Vasculature of the Back — MCQs
The vein of Galen is formed by which structure?
The thyrocervical trunk is a branch of which part of subclavian artery?
In anterior spinal artery syndrome which of the following is spared
The sternocleidomastoid muscle is supplied by all of the following arteries except?
Posterior communicating artery is a branch of?
Which of the following arteries is likely to be involved in a 3rd cranial nerve lesion?
Which of the following parts of the vertebral canal shows the first secondary curve to develop?
In a diving accident that severed the spinal cord below the sixth cervical vertebra, which of the following muscles would be affected?
Muscles attached to the greater tubercle of the humerus include which of the following?
Which of the following muscles is not in the pectoral region?
Vasculature of the Back Indian Medical PG Practice Questions and MCQs
Question 1: The vein of Galen is formed by which structure?
- A. Internal cerebral veins (Correct Answer)
- B. Basal veins of Rosenthal
- C. Inferior sagittal sinus
- D. Superior sagittal sinus
Explanation: ***Internal cerebral veins*** - The **great cerebral vein of Galen** is formed by the union of two **internal cerebral veins** and two **basal veins of Rosenthal**. - It plays a crucial role in draining the deep venous system of the brain, including the **thalamus**, **basal ganglia**, and **choroid plexus**. - While both internal cerebral veins and basal veins contribute to its formation, "internal cerebral veins" is the most commonly tested answer. *Basal veins of Rosenthal* - The **basal veins of Rosenthal** also contribute to forming the great cerebral vein of Galen along with the internal cerebral veins. - However, in most examination contexts, the internal cerebral veins are considered the primary answer. - The basal veins primarily drain structures in the midbrain, thalamus, and insula. *Inferior sagittal sinus* - The **inferior sagittal sinus** does not form the great cerebral vein. - Instead, it merges with the **great cerebral vein** to form the **straight sinus**. - The inferior sagittal sinus runs along the lower border of the falx cerebri. *Superior sagittal sinus* - The **superior sagittal sinus** does not form the great cerebral vein. - It drains into the **confluence of sinuses** (torcular Herophili), which then connects to the transverse sinuses. - It runs along the superior border of the falx cerebri and drains the superior aspects of the cerebral hemispheres.
Question 2: The thyrocervical trunk is a branch of which part of subclavian artery?
- A. 1st part (Correct Answer)
- B. 2nd part
- C. 3rd part
- D. 4th part
Explanation: ***1st part*** - The **thyrocervical trunk** is one of the three primary branches arising from the **first part** of the subclavian artery. - The first part lies medial to the **anterior scalene muscle**. *2nd part* - The **second part** of the subclavian artery gives rise to the **costocervical trunk**. - This part lies posterior to the **anterior scalene muscle**. *3rd part* - The **third part** of the subclavian artery typically has no branches or may give off the **dorsal scapular artery**. - This part lies lateral to the **anterior scalene muscle**. *4th part* - This option is incorrect as the **subclavian artery has only three parts**, divided by their relationship to the anterior scalene muscle. - There is no anatomical fourth part of the subclavian artery.
Question 3: In anterior spinal artery syndrome which of the following is spared
- A. Lateral spinothalamic tract
- B. Posterior columns (Correct Answer)
- C. Anterior spinothalamic tract
- D. Corticospinal tract
Explanation: ***Posterior columns*** - The **anterior spinal artery** supplies the anterior two-thirds of the spinal cord, leaving the **posterior columns** (dorsal columns) and often the dorsal horns with intact blood supply from the **posterior spinal arteries** [1]. - This sparing results in preserved **fine touch**, **vibration**, and **proprioception** (dorsal column function), which are the defining clinical features distinguishing it from other spinal cord syndromes [1]. *Lateral spinothalamic tract* - This tract, responsible for **pain** and **temperature** sensation, is located within the territory supplied by the **anterior spinal artery** [3]. - Damage to this tract leads to bilateral loss of pain and temperature sensation below the level of the lesion [3]. *Anterior spinothalamic tract* - The **anterior spinothalamic tract** mediates crude touch and pressure and is located anteriorly, within the vascular distribution of the **anterior spinal artery**. - Injury to this tract contributes to the overall sensory deficit observed in anterior spinal artery syndrome. *Corticospinal tract* - The **corticospinal tracts** (also known as the pyramidal tracts), responsible for **voluntary motor control**, are situated in the anterior and lateral funiculi of the spinal cord [2]. - These tracts are supplied by the **anterior spinal artery**, leading to **bilateral motor paralysis** below the lesion in anterior spinal artery syndrome.
