anaphysio

• Olfactory


  Fibers arise from olfactory receptors in the nasal mucosa and synapse with the olfactory bulbs (which, in turn, send fibers to the olfactory cortex)
• Olfactory


  • Purely sensory; carries impulses for the sense of smell
  • Subject is asked to sniff and identify aromatic substances, such as oil of cloves of vanilla
• Optic


  Fibers arise from the retina of the eye and form the optic nerve. The two optic nerves form the optic chiasma by partial crossover of fibers; the fibers continue to the optic cortex as the optic tracts
• Optic


  • Purely sensory; carries impulses for vision
  • Vision and visual field are tested with an eye chart and by testing the point at which the subject first sees an object (finger) moving into the visual field; eye interior is viewed with an ophthalmoscope
• Oculomotor

  • Fibers run from the midbrain to the eye
  • Supplies motor fibers to four of the six muscles (superior, inferior, and medial rectus, and inferior oblique) that direct the eyeball; to the eyelid; and to the internal eye muscles controlling lens shape and pupil size
• Oculomotor

  • Pupils are examined for size, shape, and size equality; pupillary reflex is tested with a penlight (pupils should constrict when illuminated); eye convergence is tested, as is the ability to follow moving objects
• Trochlear

  • Fibers run from the midbrain to the eye
  • Supplies motor fibers for one external eye muscle (superior oblique)
• Trochlear


  • Tested in common with cranial nerve III for the ability to follow moving objects
• Trigeminal


  • Fibers emerge from the pons and form three divisions that run to the face
  • Conducts sensory impulses from the skin of the face and mucosa of the nose and mouth; also contains motor fibers that activate the chewing muscles
• Trigeminal


  • Sensations of pain, touch, and temperature are tested with a safety pin and hot and cold objects; corneal reflex tested with a wisp of cotton; motor branch tested by asking the subject to open mouth against resistance and move jaw from side to side
• Abducens


  • Fibers leave the pons and run to the eye
  • Supplies motor fibers to the lateral rectus muscle, which rolls the eye laterally
• Abducens


  • Tested in common with cranial nerve III for the ability to move each eye laterally