Neuroanatomy Practice Questions

Q: Which of the following nerves does not innervate any extraocular muscles?

Ophthalmic nerve. ***Ophthalmic nerve*** - The **ophthalmic nerve (V1)** is one of the three divisions of the **trigeminal nerve** and is responsible for sensory innervation of the upper face and orbit. - It does not have any motor function and therefore plays no role in innervating extraocular muscles. *Oculomotor nerve* - The **oculomotor nerve (CN III)** innervates most of the extraocular muscles, including the **superior rectus**, **inferior rectus**, **medial rectus**, and **inferior oblique**, as well as the **levator palpebrae superioris**. - It also carries parasympathetic fibers to the ciliary ganglion, controlling pupillary constriction and accommodation. *Abducent nerve* - The **abducent nerve (CN VI)** specifically innervates the **lateral rectus muscle**. - This muscle is responsible for **abduction** (moving the eye laterally) of the eyeball. *Trochlear nerve* - The **trochlear nerve (CN IV)** uniquely innervates the **superior oblique muscle**. - This muscle is responsible for **depression**, **abduction**, and **intorsion** of the eyeball.

Q: Nerve injured in Frey’s syndrome is:

Auriculotemporal Nerve. ***Auriculotemporal Nerve*** - Frey's syndrome (also known as **auriculotemporal syndrome**) results from damage and aberrant regeneration of the **auriculotemporal nerve**. - This leads to **sweating and flushing** in the pre-auricular and temporal regions in response to salivary stimuli (e.g., eating). *Great auricular nerve* - The great auricular nerve primarily provides **sensory innervation** to the skin over the parotid gland, mastoid process, and auricle. - While it can be injured during parotid surgery, its damage typically causes **sensory deficits** (numbness) rather than gustatory sweating. *Lingual Nerve* - The lingual nerve provides **general sensation** and **taste** to the anterior two-thirds of the tongue and innervates the submandibular and sublingual glands. - Injury to this nerve leads to issues with **taste and sensation of the tongue**, not gustatory sweating in the face. *Inferior alveolar nerve* - The inferior alveolar nerve provides **sensory innervation** to the lower teeth and lower lip, and its mental branch supplies the chin. - Damage to this nerve is typically associated with **numbness or altered sensation** in the lower dental arch, lip, and chin, not Frey's syndrome.

Q: Contralateral loss of pain and temperature is due to injury to:

Lateral spinothalamic tract. ***Lateral spinothalamic tract*** - The **lateral spinothalamic tract** decussates (crosses over) shortly after entering the spinal cord, so an injury to this tract results in **contralateral loss** of pain and temperature sensation [1]. - This tract is specifically responsible for the transmission of **pain and temperature** information from the periphery to the brain [1]. *Anterior spinothalamic tract* - This tract is primarily responsible for transmitting **crude touch and pressure** sensations, not pain and temperature. - While it also decussates, its injury would lead to contralateral loss of crude touch, not the symptoms described. *Fasciculus gracilis* - This tract is part of the **dorsal column-medial lemniscus pathway**, responsible for **fine touch, vibration, and proprioception** from the lower body [1]. - Injury to this tract would cause **ipsilateral loss** of these sensations, not contralateral pain and temperature. *Fasciculus cuneatus* - Also part of the **dorsal column-medial lemniscus pathway**, it carries **fine touch, vibration, and proprioception** from the upper body [1]. - An injury here would result in **ipsilateral loss** of these specific sensations, not contralateral pain and temperature.

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

Accessory nerve. ***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**.

Q: Traumatic optic neuropathy due to closed head trauma commonly affects which part of the optic nerve?

Optic canal. ***Optic canal*** - The **optic nerve** is highly susceptible to injury within the **optic canal** due to its tight anatomical confines and the close proximity of the optic nerve to rigid bone. - Trauma to this region can lead to direct compression, shearing injury, or ischemia from damage to surrounding vasculature, resulting in significant visual impairment. *Intra ocular part* - The intraocular part of the optic nerve, including the **optic disc**, is typically protected by the globe and orbit against blunt trauma. - Direct intraocular trauma, such as a penetrating injury, would be required to significantly affect this segment, which is not usually the cause in closed head trauma. *Intracranial part* - The intracranial part of the optic nerve is relatively mobile within the cerebrospinal fluid and is less prone to direct compression or shearing forces from closed head trauma compared to the optic canal. - While it can be affected by diffuse axonal injury or mass effects within the cranium, it is not the most commonly affected segment for traumatic optic neuropathy in closed head injuries. *Optic tract* - The **optic tract** lies posterior to the optic chiasm and is part of the central nervous system pathways for vision, not the optic nerve itself. - Injuries to the optic tract are more likely to cause homonymous hemianopia rather than the profound unilateral vision loss characteristic of traumatic optic neuropathy, and are generally less vulnerable to direct mechanical trauma from closed head injury.

Q: Pupillary reflex pathway - All of the following are a part except?

