Chorda tympani is a branch of which cranial nerve?
The roof of the olfactory region is formed by?
Which muscle is the deepest in the anterior neck region?
What is the number of muscles in the middle ear?
Which of the following structures pass through the superior orbital fissure?
Vertebral arteries of both sides unite to form
Which of the following is not a tributary of the cavernous sinus?
What anatomical structure does the pineal gland form part of?
Which thalamic nucleus has the most extensive reciprocal connections with the association areas of the neocortex?
Medulla oblongata arises from which of the following?
NEET-PG 2013 - Anatomy NEET-PG Practice Questions and MCQs
Question 61: Chorda tympani is a branch of which cranial nerve?
- A. Vestibulocochlear nerve (CN VIII)
- B. Facial nerve (CN VII) (Correct Answer)
- C. Trigeminal nerve (CN V)
- D. Glossopharyngeal nerve (CN IX)
Explanation: ***Facial nerve (CN VII)*** - The **chorda tympani** is a branch of the **facial nerve (CN VII)**, carrying special sensory (taste) innervation to the anterior two-thirds of the tongue and preganglionic parasympathetic fibers to the submandibular and sublingual salivary glands. - It arises from the facial nerve within the **temporal bone**, passes through the middle ear, and then joins the lingual nerve. *Trigeminal nerve (CN V)* - The **trigeminal nerve** is primarily responsible for **sensory innervation of the face** and motor innervation of the muscles of mastication. - While the lingual nerve (a branch of the trigeminal nerve) carries the fibers of the chorda tympani, the chorda tympani itself originates from the facial nerve. *Vestibulocochlear nerve (CN VIII)* - The **vestibulocochlear nerve** is responsible for **hearing** and **balance**. - It does not have any branches that innervate taste buds or salivary glands. *Glossopharyngeal nerve (CN IX)* - The **glossopharyngeal nerve** innervates the posterior one-third of the tongue for **taste** and general sensation, the parotid gland for parasympathetic secretion, and the stylopharyngeus muscle. - It does not give rise to the chorda tympani.
Question 62: The roof of the olfactory region is formed by?
- A. Nasal bone
- B. Sphenoid
- C. Temporal bone
- D. Cribriform plate of ethmoid (Correct Answer)
Explanation: ***Cribriform plate of ethmoid*** - The **cribriform plate** of the ethmoid bone forms the superior boundary, or roof, of the nasal cavity specifically in the olfactory region [1]. - It is perforated by numerous **olfactory foramina** through which the olfactory nerves pass from the nasal cavity to the olfactory bulb of the brain [2]. *Nasal bone* - The **nasal bones** form part of the bridge of the nose and contribute to the anterior part of the bony framework of the external nose. - They do not form the roof of the olfactory region within the nasal cavity. *Sphenoid* - The **sphenoid bone** is a complex bone at the base of the skull, contributing to the posterior wall of the nasal cavity and parts of the cranial floor. - It does not directly form the roof of the olfactory region. *Temporal bone* - The **temporal bones** are located on the sides and base of the skull, housing structures related to hearing and balance. - They are not involved in forming the roof of the nasal cavity or the olfactory region.
Question 63: Which muscle is the deepest in the anterior neck region?
- A. Sternocleidomastoid
- B. Platysma
- C. Longus colli (Correct Answer)
- D. Trapezius
Explanation: ***Longus colli*** - The **longus colli** muscle is the **deepest muscle** located in the anterior neck region, running along the front of the cervical vertebral column from C1 to T3. - It lies in the **prevertebral layer**, deep to all other anterior neck structures including the carotid sheath, visceral compartment, and superficial muscles. - Its position directly anterior to the vertebral bodies makes it the deepest anterior neck muscle. *Platysma* - The platysma is the **most superficial muscle** of the neck, located just beneath the skin in the superficial fascia. - It is not a deep muscle and lies superficial to all other neck muscles. *Sternocleidomastoid* - The sternocleidomastoid is enclosed within the **investing layer of deep cervical fascia**, making it relatively superficial. - While prominent in the anterior and lateral neck, it is not the deepest anterior neck muscle. *Trapezius* - The trapezius is a large, **superficial muscle of the back and posterior neck**. - It is not located in the anterior neck and is a superficial, not deep, muscle.
Question 64: What is the number of muscles in the middle ear?
