The Cranial Nerves

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Here we have the brain as seen from the inferior view. There are twelve cranial nerves identified. Each is associated with a part of the head while one innervated the rest of the body (parts not innervated by the spinal cord). They are as follows;

  • I: Olfactory
  • II: Optic
  • III: Oculomotor
  • IV: Trochlear
  • V: Trigeminal
  • VI: Abducens
  • VII: Facial
  • VIII: Auriculo-Vestibulocochlear
  • IX: Glossopharyngeal
  • X: Vegus
  • XI: Accessory Spinal
  • XII: Hypoglossal

These structures mainly provide sensory and motor function to areas of the head and neck. The only exception here is the Vegus nerve which inervated parasympathetic function to organs in the abdomen. To the right we have a cadaver with all nerves visible.

Functions

I: The olfactory nerve controls the sense of smell.

II: The optic nerve conveys visual information from the eye to occipital lobe.

III: The oculomotor nerve (III), trochlear nerve (IV) abducens nerve (VI) and the opthalmic branch of the trigenimal nerve control eye movement.

V: The trigenimal nerve is made of three distinct parts: The Ophthalmic, the Maxillary, and the Mandibular nerves. These nerves provide feeling to the skin of the face and also controls the muscles of chewing.

VII: The seventh nerve is the facial nerve, this splits into five distinct nerve branches; Temporal, zygomatic, buccal, mandibular and cervical. Each nerve is responsible for controlling aspects of facial expression.

VIII: The auditory-vestibulocochlear nerve innervates the inner ear and contributes to balance. The ‘vestibular’ bit innervates the vestibules and semicircular canal of the inner ear. The semicircular canal is responsible for relaying information that keeps the head balanced. The cochlea is connected to the nerve (‘cochlear’) and allows us to hear.

IV: The glossopharyngial nerve provides sensory information to the oropharynx and back of the tongue. This allows us to taste, salivate and feel sensations within the mouth.

V: The Vegus is primarily responsible for parasympathetic function of abdominal organs.

VI: The Accessory spinal nerve allows response of the trapizius muscle along with other muscles that control head turning and raising the shoulder blade.

VII: Lastly, the hypoglossal nerve is responsible for tongue movement.

There is another nerve found in the adult human brain named the terminal nerve. This is used in other animals as a pheremone receptor but research suggests that it has no function in humans.


Fuller GN, Burger PC (1990). “Nervus terminalis (cranial nerve zero) in the adult human”. Clinical Neuropathology9 (6): 279–83.

Vilensky, Joel; Robertson, Wendy; Suarez-Quian, Carlos (2015). The Clinical Anatomy of the Cranial Nerves: The Nerves of “On Olympus Towering Top”. Ames, Iowa: Wiley-Blackwell.

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