NEET-PG 2018 — Anatomy

Q: Which of the following is not seen in the anterior mediastinum?

Neurogenic tumor. ***Neurogenic tumor*** - **Neurogenic tumors** typically arise from nerve tissue and are most commonly found in the **posterior mediastinum**. - The posterior mediastinum is the primary location for these tumors due to the presence of the **sympathetic chain**, intercostal nerves, and vagus nerve. *Thyroid tumour* - **Ectopic thyroid tissue** can be found in the anterior mediastinum, and this tissue can give rise to thyroid tumors [1]. - While less common than in the neck, substernal or **ectopic thyroid goiters** and carcinomas can present in this compartment [1]. *Thymoma* - The **thymus gland** is located in the anterior mediastinum, making thymoma (a tumor of the thymus) a classic anterior mediastinal mass [1]. - Thymomas are often associated with **paraneoplastic syndromes** like myasthenia gravis. *Lymphoma* - **Lymphatic tissue**, including lymph nodes, is plentiful in the anterior mediastinum [1]. - **Hodgkin's and non-Hodgkin's lymphoma** frequently present as masses in the anterior mediastinum, often causing symptoms due to compression of surrounding structures [1]. [Practice more Anatomy PYQs on OnCourse]

Q: Which of the following statements about Sibson's fascia is correct?

Covers apical part of lung. ***Covers apical part of lung*** - **Sibson's fascia**, also known as the **suprapleural membrane**, is a dense fascial layer that covers and reinforces the **apex of the lung** and pleura. - It protects the lung apex and helps to support structures in the **root of the neck**. *Part of scalenus anterior muscle* - Sibson's fascia is a **separate fascial structure** extending from the first rib to the C7 transverse process, and is not a part of the scalenus anterior muscle. - The **scalenus anterior muscle** is one of the muscles of the neck, and while anatomically related by proximity to the fascia, it is not structurally part of it. *Vessel pass above the fascia* - Key neurovascular structures like the **subclavian artery** and the **brachial plexus** pass *below* Sibson's fascia, as the fascia protects the lung apex. - The fascia acts as a barrier, separating the lung apex from the more superficial structures of the neck. *Attached to the inner border of 2nd rib* - Sibson's fascia is primarily attached to the **inner border of the first rib** and the transverse process of the seventh cervical vertebra. - Its attachment to the first rib is crucial for its supportive role over the lung apex. [Practice more Anatomy PYQs on OnCourse]

Q: Blowout fracture of the orbit most commonly involves?

Floor. ***Floor*** - The **orbital floor** is the most commonly fractured site in a blowout fracture due to its thinness and location, often leading to herniation of orbital contents into the maxillary sinus. - This type of fracture often results from a **sudden increase in intraorbital pressure** by a blunt trauma, causing the weakest part of the orbit to give way. *Medial wall* - While less common than floor fractures, the **medial wall** can also be fractured in a blowout injury, leading to herniation into the ethmoid sinuses. - Involvement of the medial wall can sometimes damage the **lacrimal drainage system** or the medial rectus muscle. *Lateral wall* - The **lateral wall** of the orbit is significantly thicker and more robust than the floor or medial wall, making isolated lateral wall fractures extremely rare. - Fractures of the lateral wall are usually associated with more extensive **zygomaticomaxillary complex (ZMC)** fractures or high-impact trauma. *Roof* - The **orbital roof** is composed of the frontal bone and is considerably stronger and thicker than the floor, making roof fractures uncommon in isolated blowout injuries. - Fractures of the orbital roof typically occur with **severe trauma** and are often associated with intracranial injury or damage to the frontal sinus. [Practice more Anatomy PYQs on OnCourse]

Q: When does the basiocciput fuse with the basisphenoid?

