Cranial nerves

CRANIAL NERVES

  • There are twelve pairs of cranial nerves.
    • The first pair or olfactory nerve joins the convex ventral face of the olfactory bulbs.
    • The second pair or optic nerve arises from the lateral geniculate bodies; the optic tracts converge to the optic chiasma and are then continued as optic nerves.
    • The third pair or oculomotor nerve arises from the ventral face of the cerebral peduncle at the interpenduncular fossa.
    • The fourth pair or trochlear nerve arises from the dorsal aspect behind the posterior colliculus of midbrain, pass outwards and emerge between the pons and the cerebral hemispheres.
    • The fifth pair or trigeminal nerve is connected to the lateral part of the pons by a large sensory and a small motor root.
    • The sixth pair or abducent nerve arises behind the pons lateral to the anterior ends of pyramids of the medulla.
    • The seventh pair or facial nerve and the eighth or auditory nerve arise close together from the lateral part of corpus trapezoideum.
    • The ninth pair or glossopharyngeal nerve
    • Tenth and eleventh- vagus nerve and spinal accessory nerve arise in a series from the lateral aspect of the medulla behind the seventh. The spinal accessory nerve has two roots-a medullary and a spinal. A spinal root arises from the first five cervical segments of spinal cord and joins with the medullary root of spinal accessory nerve.
    • The twelfth pair or hypoglossal nerve arises lateral to the posterior part of the pyramids of the medulla.
  • The brain is anatomically may be divided into cerebrum, cerebellum,pons, and medulla oblongata.For description five divisions may be considered.These are cerebral hemispheres,inter brain,mid brain,hind brain and medulla oblongata.
Last modified: Thursday, 10 November 2011, 9:43 AM