Cranial Nerves Overview

Study Notes

Cranial nerves are part of the peripheral nervous system, connected to the brain stem.
There are twelve pairs.
Each nerve has a specific function, such as sensory, motor, or both.
Olfactory (I) - Sensory nerve, responsible for smell
Optic (II) - Sends visual impulses to the brain.
Oculomotor (III) - Controls most eye muscles.
Trochlear (IV) - Controls superior oblique muscle of the eye.
Trigeminal (V) - Sensory nerve for facial sensation, and motor nerve controlling chewing muscles.
Abducens (VI) - Controls the lateral rectus eye muscle.
Facial (VII) - Sensory: taste; Motor: controls facial expressions.
Vestibulocochlear (VIII) - Sensory for hearing and balance.
Glossopharyngeal (IX) - Sensory: taste; Motor: swallowing
Vagus (X) - Sensory: sensations from internal organs; Motor: heart, lungs, and digestive organs (controls their function).
Accessory (XI) - Motor: controls muscles in neck and shoulders.
Hypoglossal (XII) - Motor: controls tongue movements.

Spinal nerves are part of the peripheral nervous system; they branch to innervate the body.
Ventral roots carry motor information away from the spinal cord.
Dorsal roots carry sensory information to the spinal cord.
Spinal cord is surrounded by three layers of protective membranes (meninges).
Dura mater is the outermost, tough layer.
Arachnoid mater is the middle, thin layer.
Pia mater is the innermost, delicate layer.
Gray matter is dominated by nerve cell bodies and dendrites.
White matter contains nerve fibers.
There are different regions within the spinal cord: ventral horn, dorsal horn etc.

Branches of the nerves stemming from the brachial plexus are crucial for upper limb function.
Different nerve bundles control various aspects of the limbs (different muscles).
These branches include:
- Axillary
- Musculocutaneous
- Median
- Radial
- Ulnar

Brain structures include parts like the:
- Cerebellum (coordinates movement)
- Brainstem (controls involuntary functions)
- Cerebrum (higher brain function)
- Different lobes, sulci, and gyri.
Gray and white matter in various brain regions.
Structures like corpus callosum, thalamus, and hypothalamus.
Ventricles and other internal spaces are also present in the brain.