Question 4: The sternocleidomastoid muscle is supplied by all of the following arteries except?
- A. Occipital
- B. Thyrocervical trunk
- C. Posterior auricular (Correct Answer)
- D. Superior thyroid
Explanation: ***Posterior auricular*** - The **posterior auricular artery** is a branch of the external carotid artery that primarily supplies structures **behind the ear** including the scalp, auricle, and parotid region. - It does **NOT** provide blood supply to the sternocleidomastoid muscle. - This artery ascends behind the ear and is not involved in the vascular supply of the SCM. *Occipital* - The **occipital artery**, a branch of the external carotid artery, provides a significant blood supply to the sternocleidomastoid muscle. - It specifically has a **sternocleidomastoid branch** that arises near the lower part of the muscle. - This is one of the main arterial supplies to the SCM. *Superior thyroid* - The **superior thyroid artery**, the first branch of the external carotid artery, gives off a **sternocleidomastoid branch** that supplies the upper part of the muscle. - While primarily known for supplying the thyroid gland, its muscular branches contribute to SCM vascularization. *Thyrocervical trunk* - The **thyrocervical trunk** (from the subclavian artery) gives rise to the **suprascapular artery**, which provides blood supply to the sternocleidomastoid muscle. - The suprascapular artery supplies the middle and deep portions of the SCM. - Other branches of the thyrocervical trunk include the inferior thyroid and transverse cervical arteries.
Question 5: Posterior communicating artery is a branch of?
- A. Internal carotid (Correct Answer)
- B. External carotid
- C. Middle cerebral
- D. Superior cerebellar
Explanation: ***Internal carotid*** - The **posterior communicating artery** connects the **internal carotid artery** circulation (anterior circulation) with the posterior cerebral artery (vertebrobasilar circulation). - It is a key component of the **circle of Willis**, ensuring collateral blood flow to the brain. *External carotid* - The **external carotid artery** primarily supplies the face, scalp, and neck, not the intracranial structures directly involved in the circle of Willis. - Its branches include the **superficial temporal artery** and **facial artery**, which are distinct from cerebral circulation. *Middle cerebral* - The **middle cerebral artery** is a **direct continuation** of the internal carotid artery, supplying large parts of the cerebral hemispheres. - While it arises from the internal carotid, the posterior communicating artery branches off the internal carotid **before** the middle cerebral artery. *Superior cerebellar* - The **superior cerebellar artery** is a branch of the **basilar artery**, supplying the superior cerebellum and parts of the brainstem. - This artery is part of the **vertebrobasilar system**, which is distinct from the primary origin of the posterior communicating artery.
Question 6: Which of the following arteries is likely to be involved in a 3rd cranial nerve lesion?
- A. Anterior communicating
- B. Posterior communicating (Correct Answer)
- C. Posterior cerebral
- D. Anterior cerebral
Explanation: ***Posterior communicating*** - The **posterior communicating artery (PCoA)** is anatomically juxtaposed to the **oculomotor nerve (CN III)** as it exits the midbrain. - An **aneurysm** of the PCoA can compress the CN III, leading to findings such as **ptosis**, **mydriasis**, and **"down and out" deviation** of the eye [1]. *Anterior communicating* - The **anterior communicating artery (AComA)** is located more anteriorly and inferiorly, primarily associated with the **optic chiasm** and **olfactory tracts**. - While aneurysms here can cause visual field defects or frontal lobe dysfunction, they are less likely to directly compress the **oculomotor nerve**. *Posterior cerebral* - The **posterior cerebral artery (PCA)** supplies regions like the **visual cortex** and midbrain. - PCA aneurysms or infarctions typically result in deficits such as **hemianopia**, **alexia**, or specific midbrain syndromes, not isolated CN III compression. *Anterior cerebral* - The **anterior cerebral artery (ACA)** supplies the medial aspects of the frontal and parietal lobes. - Aneurysms or strokes in the ACA territory commonly lead to **contralateral leg weakness** or behavioral changes, not cranial nerve palsies due to its anatomical location.
Question 7: Which of the following parts of the vertebral canal shows the first secondary curve to develop?
