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Question 1
Incorrect
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Roughly what percentage of saliva production comes from the submandibular glands?
Your Answer: 20%
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 2
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 3
Correct
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A 57-year-old patient arrives at the emergency department by ambulance following a car accident. Upon examination, it is observed that his hip is in flexion, abduction, and external rotation. An X-ray reveals that the right femoral head is larger than the left and is positioned medially to the acetabulum. No fractures or skin lesions are detected. The patient undergoes closed reduction with traction while under sedation. Later, during a physiotherapy evaluation, it is discovered that he is unable to adduct his thigh. What nerve is most likely to have been damaged?
Your Answer: Obturator nerve
Explanation:If a patient is unable to adduct their thigh after an anterior hip dislocation, it is likely due to damage to the obturator nerve. This nerve supplies the hip adductor muscles and sensation to the medial thigh. In contrast, damage to the femoral nerve would result in an inability to flex the hip or extend the knee, making it an unlikely cause for this specific symptom. Compression of the inferior gluteal nerve can cause piriformis syndrome, while compression of the lateral femoral cutaneous nerve can lead to meralgia paresthetica, but neither of these would affect the patient’s ability to adduct their leg. Damage to the superior gluteal nerve would result in a positive Trendelenburg’s sign.
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 popliteal 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 4
Incorrect
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A 15-year-old girl presents with a painful swelling in her distal femur. After diagnosis, it is revealed that she has osteoblastic sarcoma. What is the most probable site for metastasis of this lesion?
Your Answer: Common iliac lymph nodes
Correct Answer: Lung
Explanation:Sarcomas that exhibit lymphatic metastasis can be remembered using the acronym ‘RACE For MS’, which stands for Rhabdomyosarcoma, Angiosarcoma, Clear cell sarcoma, Epithelial cell sarcoma, Fibrosarcoma, Malignant fibrous histiocytoma, and Synovial cell sarcoma. Alternatively, the acronym ‘SCARE’ can be used to remember Synovial sarcoma, Clear cell sarcoma, Angiosarcoma, Rhabdomyosarcoma, and Epithelioid sarcoma. While sarcomas typically metastasize through the bloodstream and commonly spread to the lungs, lymphatic metastasis is less common but may occur in some cases. The liver and brain are typically spared from initial metastasis.
Sarcomas: Types, Features, and Assessment
Sarcomas are malignant tumors that originate from mesenchymal cells. They can either be bone or soft tissue in origin. Bone sarcomas include osteosarcoma, Ewing’s sarcoma, and chondrosarcoma, while soft tissue sarcomas are a more diverse group that includes liposarcoma, rhabdomyosarcoma, leiomyosarcoma, and synovial sarcomas. Malignant fibrous histiocytoma is a sarcoma that can arise in both soft tissue and bone.
Certain features of a mass or swelling should raise suspicion for a sarcoma, such as a large (>5cm) soft tissue mass, deep tissue or intra-muscular location, rapid growth, and a painful lump. Imaging of suspicious masses should utilize a combination of MRI, CT, and USS. Blind biopsy should not be performed prior to imaging, and where required, should be done in such a way that the biopsy tract can be subsequently included in any resection.
Ewing’s sarcoma is more common in males, with an incidence of 0.3/1,000,000 and onset typically between 10 and 20 years of age. Osteosarcoma is more common in males, with an incidence of 5/1,000,000 and peak age 15-30. Liposarcoma is rare, with an incidence of approximately 2.5/1,000,000, and typically affects an older age group (>40 years of age). Malignant fibrous histiocytoma is the most common sarcoma in adults and is usually treated with surgical resection and adjuvant radiotherapy.
In summary, sarcomas are a diverse group of malignant tumors that can arise from bone or soft tissue. Certain features of a mass or swelling should raise suspicion for a sarcoma, and imaging should utilize a combination of MRI, CT, and USS. Treatment options vary depending on the type and location of the sarcoma.
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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 19-year-old athlete presents to the orthopaedic clinic complaining of pain and swelling on the medial side of the knee joint. The pain is experienced while climbing stairs, but not while walking on level ground. On clinical examination, there is tenderness over the proximal medial tibia and the McMurray test is negative. What is the probable cause of this patient's symptoms?
Your Answer: Medial meniscus injury
Correct Answer: Pes Anserinus Bursitis
Explanation:The Pes Anserinus, also known as the goose’s foot, is formed by the combination of the tendons of the sartorius, gracilis, and semitendinous muscles as they insert into the anteromedial proximal tibia.
