilateral frozen shoulder occurs in up to 20% of patients, and the episode typically lasts between 6 months and 2 years.
The diagnosis of frozen shoulder is usually made based on clinical presentation, although imaging may be necessary for atypical or persistent symptoms. There is no single intervention that has been proven to improve long-term outcomes. Treatment options include nonsteroidal anti-inflammatory drugs (NSAIDs), physiotherapy, oral corticosteroids, and intra-articular corticosteroids. It is important to note that the management of frozen shoulder should be tailored to the individual patient, and a multidisciplinary approach may be necessary for optimal outcomes.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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