Brain Functions and the Cranial Nerves

Vocabulary flashcards covering the structure and function of the diencephalon, basal nuclei, cerebral fibers, cerebellum, brainstem, and the twelve cranial nerves.

Diencephalon

A brain region located superior to the brainstem that includes the thalamus, epithalamus, hypothalamus, and subthalamus.

Basal Nuclei

Structures composed of the striatum (caudate nucleus and putamen) and globus pallidus located on each side of the diencephalon, involved with movement control and related behavioral/cognitive functions.

Commissural Fibers

Cerebral white matter fibers that connect the right and left cerebral hemispheres, with the largest bundle contained in the corpus callosum.

Projection Fibers

Cerebral white matter fibers that connect the cerebral cortex of one hemisphere with other areas of the same hemisphere, as well as other areas of the brain and spinal cord.

Association Fibers

Cerebral white matter fibers restricted to a single hemisphere that connect the gray matter of cortical gyri with one another.

Thalamus

A diencephalon structure composed of gray matter that receives sensory and motor input from the cerebral cortex, cerebellum, basal nuclei, and limbic system, serving as a relay station for information reaching the cerebral cortex.

Hypothalamus

A region of the diencephalon containing nuclei that regulate vital survival functions, secretes oxytocin and antidiuretic hormone (ADH), and controls the pituitary gland.

Pituitary Gland

An endocrine gland connected to the hypothalamus by the infundibulum that secretes hormones affecting various endocrine glands throughout the body.

Mammillary Bodies

Structures in the diencephalon that connect the hypothalamus to the limbic system, receiving input from the hippocampus to regulate memory and behavior.

Pineal Gland

A structure within the epithalamus that secretes the hormone melatonin to regulate the sleep/wake cycle.

Cerebellum

The structure forming the posterior and inferior portion of the brain, composed of two hemispheres connected by the vermis, that functions in the coordination of movement.

Arbor Vitae

The distinctive tree-like pattern of inner white matter within the cerebellum.

Cerebellar Peduncles

Tracts of white matter that connect the cerebellum directly to the brainstem.

Brainstem

An ancient brain region consisting of the midbrain, pons, and medulla oblongata that controls basic homeostatic functions such as heart rate and breathing.

Superior Colliculi

Structures located on the posterior midbrain that are responsible for visual reflexes.

Inferior Colliculi

Structures located on the posterior midbrain that are responsible for auditory reflexes.

Pons

The middle section of the brainstem containing descending motor tracts and reticular formation nuclei that regulate movements, breathing, reflexes, sleep, and arousal.

Pyramids

Elevated ridges located on the anterior side of the medulla oblongata that contain upper motor neurons.

Reticular Formation

A network of over 100 motor nuclei across the brainstem that receives input from the cerebral cortex, limbic system, and sensory stimuli to regulate sleep, pain transmission, motor functions, mood, breathing, and blood pressure.

Olfactory Nerve (CN I)

A purely sensory cranial nerve originating in the olfactory epithelium of the nasal cavity that transmits smell stimuli to the primary olfactory cortex and limbic system.

Optic Nerve (CN II)

A purely sensory cranial nerve originating in the retina of the eye that decussates at the optic chiasma to convey visual stimuli to the primary visual cortex in the occipital lobe.

Oculomotor Nerve (CN III)

A motor cranial nerve originating in the midbrain that innervates four extraocular muscles, levator palpebrae superioris, sphincter pupillae (pupil constriction), and ciliary muscle (lens shape modification).

Trochlear Nerve (CN IV)

A motor cranial nerve originating in the inferior midbrain that innervates the superior oblique muscle to move the eye medially and inferiorly.

Trigeminal Nerve (CN V)

A mixed cranial nerve with three sensory branches (ophthalmic, maxillary, mandibular) detecting facial sensation and a motor mandibular branch innervating the masseter and temporalis muscles for mastication.

Abducens Nerve (CN VI)

A motor cranial nerve originating in the pons that innervates the lateral rectus muscle to abduct or move the gaze laterally.

Facial Nerve (CN VII)

A mixed cranial nerve providing taste for the anterior two-thirds of the tongue, somatic sensation around the external ear, motor control over muscles of facial expression via five branches, and parasympathetic stimulation to lacrimal, nasal, and salivary glands.

Vestibulocochlear Nerve (CN VIII)

A purely sensory cranial nerve consisting of a vestibular nerve for balance/equilibrium and a cochlear nerve for audition (hearing).

Glossopharyngeal Nerve (CN IX)

A mixed cranial nerve providing taste to the posterior one-third of the tongue, detecting blood pressure in the carotid artery, innervating pharyngeal constrictor muscles for swallowing, and stimulating the parotid salivary gland.

Vagus Nerve (CN X)

The principal parasympathetic mixed cranial nerve that innervates muscles of the pharynx/larynx for speech and swallowing, detects blood $CO_2$ levels, and provides visceral innervation to thoracic and abdominal organs.

Accessory Nerve (CN XI)

A motor cranial nerve with a cranial component (innervating larynx muscles for speech) and a spinal component (innervating the trapezius and sternocleidomastoid muscles).

Hypoglossal Nerve (CN XII)

A motor cranial nerve originating from the inferiormost part of the medulla oblongata that innervates intrinsic and extrinsic tongue muscles responsible for tongue movement.