Overuse injuries can lead to Pes Anserinus Bursitis, which is frequently seen in athletes. The primary symptom is pain in the medial proximal tibia. A negative McMurray test can rule out medial meniscal injury.
The Sartorius Muscle: Anatomy and Function
The sartorius muscle is the longest strap muscle in the human body and is located in the anterior compartment of the thigh. It is the most superficial muscle in this region and has a unique origin and insertion. The muscle originates from the anterior superior iliac spine and inserts on the medial surface of the body of the tibia, anterior to the gracilis and semitendinosus muscles. The sartorius muscle is innervated by the femoral nerve (L2,3).
The primary action of the sartorius muscle is to flex the hip and knee, while also slightly abducting the thigh and rotating it laterally. It also assists with medial rotation of the tibia on the femur, which is important for movements such as crossing one leg over the other. The middle third of the muscle, along with its strong underlying fascia, forms the roof of the adductor canal. This canal contains important structures such as the femoral vessels, the saphenous nerve, and the nerve to vastus medialis.
In summary, the sartorius muscle is a unique muscle in the anterior compartment of the thigh that plays an important role in hip and knee flexion, thigh abduction, and lateral rotation. Its location and relationship to the adductor canal make it an important landmark for surgical procedures in the thigh region.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 6
Correct
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A 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: 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 7
Incorrect
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A teenage boy arrives at the hospital with a biking injury. An X-ray reveals that he has fractured both his tibia and fibula. The medical team applies a cast to his leg.
However, just an hour later, the boy is experiencing excruciating pain despite receiving regular doses of morphine. As a result, the doctors decide to remove his cast.
What should be the next course of action?Your Answer: Prescribe benzodiazepine for sedation before review
Correct Answer: Notify the orthopaedic surgeon and theatre team
Explanation:The appropriate course of action in this scenario is to notify the orthopaedic surgeon and theatre team immediately for an urgent fasciotomy. Sedation, increased pain relief, or reapplying a vacuum splint would not be helpful and could potentially worsen the situation.
Compartment syndrome is a complication that can occur after fractures or vascular injuries. It is characterized by increased pressure within a closed anatomical space, which can lead to tissue death. Supracondylar fractures and tibial shaft injuries are the most common fractures associated with compartment syndrome. Symptoms include pain, numbness, paleness, and possible paralysis of the affected muscle group. Even if a pulse is present, compartment syndrome cannot be ruled out. Diagnosis is made by measuring intracompartmental pressure, with pressures over 20mmHg being abnormal and over 40mmHg being diagnostic. X-rays typically do not show any pathology. Treatment involves prompt and extensive fasciotomies, with careful attention to decompressing deep muscles in the lower limb. Patients may experience myoglobinuria and require aggressive IV fluids. In severe cases, debridement and amputation may be necessary, as muscle death can occur within 4-6 hours.
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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 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 dihydropteroate synthetase
Correct 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 9
Correct
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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: 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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Question 10
Incorrect
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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: Liver disease
Correct 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 11
Correct
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A 28-year-old presents to the hospital with severe wrist pain. He was playing basketball with his friends when he fell with his hand outstretched. On examination, there is significant tenderness at the anatomical snuffbox. Pain is elicited as the thumb is longitudinally compressed. His grip strength is also diminished.
A posteroanterior and lateral x-ray of the wrist joint is performed which gives inconclusive results. The patient's wrist is immobilized with a splint and he is advised an MRI in a week’s time for further evaluation.
The patient inquires about possible complications and the doctor expresses concern that if the blood supply is interrupted, the bone tissue may be compromised.
Which of the following structures is most likely to be responsible for this complication?Your Answer: Dorsal carpal branch of radial artery
Explanation:The primary neurovascular structure that can be affected by a scaphoid fracture is the dorsal carpal branch of the radial artery. This artery is responsible for supplying blood to the scaphoid bone, and a fracture can lead to a high risk of avascular necrosis in the proximal pole of the bone. Symptoms of a scaphoid fracture include tenderness in the anatomical snuffbox, pain when compressing the thumb longitudinally, and a loss of grip strength. While an X-ray may not provide a conclusive diagnosis, further imaging studies can confirm the presence of an occult fracture.
The other answer choices are incorrect. The common digital arteries originate from the superficial palmar arch and supply the fingers. The deep palmar arch primarily supplies the thumb and index finger. The proper digital arteries arise from the common digital arteries and supply the fingers.