5-7 years. Note: This is a NEET-PG 2018 previous year question. The provided options and marked answer reflect the exam's original content. However, standard anatomical references indicate that the spheno-occipital synchondrosis (junction between basiocciput and basisphenoid) typically fuses between 18-25 years of age, not in early childhood. 5-7 years (Marked as correct in original exam) - This was the expected answer in the NEET-PG 2018 exam. - However, standard anatomical texts (Gray's Anatomy, Standring) indicate that spheno-occipital fusion occurs much later, typically between 18-25 years. - There may be confusion with other cranial base developments that occur in early childhood. 2-4 years - This is earlier than even the exam's intended answer. - The spheno-occipital synchondrosis remains cartilaginous at this age. 8-10 years - Still within the childhood period. - The spheno-occipital synchondrosis typically remains unfused at this age. 12-15 years - Early to mid-adolescence. - The spheno-occipital synchondrosis is usually still present, though beginning to show signs of fusion in some individuals by late adolescence. Clinical Note: The fusion of the spheno-occipital synchondrosis is an important forensic marker for age estimation, with complete fusion generally occurring by the mid-20s. [Practice more Anatomy PYQs on OnCourse]

Q: What is the primary tensor of the vocal cords?

Cricothyroid. ***Cricothyroid*** - The **cricothyroid muscle** is the principal tensor of the vocal cords, responsible for stretching and thinning them. - It achieves this by tilting the **thyroid cartilage** forward relative to the **cricoid cartilage**, increasing the distance between the **thyroid** and **arytenoid cartilages**. *Lateral Cricoarytenoid* - This muscle primarily functions as an **adductor** of the vocal cords, bringing them together. - It rotates the **arytenoid cartilages** medially, closing the **rima glottidis**. *Thyroarytenoids* - The **thyroarytenoid muscles** are located within the vocal cords and primarily act to **shorten and relax** the vocal cords. - They also contribute to **adduction** and can internally tense the vocal folds, but their main role is *not* primary tension. *Posterior cricoarytenoids* - The **posterior cricoarytenoid muscles** are the *only* muscles responsible for **abducting** (opening) the vocal cords. - They rotate the **arytenoid cartilages** laterally, thus widening the **rima glottidis**. [Practice more Anatomy PYQs on OnCourse]

24 Previous Year Questions with Answers & Explanations

Questions

Which of the following is not seen in the anterior mediastinum?

Which of the following statements about Sibson's fascia is correct?

Blowout fracture of the orbit most commonly involves?

When does the basiocciput fuse with the basisphenoid?

What is the primary tensor of the vocal cords?

Which of the following is NOT part of the special visceral efferent column?

What type of joint is formed by the costal cartilages of the 8th and 9th ribs?

Acute tonsillitis affects which nerve:

Ureteric bud develops from:

Q10

Nerves of the Branchial arches are derived from:

NEET-PG 2018 - Anatomy NEET-PG Practice Questions and MCQs

Question 1: Which of the following is not seen in the anterior mediastinum?

A. Thyroid tumor
B. Neurogenic tumor (Correct Answer)
C. Lymphoma
D. Thymoma

Explanation: ***Neurogenic tumor*** - **Neurogenic tumors** typically arise from nerve tissue and are most commonly found in the **posterior mediastinum**. - The posterior mediastinum is the primary location for these tumors due to the presence of the **sympathetic chain**, intercostal nerves, and vagus nerve. *Thyroid tumour* - **Ectopic thyroid tissue** can be found in the anterior mediastinum, and this tissue can give rise to thyroid tumors [1]. - While less common than in the neck, substernal or **ectopic thyroid goiters** and carcinomas can present in this compartment [1]. *Thymoma* - The **thymus gland** is located in the anterior mediastinum, making thymoma (a tumor of the thymus) a classic anterior mediastinal mass [1]. - Thymomas are often associated with **paraneoplastic syndromes** like myasthenia gravis. *Lymphoma* - **Lymphatic tissue**, including lymph nodes, is plentiful in the anterior mediastinum [1]. - **Hodgkin's and non-Hodgkin's lymphoma** frequently present as masses in the anterior mediastinum, often causing symptoms due to compression of surrounding structures [1].

Question 2: Which of the following statements about Sibson's fascia is correct?