- A. One
- B. Two (Correct Answer)
- C. Three
- D. Four
Explanation: ***Two*** - The middle ear houses two muscles: the **tensor tympani** and the **stapedius muscle** [1]. - These muscles play a crucial role in the **acoustic reflex**, protecting the inner ear from loud sounds. *One* - This option is incorrect as there are two muscles, not one, involved in middle ear function [1]. - Specifying one muscle would neglect the complementary role of the other in the acoustic reflex. *Three* - This option is incorrect because the middle ear only contains two muscles [1]. - There are no additional muscles associated with the ossicles or tympanic membrane. *Four* - This option is incorrect as the middle ear is only comprised of the **tensor tympani** and **stapedius** muscles [1]. - The number four is not associated with the muscular anatomy of the middle ear.
Question 65: Which of the following structures pass through the superior orbital fissure?
- A. Oculomotor nerve
- B. Trochlear nerve
- C. Superior ophthalmic vein
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - The **superior orbital fissure** is a key opening in the skull that allows passage of several important cranial nerves and vessels into the orbit. - The **oculomotor nerve**, **trochlear nerve**, and **superior ophthalmic vein** are all established structures that pass through this fissure. *Oculomotor nerve* - The **oculomotor nerve (CN III)** passes through the superior orbital fissure to innervate most of the extrinsic eye muscles. - It controls movements such as **adduction**, **elevation**, and **depression** of the eyeball, and also innervates the **levator palpebrae superioris** muscle for eyelid elevation [1]. *Trochlear nerve* - The **trochlear nerve (CN IV)**, which innervates the **superior oblique muscle**, also passes through the superior orbital fissure. - The superior oblique muscle is responsible for **intorsion** and **depression** of the eye, particularly when the eye is adducted [1]. *Superior ophthalmic vein* - The **superior ophthalmic vein** drains blood from structures within the orbit and passes through the superior orbital fissure to drain into the **cavernous sinus**. - This vein provides a connection between the facial veins and the cavernous sinus, which can be clinically relevant in cases of infection spread.
Question 66: Vertebral arteries of both sides unite to form
- A. Anterior spinal artery
- B. Posterior spinal artery
- C. Medullary artery
- D. Basilar artery (Correct Answer)
Explanation: Basilar artery - The paired vertebral arteries ascend through the neck via the transverse foramina of cervical vertebrae and enter the skull through the foramen magnum. - At the level of the pontomedullary junction, the two vertebral arteries merge to form a single basilar artery. Anterior spinal artery - The anterior spinal artery is formed by the union of two small branches derived from each vertebral artery near their intracranial origin. - It supplies the anterior two-thirds of the spinal cord, running along the anterior median fissure. Posterior spinal artery - The posterior spinal arteries are typically two vessels, one arising from each vertebral artery (or less commonly from the posterior inferior cerebellar artery). - They supply the posterior one-third of the spinal cord and do not form a single major merged vessel in the brainstem. Medullary artery - There is no single major artery termed the "medullary artery" formed by the union of the vertebral arteries. - The medulla oblongata is supplied by branches directly from the vertebral arteries and the basilar artery, such as the posterior inferior cerebellar artery (PICA) and direct medullary branches.
Question 67: Which of the following is not a tributary of the cavernous sinus?
- A. Central vein of retina
- B. Sphenoparietal sinus
- C. Inferior cerebral vein (Correct Answer)
- D. Superior ophthalmic vein
Explanation: Detailed anatomical knowledge of the dural venous sinuses is required to answer this question. Venous drainage from the brain by way of the deep veins and dural sinuses typically empties principally into the internal jugular veins, though blood also drains via the ophthalmic and pterygoid venous plexuses [1]. ***Inferior cerebral vein*** - The **inferior cerebral veins** drain the inferior surface of the cerebral hemispheres and typically empty into the **basal vein of Rosenthal**, **transverse sinus**, or other dural sinuses. - They do **not directly drain** into the cavernous sinus, making this the correct answer. - While some small inferior cerebral veins may occasionally communicate with the cavernous sinus, they are not considered standard tributaries. *Central vein of retina* - The **central vein of retina** drains the retina and exits the eye through the optic nerve. - It drains into the **superior ophthalmic vein**, which then empties into the cavernous sinus. - It is an **indirect tributary** via the superior ophthalmic vein, not a direct tributary itself. *Sphenoparietal sinus* - The **sphenoparietal sinus** is a dural venous sinus that runs along the posterior edge of the lesser wing of the sphenoid bone. - It is a **direct tributary** that drains anteriorly into the cavernous sinus. - This is one of the standard tributaries listed in anatomical texts. *Superior ophthalmic vein* - The **superior ophthalmic vein** is the **major tributary** draining orbital structures including the eyeball, extraocular muscles, and eyelids. - It passes posteriorly through the **superior orbital fissure** to drain directly into the cavernous sinus. - This is the most clinically significant tributary, as infections can spread from the face to the cavernous sinus via this route.