A scaphoid fracture is a type of wrist fracture that usually occurs when a person falls onto an outstretched hand or during contact sports. It is important to identify scaphoid fractures as they can lead to avascular necrosis due to the unusual blood supply of the scaphoid bone. Patients with scaphoid fractures typically experience pain along the radial aspect of the wrist and loss of grip or pinch strength. Clinical examination involves checking for tenderness over the anatomical snuffbox, wrist joint effusion, pain on telescoping of the thumb, tenderness of the scaphoid tubercle, and pain on ulnar deviation of the wrist. Plain film radiographs and scaphoid views are used to diagnose scaphoid fractures, but MRI is considered the definitive investigation. Initial management involves immobilization with a splint or backslab and referral to orthopaedics. Orthopaedic management depends on the type of fracture, with undisplaced fractures typically treated with a cast and displaced fractures requiring surgical fixation. Complications of scaphoid fractures include non-union and avascular necrosis.
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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 52-year-old retired teacher presents to her new family physician with complaints of a painful ankle after going for a jog in the park. She reports no trauma to the area but has a history of joint dislocation. The patient also has a heart valve problem and is being treated by a cardiologist. During the examination, the physician notes hyperextensible skin and redness, swelling, and warmth in the ankle joint. What condition is associated with this patient's presentation?
Your Answer: Cerebral venous sinus thrombosis
Correct Answer: Subarachnoid hemorrhage
Explanation:1. The presence of joint hypermobility and hyperextensible skin, along with a history of repeated joint dislocations and heart valve disease treatment, suggest a diagnosis of Ehlers-Danlos syndrome. This genetic disorder is caused by a defect in collagen synthesis and can lead to various complications, including the development of berry aneurysms in the cerebral circulation, which can rupture and cause subarachnoid hemorrhage.
2. Lacunar infarcts occur when small penetrating arteries in the brain become obstructed, affecting deeper brain structures such as the internal capsule, brain nuclei, and pons. These infarcts share the same pathophysiology as ischemic strokes and are often caused by risk factors such as diabetes, hypertension, hypercholesterolemia, and smoking.
3. Cerebral venous sinus thrombosis is characterized by the formation of blood clots in the venous sinuses of the brain, leading to congestion and symptoms such as headaches and seizures. This condition is more likely to occur in individuals with a high tendency to form blood clots, such as during pregnancy or in the presence of clotting factor abnormalities or inflammatory conditions.
4. Subdural hemorrhage occurs when there is bleeding in the space between the dura and arachnoid mater, often caused by sudden shearing forces that tear bridging veins. This bleeding can cause brain compression and is more likely to occur in individuals with brain atrophy, such as alcoholics and the elderly.
5. No input provided.Ehler-Danlos syndrome is a genetic disorder that affects the connective tissue, specifically type III collagen. This causes the tissue to be more elastic than usual, resulting in increased skin elasticity and joint hypermobility. Common symptoms include fragile skin, easy bruising, and recurrent joint dislocation. Additionally, individuals with Ehler-Danlos syndrome may be at risk for serious complications such as aortic regurgitation, mitral valve prolapse, aortic dissection, subarachnoid hemorrhage, and angioid retinal streaks.
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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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Sophie, a 27-year-old female, is brought to the Emergency Department by ambulance after being involved in a car accident. Upon examination, it is discovered that she has a surgical neck fracture of the humerus on X-ray.
What is the structure that is most commonly at risk of damage with a surgical neck fracture of the humerus?Your Answer: Axillary nerve
Explanation:The most frequently occurring nerve injury in a surgical neck fracture of the humerus is damage to the axillary nerve. The radial nerve is at risk of injury in a mid shaft fracture of the humerus, as it passes through the radial groove. A supracondylar fracture of the humerus increases the likelihood of injury to the brachial artery, which can lead to volkmaan’s ischemic contractures.
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 14
Incorrect
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Which ligament contains the artery supplying the head of femur in infants?
Your Answer: Pubofemoral ligament
Correct Answer: Ligamentum teres
Explanation:Anatomy of the Hip Joint
The hip joint is formed by the articulation of the head of the femur with the acetabulum of the pelvis. Both of these structures are covered by articular hyaline cartilage. The acetabulum is formed at the junction of the ilium, pubis, and ischium, and is separated by the triradiate cartilage, which is a Y-shaped growth plate. The femoral head is held in place by the acetabular labrum. The normal angle between the femoral head and shaft is 130 degrees.
There are several ligaments that support the hip joint. The transverse ligament connects the anterior and posterior ends of the articular cartilage, while the head of femur ligament (ligamentum teres) connects the acetabular notch to the fovea. In children, this ligament contains the arterial supply to the head of the femur. There are also extracapsular ligaments, including the iliofemoral ligament, which runs from the anterior iliac spine to the trochanteric line, the pubofemoral ligament, which connects the acetabulum to the lesser trochanter, and the ischiofemoral ligament, which provides posterior support from the ischium to the greater trochanter.
