Cranial nerves in reptiles, birds, and mammals – origin, nature and functions

The brain of reptiles, birds, and mammals is connected to twelve pairs of cranial nerves. Out of these spinal accessory and hypoglossal (XI and XII) are’ not present in fishes. Following is a table of cranial nerves of a mammal with their branches.

Name with main
Origin from
Distribution Nature
Olfactory Olfactory lobe Olfactory epithelium Sensory
Optic Optic thalamus Retina of eye Sensory
Oculomotor (Four) Crura cerebri of mid brain inferior oblique, inferior rectussuperior rectus, inferior rectus, iris, ciliary body Motor
Superior oblique eye muscles
Trochlear (Pathetic) Midbrain Superior oblique eye muscles Motor
Trigeminal Pons Varolii Mixed
V1 Ophthalmic (side of medula) Eye, eyelids, snout Sensory
V2 Maxillary Upper jaw, vibrissae Sensory
nose, lower eyelid
V3 Mandibular Lower jaw and lip, external ear, tongue Mixed
Abducens Pons Varolii (ventral side of medulla) External rectus muscle of eyeball Motor
VII Facial Pons Varolii
(side of medula)
V111 Palatine Palate Sensory
VII2 Chorda tympani Tongue, salivary glands, taste buds. Sensory
V113Hyomondibular Lower jaw, neck, pinna, hyoid Mixed
Auditory Medulla Sensory
II1 Vestibular Internal ear Sensory
Vl12 Cochlear Cochlea Sensory
Glosopharyngeal Medulla
X1 Lingual Tongue, pharynx, salivary glands Mixed
X2 Pharyngeal —- Pharynx, salivary glands Mixed
Vagus Posterior part of medulla
X1 Anterior laryngeal Cricoid, thyroid muscles of larynx Motor
X2 Recurrenl laryngeal All muscles of Larynx Motor
X3 Cardiac depressor Heart Motor
X4Pneumogastric Lungs, esophagus, stomach, ileum Sensory & Motor
Spinal accessory Medulla Pharynx, larynx, neck, shoulder Motor
Hypoglossal Medulla Neck and tongue Motor




  1. Oelfactory nerve is concerned with the sense of smell.
  2. Optic nerve is concerned with vision
  3. Oculomotor nerve is concerned with eyelids, eyes, adjustments of light entering the eyeball, focusing of the lens, movement of eyeball.
  4. Trochlear nerve is concerned with movement of eyeball.
  5. Trigeminal nerve is concerned with condition of facial muscles (sensory). Its ophthalmic branch is sensory and concerned with eyes, tear glands, scalp, forehead, and upper eyelids. Its maxillary branches are concerned with upper teeth, upper gum, upper lip, lining of the palate, and skin of the face (sensory). The mandibular branches connect to scalp, skin of lower jaw, lower gum and teeth and lower lip.
  6. Abducens nerve connects to external rectus muscle and moves the eyeball.
  7. Facial nerve is concerned with face muscles (sensory), taste receptors of anterior tongue (sensory), and facial expression, tear glands, and salivary glands (motor).

VIII Auditory or Vestibulocochlear nerve, its vestibular branche is concerned with equilibrium, and cochlear branch with hearing.

  1. Glossopharyngeal nerve connects to pharynx, tonsils, posterior tongue, and carotid arteries (sensory), pharynx and salivary glands (motor).
  2. Vagus nerve is concerned with speech, swallowing, heart and visceral organs in the thorax and abdomen (motor. pharynx, larynx, esophagus, and visceral organs (sensory).

Xl. Accessory spinal nerve Its cranial branch connects to soft palate, pharynx and larynx, while its spinal branch supplies neck and back.

XII. Hypoglossal nerve connects to tongue muscles, and controls tongue movements.

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