A 17-year-old boy comes to the physician because of a 3-month history of pain in his right shoulder. He reports that he has stopped playing for his high school football team because of persistent difficulty lifting his right arm. Physical examination shows impaired active abduction of the right arm from 0 to 15 degrees. After passive abduction of the right arm to 15 degrees, the patient is able to raise his arm above his head. The dysfunctional muscle in this patient is most likely to be innervated by which of the following nerves?
Q2
A neurology resident sees a stroke patient on the wards. This 57-year-old man presented to the emergency department after sudden paralysis of his right side. He was started on tissue plasminogen activator within 4 hours, as his wife noticed the symptoms and immediately called 911. When the resident asks the patient how he is doing, he replies by saying that his apartment is on Main St. He does not seem to appropriately answer the questions being asked, but rather speaks off topic. He is able to repeat the word "fan." His consciousness is intact, and his muscle tone and reflexes are normal. Upon striking the lateral part of his sole, his big toe extends upward and the other toes fan out. Which of the following is the area most likely affected in his condition?
Q3
A patient undergoes spinal surgery at the L4-L5 level. During the procedure, which of the following ligaments must be divided first to access the spinal canal?
Q4
A 40-year-old male presents to the physician's office complaining of an inability to push doors open. He has had this problem since he was playing football with his children and was tackled underneath his right arm on his lateral chest. On examination, he has a winged scapula on the right side. Which of the following nerves is most likely the cause of this presentation?
Q5
A young researcher is responsible for graphing laboratory data involving pulmonary blood flow and ventilation pattern obtained from a healthy volunteer who was standing in an upright position. After plotting the following graph, the researcher realizes he forgot to label the curves and the x-axis (which represents the position in the lung). Which of the following is the appropriate label for each point on the graph?
Q6
An MRI of a patient with low back pain reveals compression of the L5 nerve root. Which of the following muscles would most likely show weakness during physical examination?
Q7
A 24-year-old woman comes to the emergency department because of abdominal pain, fever, nausea, and vomiting for 12 hours. Her abdominal pain was initially dull and diffuse but has progressed to a sharp pain on the lower right side. Two years ago she had to undergo right salpingo-oophorectomy after an ectopic pregnancy. Her temperature is 38.7°C (101.7°F). Physical examination shows severe right lower quadrant tenderness with rebound tenderness; bowel sounds are decreased. Laboratory studies show leukocytosis with left shift. An abdominal CT scan shows a distended, edematous appendix. The patient is taken to the operating room for an appendectomy. During the surgery, the adhesions from the patient's previous surgery make it difficult for the resident physician to identify the appendix. Her attending mentions that she should use a certain structure for guidance to locate the appendix. The attending is most likely referring to which of the following structures?
Q8
The Image shows the growth curve of different organs with age. Identify A in the graph.
Q9
Identify the labeled structures correctly in the axial CT image of the thorax
Q10
Linear growth of bone is disturbed when a fracture occurs in which part?
Anatomical terminology and positions US Medical PG Practice Questions and MCQs
Question 1: A 17-year-old boy comes to the physician because of a 3-month history of pain in his right shoulder. He reports that he has stopped playing for his high school football team because of persistent difficulty lifting his right arm. Physical examination shows impaired active abduction of the right arm from 0 to 15 degrees. After passive abduction of the right arm to 15 degrees, the patient is able to raise his arm above his head. The dysfunctional muscle in this patient is most likely to be innervated by which of the following nerves?
A. Long thoracic nerve
B. Suprascapular nerve (Correct Answer)
C. Upper subscapular nerve
D. Accessory nerve
E. Axillary nerve
Explanation: ***Suprascapular nerve***
- The patient exhibits impaired active abduction from 0 to 15 degrees but normal abduction after passive assistance, indicating dysfunction of the **supraspinatus muscle**.
- The **supraspinatus muscle** is responsible for **initiating shoulder abduction** from 0 to 15 degrees, after which the deltoid muscle takes over for continued abduction.
