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
What is the anatomical significance of the Rhinion in relation to the osseocartilaginous junction?
Primordial germ cells are derived from:
The thoracic duct crosses from the right to the left at the level of
Which structures are located anterior to the transverse sinus?
Anal valve is found in which part of anal canal?
In patients with penile or urethral injury, Colle's fascia prevents extravasation of urine from spreading into which anatomical space?
Which lymph nodes are involved in the lymphatic drainage of the lateral wall of the nose?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 71: 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 72: 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 73: 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 74: What is the anatomical significance of the Rhinion in relation to the osseocartilaginous junction?
- A. Nasion
- B. Rhinion (Correct Answer)
- C. Radix
- D. Columella
Explanation: ***Correct Answer: Rhinion*** - The **rhinion** is the **most prominent anterior point of the nasal bone**, often palpable as a slight bump or angulation on the dorsum of the nose. - It marks the anatomical location of the **osseocartilaginous junction** of the nasal dorsum, where the bony nasal framework transitions to the cartilaginous framework. - This is the key anatomical landmark that defines the transition from bone to cartilage in the external nose. *Incorrect: Nasion* - The **nasion** is located at the **root of the nose**, specifically at the most anterior and superior point of the nasofrontal suture. - It is a bony landmark and does not directly relate to the osseocartilaginous junction of the nasal dorsum. *Incorrect: Radix* - The **radix** (or nasal root) refers to the **uppermost part of the nose**, corresponding to the nasion. - It defines the point where the nose begins to project from the forehead and is a bony landmark, not directly related to the osseocartilaginous junction. *Incorrect: Columella* - The **columella** is the **fleshy, narrow strip of tissue that separates the nostrils**. - It forms the inferior segment of the nasal septum and is composed of skin, soft tissue, and the medial crura of the alar cartilages, thus having no direct relation to the osseocartilaginous junction of the nasal dorsum.
Question 75: 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 76: 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.
Question 77: Which structures are located anterior to the transverse sinus?
- A. Right atrium
- B. Left atrium
- C. Right pulmonary artery
- D. Aorta (Correct Answer)
Explanation: ***Aorta*** - The **transverse sinus of the pericardium** is a passage within the pericardial cavity that separates the great arteries (aorta and pulmonary trunk) anteriorly from the atria and great veins posteriorly. - The **ascending aorta** and **pulmonary trunk** are both located anterior to the transverse sinus. - This anatomical relationship is clinically important during cardiac surgery, as the transverse sinus can be used to pass ligatures around the great vessels. *Right atrium* - The **right atrium** is located posterior to the transverse sinus. - It forms part of the posterior wall of the pericardial cavity and receives the superior and inferior venae cavae. - The transverse sinus separates the atria from the anteriorly positioned great arteries. *Left atrium* - The **left atrium** is also positioned posterior to the transverse sinus. - It forms the base of the heart and receives the pulmonary veins. - Like the right atrium, it lies behind the plane of the transverse sinus. *Right pulmonary artery* - The **right pulmonary artery** is a branch of the pulmonary trunk that passes to the right lung. - While the **pulmonary trunk** itself is anterior to the transverse sinus, the **right pulmonary artery** branch courses laterally and posteriorly, passing behind the ascending aorta and superior vena cava. - Therefore, the right pulmonary artery is NOT considered anterior to the transverse sinus in the same way the main great vessels (aorta and pulmonary trunk) are.
Question 78: Anal valve is found in which part of anal canal?
- A. Lower
- B. At anus
- C. Middle (Correct Answer)
- D. Upper
Explanation: ***Middle*** - The **anal valves** are crescentic folds located at the level of the **pectinate (dentate) line** in the middle portion of the anal canal. - They mark the inferior limit of the **anal columns** and form small recesses called **anal sinuses**. *Lower* - The lower part of the anal canal, below the pectinate line, is lined by **anoderm** and lacks anal valves. - This region is sensitive to pain due to somatic innervation. *At anus* - The anus refers to the external opening and perianal skin, which does not contain anal valves. - The anal canal transitions into the perianal skin at the anocutaneous line. *Upper* - The upper part of the anal canal, above the pectinate line, contains the **anal columns (columns of Morgagni)** but not the anal valves themselves, which are located at the base of these columns. - This region is lined by columnar epithelium and is relatively insensitive to pain.
Question 79: In patients with penile or urethral injury, Colle's fascia prevents extravasation of urine from spreading into which anatomical space?
- A. Superficial perineal space
- B. None of the options
- C. Ischiorectal fossa (Correct Answer)
- D. Abdomen
Explanation: ***Ischiorectal fossa*** - Colle's fascia (superficial perineal fascia) is the membranous layer that defines the boundaries of the **superficial perineal space**. - When urethral injury occurs, urine extravasates into the superficial perineal space but is **prevented from spreading laterally and posteriorly** into the ischiorectal fossa because Colle's fascia fuses with the **ischiopubic rami** laterally and the **perineal membrane** posteriorly [1]. - The ischiorectal fossa is a space lateral to the **anal canal** that is separated from the superficial perineal space by these fascial attachments. *Superficial perineal space* - This is actually the space **into which** urine extravasates when penile or urethral injury occurs, not the space that is protected from extravasation [1]. - Colle's fascia forms the inferior boundary of this space, so urine collects here rather than being prevented from entering. *Abdomen* - Colle's fascia in the perineum is continuous with **Scarpa's fascia** of the anterior abdominal wall. - Due to this continuity, urine can actually **track superiorly** into the anterior abdominal wall along this fascial plane. - Therefore, Colle's fascia does NOT prevent spread to the abdomen. *None of the options* - This option is incorrect because Colle's fascia specifically prevents lateral and posterior spread into the ischiorectal fossa through its anatomical attachments.
Question 80: Which lymph nodes are involved in the lymphatic drainage of the lateral wall of the nose?
- A. Deep cervical nodes
- B. Retropharyngeal nodes
- C. Submandibular nodes
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - The lymphatic drainage from the **lateral wall of the nose** follows a sequential pathway involving **submandibular nodes**, **retropharyngeal nodes**, and ultimately the **deep cervical nodes**. - This question tests understanding of the complete lymphatic drainage pathway, not just the primary drainage site. - All three node groups are anatomically involved in draining lymph from the lateral nasal wall. **Drainage Pathway:** - **Submandibular nodes** (Primary): The anterior and middle portions of the lateral nasal wall drain primarily to the submandibular lymph nodes. - **Retropharyngeal nodes** (Secondary): The posterior portions of the lateral wall and areas near the nasal pharynx drain to retropharyngeal nodes. - **Deep cervical nodes** (Final pathway): Lymph from both submandibular and retropharyngeal nodes eventually drains into the deep cervical chain, particularly the jugulodigastric and juguloomohyoid nodes. *Why not just one node group?* - The lateral wall of the nose has an extensive lymphatic network with multiple drainage routes. - Different regions of the lateral wall have preferential drainage to different node groups. - Understanding the complete drainage pathway is clinically important for assessing spread of infections and malignancies from the nasal cavity.