The blood supply to the hip joint comes from 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 of the femur.
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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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A 78-year-old man presents with symptoms of claudication. It is decided to assess his ankle brachial pressure index. Using a handheld doppler device, the signal from the dorsalis pedis artery is detected. Which vessel does this artery continue from?
Your Answer: Peroneal artery
Correct Answer: Anterior tibial artery
Explanation:The anterior tibial artery continues as the dorsalis pedis.
The foot has two arches: the longitudinal arch and the transverse arch. The longitudinal arch is higher on the medial side and is supported by the posterior pillar of the calcaneum and the anterior pillar composed of the navicular bone, three cuneiforms, and the medial three metatarsal bones. The transverse arch is located on the anterior part of the tarsus and the posterior part of the metatarsus. The foot has several intertarsal joints, including the sub talar joint, talocalcaneonavicular joint, calcaneocuboid joint, transverse tarsal joint, cuneonavicular joint, intercuneiform joints, and cuneocuboid joint. The foot also has various ligaments, including those of the ankle joint and foot. The foot is innervated by the lateral plantar nerve and medial plantar nerve, and it receives blood supply from the plantar arteries and dorsalis pedis artery. The foot has several muscles, including the abductor hallucis, flexor digitorum brevis, abductor digit minimi, flexor hallucis brevis, adductor hallucis, and extensor digitorum brevis.
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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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A 26-year-old male is brought to the emergency department following an injury sustained during his weightlifting routine. He is an avid powerlifter and his training involves quick, forceful movements with heavy weights.
During the examination, the doctor observes weakness in knee flexion and some localized swelling in the knee area. The doctor suspects a possible detachment of the biceps femoris from its insertion site and requests an orthopedic consultation.
Can you identify the location of the insertion site for the long and short head of the biceps femoris?Your Answer: Head of the fibula
Explanation:The fibular head serves as the insertion point for both the long and short head of the biceps femoris muscle.
Muscle Insertion Site
Sartorius Medial surface of the proximal tibia
Rectus femoris Tibial tuberosity
Biceps femoris Fibular head
Semimembranosus Medial tibial condyle
PectineusThe 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 17
Correct
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Jill, a 24-year-old female, falls on an outstretched hand and is diagnosed with a scaphoid fracture. During examination, she exhibits tenderness in the anatomical snuffbox. What structures form the lateral border of the anatomical snuffbox?
Your Answer: Extensor pollicis brevis and the ABductor pollicis longus tendons
Explanation:The lateral border of the anatomical snuffbox is formed by the tendons of the extensor pollicis brevis and the abductor pollicis longus, not the muscles.
To remember the borders, use the phrase Brevis sandwich which stands for the abductor pollicis longus tendons, extensor pollicis brevis, and extensor pollicis longus.
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 18
Incorrect
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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: Insulin
Correct 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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- Musculoskeletal System And Skin
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Question 19
Incorrect
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A 9-year-old girl presents to the pediatrician with her mother. The mother reports that she has noticed the child's ankles have become swollen over the past few months. There is no history of any trauma and the girl has no other past medical history.
On examination the child is underweight and appears malnourished. She is alert and otherwise systemically well. Bony swellings are noted in both ankles.
Blood tests and an X-ray are ordered.
Bilirubin 8 µmol/L (3 - 17)
ALP 320 u/L (30 - 100)
ALT 29 u/L (3 - 40)
γGT 18 u/L (8 - 60)
Albumin 37 g/L (35 - 50)
X-ray both ankles cupping and fraying of the metaphyseal region
What is the pathophysiological process causing this child's symptoms?Your Answer: Excessive mineralised osteoid
Correct Answer: Excessive non-mineralised osteoid
Explanation:Rickets is a condition where the growth plate in the wrist joints widens due to an excess of non-mineralized osteoid. This is caused by a deficiency in vitamin D or calcium, which is usually due to poor dietary intake. Calcium is necessary for the mineralization of osteoid and the formation of mature bone tissue. When this process is disrupted, rickets can occur.
Monoclonal antibodies used to treat osteoporosis target RANKL, an enzyme that activates osteoclasts and promotes bone resorption. However, RANKL is not the cause of rickets.
Excessive mineralized osteoid is not the cause of rickets. Instead, rickets is caused by inadequate calcium for mineralization, leading to a buildup of non-mineralized osteoid.