- The **suprascapular nerve** innervates both the **supraspinatus** and **infraspinatus muscles**, with the supraspinatus being crucial for the initial phase of abduction.
*Long thoracic nerve*
- This nerve innervates the **serratus anterior muscle**, which is responsible for **scapular protraction** and upward rotation.
- Damage to the long thoracic nerve would typically result in **winged scapula**, not difficulty in initiating abduction.
*Upper subscapular nerve*
- The upper subscapular nerve innervates the **subscapularis muscle**, part of the rotator cuff.
- This muscle is primarily involved in **internal rotation** of the shoulder and contributes to adduction, not abduction.
*Accessory nerve*
- The accessory nerve (cranial nerve XI) innervates the **sternocleidomastoid** and **trapezius muscles**.
- Damage to this nerve would most likely present with weakness in **shrugging the shoulders** or turning the head, not difficulty with shoulder abduction.
*Axillary nerve*
- This nerve innervates the **deltoid muscle** and the **teres minor muscle**, and provides sensory input from the shoulder joint and lateral arm.
- The deltoid is responsible for **shoulder abduction** from 15 to 90 degrees; a deficit here would affect a different range of motion than what is described.
Question 2: A neurology resident sees a stroke patient on the wards. This 57-year-old man presented to the emergency department after sudden paralysis of his right side. He was started on tissue plasminogen activator within 4 hours, as his wife noticed the symptoms and immediately called 911. When the resident asks the patient how he is doing, he replies by saying that his apartment is on Main St. He does not seem to appropriately answer the questions being asked, but rather speaks off topic. He is able to repeat the word "fan." His consciousness is intact, and his muscle tone and reflexes are normal. Upon striking the lateral part of his sole, his big toe extends upward and the other toes fan out. Which of the following is the area most likely affected in his condition?
A. Caudate nucleus
B. Broca’s area
C. Arcuate fasciculus
D. Temporal lobe (Correct Answer)
E. Cuneus gyrus
Explanation: ***Temporal lobe***
- The patient exhibits features of **Wernicke's aphasia**, characterized by **fluent but nonsensical speech** ("apartment is on Main St." when asked how he is), poor comprehension, and the ability to repeat words. **Wernicke's area**, responsible for language comprehension, is located in the **posterior part of the superior temporal gyrus**.
- **Sudden paralysis of the right side** indicates involvement of the left cerebral hemisphere (**contralateral motor cortex** lesion), while speech disturbances point to the dominant hemisphere, which is typically the **left temporal lobe**.
*Caudate nucleus*
- Lesions of the **caudate nucleus** are primarily associated with **movement disorders** (e.g., chorea) and **behavioral changes**, not typically with fluent aphasia as described.
- While it plays a role in cognitive functions, its direct involvement in the specific language deficits presented is less likely.
*Broca’s area*
- Damage to **Broca's area**, located in the **frontal lobe**, causes **Broca's aphasia**, characterized by **non-fluent, halting speech** with good comprehension and poor repetition.
- The patient's speech is **fluent**, though off-topic, which contrasts with the typical presentation of Broca's aphasia.
*Arcuate fasciculus*
- The **arcuate fasciculus** connects Broca's and Wernicke's areas, and damage to it typically causes **conduction aphasia**, characterized by **impaired repetition** despite fluent speech and good comprehension.
- While the patient has impaired comprehension, his ability to repeat "fan" makes conduction aphasia less likely than Wernicke's aphasia, where repetition can vary but comprehension is profoundly affected.
*Cuneus gyrus*
- The **cuneus gyrus** is located in the **occipital lobe** and is primarily involved in **visual processing**.
- Damage to this area would lead to **visual field deficits** (e.g., hemianopia) rather than the language and comprehension problems described.
Question 3: A patient undergoes spinal surgery at the L4-L5 level. During the procedure, which of the following ligaments must be divided first to access the spinal canal?