Medial geniculate body. ***Medial geniculate body*** - The **medial geniculate body** is part of the **auditory pathway**, involved in processing sound information [2]. - It does not play a role in the **afferent** or **efferent** limbs of the pupillary light reflex. *Edinger Westphal nucleus* - The **Edinger-Westphal nucleus** is the **parasympathetic nucleus** of cranial nerve III (**oculomotor nerve**) [1]. - It provides preganglionic parasympathetic fibers that lead to pupillary constriction via the **ciliary ganglion** [1]. *Pretectal nuclei* - The **pretectal nuclei** receive input from the **retina** and are critical for the **afferent limb** of the pupillary light reflex [1], [3]. - They send fibers to the **Edinger-Westphal nuclei** bilaterally, mediating the direct and consensual light reflexes [1]. *Retinal ganglion cell* - **Retinal ganglion cells** are responsible for transmitting visual information from the **retina** to the brain [4]. - A subset of these cells, containing **melanopsin**, are photosensitive and specifically mediate the input for the **pupillary light reflex** [3].

Q: Myelination in peripheral nervous system is done by

Schwann cells. ***Schwann cells*** - **Schwann cells** are glial cells found in the **peripheral nervous system (PNS)** that wrap around axons to form the myelin sheath [4]. - The **myelin sheath** insulates the axon and increases the speed of nerve impulse conduction [1]. *Astrocytes* - **Astrocytes** are star-shaped glial cells found in the **central nervous system (CNS)** [2]. - They play roles in structural support, nutrient supply, and blood-brain barrier formation, but not myelination. *Oligodendrocytes* - **Oligodendrocytes** are glial cells responsible for **myelination in the central nervous system (CNS)** [1], [3]. - Each oligodendrocyte can myelinate multiple axons or multiple segments of the same axon [3]. *Ependymal cells* - **Ependymal cells** are glial cells that line the ventricles of the brain and the central canal of the spinal cord in the **CNS**. - They are involved in the production and circulation of **cerebrospinal fluid (CSF)**.

Q: From which structure is the greater petrosal nerve formed?

Geniculate ganglion. ***Geniculate ganglion*** - The **greater petrosal nerve** arises directly from the **geniculate ganglion** of the **facial nerve (cranial nerve VII)**. - This nerve carries **preganglionic parasympathetic fibers** destined for the lacrimal gland and mucous glands of the nose, palate, and pharynx, as well as **taste fibers** from the palate. *Plexus around ICA* - The **plexus around the internal carotid artery (ICA)** typically carries **postganglionic sympathetic fibers**, primarily for structures in the head, including the dilator pupillae muscle. - It does not give rise to the greater petrosal nerve, which is predominantly parasympathetic and sensory. *Plexus around middle meningeal artery* - The **plexus around the middle meningeal artery** consists mainly of **sympathetic fibers** that supply the artery itself and surrounding structures. - It has no direct connection or contribution to the formation of the greater petrosal nerve. *None of the options* - This option is incorrect because the **greater petrosal nerve** does indeed arise from the **geniculate ganglion**.

Q: Which intrinsic ocular muscle responsible for pupillary constriction is supplied by parasympathetic innervation?

Constrictor pupillae. ***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 1

Which of the following nerves does not innervate any extraocular muscles?

Accepted Answer

Ophthalmic nerve

Answer

Oculomotor nerve

Answer

Abducent nerve

Answer

Trochlear nerve

Question 2

Nerve injured in Frey’s syndrome is:

Accepted Answer

Auriculotemporal Nerve

Answer

Great auricular nerve

Answer

Lingual Nerve

Answer

Inferior alveolar nerve

Question 3

Contralateral loss of pain and temperature is due to injury to:

Accepted Answer

Lateral spinothalamic tract

Answer

Anterior spinothalamic tract

Answer

Fasciculus gracilis

Answer

Fasciculus cuneatus

Question 4

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

Accepted Answer

Accessory nerve

Answer

Nucleus ambiguus

Answer

Glossopharyngeal n

Answer

Vagus nerve

Question 5

Traumatic optic neuropathy due to closed head trauma commonly affects which part of the optic nerve?

Accepted Answer

Optic canal

Answer

Intraocular part

Answer

Intracranial part

Answer

Optic tract

Question 6

Pupillary reflex pathway - All of the following are a part except?

Accepted Answer

Medial geniculate body

Answer

Edinger Westphal nucleus

Answer

Pretectal nuclei

Answer

Retinal ganglion cell

Question 7

Myelination in peripheral nervous system is done by

Accepted Answer

Schwann cells

Answer

Astrocytes

Answer

Oligodendrocytes

Answer

Ependymal cells

Question 8

Hilton's law primarily relates to which of the following?

Accepted Answer

Nerve supply of joints, muscles moving them, and overlying skin

Answer

Nerve innervation only

Answer

Blood supply to joints

Answer

None of the above

Question 9

From which structure is the greater petrosal nerve formed?

Accepted Answer

Geniculate ganglion

Answer

Plexus around ICA

Answer

Plexus around middle meningeal artery

Answer

None of the options

Question 10

Which intrinsic ocular muscle responsible for pupillary constriction is supplied by parasympathetic innervation?

Accepted Answer

Constrictor pupillae

Answer

Dilator pupillae

Answer

Levator palpebrae superioris

Answer

Ciliary muscle

Neuroanatomy — MCQs

Neuroanatomy — MCQs

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