While excessive osteoclast activity can cause diseases like osteoporosis and Paget’s disease, it is not the cause of rickets. Similarly, a deficiency of osteoclast activity can result in osteopetrosis, but not rickets.
Understanding Rickets
Rickets is a condition that occurs when bones in developing and growing bodies are inadequately mineralized, resulting in soft and easily deformed bones. This condition is usually caused by a deficiency in vitamin D. In adults, a similar condition is called osteomalacia.
There are several factors that can predispose individuals to rickets, including a dietary deficiency of calcium, prolonged breastfeeding, unsupplemented cow’s milk formula, and a lack of sunlight.
Symptoms of rickets include aching bones and joints, lower limb abnormalities such as bow legs or knock knees, swelling at the costochondral junction (known as a rickety rosary), kyphoscoliosis, craniotabes (soft skull bones in early life), and Harrison’s sulcus.
To diagnose rickets, doctors may check for low vitamin D levels, reduced serum calcium, and raised alkaline phosphatase. Treatment typically involves oral vitamin D supplementation.
Overall, understanding rickets and its causes can help individuals take steps to prevent this condition and ensure proper bone development and growth.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 20
Incorrect
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As a medical student on placement, while practising orthopaedic examinations, you come across a patient whose knee observation reveals that the centre of gravity is medial to the knee joint, causing the knees to bow outwards. What is the appropriate term for this condition?
Your Answer: Hallux varum
Correct Answer: Genu varum
Explanation: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 21
Incorrect
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Which one of the following structures does not pass anterior to the lateral malleolus?
Your Answer: Peroneus tertius
Correct Answer: Peroneus brevis
Explanation:The lateral malleolus is located posterior to the path of the peroneus brevis.
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 22
Incorrect
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A 65-year-old female presents to the emergency department with a three-week history of gradual-onset left knee pain. She has a known history of hyperparathyroidism, but is not on any regular medications.
Upon examination, there are no visible changes to the joint and the temperature over the knee is normal. However, she experiences tenderness over passive and active movement, but no restriction of joint movement.
A joint radiograph reveals no fracture but chondrocalcinosis. Further, a joint aspiration under polarised light shows positively birefringent rhomboid-shaped crystals.
What is the underlying pathology, given the likely diagnosis?Your Answer: Patellar fracture
Correct Answer: Calcium pyrophosphate dihydrate deposition
Explanation:The most probable diagnosis for this patient is pseudogout, which is characterized by the deposition of calcium pyrophosphate dihydrate crystals in the synovium, resulting in pain during movement. The knee joint is commonly affected, and the presence of rhomboid-shaped crystals that are positively birefringent in polarised-light microscopy of joint aspirate confirms the diagnosis. Radiography may also reveal chondrocalcinosis.
A fracture would require a history of trauma and would be visible on the radiograph, neither of which is present in this case, making it an unlikely diagnosis.
Reactive arthritis is associated with immune-mediated destruction of the joint, but there is no recent history of diarrhoea, coryza, conjunctivitis, or urethritis, which are commonly associated with this condition. The light microscopy of joint aspirate and radiography findings do not support this diagnosis.
Joint infection typically presents with a hot, swollen joint that rapidly develops after a history of trauma. The joint aspirate would be expected to contain turbid fluid and grow organisms. However, none of these features are present in this patient, making joint infection an unlikely diagnosis.
Understanding Pseudogout
Pseudogout, also known as acute calcium pyrophosphate crystal deposition disease, is a type of microcrystal synovitis that occurs when calcium pyrophosphate dihydrate crystals are deposited in the synovium. This condition is commonly associated with increasing age, but younger patients who develop pseudogout usually have an underlying risk factor such as haemochromatosis, hyperparathyroidism, low magnesium or phosphate levels, acromegaly, or Wilson’s disease.
The knee, wrist, and shoulders are the most commonly affected joints in pseudogout. Diagnosis is made through joint aspiration, which reveals weakly-positively birefringent rhomboid-shaped crystals, and x-rays, which show chondrocalcinosis. In the knee, linear calcifications of the meniscus and articular cartilage can be seen.
Management of pseudogout involves joint fluid aspiration to rule out septic arthritis, followed by treatment with NSAIDs or intra-articular, intra-muscular, or oral steroids, similar to the treatment for gout. Understanding the risk factors and symptoms of pseudogout can help with early diagnosis and effective management of this condition.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 23
Incorrect
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A 68-year-old man presents to an orthopedic surgeon with a two-month history of dull pain in his left knee that is worse at night and unresponsive to over-the-counter pain relievers. Both knees appear normal with no swelling, tendon or ligament abnormalities, and no limited range of motion. The patient has a history of Paget disease of the bone and takes alendronic acid. The orthopedic surgeon notes a Codman triangle on knee X-ray due to periosteum elevation. What is the most likely condition affecting this patient?
