A Brief Description of the cranial nerves

Here i have described about the cranial nerves their function and their supply to respective structures. Cranial nerves are important Nerves of the Head and Neck region having both Motor and Sensory function. Apart from the Vagus nerve which supply to the Other organs of the body, all other nerves supply to the Head and Neck region.

Cranial Nerves and their Function – © Netters Atlas

1. Olfactory Nerve: It is a type of sensory nerve,

• Supply: It supplies to the Olfactory Epithelium(cells)
• Function: Perception of smell from the nasal cavity.

2. Optic Nerve: It is a type of sensory nerve,

• Supply: Retina (ganglion cells)
• Function: Vision of retina.

3. Oculomotor Nerve: It i a type of motor nerve,

• Supply: Midbrain, presynaptic midbrain, postsynaptic ciliary ganglion
• Function: Motor function to superior rectus and inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris muscles, raises superior eyelid and also turns eyeball superiorly, inferiorly and medially, constricts pupil and accomidates lens of eye.

4. Trochlear Nerve: It is a type of motor nerve,

• Supply: Midbrain
• Function: to the superior oblique muscle that assists in turning of the eye inferio laterally.

5. Trigeminal Nerve: It has 3 branches:

i) Opthalmic nerve: It is the sensory nerve.

• Supply: Trigeminal ganglion.
• Function: Sensation from cornea, skin of scalp, eyelids, nose and mucosa of nasal cavity.

ii) Maxillary nerve: It is also a type of sensory nerve.

• Supply: Trigeminal Ganglion.
• Function: Sensation from skin face of face over maxilla, upper lip, maxillary teeth, mucosa of nose, maxillary sinuses and palate.

iii) Mandibular nerve: It is a type of motor nerve.

• Supply: Pons, to the muscles of mastication.
• Function: Motor supply to the muscles of mastication, mylohyoid, anterior belly of digastric, tensor villi palatini and tensor tympani.

6. Abducent: It is a type of motor nerve.

• Supply: Pons, to the lateral rectus
• Function: To turn the eye laterally.

7. Facial: It is of a mixed type with both sensory and motor functions.

• Supply: Pons, Geniculate ganglion, Sub mandibular ganglion, pterygopalatine ganglion, muscles of facial expression in scalp, stapedius of middle ear, stylohyoid and posterior belly of digastric, anterior two thirds of the tongue, to submandibular salivary glands, lacrimal glands and glands of nose and palate.
• Function: Taste from anterior two thirds of the tongue, motor function to the muscles of facial expression and scalp.

8. Vestibulocochlear: It is a type of sensory nerve.

• Supply: Vestibular ganglion and spiral ganglion.
• Function: Vestibular sensation from the semicircular ducts, utricle and saccule related to position and movement of head, hearing from spinal organ.

9. Glossopharyngeal: It is a mixed type with both sensory and motor functions.

• Supply: Stylopharyngeus, parotid gland, acotid body, pharynx and middle ear, external ear.
• Function: Assists in swallowing, taste perception from the posterior third of the tongue, cutaneous sensation from the external ear.

10. Vagus: It is also a type of mixed nerve with both motor and sensory functions.

• Supply: Superior ganglion, inferior ganglion, medulla, constrictor muscles of pharynx, intrinsic muscles of larynx, muscles of palate, striated muscles in two thirds of esophagus, smoot muscles of trachea, bronchi, cardiac muscles of heart, base of tongue, epiglottis, palate.
• Function: Motor function in the constrictor muscles of pharynx, intrinsic muscles of larynx, muscles of palate, striated muscles in two thirds of esophagus, taste perception from the epiglottis and palate, sensation from the auricle, external acoustic meatus, dura matter of cranial fossa.

11. Spinal accessory nerve: It is type of motor nerve.

• Supply: Spinal cord, sternocleidomastoid and trapezius muscle.
• Function: Motor supply to the sternocleidomastoid and trapezius muscle.

12. Hypoglossal: It is a type of motor nerve.

• Supply: Medulla, and to the intrinsic and extrinsic muscles of tongue.
• Function: Motor supply to intrinsic and extrinsic muscles of the tongue.

Some Important facts and points about Cranial Nerves – For USMLE, NBDE, NEET examinations. 

1. Trigeminal nerve is the Largest Cranial Nerve
2. Olfactory is the smallest cranial nerve
3. Vagus Nerve is with Vague or Extensive Distribution
4. Trochlear nerve shows largest intracranial course
5. Smallest branch of Trigeminal nerve is the Opthalmic branch
6. Largest branch of Trigeminal nerve is Mandibular branch
7. Buccal nerve is the only Sensory branch of anterior division of the Mandibular Nerve
8. Smallest of 3 terminal branches of opthalmic nerve is lacrimal nerve and frontal nerve is the largest terminal branch of opthalmic nerve
9. Posterior Ethmoidal is the branch of Nasociliary which is frequently absent.
10. Posterior Superior alveolar nerve is the branch of maxillary nerve in Pterygopalatine fossa
11. Middle superior alveolar nerve is present in only 28% of the individuals
12. Greater palatine nerve = Anterior palatine nerve
13. Lesser Palatine Nerve = Middle and Posterior palatine branches
14. Nervus Intermedius is Sensory branch of facial nerve