Which of the following is not a boundary of the triangle of auscultation?
Sympathetic supply to the heart arises from which of the following spinal segments?
Which structure is located immediately posterior to the head of the pancreas?
Ophthalmic artery is a branch of:
Sensory supply of the palm is from which nerves?
Which of the following is not the part of ethmoid bone?
Primary and secondary palates are divided by
Primordial germ cells are derived from:
Pituicytes are seen in ?
The thoracic duct crosses from the right to the left at the level of
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 71: Which of the following is not a boundary of the triangle of auscultation?
- A. Trapezius
- B. Scapula
- C. Rhomboid major (Correct Answer)
- D. Latissimus dorsi
Explanation: ***Rhomboid major*** - The **rhomboid major** muscle forms the **floor** of the triangle of auscultation, not one of its boundaries. - Its function is to **retract** and **rotate** the scapula, anchoring it to the thoracic wall. *Trapezius* - The **trapezius** muscle forms the **superior** and **medial** boundary of the triangle of auscultation. - It defines the upper limit of this anatomical space on the back. *Scapula* - The **medial border of the scapula** forms the **lateral** boundary of the triangle of auscultation. - This bony landmark helps to delineate the outer edge of the triangle. *Latissimus dorsi* - The **latissimus dorsi** muscle forms the **inferior** boundary of the triangle of auscultation. - It defines the lower limit of this region, allowing for better sound transmission to the thoracic cavity.
Question 72: Sympathetic supply to the heart arises from which of the following spinal segments?
- A. T1 to T5 (Correct Answer)
- B. T2 to T6
- C. T3 to T7
- D. T4 to T8
Explanation: The preganglionic sympathetic fibers that innervate the heart originate from the lateral horns of the thoracic spinal segments T1 to T5. These fibers synapse in the cervical and upper thoracic sympathetic ganglia, from which postganglionic fibers extend to the heart. While there is some overlap, the primary and most significant sympathetic innervation to the heart stems predominantly from T1 to T5, making T2 to T6 a less precise answer. Including T6 would extend past the typical primary cardiac sympathetic innervation, which largely concludes at T5. This range is too caudal and largely beyond the principal segments providing sympathetic innervation to the heart. Segments T6-T8 are more involved in sympathetic supply to abdominal organs and other structures rather than direct cardiac control.
Question 73: Which structure is located immediately posterior to the head of the pancreas?
- A. Portal vein (Correct Answer)
- B. Splenic artery
- C. Inferior mesenteric vein
- D. Coeliac trunk
Explanation: ***Portal vein*** - The **portal vein** is formed by the union of the **splenic vein** and the **superior mesenteric vein** (SMV) posterior to the **neck** of the pancreas [1]. - It then runs in a **groove on the posterior surface** of the head of the pancreas, lying anterior to the **inferior vena cava** (IVC). - Among the given options, the portal vein has the most direct posterior relationship to the head of the pancreas. *Splenic artery* - The **splenic artery** runs along the **superior border** of the pancreas, following its body and tail. - It does not lie posterior to the head of the pancreas. - It is a branch of the **celiac trunk** and supplies the spleen. *Inferior mesenteric vein* - The **inferior mesenteric vein** typically drains into the **splenic vein** or the junction of the splenic and superior mesenteric veins. - It ascends **anterior** to the left kidney and does not lie immediately posterior to the head of the pancreas. *Coeliac trunk* - The **celiac trunk** originates from the **abdominal aorta** at the level of T12-L1 vertebra. - It lies **superior and anterior** to the pancreas, giving off the splenic artery, common hepatic artery, and left gastric artery. - It is not located posterior to the head of the pancreas.
