NEET-PG 2015 Practice Questions

Q: Root value of the thoracodorsal nerve

C6, C7, C8. ***C6, C7, C8*** - The **thoracodorsal nerve**, also known as the middle subscapular nerve, originates from the **posterior cord of the brachial plexus**. - Its specific root values are **C6, C7, and C8**, which supply motor innervation to the **latissimus dorsi muscle** [1]. - This nerve is one of the three subscapular nerves arising from the posterior cord [1]. *C5, C6, C7* - While these roots contribute to the **posterior cord**, the thoracodorsal nerve specifically arises from **C6, C7, C8**. - **C5** primarily contributes to the **upper and middle trunk** and is more associated with nerves like the **suprascapular** and **axillary nerves**. *C6, T1* - These root values contribute to various nerves of the **brachial plexus**, but not specifically the thoracodorsal nerve. - **T1** contributes mainly to the **medial cord** and its branches like the **ulnar nerve**, not the posterior cord from which the thoracodorsal nerve arises. *T1, T2* - These are typical root values for **intercostal nerves** and contribute to the **sympathetic trunk**, not the **brachial plexus** or its branches like the thoracodorsal nerve. - The brachial plexus predominantly arises from **C5 to T1 spinal nerve roots**, and **T2** is not part of the brachial plexus.

Q: Haustrations are present in -

Colon. ***Colon*** - **Haustrations** are characteristic sacculations or pouches that give the colon its segmented appearance [1]. - They are formed by the tonic contractions of the **teniae coli**, which are three distinct bands of longitudinal smooth muscle found in the muscularis externa of the colon. *Duodenum* - The duodenum is the first part of the small intestine and is characterized by **plicae circulares (circular folds)** and **villi**, not haustrations. - Its primary role is chemical digestion and initial absorption, with a smooth, folded inner surface. *Ileum* - The ileum is the final and longest part of the small intestine, featuring **Peyer's patches** (lymphoid nodules) and prominent plicae circulares [2], but lacks haustrations. - Its main function is the absorption of vitamin B12 and bile salts [2]. *Jejunum* - The jejunum is the middle section of the small intestine, known for its tall and numerous **plicae circulares** and villi, making it highly efficient for nutrient absorption. - It does not possess haustrations, which are unique to the large intestine.

Q: Which of the following is not a posterior relation of the right kidney?

11th rib. ***11th rib*** - The right kidney typically extends from the 12th thoracic vertebra to the 3rd lumbar vertebra, usually covered by the **12th rib**. - The **11th rib** is usually a posterior relation of the **left kidney**, due to the lower position of the right kidney compared to the left kidney. *Diaphragm* - The diaphragm lies **posterior** to both the right and left kidneys, separating them from the pleura and lungs. - This anatomical relationship means that renal procedures or severe kidney infections can sometimes affect the thoracic cavity. *Subcostal nerve* - The **subcostal nerve** (T12) runs inferior to the 12th rib and passes **posterior** to both kidneys. - It provides sensory innervation to the skin and motor innervation to abdominal muscles. *Ilioinguinal nerve* - The **ilioinguinal nerve** (L1) emerges from the lumbar plexus and travels **posterior** to the inferior pole of both kidneys [1]. - It primarily provides sensory innervation to the groin and parts of the external genitalia.

Q: Which of the following statements about the blood supply of the kidney is NOT true?

Renal artery is a branch of common iliac artery. ***Renal artery is a branch of common iliac artery.*** - The **renal arteries** originate directly from the **abdominal aorta**, not the common iliac arteries. - The common iliac arteries branch subsequently from the **abdominal aorta** lower down to supply the pelvis and lower limbs. *Renal vein drains into IVC* - The **renal veins** are responsible for draining deoxygenated blood from the kidneys and typically empty directly into the **inferior vena cava (IVC)** [1]. - This is a correct anatomical relationship, essential for returning filtered blood to systemic circulation. *Right renal artery passes behind IVC* - The **right renal artery** typically originates from the aorta and passes **posterior to the inferior vena cava (IVC)** to reach the right kidney. - This anatomical arrangement is correct due to the position of the aorta and IVC relative to the kidneys. *Branches of renal artery are end arteries* - The intralobar and interlobar branches of the renal artery are considered **functional end arteries**, meaning they provide the sole blood supply to the kidney segments they perfuse. - This characteristic makes the kidney particularly susceptible to **ischemic damage** if these arteries are occluded, as there is little to no collateral circulation.