A. Nuchal ligament
B. Anterior longitudinal ligament
C. Supraspinous ligament
D. Ligamentum flavum (Correct Answer)
Explanation: ***Ligamentum flavum***
- The **ligamentum flavum** connects the laminae of adjacent vertebrae and forms the posterior boundary of the spinal canal, making it the first ligament encountered anteriorly after removing the lamina.
- While performing a posterior approach **laminectomy**, the ligamentum flavum is typically divided or removed to gain access to the neural structures within the spinal canal.
*Nuchal ligament*
- The **nuchal ligament** is located in the cervical spine and provides attachment for muscles, extending from the external occipital protuberance to the spinous process of C7.
- It is not present at the **L4-L5 level** and therefore plays no role in lumbar spinal surgery.
*Anterior longitudinal ligament*
- The **anterior longitudinal ligament** runs along the anterior surfaces of the vertebral bodies and intervertebral discs.
- It would be encountered during an **anterior surgical approach** to the spine, not a posterior approach to access the spinal canal.
*Supraspinous ligament*
- The **supraspinous ligament** connects the tips of the spinous processes and is the most superficial ligament posteriorly.
- While it is incised during a posterior approach, it is **superficial to the lamina** and ligamentum flavum; therefore, the lamina and ligamentum flavum must be removed or divided first to access the canal.
Question 4: A 40-year-old male presents to the physician's office complaining of an inability to push doors open. He has had this problem since he was playing football with his children and was tackled underneath his right arm on his lateral chest. On examination, he has a winged scapula on the right side. Which of the following nerves is most likely the cause of this presentation?
A. Phrenic nerve
B. Spinal accessory nerve
C. Long thoracic nerve (Correct Answer)
D. Greater auricular nerve
E. Musculocutaneous nerve
Explanation: ***Long thoracic nerve***
- The **long thoracic nerve** innervates the **serratus anterior muscle**, which is responsible for scapular protraction and upward rotation.
- Damage to this nerve, often from trauma to the lateral chest wall (tackled underneath the arm), leads to paralysis of the serratus anterior and a characteristic **winged scapula** with lateral and inferior prominence.
- Patients have difficulty with **pushing movements** (protraction) and overhead activities.
*Phrenic nerve*
- The **phrenic nerve** primarily innervates the **diaphragm** and is crucial for respiration.
- Damage to the phrenic nerve would cause respiratory compromise, not a winged scapula or difficulty pushing doors.
*Spinal accessory nerve*
- The **spinal accessory nerve (cranial nerve XI)** innervates the **sternocleidomastoid** and **trapezius muscles**.
- Injury to this nerve can cause scapular winging due to **trapezius paralysis**, but the winging is typically **medial** with the inferior angle moving medially, unlike the lateral winging from serratus anterior paralysis.
- The mechanism of injury (lateral chest trauma during tackling) and inability to push are classic for **long thoracic nerve** injury, not spinal accessory nerve.
*Greater auricular nerve*
- The **greater auricular nerve** is a cutaneous nerve that provides sensation to the skin over the parotid gland, mastoid process, and auricle.
- Damage to this nerve would result in sensory loss in these areas and is unrelated to muscle weakness or a winged scapula.
*Musculocutaneous nerve*
- The **musculocutaneous nerve** innervates the **biceps brachii**, **brachialis**, and **coracobrachialis muscles**, responsible for elbow flexion and forearm supination.
- Damage to this nerve would primarily affect these movements and sensation in the lateral forearm, not leading to a winged scapula.
Question 5: A young researcher is responsible for graphing laboratory data involving pulmonary blood flow and ventilation pattern obtained from a healthy volunteer who was standing in an upright position. After plotting the following graph, the researcher realizes he forgot to label the curves and the x-axis (which represents the position in the lung). Which of the following is the appropriate label for each point on the graph?