Question 74: Ophthalmic artery is a branch of:
- A. Cavernous part of ICA
- B. Cerebral part of ICA (Correct Answer)
- C. MCA
- D. Facial artery
Explanation: ***Cerebral part of ICA*** - The **ophthalmic artery** is typically the first major branch off the **internal carotid artery (ICA)** once it exits the cavernous sinus and enters the cranial cavity. - This segment of the ICA is also known as the supraclinoid or **cerebral part**, underscoring its proximity to the brain. *Cavernous part of ICA* - The **cavernous part of the ICA** is located within the cavernous sinus and typically gives off smaller branches such as the **meningohypophyseal trunk** and the **inferolateral trunk**, which supply structures within and around the sinus. - The ophthalmic artery emerges after the ICA exits the cavernous sinus, not from within it. *MCA* - The **middle cerebral artery (MCA)** is a major terminal branch of the internal carotid artery, supplying large parts of the cerebrum. - It does not give rise to the ophthalmic artery, which branches off the ICA before the ICA bifurcates into the MCA and anterior cerebral artery. *Facial artery* - The **facial artery** is a branch of the **external carotid artery**, supplying structures of the face. - The ophthalmic artery is a primary supply to the orbit and is derived from the internal carotid artery, a completely separate vascular system.
Question 75: Sensory supply of the palm is from which nerves?
- A. Median nerve and Radial nerve
- B. Radial nerve and ulnar nerve
- C. Ulnar nerve and Median nerve (Correct Answer)
- D. Musculocutaneous nerve and Radial nerve
Explanation: **Ulnar nerve and Median nerve** *(Correct)* - The **median nerve** provides sensory innervation to the lateral palm, including the thumb, index, middle, and radial half of the ring finger [1]. - The **ulnar nerve** supplies sensory innervation to the medial palm, including the little finger and the ulnar half of the ring finger [1]. - Together, these two nerves provide complete sensory coverage of the palm [1]. *Median nerve and Radial nerve* (Incorrect) - While the **median nerve** innervates a significant portion of the palm, the **radial nerve** primarily supplies the dorsal aspect of the hand and a small area of the thenar eminence, not the entire palm. - The radial nerve's sensory supply to the palm is usually limited to a very small area at the base of the thumb. - This combination does not provide complete palmar sensory coverage. *Radial nerve and ulnar nerve* (Incorrect) - The **radial nerve** mainly supplies the dorsum of the hand and digits, with minimal palmar contribution, making this option incorrect for primary palmar sensory supply. - The **ulnar nerve** does innervate part of the palm, but the combination with the radial nerve for complete palmar supply is inaccurate. - The median nerve, not the radial nerve, is the other major contributor to palmar sensation. *Musculocutaneous nerve and Radial nerve* (Incorrect) - The **musculocutaneous nerve** primarily innervates the lateral aspect of the forearm (as the lateral antebrachial cutaneous nerve) and does not contribute to the sensory supply of the palm. - The **radial nerve** also has a limited role in palmar sensation. - Neither of these nerves provides significant sensory innervation to the palm.
Question 76: Which of the following is not the part of ethmoid bone?
- A. Agger nasi
- B. Crista galli
- C. Uncinate process
- D. Inferior turbinate (Correct Answer)
Explanation: ***Inferior turbinate*** - The **inferior turbinate** (or inferior nasal concha) is a separate paired facial bone, distinct from the ethmoid bone. - It articulates with the maxilla, lacrimal, palatine, and ethmoid bones but is not a component of the ethmoid. *Agger nasi* - The **agger nasi** is an anatomical variant, an anterior expansion of the ethmoid air cells, and is thus functionally part of the ethmoid complex. - While not a distinct bone, it is an **ethmoid cell** that can be found in the anterior aspect of the middle meatus. *Crista galli* - The **crista galli** is a prominent, upward projection from the cribriform plate of the ethmoid bone, serving as an attachment point for the falx cerebri. - It is an integral and easily recognizable part of the **ethmoid bone**. *Uncinate process* - The **uncinate process** is a sickle-shaped bony projection that arises from the inferior aspect of the ethmoid bone. - It forms the anterior boundary of the **hiatus semilunaris** and is crucial for the drainage of the frontal and maxillary sinuses.
