Cranial Nerves

12 Cranial Nerves

12 Cranial Nerves - Function

I. Olfactory Nerves

Olfactory Nerves

Purely sensory; carry afferent impulses for sense of smell.

The olfactory nerve is purely sensory.

  • The olfactory nerve is purely sensory.
  • The special sense of taste is monitored by the olfactory nerve.

II. Optic Nerves

Optic Nerves

Purely sensory; carry afferent impulses for vision.

The optic nerves are which cranial nerve?

  • I.
  • II.
  • III.
  • The cranial nerves are not numbered.

III. Oculomotor Nerves

Oculomotor Nerves

Mainly motor nerves, contains a few proprioceptive afferents.  

Somatic motor fibers for four of the six extrinsic eye muscles.  Sensory afferents  run from the four muscles to midbrain.  Parasympathetic motor fibers to pupil.  

Oculomotor - true/false

  • The oculomotor nerves control four of the six muscles of the eye.
  • The oculomotor nerves control all muscles of the eye.

IV. Trochlear Nerves

Trochlear Nerves

Primarily motor nerves; supply somatic motor fibers to (and carry proprioceptor fibers from) one of the extrinsic eye muscles, the superior oblique muscle, which passes through the pulley-shaped trochlea.

The trochlear nerves pass through which opening?

  • pupil
  • optic canal
  • inferior orbital fissure
  • superior orbital fissure

V. Trigeminal Nerves

Trigeminal Nerves

Longest cranial nerves; fibers extend from pons to face, and form three divisions (trigemina = threefold): ophthalmic, maxillary, and mandibular.

Match the division of the trigeminal nerves to the description.

  • Ophthalmic Division
    Fibers run from face to pons via superior orbital fissure.  Conveys sensory impulses from skin of anterior scalp, upper eyelid, nose, nasal cavity mucosa, cornea and lacrimal gland.
  • Maxillary Division
    Fibers run from face to pons via foramen rotundum.  Conveys sensory impulses from nasal cavity mucosa, palate, upper teeth, skin of cheek, upper lip and lower eyelid.
  • Mandibular Division
    Fibers pass through skull via foramen ovale.  Conveys sensory impulses from anterior tongue (except taste buds), lower teeth, skin of chin, temporal region of scalp.  Supplies motor fibers to and carries proprioceptor fibers from, muscles of mastication.

Trigeminal - true/false

  • The trigeminal nerves are the longest of cranial nerves.
  • The trigeminal nerves are divided into five divisions.

VI. Abducens Nerves

Abducens Nerves

Primarily motor; supply somatic motor fibers to lateral rectus muscle, an extrinsic muscle of the eye.  Convey proprioceptor impulses from the same muscle to the brain.

Abducens fill in the blank.

The abducens nerves are  to the trochlear nerves.

VII. Facial Nerves

Facial Nerves

Mixed nerves that are the chief motor nerves of the face.  Five major branches: temporal, zygomatic, buccal, mandibular, and cervical.

Facial - true/false

  • The facial nerves have five major branches.
  • The facial nerves are primarily sensory.

Which of the following is not a main branch of the facial nerves?

  • temporal
  • glossus
  • buccal
  • mandibular

VIII. Vestibulocochlear Nerves

Vestibulocochlear Nerves

Mostly sensory.  Vestibular branch transmits afferent impulses for sense of equilibrium, and sensory nerve bodies are located in vestibular ganglia.  Small motor component adjusts the sensitivity of sensory receptors.

Vestibulocochlear - true/false

  • The vestibulocochlear nerves transmit afferent impulses for the sense of equilibrium.
  • The vestibulocochlear nerves are purely sensory.

IX. Glossopharyngeal Nerves

Glossopharyngeal Nerves

Mixed nerves that innervate part of the tongue and pharynx.  Provide somatic fibers to, and carry proprioceptor fibers from, a superior pharyngeal muscle called the stylopharyngeus, which elevates the pharynx in swallowing.  Provide parasympathetic motor fibers to parotid salivary glands.

Glossopharyngeal - true/false

  • The glossopharyngeal nerves are mixed nerves (sensory and motor).
  • The glossopharyngeal nerves provide parasympathetic motor fibers to salivary glands.

X. Vagus Nerves

Vagus Nerves

Only cranial nerve to extend beyond the head and neck region.  

Mixed nerves.  Nearly all motor nerves are parasympathetic efferents, except those serving skeletal muscles of pharynx and larynx.  Parasympathetic motor fibers supply heart, lungs, and abdominal viscera and are involved in heart rate, breathing, and digestive system activity.  Transmit sensory impulses from thoracic and abdominal viscera.

The vagus nerves are the only nerves which extend to where?

  • beyond the head and neck region
  • to the patella
  • to the Achilles tendon.

XI. Accessory Nerves

Accessory Nerves

Mixed nerves, but primarily motor function.  Supply motor fibers to trapezius and sternocleidomastoid muscles, which together move head and neck, and convey proprioceptor impulses from same muscles.

Accessory nerves supply motor fibers to which areas.

  • muscles that move head and neck
  • muscles that move fingers and toes
  • muscles that move appendicular skeleton

XII. Hypoglossal Nerves

Hypoglossal Nerves

Mixed nerves, but primarily motor in function.  Carry somatic motor fibers to intrinsic and extrinsic muscles of the tongue, and proprioceptor fibers from the same muscles to the brain stem.  Hypoglossal nerve control allows tongue movements that mix and manipulate food during chewing, and contribute to swallowing and speech. 

The hypoglossal nerves control which of the following functions?

  • mix and manipulate food
  • swallowing
  • speech
  • all of the above