A. A: Ventilation B: Blood flow C: Base of the lung D: Apex of the lung (Correct Answer)
B. A: Ventilation B: Blood flow C: Mid-portion of the lung D: Apex of the lung
C. A: Dead Space B: Shunt C: Base of the lung D: Apex of the lung
D. A: Blood flow B: Ventilation C: Base of the lung D: Lung hilum
E. A: Blood flow B: Ventilation C: Apex of the lung D: Lung hilum
Explanation: ***A: Ventilation B: Blood flow C: Base of the lung D: Apex of the lung***
- In an upright individual, both **ventilation** and **blood flow** are greater at the **base of the lung** than at the apex due to gravity.
- However, the increase in **perfusion** from apex to base (curve B) is proportionally much greater than the increase in **ventilation** (curve A), leading to a higher V/Q ratio at the apex and a lower V/Q ratio at the base.
*A: Ventilation B: Blood flow C: Mid-portion of the lung D: Apex of the lung*
- This option correctly identifies curves A and B but incorrectly labels C as the **mid-portion of the lung** instead of the base.
- The x-axis represents the lung from base to apex or vice-versa, and the curve indicates the highest values at C.
*A: Dead Space B: Shunt C: Base of the lung D: Apex of the lung*
- This option incorrectly identifies curves A and B; they represent **ventilation** and **blood flow**, not dead space and shunt, which are concepts related to V/Q mismatch.
- **Dead space** refers to ventilated but unperfused areas, while a **shunt** is perfused but unventilated.
*A: Blood flow B: Ventilation C: Base of the lung D: Lung hilum*
- This option incorrectly reverses the labels for curves A and B, as **blood flow** increases more steeply than **ventilation** towards the base.
- The x-axis represents the lung position from base to apex, not the **hilum**, which is a specific anatomical region.
*A: Blood flow B: Ventilation C: Apex of the lung D: Lung hilum*
- This option incorrectly reverses the labels for curves A and B, in addition to mislabeling C as the **apex of the lung**, where values are lowest, not highest.
- The X-axis represents the lung position from base to apex, not focusing on the **hilum**.
Question 6: An MRI of a patient with low back pain reveals compression of the L5 nerve root. Which of the following muscles would most likely show weakness during physical examination?
A. Tibialis posterior
B. Tibialis anterior (Correct Answer)
C. Gastrocnemius
D. Quadriceps femoris
Explanation: ***Tibialis anterior***
- The **L5 nerve root** primarily innervates muscles responsible for **dorsiflexion** of the foot, with the **tibialis anterior** being the primary dorsiflexor.
- Weakness of the tibialis anterior would manifest as difficulty lifting the front of the foot, potentially leading to a **foot drop** gait.
*Tibialis posterior*
- The **tibialis posterior** is primarily innervated by the **tibial nerve** (S1-S2) and is responsible for **plantarflexion** and **inversion** of the foot.
- Weakness in this muscle would not be the most likely presentation of L5 nerve root compression.
*Gastrocnemius*
- The **gastrocnemius** muscle is primarily innervated by the **tibial nerve** (S1-S2) and is a powerful **plantarflexor** of the foot.
- Weakness in this muscle would indicate an S1 or S2 nerve root issue, not typically L5.
*Quadriceps femoris*
- The **quadriceps femoris** is innervated by the **femoral nerve**, predominantly originating from the **L2, L3, and L4 nerve roots**.
- Weakness would manifest as difficulty extending the knee, which is not characteristic of L5 compression.
Question 7: A 24-year-old woman comes to the emergency department because of abdominal pain, fever, nausea, and vomiting for 12 hours. Her abdominal pain was initially dull and diffuse but has progressed to a sharp pain on the lower right side. Two years ago she had to undergo right salpingo-oophorectomy after an ectopic pregnancy. Her temperature is 38.7°C (101.7°F). Physical examination shows severe right lower quadrant tenderness with rebound tenderness; bowel sounds are decreased. Laboratory studies show leukocytosis with left shift. An abdominal CT scan shows a distended, edematous appendix. The patient is taken to the operating room for an appendectomy. During the surgery, the adhesions from the patient's previous surgery make it difficult for the resident physician to identify the appendix. Her attending mentions that she should use a certain structure for guidance to locate the appendix. The attending is most likely referring to which of the following structures?
