The sternocleidomastoid muscle is examined by
What muscle is attached to the superior nuchal line?
Which of the following structures is not related to the third part of the duodenum?
Which nerve is preserved in dissecting the superficial and deep lobes of the parotid gland?
Which intrinsic ocular muscle responsible for pupillary constriction is supplied by parasympathetic innervation?
Lips do not drain into which group of lymph nodes?
Which nerve supplies the postganglionic fibers to the parotid gland?
Secretomotor fibers to parotid gland are through?
The nerve which has the longest intracranial course is:
Largest cranial nerve is:
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 61: The sternocleidomastoid muscle is examined by
- A. Shrugging of shoulder
- B. Overhead abduction
- C. Turning the head towards the same side to assess the muscle on that side
- D. Turning the head towards the opposite side to assess the muscle on that side (Correct Answer)
Explanation: ***Turning the head towards the opposite side to assess the muscle on that side*** - The **sternocleidomastoid muscle** unilaterally acts to rotate the head to the **contralateral side**. - To palpate or visually inspect the right sternocleidomastoid, the patient would turn their head to the left, making the right muscle prominent. *Turning the head towards the same side to assess the muscle on that side* - Turning the head towards the same side primarily engages the **ipsilateral deep neck flexors** and **splenius capitis**, not the sternocleidomastoid. - This action would relax the sternocleidomastoid on the side towards which the head is turned, making it difficult to assess. *Shrugging of shoulder* - Shrugging the shoulder is primarily an action of the **trapezius** and **levator scapulae muscles**. - The sternocleidomastoid does not contribute significantly to shoulder elevation. *Overhead abduction* - Overhead abduction of the arm is primarily performed by the **deltoid muscle** and assisted by the **supraspinatus**. - This movement is entirely unrelated to the function of the sternocleidomastoid muscle.
Question 62: What muscle is attached to the superior nuchal line?
- A. Trapezius muscle (Correct Answer)
- B. Scalenus anterior
- C. Coracobrachialis muscle
- D. Biceps Brachii muscle
Explanation: ***Trapezius muscle*** - The **trapezius muscle** is a large, triangular muscle of the back that extends from the **occipital bone** (including the superior nuchal line) to the lower thoracic vertebrae. - Its **superior fibers** originate from the **medial one-third of the superior nuchal line** and the external occipital protuberance. *Scalenus anterior* - The **scalenus anterior** muscle originates from the **transverse processes of cervical vertebrae**, specifically C3-C6. - It inserts onto the **first rib** and is involved in neck flexion and elevation of the first rib during forced inspiration. *Coracobrachialis muscle* - The **coracobrachialis muscle** originates from the **coracoid process of the scapula**. - It inserts into the **medial surface of the humerus** and is involved in shoulder flexion and adduction. *Biceps Brachii muscle* - The **biceps brachii muscle** has two heads: the short head originates from the **coracoid process**, and the long head originates from the **supraglenoid tubercle of the scapula**. - It inserts onto the **radial tuberosity** and is primarily responsible for elbow flexion and forearm supination.
Question 63: Which of the following structures is not related to the third part of the duodenum?
- A. Superior mesenteric vessels
- B. Right ureter
- C. Head of pancreas
- D. Quadrate lobe of liver (Correct Answer)
Explanation: ***Quadrate lobe of liver*** - The **quadrate lobe of the liver** is located on the visceral surface of the liver, bounded by the gallbladder fossa, ligamentum teres, and porta hepatis. [1] - It is anatomically related to the **first part of the duodenum** and the pylorus, but has **no direct relationship** with the retroperitoneal **third part of the duodenum**, which lies at the L3 vertebral level. [2] - The third part of the duodenum is too inferior and posterior to have any relationship with the quadrate lobe. *Superior mesenteric vessels* - The **superior mesenteric artery** and **vein** cross **anteriorly** to the **third part of the duodenum** as it runs horizontally from right to left. - The duodenum passes between the aorta posteriorly and the superior mesenteric vessels anteriorly, creating a potential site for compression (**superior mesenteric artery syndrome**). *Right ureter* - The **right ureter** is a **posterior relation** of the **third part of the duodenum**, as both structures are retroperitoneal. [2] - The ureter descends on the psoas major muscle, passing behind the third part of the duodenum during its course toward the pelvis. *Head of pancreas* - The **head of pancreas**, specifically the **uncinate process**, lies **superior and posterior** to the **third part of the duodenum**. - The uncinate process hooks around posteriorly to the superior mesenteric vessels and has an intimate relationship with the third part of the duodenum.
Question 64: Which nerve is preserved in dissecting the superficial and deep lobes of the parotid gland?