A. Part of scalenus anterior muscle
B. Vessel pass above the fascia
C. Covers apical part of lung (Correct Answer)
D. Attached to the inner border of 2nd rib

Explanation: ***Covers apical part of lung*** - **Sibson's fascia**, also known as the **suprapleural membrane**, is a dense fascial layer that covers and reinforces the **apex of the lung** and pleura. - It protects the lung apex and helps to support structures in the **root of the neck**. *Part of scalenus anterior muscle* - Sibson's fascia is a **separate fascial structure** extending from the first rib to the C7 transverse process, and is not a part of the scalenus anterior muscle. - The **scalenus anterior muscle** is one of the muscles of the neck, and while anatomically related by proximity to the fascia, it is not structurally part of it. *Vessel pass above the fascia* - Key neurovascular structures like the **subclavian artery** and the **brachial plexus** pass *below* Sibson's fascia, as the fascia protects the lung apex. - The fascia acts as a barrier, separating the lung apex from the more superficial structures of the neck. *Attached to the inner border of 2nd rib* - Sibson's fascia is primarily attached to the **inner border of the first rib** and the transverse process of the seventh cervical vertebra. - Its attachment to the first rib is crucial for its supportive role over the lung apex.

Question 3: Blowout fracture of the orbit most commonly involves?

A. Floor (Correct Answer)
B. Medial wall
C. Lateral wall
D. Roof

Explanation: ***Floor*** - The **orbital floor** is the most commonly fractured site in a blowout fracture due to its thinness and location, often leading to herniation of orbital contents into the maxillary sinus. - This type of fracture often results from a **sudden increase in intraorbital pressure** by a blunt trauma, causing the weakest part of the orbit to give way. *Medial wall* - While less common than floor fractures, the **medial wall** can also be fractured in a blowout injury, leading to herniation into the ethmoid sinuses. - Involvement of the medial wall can sometimes damage the **lacrimal drainage system** or the medial rectus muscle. *Lateral wall* - The **lateral wall** of the orbit is significantly thicker and more robust than the floor or medial wall, making isolated lateral wall fractures extremely rare. - Fractures of the lateral wall are usually associated with more extensive **zygomaticomaxillary complex (ZMC)** fractures or high-impact trauma. *Roof* - The **orbital roof** is composed of the frontal bone and is considerably stronger and thicker than the floor, making roof fractures uncommon in isolated blowout injuries. - Fractures of the orbital roof typically occur with **severe trauma** and are often associated with intracranial injury or damage to the frontal sinus.

Question 4: When does the basiocciput fuse with the basisphenoid?

A. 8-10 years
B. 2-4 years
C. 12-15 years
D. 5-7 years (Correct Answer)

Explanation: Note: This is a NEET-PG 2018 previous year question. The provided options and marked answer reflect the exam's original content. However, standard anatomical references indicate that the spheno-occipital synchondrosis (junction between basiocciput and basisphenoid) typically fuses between 18-25 years of age, not in early childhood. 5-7 years (Marked as correct in original exam) - This was the expected answer in the NEET-PG 2018 exam. - However, standard anatomical texts (Gray's Anatomy, Standring) indicate that spheno-occipital fusion occurs much later, typically between 18-25 years. - There may be confusion with other cranial base developments that occur in early childhood. 2-4 years - This is earlier than even the exam's intended answer. - The spheno-occipital synchondrosis remains cartilaginous at this age. 8-10 years - Still within the childhood period. - The spheno-occipital synchondrosis typically remains unfused at this age. 12-15 years - Early to mid-adolescence. - The spheno-occipital synchondrosis is usually still present, though beginning to show signs of fusion in some individuals by late adolescence. Clinical Note: The fusion of the spheno-occipital synchondrosis is an important forensic marker for age estimation, with complete fusion generally occurring by the mid-20s.

Question 5: What is the primary tensor of the vocal cords?

