The nerves arising from different parts of the brain are called cranial nerves. Man possess twelve pairs of cranial nerves. Twelve pair of cranial nerves are: (I) Olfactory, (II) Optic, (III) Oculomotor, (IV) Trochlear, (V) Trigeminal, (VI) Abducens, (VII) Facial, (VIII) Auditory, (IX) Glossopharyngeal, (X) Vagus, (XI) Spinal Accessory and (XII) Hypoglossal. There are 3 pair of sensory, 5 pair of motor and 4 pair of mixed cranial nerves. Trochlear (IV) is the smallest cranial nerve and Vagus (X) is the longest cranial nerve.
The following table gives the name, natures, distribution and major functions of cranial nerves
No, Name and Nature of Fibre
(S - Sensory, M -Motor, B - Both)
Distribution(D) and Functions(F)
|I - Olfactory (S)||D: Olfactory Mucosa|
|II -Optic (S) ||D: Retina of Eye|
|III - Oculomotor (M)||D: Eye muscles, ciliary muscles, tear glands.|
F: Regulated the movement of eye
|IV - Trochlear (M)||D: Eye ball muscle|
F: Eye ball movement.
|V - Trigeminal (B)||D: Muscle of mouth, gums of both jaws and skin of face. |
F: Movement of mastication, sensation for the anterior part of tongue.
|VI - Abducens (M)||D: Eye ball muscle|
F: Eye ball movement
|VII - Facial (B)||D: Salivary gland, taste buds and neck muscles|
F: Salivation and tear secretion.
|VIII - Auditory (S)||D: Inner ear|
F: Hearing and equilibrium
|IX - Glossopharyngeal (B)||D: Tongue and salivary gland|
F: Salivation and taste.
|X - Vagus (B)||D: Heart, respiratory tract, alimentary canal|
F: Gastric secretion, cardiac slowing, respiratory reflexes and vasomotor reflexes.
|XI - Spinal Accessory (M)||D: Neck and shoulder muscles|
F: Muscle movements
|XII - Hypoglossal (M)||D: Tongue|
F: Tongue movements