Your Answer: Osteochondroma
Correct Answer: Osteosarcoma
Explanation:The presence of a Codman triangle on an X-ray is a strong indication of osteosarcoma, a bone tumor that can cause night pain and is unresponsive to analgesics. This condition is often associated with Paget disease of the bone, which increases the risk of developing osteosarcoma. Giant cell tumor is another bone tumor that can occur in young adults and has a characteristic ‘soap bubble’ appearance on X-ray. Osteochondroma is a common benign bone tumor that can rarely transform into a malignant chondrosarcoma. Osteoarthritis is a painful joint condition caused by mechanical destruction of the cartilage, often worsened by factors such as obesity and age. Treatment options for osteoarthritis include pain relief medication and joint replacement surgery.
Types of Bone Tumours
Benign and malignant bone tumours are two types of bone tumours. Benign bone tumours are non-cancerous and do not spread to other parts of the body. Osteoma is a benign overgrowth of bone that usually occurs on the skull and is associated with Gardner’s syndrome. Osteochondroma, the most common benign bone tumour, is a cartilage-capped bony projection on the external surface of a bone. Giant cell tumour is a tumour of multinucleated giant cells within a fibrous stroma that occurs most frequently in the epiphyses of long bones.
Malignant bone tumours are cancerous and can spread to other parts of the body. Osteosarcoma is the most common primary malignant bone tumour that mainly affects children and adolescents. It occurs most frequently in the metaphyseal region of long bones prior to epiphyseal closure. Ewing’s sarcoma is a small round blue cell tumour that mainly affects children and adolescents. It occurs most frequently in the pelvis and long bones and is associated with t(11;22) translocation. Chondrosarcoma is a malignant tumour of cartilage that most commonly affects the axial skeleton and is more common in middle-age.
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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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Liam, a 4-year-old boy, is brought to the emergency department by his parents. They report that Liam has been holding his left arm close to his body and not using it much since they were playing catch in the backyard.
During examination, the doctor observes that Liam's left arm is slightly bent at the elbow and turned inward. The doctor diagnoses a pulled elbow and successfully reduces it.
What is the anomaly associated with this condition?Your Answer: Dislocation of ulnar head
Correct Answer: Subluxation of radial head
Explanation:In children, the annular ligament is weaker, which can result in subluxation of the radial head during a pulled elbow. It’s important to note that a subluxation is a partial dislocation, meaning there is still some joint continuity, whereas a dislocation is a complete disruption of the joint. Additionally, a fracture refers to a break in the bone itself. It’s worth noting that the ulnar is not implicated in a pulled elbow.
Subluxation of the Radial Head in Children
Subluxation of the radial head, also known as pulled elbow, is a common upper limb injury in children under the age of 6. This is because the annular ligament covering the radial head has a weaker distal attachment in children at this age group. The signs of this injury include elbow pain and limited supination and extension of the elbow. However, children may refuse examination on the affected elbow due to the pain.
To manage this injury, analgesia is recommended to alleviate the pain. Additionally, passively supinating the elbow joint while the elbow is flexed to 90 degrees can help alleviate the subluxation. It is important to seek medical attention if the pain persists or worsens.
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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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Which muscle is connected to the front of the fibrous capsule that surrounds the elbow joint?
Your Answer: Pronator teres
Correct Answer: Brachialis
Explanation:When the brachialis muscle contracts, it aids in elbow flexion by inserting some of its fibers into the fibrous joint of the elbow capsule.
Anatomy of the Elbow Joint
The elbow joint is a large synovial hinge joint that connects the bones of the forearm to the lower end of the humerus. It consists of the humeral articular surface, which comprises the grooved trochlea, the spheroidal capitulum, and the sulcus between them, and the ulnar and radial surfaces. The joint is encased within a fibrous capsule that is relatively weak anteriorly and posteriorly but strengthened at the sides to form the radial and ulnar collateral ligaments. The synovial membrane follows the attachments of the fibrous capsule, and the joint is innervated by the musculocutaneous, median, radial, and ulnar nerves.