A. Cricothyroid (Correct Answer)
B. Lateral Cricoarytenoid
C. Thyroarytenoids
D. Posterior cricoarytenoids

Explanation: ***Cricothyroid*** - The **cricothyroid muscle** is the principal tensor of the vocal cords, responsible for stretching and thinning them. - It achieves this by tilting the **thyroid cartilage** forward relative to the **cricoid cartilage**, increasing the distance between the **thyroid** and **arytenoid cartilages**. *Lateral Cricoarytenoid* - This muscle primarily functions as an **adductor** of the vocal cords, bringing them together. - It rotates the **arytenoid cartilages** medially, closing the **rima glottidis**. *Thyroarytenoids* - The **thyroarytenoid muscles** are located within the vocal cords and primarily act to **shorten and relax** the vocal cords. - They also contribute to **adduction** and can internally tense the vocal folds, but their main role is *not* primary tension. *Posterior cricoarytenoids* - The **posterior cricoarytenoid muscles** are the *only* muscles responsible for **abducting** (opening) the vocal cords. - They rotate the **arytenoid cartilages** laterally, thus widening the **rima glottidis**.

Question 6: Which of the following is NOT part of the special visceral efferent column?

A. Nucleus ambiguus
B. Accessory nerve (Correct Answer)
C. Glossopharyngeal n
D. Vagus nerve

Explanation: ***Accessory nerve*** - The **accessory nerve (CN XI)** has two components: a **cranial part** and a **spinal part**. - The **spinal part** (which forms the main functional component) carries **somatic efferent fibers** to the **sternocleidomastoid** and **trapezius muscles** and is **NOT part of the special visceral efferent column**. - The cranial part briefly joins the vagus nerve and is functionally part of the vagus; the spinal accessory is the clinically and anatomically distinct component. - SVE specifically innervates muscles derived from **pharyngeal arches**, not muscles like SCM and trapezius. *Glossopharyngeal n* - The **glossopharyngeal nerve (CN IX)** contains **special visceral efferent fibers** that innervate the **stylopharyngeus muscle**, which is derived from the **third pharyngeal arch**. - These fibers originate from the **nucleus ambiguus**. *Nucleus ambiguus* - The **nucleus ambiguus** is a brainstem nucleus that contains the cell bodies of **special visceral efferent neurons**. - These neurons send axons through the **glossopharyngeal (CN IX), vagus (CN X)**, and **cranial part of accessory (CN XI) nerves** to innervate muscles of the pharynx and larynx derived from pharyngeal arches. *Vagus nerve* - The **vagus nerve (CN X)** carries **special visceral efferent fibers** that innervate muscles of the **pharynx** and **larynx** involved in swallowing and speech. - These fibers originate from the **nucleus ambiguus** and supply muscles derived from the **fourth and sixth pharyngeal arches**.

Question 7: What type of joint is formed by the costal cartilages of the 8th and 9th ribs?

A. Synovial joint
B. Costochondral joint
C. Costovertebral joint
D. Interchondral joint (Correct Answer)

Explanation: ***Interchondral joint*** - The **8th, 9th, and 10th costal cartilages** articulate with the cartilage immediately above them, forming **interchondral joints**. - These are typically **synovial plane joints** that allow for some gliding movement during respiration. *Costochondral joint* - This joint type is formed between the **rib bone** and its respective **costal cartilage**. - These are **primary cartilaginous joints (synchondroses)** and are generally immobile. *Synovial joint* - While interchondral joints are a type of synovial joint, this option is too general and does not specify the unique anatomical arrangement. - Synovial joints are characterized by a **joint capsule**, **synovial fluid**, and **articular cartilage**, allowing for free movement. *Costovertebral joint* - This joint is formed between the **head of a rib** and the **bodies of two adjacent vertebrae** and their intervertebral disc. - It is a **synovial plane joint** crucial for respiratory mechanics, but not related to the articulation of costal cartilages with each other.