- A. Glossopharyngeal
- B. Hypoglossal
- C. Lingual
- D. Facial (Correct Answer)
Explanation: ***Correct: Facial*** - The **facial nerve (CN VII)** passes directly through the parotid gland, dividing it into superficial and deep lobes. Dissection of these lobes requires careful identification and preservation of the facial nerve and its branches to avoid paralysis. - Injury to the facial nerve during parotidectomy can lead to various degrees of **facial paralysis**, affecting muscle movements like smiling, eye closure, and forehead wrinkling. *Incorrect: Glossopharyngeal* - The **glossopharyngeal nerve (CN IX)** supplies the carotid sinus and stylopharyngeus muscle and provides secretomotor innervation to the parotid gland via the otic ganglion. - It does not traverse the parotid gland itself, so it is not directly at risk during the dissection of the superficial and deep lobes. *Incorrect: Hypoglossal* - The **hypoglossal nerve (CN XII)** primarily controls the intrinsic and extrinsic muscles of the tongue, responsible for tongue movement. - It is located inferior to the parotid gland and is not in the field of dissection for separating the parotid lobes. *Incorrect: Lingual* - The **lingual nerve**, a branch of the mandibular nerve (CN V3), provides sensation to the **anterior two-thirds of the tongue** and carries parasympathetic fibers for submandibular and sublingual glands. - While it is in the general vicinity of the orofacial region, it does not pass through the parotid gland and is therefore not directly at risk during the dissection of the parotid lobe.
Question 65: Which intrinsic ocular muscle responsible for pupillary constriction is supplied by parasympathetic innervation?
- A. Constrictor pupillae (Correct Answer)
- B. Dilator pupillae
- C. Levator palpebrae superioris
- D. Ciliary muscle
Explanation: ***Constrictor pupillae*** - The **constrictor pupillae** (or **sphincter pupillae**) muscle is responsible for **miosis** (pupil constriction) and is innervated by **parasympathetic fibers** from the **oculomotor nerve (CN III)** via the **ciliary ganglion** [1]. - Stimulation of this muscle reduces the pupil size, which is a key part of the **light reflex** and **accommodation reflex** [1]. - This is the **only pupillary muscle** with parasympathetic innervation. *Ciliary muscle* - The **ciliary muscle** is involved in **accommodation**, altering the shape of the lens for focusing on near objects [1]. - While it also receives **parasympathetic innervation** from the ciliary ganglion, it does **not control pupil size**. - Its function is to change **lens curvature**, not pupillary diameter. *Levator palpebrae superioris* - This muscle is responsible for **elevating the upper eyelid**. - It is innervated by the **somatic motor fibers** of the **oculomotor nerve (CN III)**, not parasympathetic fibers. - It is **not an intrinsic ocular muscle** but rather an extraocular muscle. *Dilator pupillae* - The **dilator pupillae** muscle causes **mydriasis** (pupil dilation). - This muscle is innervated by **sympathetic fibers**, originating from the superior cervical ganglion, not parasympathetic fibers.
Question 66: Lips do not drain into which group of lymph nodes?
- A. Submandibular nodes
- B. Preauricular parotid (Correct Answer)
- C. None of the options
- D. Submental nodes
Explanation: ***Preauricular parotid*** - Lymph from the lips primarily drains into the **submental**, **submandibular**, and **deep cervical lymph nodes** [1]. - **Preauricular parotid nodes** primarily drain the lateral surface of the auricle, external auditory canal, temporoparietal scalp, and lateral parts of the eyelids and cheek. - The lips do **NOT** drain into preauricular nodes. *Submandibular nodes* - The **lateral parts of the lower lip** and the **entire upper lip** drain into the submandibular lymph nodes [1]. - These nodes are a primary drainage pathway for the oral region. *Submental nodes* - The **central part of the lower lip** drains into the submental lymph nodes [1]. - These nodes lie between the anterior bellies of the digastric muscles beneath the chin. - They receive lymph from the central lower lip, floor of mouth, and tip of tongue. *None of the options* - This option is incorrect because there is a specific group of nodes listed that the lips do *not* drain into (preauricular parotid).
Question 67: Which nerve supplies the postganglionic fibers to the parotid gland?