Movement occurs around a transverse axis, with flexion occurring when the forearm makes anteriorly a diminishing angle with the upper arm and extension when the opposite occurs. The axis of movement passes through the humeral epicondyles and is not at right angles with either the humerus or bones of the forearm. In full extension with the forearm supinated, the arm and forearm form an angle which is more than 180 degrees, the extent to which this angle is exceeded is termed the carrying angle. The carrying angle is masked when the forearm is pronated.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 26
Incorrect
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You are observing a GP during their morning consultations. A 60-year-old man has presented to the clinic with elevated liver function tests discovered during routine blood tests over the past month. Despite being asymptomatic, the patient has a history of osteoarthritis in his knees, one of which underwent total replacement surgery three months ago. He also has arthritis affecting the small joints in his hands and feet, which is well-controlled with medication, as well as hypertension that is stable with medication. What is an important cause of hepatic damage that should be ruled out in this case?
Your Answer: ACE inhibitor use
Correct Answer: Immune suppression medication for arthritis
Explanation:The patient has both osteoarthritis and rheumatoid arthritis, with the latter affecting the smaller joints of the hands and feet. Methotrexate is a commonly used immunosuppressive medication for rheumatoid arthritis, but it can cause hepatotoxicity as a significant side effect.
Although fat emboli are a potential risk after orthopaedic surgery, they usually cause neural and respiratory symptoms rather than liver damage. Additionally, the onset of fat emboli occurs within hours to days after the operation, not three months later.
While calcium channel blockers, ACE inhibitors, and opioid medications have their own side effects, they typically do not affect liver function.
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 27
Incorrect
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A 33-year-old female visits her doctor complaining of a red rash on her hands. She first noticed the rash a few weeks ago after moving into her new apartment with her partner. However, in the past few days, the rash has become extremely itchy and is keeping her up at night. Despite using her regular moisturizer cream, the rash has not improved. Upon examination, the doctor observes a bilateral erythematous rash on both hands that extends into the interdigital spaces, with multiple excoriation marks. The rash is not present anywhere else, and there are no other significant findings.
What is the likely diagnosis, and what is the underlying mechanism behind this patient's presentation?Your Answer: Hyperproliferation of keratinocytes in the epidermis
Correct Answer: Delayed-type IV hypersensitivity reaction
Explanation:The severe itching caused by scabies is a result of a delayed-type IV hypersensitivity reaction to the mites and their eggs, which occurs around 30 days after infestation. This type of reaction involves T-cells and antigen-presenting cells, leading to an inflammatory response. Scabies is typically spread through close skin-to-skin contact with an infected person. An allergic reaction to the patient’s regular moisturizer would be a type I hypersensitivity reaction, which causes acute itching. Antigen-antibody complex deposition in the epidermis would be a type III hypersensitivity reaction, while psoriasis is caused by hyperproliferation of epidermal keratinocytes and presents with red, scaly patches on extensor surfaces. Bacterial skin infections like cellulitis cause warm, swollen, and red skin with systemic symptoms like fever.
Scabies: Causes, Symptoms, and Treatment
Scabies is a skin condition caused by the mite Sarcoptes scabiei, which is spread through prolonged skin contact. It is most commonly seen in children and young adults. The mite burrows into the skin, laying its eggs in the outermost layer. The resulting intense itching is due to a delayed hypersensitivity reaction to the mites and eggs, which occurs about a month after infection. Symptoms include widespread itching, linear burrows on the fingers and wrists, and secondary features such as excoriation and infection.
The first-line treatment for scabies is permethrin 5%, followed by malathion 0.5% if necessary. Patients should be advised to avoid close physical contact until treatment is complete and to treat all household and close contacts, even if asymptomatic. Clothing, bedding, and towels should be laundered, ironed, or tumble-dried on the first day of treatment to kill off mites. The insecticide should be applied to all areas, including the face and scalp, and left on for 8-12 hours for permethrin or 24 hours for malathion before washing off. Treatment should be repeated after 7 days.
Crusted scabies, also known as Norwegian scabies, is a severe form of the condition seen in patients with suppressed immunity, particularly those with HIV. The skin is covered in hundreds of thousands of mites, and isolation is essential. Ivermectin is the treatment of choice.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 28
Incorrect
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A 55-year-old woman reports a gradual onset of numbness and tingling that extends from her heel to the first three toes over the past six months. She experiences increased symptoms when pressure is applied to the area behind the medial malleolus for thirty seconds.
Which foot movement is likely to worsen this patient's discomfort?Your Answer:
Correct Answer: Plantarflexion of the foot
Explanation:The structures that pass behind the medial malleolus can be remembered using the mnemonic Tom, Dick and Very Nervous Harry which stands for Tibialis posterior, flexor Digitorum longus, posterior tibial Artery, posterior tibial Vein, tibial Nerve and flexor Hallucis longus.