Q: Azygos vein drains into:

Superior vena cava. ***Superior vena cava*** - The **azygos vein** is a major venous channel that drains the walls of the thorax and abdomen, emptying directly into the **superior vena cava (SVC)**. [1] - This connection is crucial for venous return from the posterior thoracic wall, pericardium, and bronchi, especially bypassing the inferior vena cava if it's obstructed. [1] *Right subcostal vein* - The right subcostal vein is a tributary that helps form the **azygos vein**; it does not receive drainage from the azygos vein. - It contributes to the initial formation of the azygos system, not its termination. *Brachiocephalic* - The **brachiocephalic veins** are formed by the union of the internal jugular and subclavian veins, and they merge to form the **superior vena cava**. - The azygos vein drains into the superior vena cava, not directly into the brachiocephalic veins. *Right ascending lumbar vein* - The **right ascending lumbar vein** is a major tributary that contributes to the formation of the **azygos vein** in the lumbar region. - It drains into the azygos system, illustrating its origin rather than its termination.

Q: A nerve injured during axillary lymph node dissection leads to loss of sensation in the medial side of the arm. Which nerve is injured?

Intercostobrachial nerve. ***Intercostobrachial nerve*** - The **intercostobrachial nerve** (T2) is the nerve most commonly injured during **axillary lymph node dissection** - It provides **sensory innervation to the medial side of the upper arm**, specifically the skin over the medial and posterior aspects of the arm [1] - This nerve arises from the **lateral cutaneous branch of the second intercostal nerve** and crosses the axilla to reach the arm [1] - Injury during axillary surgery results in **numbness or paresthesia** in the medial upper arm region, which is a well-recognized complication of breast cancer surgery with axillary node dissection [1] - Studies show **30-80% of patients** undergoing axillary dissection experience intercostobrachial nerve injury *Long thoracic nerve* - The **long thoracic nerve** (C5-C7) innervates the **serratus anterior muscle**, which is crucial for scapular protraction and rotation - Damage to this nerve causes **"winged scapula"**, where the scapula protrudes posteriorly - This is a **motor nerve**, not sensory, so injury does not result in sensory deficits in the arm *Medial pectoral nerve* - The **medial pectoral nerve** (C8-T1) primarily innervates the **pectoralis major** and **pectoralis minor** muscles [1] - This is a **motor nerve** playing a role in muscle function rather than sensation [1] - Injury would result in weakness of these muscles, not sensory loss *Accessory nerve* - The **accessory nerve** (cranial nerve XI) innervates the **sternocleidomastoid** and **trapezius muscles** - This nerve is located in the **posterior triangle of the neck**, not in the axilla - Injury would lead to weakness in shrugging the shoulders or turning the head, not sensory loss in the arm during axillary dissection

Q: Which nerve roots are primarily involved in Erb's palsy?

C5, C6. C5, C6 - **Erb's palsy** primarily involves injury to the **upper trunk of the brachial plexus**, which is formed by the ventral rami of **C5 and C6** spinal nerves. - This lesion results in a characteristic "waiter's tip" posture due to paralysis of muscles supplied by these nerve roots, including the **deltoid**, **biceps**, and **brachialis**. *C4, C5* - While C5 is involved, **C4** is typically associated with the **phrenic nerve** and diaphragm function, and its primary involvement is not characteristic of Erb's palsy. - Injury to C4 and C5 alone would not produce the comprehensive motor deficits seen in Erb's palsy involving shoulder and elbow flexion. *C5, C7* - This option includes C5 but also **C7**, which is more commonly associated with the **middle trunk** of the brachial plexus. - While C7 can be involved in extended brachial plexus injuries, its primary involvement alone is not the classic presentation of Erb's palsy. *C6, C8* - This combination includes C6 but introduces **C8**, which is part of the **lower trunk** of the brachial plexus. - Injuries involving C8 and T1 are characteristic of **Klumpke's palsy**, affecting intrinsic hand muscles and causing a "claw hand" deformity, which is distinct from Erb's palsy.

Q: Arch of aorta begins at which vertebral level?

T4. ***T4*** - The **arch of the aorta** typically begins at the level of the **upper border of the fourth thoracic vertebra (T4)**. - This anatomical landmark is crucial for understanding the **topography of the mediastinum** and the branching of the great vessels. *T2* - The **T2 vertebral level** is too high; the arch of the aorta does not begin this superiorly. - This level is often associated with structures like the **trachea** and **esophagus** in the superior mediastinum, but not the aortic arch's origin. *T3* - The **T3 vertebral level** is also too high for the typical origin of the aortic arch. - The **manubrium of the sternum** generally extends down to this level, but the aorta's arch begins slightly lower. *T5* - The **T5 vertebral level** is too low; at this point, the arch of the aorta has usually already passed posteriorly and begun its descent as the **descending aorta** [1]. - The **bifurcation of the trachea** typically occurs at the T4/T5 intervertebral disc level. *T2* - The left recurrent laryngeal nerve (RLN) separates from the vagus as it passes anterior to the arch of the aorta [1].

