Download 14. Cranial Nerves

• Inferior
surface of the
brain as it
appears on
gross
dissection.
The Olfactory nerve (I) – for sense of smell.
Nerves in nasal cavity synapse within olfactory bulbs.
Anosmia – loss of smell.
Sensory
The Optic nerve (II) - visual information.
50-50 cross over
Anopsias – visual defects.
Sensory
6 Extrinsic Eye Muscles
4 Rectus Muscles
2 Oblique Muscles
oblique
rectus
rectus
Nose
here
oblique
The Oculomotor nerve (III) - Controls 4 of
the 6 extrinsic muscles of the eye. Motor
External Strabismus – lateral drift.
Ptosis.
The Trochlear nerve (IV)
– Innervates superior oblique eye muscle. Motor
• The Trigeminal nerve (V)
Mixed
Largest cranial nerve
Has 3 Branches
1) Ophthalmic branch
skin, lacrimal gland
2) Maxillary branch
lower eyelid, upper jaw
3) Mandibular branch
tongue, lower teeth
e.g., Tic Douloureux.
The Abducens nerve (VI)
Motor
Innervates lateral rectus muscle of eye (abduction!)
Internal Strabismus – cross eyed.
The Facial nerve (VII)
Mixed
Controls muscles of scalp and facial expression.
Muscles of mastication and speech.
Pressure sensations from face.
Taste sensations from anterior 2/3 of tongue.
e.g., Bell’s palsy.
The Facial nerve (VII)
Mixed
The Vestibulocochlear nerve (VIII)
Sensory
– Sense of balance, position and body movement.
Loss of balance, nausea, vomiting.
– Sense of sound (hearing).
Deafness.
The Glossopharyngeal nerve (IX)
Taste sensation
from posterior
1/3 tongue.
Controls swallowing
Detects O2 and CO2
content of blood
in carotid artery.
Impairment of taste and swallowing.
Mixed
The Vagus nerve (X)
Mixed
Controls
vocal folds
Hoarseness
of voice.
Regulates
heart
Impaired
regulation
of heart.
Controls
G.I. Tract
Impaired
G.I. tract
motility.
Vital to autonomic control of visceral function
The Accessory nerve (XI)
Motor
– Internal branch
Innervates swallowing muscles.
– External branch
Controls sternocleidomastoid and trapezius.
Turn toward injured side.
Impaired shrugging.
The Hypoglossal nerve (XII)
Motor
Voluntary food mixing, swallowing and speech.
Control of tongue movements.
Impaired swallowing.
Deviating tongue (atrophy).
• The Accessory nerve (XI) and Hypoglossal nerve (XII)