Question 8: Acute tonsillitis affects which nerve:

A. Glossopharyngeal Nerve (Correct Answer)
B. Facial Nerve
C. Trigeminal nerve
D. Vagus Nerve

Explanation: ***Correct: Glossopharyngeal Nerve*** - The **glossopharyngeal nerve (CN IX)** provides the **primary sensory innervation** to the palatine tonsils - This innervation is responsible for the sensation of **sore throat** and **referred otalgia** (ear pain) commonly experienced during acute tonsillitis - The tonsillar branch of CN IX specifically innervates the tonsillar region *Incorrect: Facial Nerve* - The **facial nerve (CN VII)** is primarily responsible for **facial expression**, taste sensation from the anterior two-thirds of the tongue, and innervation of tear and salivary glands - It has no direct sensory or motor innervation of the tonsils *Incorrect: Trigeminal Nerve* - The **trigeminal nerve (CN V)** provides sensory innervation to the **face**, sinuses, and teeth, and motor innervation to the muscles of mastication - It does not directly innervate the tonsils *Incorrect: Vagus Nerve* - The **vagus nerve (CN X)** innervates structures in the pharynx, larynx, and abdominal organs through the pharyngeal plexus - While it contributes to pharyngeal sensation, the **glossopharyngeal nerve** is the primary sensory innervation for the tonsils themselves in acute tonsillitis

Question 9: Ureteric bud develops from:

A. Mesonephros (Correct Answer)
B. Metanephros
C. Pronephros
D. Genital sinus

Explanation: ***Mesonephros*** - The **ureteric bud** arises as an outgrowth of the **mesonephric duct** (Wolffian duct), which is the duct of the mesonephros. - The ureteric bud emerges from the **caudal portion of the mesonephric duct** near its entry into the cloaca around the 5th week of development. - It plays a crucial role in forming the **collecting system of the kidney**, including the ureter, renal pelvis, major and minor calyces, and collecting ducts. - **Note:** While technically the ureteric bud arises from the mesonephric duct (not the mesonephric tubules), "mesonephros" is accepted as the answer referring to the mesonephric duct system. *Metanephros* - The **metanephric mesoderm** (metanephric blastema) is induced by the ureteric bud to form the **definitive kidney**. - The metanephros forms the **nephrons** (from Bowman's capsule to distal convoluted tubule). - It does not give rise to the ureteric bud; rather, it interacts with it through **reciprocal induction**. *Pronephros* - The **pronephros** is the first, transient, and **non-functional** kidney structure in human embryonic development. - It appears in the **cervical region** around week 4 and completely **regresses** by week 5. - It does not contribute to the formation of the ureteric bud or the adult kidney. *Genital sinus* - The **urogenital sinus** is derived from the ventral part of the cloaca after division by the urorectal septum. - It gives rise to the **bladder**, parts of the urethra, and contributes to external genitalia. - It is not involved in the development of the ureteric bud or the kidney's collecting system.

Question 10: Nerves of the Branchial arches are derived from:

A. Mesoderm
B. Neuroectoderm (Correct Answer)
C. Endoderm
D. Neural crest

Explanation: ***Neuroectoderm*** - The **cranial nerves** (CN V, VII, IX, X) that supply the branchial arches are derived from **neuroectoderm**. - **Motor components** arise from motor nuclei in the brainstem (neural tube derivative). - **Sensory components** arise from sensory nuclei in the brainstem and from ectodermal placodes. - Neuroectoderm gives rise to the **neurons** that form the actual nerve fibers innervating branchial arch derivatives. *Neural crest* - While neural crest cells migrate extensively and are crucial to branchial arch development, they do **not** form the nerves themselves. - Neural crest contributes to **sensory and autonomic ganglia**, **Schwann cells**, and other supporting structures. - The actual **nerve fibers (axons)** of cranial nerves come from neuroectodermal neurons, not neural crest. *Mesoderm* - **Mesoderm** forms the muscles, cartilage, bones, and blood vessels of the branchial arches. - It does not contribute to the formation of the nervous tissue or nerves. *Endoderm* - **Endoderm** lines the pharyngeal pouches and forms glandular structures (thymus, parathyroid). - It has no role in nerve formation.