- A. Auriculotemporal nerve (Correct Answer)
- B. Glossopharyngeal nerve
- C. Facial nerve
- D. Greater superficial petrosal nerve
Explanation: ***Auriculotemporal nerve*** - This nerve carries the **postganglionic parasympathetic fibers** from the **otic ganglion** to the parotid gland, stimulating saliva production. - These fibers originate from the **glossopharyngeal nerve (CN IX)**, synapse in the otic ganglion, and then join the auriculotemporal nerve. *Glossopharyngeal nerve* - The glossopharyngeal nerve (CN IX) provides the **preganglionic parasympathetic fibers** that ultimately reach the parotid gland. - These preganglionic fibers synapse in the **otic ganglion**, not directly supply the gland with postganglionic fibers. *Facial nerve* - The facial nerve (CN VII) supplies the **submandibular** and **sublingual glands** with parasympathetic innervation, via the chorda tympani and submandibular ganglion. - It does not innervate the parotid gland for salivary secretion. *Greater superficial petrosal nerve* - This nerve (a branch of the facial nerve) carries **preganglionic parasympathetic fibers** to the pterygopalatine ganglion, innervating the **lacrimal gland** and glands in the nasal and oral cavities. - It is not involved in the postganglionic innervation of the parotid gland.
Question 68: Secretomotor fibers to parotid gland are through?
- A. Tympanic plexus (Correct Answer)
- B. Greater petrosal nerve
- C. Geniculate ganglion
- D. None of the options
Explanation: This is an easy question, and the expected Bloom's level is low (L1) with an expectation of just remembering the right answer. ***Tympanic plexus*** - The secretomotor fibers to the parotid gland originate from the inferior **salivatory nucleus**, travel via the **glossopharyngeal nerve (CN IX)** to the tympanic plexus. - From the tympanic plexus, these preganglionic parasympathetic fibers form the **lesser petrosal nerve**, which synapses in the otic ganglion, and postganglionic fibers then join the **auriculotemporal nerve** to reach the parotid gland. *Greater petrosal nerve* - The **greater petrosal nerve** carries preganglionic parasympathetic fibers that primarily innervate the **lacrimal gland** and glands of the nasal cavity and palate, not the parotid gland. - It is a branch of the **facial nerve (CN VII)**, whereas secretomotor innervation to the parotid is from the glossopharyngeal nerve (CN IX). *Geniculate ganglion* - The **geniculate ganglion** is a sensory ganglion of the **facial nerve (CN VII)**, containing cell bodies for taste sensation from the anterior two-thirds of the tongue. - It is not directly involved in transmitting secretomotor fibers to the parotid gland. *None of the options* - As the **tympanic plexus** is the correct conduit for the secretomotor fibers to the parotid gland, this option is incorrect. - The pathway involves a specific sequence of nerves and ganglia, which includes the tympanic plexus as a key relay point.
Question 69: The nerve which has the longest intracranial course is:
- A. Trochlear nerve (Fourth cranial nerve) (Correct Answer)
- B. Oculomotor nerve (Third cranial nerve)
- C. Abducens nerve (Sixth cranial nerve)
- D. Trigeminal nerve (Fifth cranial nerve)
Explanation: The nerve which has the longest intracranial course is: ***Trochlear nerve (Fourth cranial nerve)*** - This nerve has the **longest intracranial course** of all the cranial nerves, emerging from the dorsal aspect of the midbrain. - Its long path makes it particularly susceptible to **injury** from head trauma or increased intracranial pressure. *Oculomotor nerve (Third cranial nerve)* - While significant in length, the **oculomotor nerve** does not have the longest intracranial course; it emerges from the ventral midbrain. [1] - It controls most of the **extraocular muscles**, but its intracranial path is shorter than that of the trochlear nerve. *Abducens nerve (Sixth cranial nerve)* - The **abducens nerve** has a relatively long course within the pons and across the clivus but is not the longest. - It is often impacted in conditions causing **elevated intracranial pressure** or skull base fractures due to its path. *Trigeminal nerve (Fifth cranial nerve)* - The **trigeminal nerve** has a large sensory ganglion and extensive peripheral branches but its intracranial course is comparatively short, emerging from the pons. - It is primarily responsible for **facial sensation** and mastication.
Question 70: Largest cranial nerve is:
- A. Trochlear
- B. Trigeminal (Correct Answer)
- C. Oculomotor
- D. Vagus
Explanation: ***Trigeminal*** - The **trigeminal nerve (CN V)** is the largest cranial nerve, both in terms of its overall diameter and the number of fibers it contains. - It has three major divisions: **ophthalmic, maxillary, and mandibular**, providing extensive sensory innervation to the face and motor innervation to the muscles of mastication. *Trochlear* - The **trochlear nerve (CN IV)** is the smallest cranial nerve in terms of diameter and number of axons. - It primarily innervates a single muscle, the **superior oblique muscle** of the eye. *Oculomotor* - The **oculomotor nerve (CN III)** is responsible for innervating several extrinsic eye muscles and plays a role in pupil constriction. - While significant, it is not the largest cranial nerve. *Vagus* - The **vagus nerve (CN X)** has the longest anatomical course among all cranial nerves, extending into the abdomen, but it is not the largest in terms of overall size or fiber count. - It carries extensive **parasympathetic fibers** and has broad effects on visceral organs.