Cranial Nerves and Human Anatomy Lecture Review

Comprehensive vocabulary flashcards covering the cranial nerves, nervous system physiology, glial cells, and the anatomy of the neck, pharynx, and larynx.

Trochlear nerve (IV)

A motor nerve originating from the midbrain that supplies one extraocular muscle (superior oblique) and is the only cranial nerve to exit the brainstem from its posterior surface.

Superior orbital Tissure

The opening through which the trochlear nerve (IV), abducens nerve (VI), and ophthalmic division of the trigeminal nerve (V) enter the orbit.

Trigeminal nerve (V)

A tripartite nerve that is the principal regulator of sensory modalities of the head, divided into ophthalmic (CN V1), maxillary (CN V2), and mandibular (CN V3) divisions.

Trigeminal cave

A cave-like wrapping of dura mater that contains the trigeminal ganglion, found in a depression on the anterior surface of the petrous part of the temporal bone.

Ophthalmic branch (CN V1)

A purely sensory division of the trigeminal nerve that carries stimuli for pain, light touch, and temperature from the upper eyelids and supraorbital region to the vertex of the head.

Abducens nerve (VI)

A motor nerve originating from the pons that innervates the lateral rectus muscle to move the eyeball laterally.

Facial nerve (VII)

A multimodal nerve originating from the brainstem as a larger primary motor root and a smaller sensory/parasympathetic intermediate nerve, exiting the skull via the stylomastoid foramen.

Chorda tympani

A branch of the facial nerve (VII) responsible for transmitting taste sensation from the anterior two-thirds of the tongue.

Vestibulocochlear nerve (VIII)

A special sensory nerve with two divisions: the vestibular root for balance and equilibrium, and the cochlear root for hearing.

Organ of Corti

The structure in the inner ear where receptors provide stimuli to the first-order neurons of the cochlear nerve.

Glossopharyngeal nerve (IX)

A mixed nerve that enables swallowing, salivation, and taste; it exits the skull through the jugular foramen and supplies the posterior one-third of the tongue.

Vagus nerve (X)

A mixed nerve with the most extensive course in the body, primarily associated with the parasympathetic division, traversing the neck, thorax, and abdomen.

Accessory nerve (XI)

An efferent nerve originating from the brainstem and spinal cord that enables phonation and movements of the head and shoulders by innervating the trapezius and sternocleidomastoid muscles.

Hypoglossal nerve (XII)

A general somatic efferent nerve that leaves the cranium through the hypoglossal canals to enable tongue movements.

Nerve

A bundle of nerve fibers wrapped in fibrous connective tissue that emerges from the CNS through foramina of the skull and vertebral column.

Ganglion

A knotlike swelling in a nerve where the cell bodies of neurons are concentrated.

Sympathetic division

A division of the autonomic nervous system that prepares the body for action by accelerating heartbeat and increasing respiratory airflow while inhibiting digestion.

Parasympathetic division

A division of the autonomic nervous system that adapts the body to a state of rest by reducing heart rate and stimulating digestion.

Nissl bodies

Dark-staining regions unique to neurons, created by neurofibrils compartmentalizing the rough endoplasmic reticulum.

Lipofuscin

A golden brown 'wear-and-tear' pigment that is an end product of lysosomal digestion; it collects with age and can push the nucleus to one side.

Axon hillock

The mound on one side of the soma from which the axon (nerve fiber) originates.

Synapse

The meeting point between a neuron and any other cell, acting as a decision-making device to determine if the next cell will respond.

GABA (gamma-aminobutyric acid)

The most widely used inhibitory neurotransmitter in the brain.

Oligodendrocytes

Glial cells in the CNS that use armlike processes to spiral around nerve fibers, forming the myelin sheath.

Astrocytes

The most abundant CNS glia that form a supportive framework, contribute to the blood-brain barrier, and create scar tissue through astrocytosis.

Ependymal cells

Ciliated cuboidal cells lining the internal cavities of the brain and spinal cord that produce cerebrospinal fluid (CSF).

Schwann cells

Glial cells that envelop nerve fibers of the PNS, forming the neurilemma and assisting in the regeneration of damaged fibers.

Neurilemma

The outermost coil of a Schwann cell, which contains its nucleus and most of its cytoplasm.

Nodes of Ranvier

Gaps between myelinated segments (internodes) along an axon.

Nociceptors

Pain receptors that respond to tissue damage resulting from trauma, ischemia, or excessive thermal/chemical stimulation.

Ansa cervicalis

A nerve loop formed by cervical nerves $C1$ to $C3$ that innervates the 'strap muscles' (infrahyoid muscles).

Thyroid gland

A large endocrine gland weighing about $30\,g$, consisting of two lateral lobes joined by an isthmus, responsible for producing thyroxine ($T4$) and triiodothyronine ($T3$).

Pharynx

A musculofascial half-cylinder about $13\,cm$ long that links the oral and nasal cavities to the larynx and esophagus.

Epiglottis

A leaf-shaped piece of elastic cartilage that acts as a trap door to close off the larynx during swallowing.

Glottis

The narrowed passageway through the larynx consisting of the vocal folds and the space between them called the rima glottidis.