Q: Intercostal nerve is a branch of?

Ventral rami of thoracic spinal nerves. ***Ventral rami of thoracic spinal nerves*** - Intercostal nerves are direct continuations of the **ventral rami of the thoracic spinal nerves** (T1-T11) [1]. - These nerves run within the **intercostal spaces**, providing sensory and motor innervation to the thoracic wall [2]. *Brachial plexus* - The brachial plexus is formed by the **ventral rami of spinal nerves C5-T1**. - It primarily innervates the **upper limb**, not the intercostal spaces. *Dorsal rami of thoracic spinal nerves* - The dorsal rami of thoracic spinal nerves supply the **deep back muscles** and the skin over the back. - They do not contribute to the innervation of the intercostal spaces or the anterior/lateral thoracic wall. *Ventral rami of cervical spinal nerves* - The ventral rami of cervical spinal nerves form the **cervical plexus (C1-C4)** and contribute to the **brachial plexus (C5-T1)**. - They innervate structures in the neck, diaphragm, and upper limb, but not the intercostal region.

Q: Distance of cricopharynx from incisor teeth

Approximately 15 cm. ***Approximately 15 cm*** - The **cricopharynx** (upper esophageal sphincter at C6 level), which is the narrowest part of the pharynx, is typically located about **15 cm** from the incisor teeth in adults. - This anatomical landmark is crucial in procedures such as **endoscopy**, **intubation**, and **nasogastric tube insertion** to avoid injury. *22 cm* - This distance corresponds to the level of the **aortic arch** (second physiological narrowing of the esophagus). - This is where the aorta crosses anterior to the esophagus, creating the broncho-aortic constriction. *27 cm* - A distance of 27 cm from the incisor teeth corresponds to the level where the **left main bronchus** crosses the esophagus (third physiological narrowing). - This is well beyond the location of the **cricopharynx** and represents the mid-esophageal region. *40 cm* - This measurement represents the approximate total length of the **esophagus**, reaching the **gastroesophageal junction** at the level of the **diaphragmatic hiatus** (cardia of the stomach). - The **cricopharynx** is at the very beginning of this path, much closer to the incisors.

Question 1

Root value of the thoracodorsal nerve

Accepted Answer

C6, C7, C8

Answer

T1, T2

Answer

C5, C6, C7

Answer

C6, T1

Question 2

Haustrations are present in -

Accepted Answer

Colon

Answer

Duodenum

Answer

Ileum

Answer

Jejunum

Question 3

Which of the following is not a posterior relation of the right kidney?

Accepted Answer

11th rib

Answer

Subcostal nerve

Answer

Diaphragm

Answer

Ilioinguinal nerve

Question 4

Which of the following statements about the blood supply of the kidney is NOT true?

Accepted Answer

Renal artery is a branch of common iliac artery

Answer

Right renal artery passes behind IVC

Answer

Branches of renal artery are end arteries

Answer

Renal vein drains into IVC

Question 5

Azygos vein drains into:

Accepted Answer

Superior vena cava

Answer

Right subcostal vein

Answer

Right ascending lumbar vein

Answer

Brachiocephalic

Question 6

A nerve injured during axillary lymph node dissection leads to loss of sensation in the medial side of the arm. Which nerve is injured?

Accepted Answer

Intercostobrachial nerve

Answer

Long thoracic nerve

Answer

Medial pectoral nerve

Answer

Accessory nerve

Question 7

Which nerve roots are primarily involved in Erb's palsy?

Accepted Answer

C5, C6

Answer

C4, C5

Answer

C5, C7

Answer

C6, C8

Question 8

Arch of aorta begins at which vertebral level?

Accepted Answer

T4

Answer

T2

Answer

T5

Answer

T3

Question 9

Intercostal nerve is a branch of?

Accepted Answer

Ventral rami of thoracic spinal nerves

Answer

Brachial plexus

Answer

Dorsal rami of thoracic spinal nerves

Answer

Ventral rami of cervical spinal nerves

Question 10

Distance of cricopharynx from incisor teeth

Accepted Answer

Approximately 15 cm

Answer

22 cm

Answer

27 cm

Answer

40 cm

NEET-PG 2015

Anatomy