- A. Lumbar Vertebral Canal
- B. Thoracic Vertebral Canal
- C. Cervical Vertebral Canal (Correct Answer)
- D. Sacral Vertebral Canal
Explanation: ***Cervical Vertebral Canal*** - The **cervical curve** is the **first secondary curve** to develop as an infant learns to hold their head up (around 3-4 months). - This **lordotic curve** is concave posteriorly and helps to balance the head on the vertebral column. - It develops before the lumbar curve, making it the earliest secondary curvature. *Lumbar Vertebral Canal* - The **lumbar curve** is also a **secondary curve** but develops later when an infant begins to stand and walk (around 12-18 months). - It is a **lordotic curve**, concave posteriorly, and helps maintain an upright posture. - This is the second secondary curve to develop. *Thoracic Vertebral Canal* - The **thoracic curve** is a **primary curve**, meaning it is present at birth. - This **kyphotic curve** is convex posteriorly and accommodates the thoracic organs. *Sacral Vertebral Canal* - The **sacral curve** is another **primary curve**, also present at birth. - It is a **kyphotic curve**, convex posteriorly, and contributes to the pelvic basin's shape.
Question 8: In a diving accident that severed the spinal cord below the sixth cervical vertebra, which of the following muscles would be affected?
- A. Deltoid
- B. Infraspinatus
- C. Levator Scapulae
- D. Latissimus Dorsi (Correct Answer)
Explanation: ***Latissimus Dorsi*** - The **latissimus dorsi muscle** is primarily innervated by the **thoracodorsal nerve**, which arises from the **C6, C7, and C8** nerve roots (with C7 and C8 being the predominant contributors) [1]. - A spinal cord injury below the sixth cervical vertebra would affect the C7 and C8 segments, thereby disrupting the nerve supply to the latissimus dorsi, leading to weakness or paralysis. - This muscle is responsible for adduction, extension, and internal rotation of the shoulder. *Deltoid* - The **deltoid muscle** is innervated by the **axillary nerve**, which arises predominantly from the **C5 and C6** nerve roots. - Since the injury is below the C6 vertebra, the upper cervical segments (C5 and C6) would remain intact above the level of injury. - Therefore, deltoid function would be preserved. *Infraspinatus* - The **infraspinatus muscle** is innervated by the **suprascapular nerve**, which arises from the **C5 and C6** nerve roots. - Similar to the deltoid, its innervation originates above the level of the spinal cord injury and would be spared. *Levator Scapulae* - The **levator scapulae muscle** receives innervation from the **C3, C4, and C5** spinal nerves, as well as contributions from the dorsal scapular nerve (predominantly C5). - All of these nerve roots originate well above the level of injury, so this muscle would not be affected.
Question 9: Muscles attached to the greater tubercle of the humerus include which of the following?
- A. Latissimus dorsi
- B. Teres major
- C. Pectoralis major
- D. Supraspinatus (Correct Answer)
Explanation: ***Supraspinatus*** - The **supraspinatus muscle** is one of the four rotator cuff muscles and inserts onto the **superior facet of the greater tubercle** of the humerus. - Its primary function is to **abduct the arm** in the initial 15 degrees. *Latissimus dorsi* - The **latissimus dorsi** inserts onto the **floor of the bicipital groove** of the humerus, not the greater tubercle. - It is primarily responsible for **extension, adduction, and internal rotation** of the arm. *Teres major* - The **teres major muscle** inserts onto the **medial lip of the bicipital groove** (intertubercular sulcus) of the humerus. - Its actions are similar to the latissimus dorsi, including **adduction, extension, and internal rotation** of the arm. *Pectoralis major* - The **pectoralis major muscle** inserts onto the **lateral lip of the bicipital groove** (intertubercular sulcus) of the humerus. - Its main actions are **adduction, internal rotation**, and **flexion of the humerus**.
Question 10: Which of the following muscles is not in the pectoral region?
- A. Pectoralis major
- B. Infraspinatus (Correct Answer)
- C. Pectoralis minor
- D. Subclavius
Explanation: ***Infraspinatus*** - The **infraspinatus** muscle is located in the **posterior scapular region**, specifically on the posterior aspect of the scapula, filling the infraspinous fossa. - Its primary function is **external rotation** of the humerus, and it is a key component of the **rotator cuff**. *Pectoralis major* - The **pectoralis major** is a large, superficial muscle located in the **anterior chest wall**, forming the bulk of the chest. [1] - It plays a significant role in **adduction**, **flexion**, and **medial rotation** of the humerus. *Pectoralis minor* - The **pectoralis minor** is a smaller, triangular muscle situated beneath the pectoralis major in the **anterior thoracic wall**. [1] - Its functions include **stabilizing the scapula** by pulling it inferiorly and anteriorly, and assisting in forced inspiration. [1] *Subclavius* - The **subclavius** is a small, triangular muscle located inferior to the clavicle in the **pectoral region**. - Its primary role is to **depress and stabilize the clavicle**, protecting the underlying neurovascular structures.
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