(4.3) CRANIAL NERVES

Cranial nerve III that controls eye movement and pupil constriction.

Drooping of the upper eyelid, caused by damage to the levator palpebrae superioris muscle.

A condition where the eyes do not look in the same direction, causing double vision.

Muscle that elevates the upper eyelid.

Ganglion that relays autonomic signals for pupil constriction or accommodation.

The narrowing of the pupil of the eye.

The process of changing the shape of the lens to focus light on the retina.

Intense pulsating pain caused by inflammation of a branch of the trigeminal nerve.

Cranial nerve responsible for facial expressions and special sensory tastes.

Ganglion containing sensory neurons of the facial nerve, located near the inner ear.

Group of muscles involved in chewing (mastication).

Opening where branches of the facial nerve exit the skull.

Eye muscle responsible for moving the eye laterally (away from the nose).

Cranial nerve responsible for controlling the lateral rectus muscle.

Eye muscle controlled by the trochlear nerve, responsible for downward and inward eye movement.

Cranial nerve that innervates the superior oblique muscle.

Double vision, a symptom of strabismus.

Damage affecting nerves and muscles controlling eye movement.

Specific cranial nerves responsible for moving the eyes.

Widening of the pupil, often a sign of nerve damage.

Abducens nerve, controlling eye movement.

Cranial nerves are 12 pairs of nerves that emerge from the brain, numbered using Roman numerals. They carry different types of information like motor, sensory, and autonomic functions. Their nuclei are located in the brainstem, except for CN I and II, and they travel through openings in the skull.

Cranial nerves can carry one or more of the following: Somatic motor (voluntary muscle control), Visceral motor (involuntary muscle control), Somatic sensory (general senses), Visceral sensory (internal organ senses), Special sensory (vision, hearing, taste, smell).

Cranial nerve nuclei are clusters of nerve cells in the brainstem that receive and process information from the cranial nerves. They function as relay stations for sensory and motor signals.

Cranial nerves can communicate by exchanging fibers along their course. A nerve may start as sensory, but receive motor fibers later on, leading to a more complex function.

Somatic motor fibers carry signals from the brain to skeletal muscles, allowing for voluntary movement.

Visceral motor fibers control involuntary muscle movement and bodily functions like heart rate and digestion. These are also known as autonomic fibers.

Somatic sensory fibers carry signals from the skin and mucous membranes to the brain, providing sensations like touch, pressure, heat, and cold.

The cranial nerve responsible for the sense of smell.

The cranial nerve responsible for vision.

The cranial nerve responsible for most eye movements, pupil constriction, and controlling the eyelid.

The cranial nerve responsible for controlling the superior oblique muscle, which moves the eye inferolaterally.

Partial or complete loss of the sense of smell.

Visual defects or loss of sight.

Tiny holes in the ethmoid bone that allow olfactory nerves to pass through.

The point where the optic nerves from each eye cross over.

The Facial Nerve (CN VII) controls facial expressions, taste from the anterior 2/3 of the tongue (via the chorda tympani), and innervates salivary glands (submandibular and sublingual) and the lacrimal gland.

The motor function of the Glossopharyngeal Nerve (CN IX) synapses in the Otic ganglion, which then controls the parotid salivary gland.

The Vagus Nerve (CN X) is responsible for motor functions of the throat and larynx, visceral motor control of most thoracic and abdominal organs, sensory input from the ear and pharynx, and visceral sensory input from the heart, lungs, and most abdominal organs.

The Spinal Accessory Nerve (CN XI) controls the sternocleidomastoid and trapezius muscles, responsible for head movement and shoulder elevation.

The Hypoglossal Nerve (CN XII) controls the majority of the tongue muscles, essential for speech and swallowing.