A. Epiploic appendages
B. Right ureter
C. Deep inguinal ring
D. Ileocolic artery
E. Teniae coli (Correct Answer)
Explanation: ***Teniae coli***
- The **teniae coli** are three distinct longitudinal bands of smooth muscle that run along the length of the cecum and colon, converging at the base of the **appendix**.
- Following these bands inferiorly from the ascending colon or cecum during surgery is a reliable method to locate the **vermiform appendix**, especially in the presence of adhesions.
*Epiploic appendages*
- These are small, fat-filled sacs that protrude from the surface of the **large intestine** but are not directly used as a reliable landmark for locating the appendix.
- While present in the vicinity, they do not consistently lead to the base of the appendix like the teniae coli.
*Right ureter*
- The **right ureter** is located retroperitoneally, deep to the cecum and appendix, and is not a direct anatomical landmark used for identifying the appendix during an appendectomy.
- Identifying the ureter is important to avoid injury, but not for localizing the appendix.
*Deep inguinal ring*
- The **deep inguinal ring** is an opening in the transversalis fascia, involved in the formation of the inguinal canal, and is located far anterior and inferior to the region of the appendix.
- It has no anatomical relationship that would guide a surgeon to locate the appendix.
*Ileocolic artery*
- The **ileocolic artery** branches from the superior mesenteric artery and supplies the terminal ileum, cecum, and appendix. While it provides blood supply to the appendix, it is not a direct or consistent surface landmark for locating the appendix itself, especially in complex cases with adhesions.
- Locating the artery would be more complex and less reliable for initial identification compared to the teniae coli.
Question 8: The Image shows the growth curve of different organs with age. Identify A in the graph.
A. Brain Growth
B. Somatic Growth
C. Lymphoid Growth (Correct Answer)
D. Gonadal Growth
E. Reproductive Growth
Explanation: ***Lymphoid Growth***
- Curve 'A' shows a rapid increase in size during **childhood**, peaking around **10-12 years of age**, and then declining to adult levels.
- This pattern is characteristic of **lymphoid tissues** (e.g., thymus, lymph nodes, tonsils), which are larger relative to body size in childhood and undergo involution post-puberty.
*Brain Growth*
- **Neural growth** (like the brain) typically shows very rapid growth in early childhood, reaching close to adult size by about 6-7 years of age, and then leveling off.
- Curve 'A' continues to grow rapidly much longer than expected for brain development and then shows a distinct decline.
*Somatic Growth*
- **General somatic growth** (e.g., body as a whole) shows a sigmoid curve, with rapid growth in infancy and adolescence, and a plateau in adulthood.
- Curve 'A' peaks significantly above the 100% mark and then declines, which is not characteristic of overall somatic growth.
*Gonadal Growth*
- **Genital (gonadal) growth** remains relatively flat until puberty, after which it experiences a rapid increase.
- Curve 'A' shows significant growth in early childhood and a peak before puberty, which is inconsistent with typical gonadal development.
*Reproductive Growth*
- **Reproductive growth** follows the same pattern as gonadal growth, remaining minimal until puberty with subsequent rapid increase.
- Curve 'A' demonstrates early childhood growth and pre-pubertal peak, which does not match the reproductive growth pattern.