Question 77: Primary and secondary palates are divided by
- A. Greater palatine foramen
- B. Canine teeth
- C. Alveolar arch
- D. Incisive foramen (Correct Answer)
Explanation: ***Incisive foramen*** - The **incisive foramen** is an anatomical landmark located just posterior to the central incisors, and it marks the boundary between the developmentally distinct primary and secondary palates. - The **primary palate** develops from the median palatine process, while the **secondary palate** develops from the palatal shelves of the maxillary prominences [1]. *Greater palatine foramen* - The **greater palatine foramen** is located near the posterior border of the hard palate, transmitting the greater palatine nerve and vessels. - It lies within the **secondary palate** and does not delineate the boundary between the primary and secondary palatal structures. *Canine teeth* - The **canine teeth** are part of the dental arch and play a role in mastication. - While located in the anterior part of the oral cavity, they are not a developmental or anatomical boundary marker for palatal divisions [1]. *Alveolar arch* - The **alveolar arch** is the bone that supports the teeth, forming the curved ridge of the maxilla and mandible [1]. - It is distinct from the palate and does not serve as a divider between the primary and secondary palatal components.
Question 78: Primordial germ cells are derived from:
- A. Neural crest
- B. Genital ridge
- C. Somatopleuritic mesoderm
- D. Yolk sac (Correct Answer)
Explanation: ***Yolk sac*** - **Primordial germ cells (PGCs)** arise from **epiblast** cells but are first identifiable in the wall of the **yolk sac** during the **3rd week** of development. - From the yolk sac, they migrate during the **4th-6th week** through the dorsal mesentery to reach the developing **genital ridges** (gonads) where they form **gametes** [2]. - The yolk sac is considered the site where PGCs are recognized and begin their journey to the gonads. *Neural crest* - Neural crest cells are multipotent cells that migrate to various locations and differentiate into structures like **neurons**, **glial cells**, **melanocytes**, and **facial cartilage**, not germ cells. - They arise from the dorsal part of the **neural tube** during neurulation. *Genital ridge* - The genital ridge is the embryonic structure that develops into the **gonads** (testes or ovaries) [1]. - Primordial germ cells migrate *to* the genital ridge, but they do not originate *from* it — it is their destination, not their source. *Somatopleuritic mesoderm* - **Somatopleuritic mesoderm** (somatic mesoderm) forms the **parietal layer** of serous membranes, the dermis of the body wall, and the skeletal elements of the limbs. - It does not give rise to **primordial germ cells**.
Question 79: Pituicytes are seen in ?
- A. Anterior lobe
- B. Posterior lobe (Correct Answer)
- C. Intermediate lobe
- D. All of the options
Explanation: ***Posterior lobe*** - **Pituicytes** are specialized glial cells found exclusively in the **posterior pituitary** (neurohypophysis). [1] - They provide structural support and regulation for the nerve terminals that release **antidiuretic hormone (ADH)** and **oxytocin**. [1] *Anterior lobe* - The anterior pituitary, or **adenohypophysis**, consists of glandular epithelial cells that synthesize and secrete various hormones. [2] - It does not contain pituicytes, which are glial cells. [2] *Intermediate lobe* - The intermediate lobe is a rudimentary part of the pituitary gland in humans, primarily producing **melanocyte-stimulating hormone (MSH)**. [1] - While it is part of the pituitary, it does not contain pituicytes. *All of the options* - Pituicytes are specific to the posterior pituitary, so they are not found in all parts of the gland. - Different lobes of the pituitary gland have distinct cellular compositions and functions.
Question 80: The thoracic duct crosses from the right to the left at the level of
- A. T12 vertebra
- B. T2 vertebra
- C. T4-T5 vertebra (Correct Answer)
- D. T6 vertebra
Explanation: ***T4-T5 vertebra*** - The **thoracic duct** crosses from the right to the left side of the vertebral column at the level of the **T4-T5 vertebrae**, specifically just above the root of the left lung. - This crossover is an important anatomical landmark as it signifies the duct's ascent towards the neck to drain into the left subclavian vein. *T12 vertebra* - The **thoracic duct** originates from the **cisterna chyli** at the level of the L1 or L2 vertebra and ascends into the thorax at or below the T12 vertebra, it does not cross over at this level. - This level primarily marks its entry into the thoracic cavity, not its main crossover point. *T6 vertebra* - While the **thoracic duct** is present in the thorax at this level, it does not undergo its characteristic crossover from right to left at the T6 vertebra. - The duct continues its ascent along the right side of the vertebral column before moving across. *T2 vertebra* - By the level of the T2 vertebra, the **thoracic duct** has already crossed to the left side of the vertebral column and is ascending towards its termination in the neck. - The crossover event occurs more inferiorly, at the T4-T5 level.