Question 68: What anatomical structure does the pineal gland form part of?
- A. Part of the anterior wall of the third ventricle
- B. Part of the roof of the third ventricle (Correct Answer)
- C. Part of the floor of the third ventricle
- D. Part of the posterior wall of the third ventricle
Explanation: **_Part of the roof of the third ventricle_** - The **pineal gland** is a small, pinecone-shaped endocrine gland that forms part of the **roof of the third ventricle** [1]. - It is attached to the roof by the **pineal stalk** and projects posteriorly from the **epithalamus**. - The roof of the third ventricle consists of the **tela choroidea**, the **pineal gland**, and the **choroid plexus** [1]. - The pineal gland regulates circadian rhythms through **melatonin** secretion. *Part of the posterior wall of the third ventricle* - The **posterior wall** of the third ventricle is formed by the **posterior commissure**, the **pineal recess**, and the **habenular commissure**. - While the pineal gland is located posteriorly, it is anatomically classified as part of the roof, not the posterior wall itself. *Part of the anterior wall of the third ventricle* - The **anterior wall** is formed by the **lamina terminalis**, **anterior commissure**, and columns of the fornix. - This is located at the opposite end of the third ventricle from the pineal gland. *Part of the floor of the third ventricle* - The **floor** is formed by structures of the **hypothalamus**, including the **optic chiasm**, **tuber cinereum**, **infundibulum**, and **mammillary bodies**. - The pineal gland is situated dorsally (superiorly), not in the floor.
Question 69: Which thalamic nucleus has the most extensive reciprocal connections with the association areas of the neocortex?
- A. Intralaminar
- B. Anterior
- C. Pulvinar (Correct Answer)
- D. None of the options
Explanation: ***Pulvinar*** - The **pulvinar nucleus** is the largest thalamic nucleus and has the most extensive **妥reciprocal connections** with the **association cortices** of the parietal, temporal, and occipital lobes. - It plays a crucial role in **visual attention**, integration of visual and other sensory information, and facilitating cortico-cortical communication. - The pulvinar is unique in its dense, bidirectional connectivity with higher-order association areas, distinguishing it from other thalamic nuclei. *Intralaminar* - **Intralaminar nuclei** (centromedian, parafascicular) project **diffusely and non-specifically** to widespread cortical areas and the striatum [1]. - They are involved in arousal, attention, and consciousness but lack the **specific, reciprocal connections** with association cortices that characterize the pulvinar. - Their projections are more related to generalized cortical activation rather than specific sensory or cognitive processing [1]. *Anterior* - The **anterior nuclear group** (anteromedial, anterodorsal, anteroventral) projects primarily to the **cingulate gyrus** as part of the limbic system [1]. - While the cingulate is cortical tissue, it is **limbic cortex** with specific emotional and memory functions, not association neocortex involved in higher-order sensory integration. - Receives input from mammillary bodies and is part of the Papez circuit for memory and emotion. *None of the options* - This is incorrect because the **pulvinar nucleus** has well-established, extensive reciprocal connections with association areas of the neocortex. - The pulvinar is considered a "higher-order" thalamic nucleus specifically connecting cortical areas to each other via the thalamus.
Question 70: Medulla oblongata arises from which of the following?
- A. Mesencephalon
- B. Myelencephalon (Correct Answer)
- C. Rhombencephalon
- D. None of the options
Explanation: ***Myelencephalon*** - The **myelencephalon** is the most caudal of the three primary brain vesicles and is the developmental origin of the **medulla oblongata**. - It differentiates from the **rhombencephalon** (hindbrain) and is responsible for vital autonomic functions. *Rhombencephalon* - The **rhombencephalon** is the hindbrain and is a primary brain vesicle that further divides into the **metencephalon** and **myelencephalon**. - While it is the parent structure, it does not directly give rise to the medulla oblongata as a final differentiated structure without further division. *Mesencephalon* - The **mesencephalon** is the midbrain, a primary brain vesicle that develops into structures like the **tectum** and **tegmentum** [1]. - It is located rostral to the rhombencephalon and is not involved in the development of the medulla oblongata [1]. *None of the options* - This option is incorrect because the **myelencephalon** is the direct embryonic precursor of the medulla oblongata.