The patient in this case is experiencing tarsal tunnel syndrome which is characterized by numbness and tingling along the distribution of the posterior tibial nerve. Tinel’s test, which involves tapping on the area behind the medial malleolus, can help diagnose nerve compression.
The abductor hallucis muscle is responsible for abducting the big toe and its tendon does not pass through the tarsal tunnel. Dorsiflexion of the foot is primarily performed by the tibialis anterior muscle, while the tibialis posterior tendon runs through the tarsal tunnel. Extension of the big toe is performed by the extensor hallucis brevis and longus muscles, while extension of the toes is primarily performed by the extensor digitorum longus muscle. The big toe can be extended independently from the other toes due to the action of the extensor hallucis muscles.
Anatomy of the Ankle Joint
The ankle joint is a type of synovial joint that is made up of the tibia and fibula superiorly and the talus inferiorly. It is supported by several ligaments, including the deltoid ligament, lateral collateral ligament, and talofibular ligaments. The calcaneofibular ligament is separate from the fibrous capsule of the joint, while the two talofibular ligaments are fused with it. The syndesmosis is composed of the antero-inferior tibiofibular ligament, postero-inferior tibiofibular ligament, inferior transverse tibiofibular ligament, and interosseous ligament.
The ankle joint allows for plantar flexion and dorsiflexion movements, with a range of 55 and 35 degrees, respectively. Inversion and eversion movements occur at the level of the sub talar joint. The ankle joint is innervated by branches of the deep peroneal and tibial nerves.
Reference:
Golano P et al. Anatomy of the ankle ligaments: a pictorial essay. Knee Surg Sports Traumatol Arthrosc. 2010 May;18(5):557-69. -
This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 29
Incorrect
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A nine-year-old tumbles from the climbing equipment at the park and is taken to the emergency department. X-rays reveal a supracondylar fracture of the left distal humerus. During the examination, the child exhibits weakened finger flexion in the left hand, inability to perform opposition of the left thumb and little finger, and altered sensation over the lateral aspect of the palm and first three digits. Can you identify the location of the damaged structure in the antecubital fossa?
Your Answer:
Correct Answer: Medial to the brachial artery
Explanation:The cubital fossa contains the following structures in order from lateral to medial: radial nerve, brachial tendon, brachial artery, and median nerve. In this case, the damaged nerve is the median nerve, which is located most medially in the cubital fossa, next to the brachial artery.
In the antecubital fossa, the radial nerve is located deep and laterally, next to the biceps tendon. The biceps tendon serves as a marker for finding the brachial artery, which is located medially to it.
It is incorrect to say that there is a nerve located between the biceps tendon and the brachial artery in the antecubital fossa.
The Antecubital Fossa: Anatomy and Clinical Significance
The antecubital fossa is a depression located on the anterior aspect of the arm, between the arm and forearm. It is an important area for medical professionals as it is where venous blood samples are typically taken from. The borders of the antecubital fossa are the brachioradialis muscle laterally, the pronator teres medially, and a line between the medial and lateral epicondyles superiorly.
There are both deep and superficial structures found in the antecubital fossa. Deep structures include the radial nerve, tendon of the biceps muscle, brachial artery, and medial nerve. Superficial structures consist of a network of veins, including the cephalic vein and basilic vein, which come together as the median cubital vein.
The main clinical relevance of the antecubital fossa is its use for blood sampling and cannulation. However, it is also important to have a working knowledge of the anatomy as structures can become damaged. Excessive straining of the biceps tendon can cause it to rupture, leading to a ‘Popeye sign’. Damage to the medial nerve can also occur, resulting in muscle paralysis in the forearm and hand. Overall, understanding the anatomy and clinical significance of the antecubital fossa is crucial for medical professionals.
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This question is part of the following fields:
- Musculoskeletal System And Skin
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Question 30
Incorrect
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A 56-year-old man presents to his GP complaining of numbness and tingling in his thumb, middle, and index fingers for the past 8 months. This is beginning to interfere with his work as a financial analyst. He has a history of hypothyroidism for which he takes 100 micrograms of thyroxine daily.
Which nerves are involved in this condition?Your Answer:
Correct Answer: Median nerve
Explanation:To identify the affected nerve, it is crucial to accurately diagnose the underlying condition. The patient’s symptoms, such as numbness and tingling in the thumb and middle finger (and possibly the radial half of the ring finger), suggest carpal tunnel syndrome. Additionally, the patient’s occupation involving computer use and hypothyroidism are risk factors for this condition.
Carpal tunnel syndrome occurs when the median nerve is compressed at the carpal tunnel as it passes through the wrist.
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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