Question 9: Identify the labeled structures correctly in the axial CT image of the thorax
A. A - Pulmonary trunk, B - Ascending aorta, C - Superior vena cava, D - Descending aorta
B. A - Superior vena cava, B - Pulmonary trunk, C - Ascending aorta, D - Descending aorta
C. A - Ascending aorta, B - Pulmonary trunk, C - Superior vena cava, D - Descending aorta (Correct Answer)
D. A - Ascending aorta, B - Superior vena cava, C - Pulmonary trunk, D - Descending aorta
E. A - Pulmonary trunk, B - Superior vena cava, C - Ascending aorta, D - Descending aorta
Explanation: ***A - Ascending aorta, B - Pulmonary trunk, C - Superior vena cava, D - Descending aorta***
- **A** points to the **ascending aorta**, which is the large artery arising from the left ventricle and supplying oxygenated blood to the systemic circulation. On this axial view, it is typically located anterior and to the right of the pulmonary artery.
- **B** points to the **pulmonary trunk**, which emerges from the right ventricle and bifurcates into the pulmonary arteries to carry deoxygenated blood to the lungs. It is positioned anterior and to the left of the ascending aorta at this level.
- **C** points to the **superior vena cava**, a large vein that collects deoxygenated blood from the upper half of the body and drains into the right atrium. It is typically located to the right and slightly posterior to the ascending aorta at this level.
- **D** points to the **descending aorta**, which continues from the aortic arch downwards through the chest and abdomen to supply blood to the lower body. It is visible posteriorly and to the left of the vertebral body on this axial CT image.
*A - Pulmonary trunk, B - Ascending aorta, C - Superior vena cava, D - Descending aorta*
- This option incorrectly identifies A as the pulmonary trunk and B as the ascending aorta; the **ascending aorta** is typically positioned more anteriorly and to the right compared to the **pulmonary trunk** at this level.
- The relative positions of the pulmonary trunk and ascending aorta are swapped, leading to an incorrect labeling.
*A - Superior vena cava, B - Pulmonary trunk, C - Ascending aorta, D - Descending aorta*
- This option incorrectly identifies A as the superior vena cava and C as the ascending aorta. The **superior vena cava** is typically located to the right of the ascending aorta, not anterior-central.
- The **ascending aorta** is usually the most anterior and central great vessel in the mediastinum at this level, which does not correspond to C.
*A - Ascending aorta, B - Superior vena cava, C - Pulmonary trunk, D - Descending aorta*
- This option incorrectly identifies B as the superior vena cava and C as the pulmonary trunk. **Superior vena cava** is a venous structure and is not typically located in the position of B, which is an arterial structure (pulmonary trunk).
- The **pulmonary trunk** is usually more anterior and central than the position of C, which correctly identifies the superior vena cava in other options.
Question 10: Linear growth of bone is disturbed when a fracture occurs in which part?
A. Epiphysis
B. Diaphysis
C. Metaphysis
D. Epiphyseal plate (Correct Answer)
E. Periosteum
Explanation: ***Epiphyseal plate***
- The **epiphyseal plate**, also known as the **growth plate**, is a cartilaginous disc responsible for the **longitudinal growth** of long bones.
- A fracture in this region can damage the **chondrocytes** and disrupt the normal process of endochondral ossification, leading to **growth arrest** or limb length discrepancy.
*Epiphysis*
- The **epiphysis** is the end part of a long bone, often covered by **articular cartilage**, forming a joint.
- While an epiphyseal fracture can affect joint function, it typically does not directly disturb the **linear growth** of the bone unless it extends into the growth plate.
*Diaphysis*
- The **diaphysis** is the main or midsection of a long bone, composed primarily of **compact bone**.
- Fractures in the diaphysis generally heal through **callus formation** and remodeling, usually without significantly impacting the overall **linear growth** of the bone.
*Metaphysis*
- The **metaphysis** is the wider portion of a long bone, adjacent to the growth plate and diaphysis.
- Though highly vascular, fractures to the metaphysis usually heal well and do not directly control **linear bone growth** like the epiphyseal plate.
*Periosteum*
- The **periosteum** is the fibrous membrane covering the outer surface of bones, important for **appositional growth** (bone widening) and fracture healing.
- While it contains osteogenic cells that contribute to bone repair and thickness, it does not control **longitudinal bone growth**, which is the function of the epiphyseal plate.
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