BRAINSTEM, CEREBELLUM, DIENCEPHALON.

CRS101

Midbrain (Mesencephalon)

smallest and topmost region of the brainstem located just superior to the pons

Tectum of the midbrain

contains the corpora quadrigemina

Corpora quadrigemina

a collection of four nuclei located on the dorsal surface of the midbrain consisting of 1 pair of superior colliculi and 1 pair of inferior colliculi

Superior colliculi

receives sensory input from visual auditory and tactile sensory systems and are involved in the reflex movements of the head eyes and body toward these stimuli such as loud noises flashing lights or startling pain

Inferior colliculi

involved in hearing and are an integral part of the auditory pathways in the CNS conducting action potentials from the structures of the inner ear

Tegmentum of the midbrain

largely consists of ascending tracts such as the spinothalamic tract and the medial lemniscus that carry sensory information from the spinal cord to the brain and also contains the red nuclei the cerebral peduncles and the substantia nigra

Cerebral peduncles

the portion of the midbrain ventral to the tegmentum consisting primarily of descending tracts which carry motor information from the cerebrum to the brainstem and spinal cord

Red nuclei

aids in the unconscious regulation and coordination of motor activities

Substantia Nigra

involved in maintaining muscle tone and coordinating movements

Pons

contains ascending and descending tracts several nuclei the pontine sleep center which initiates rapid eye movement sleep and the pontine respiratory center which works with the respiratory centers in the medulla oblongata to help control respiratory movement

Medulla oblongata

the most inferior part of the brainstem and is continuous inferiorly with the spinal cord containing sensory and motor tracts cranial nerve nuclei and related nuclei functioning as centers for vital reflexes

Pyramids

two prominent enlargements on the anterior surface of the medulla oblongata at the side of the ventral median sulcus composed of corticospinal fibers formed by the large descending motor tracts involved in the conscious control of skeletal muscles where most of the fibers of the descending tracts cross to the opposite side or decussate near their inferior ends

Olives

two rounded oval structures that protrude from the anterior surface of the medulla oblongata just lateral to the superior ends of the pyramids being nuclei involved in functions such as balance coordination and modulation of sound from the inner ear

Reticular formation

neurons that are loosely scattered in the brainstem that play roles in arousal and awareness controlling the state of alertness and consciousness including the sleep-wake cycle and coordinating the rhythmic activities of swallowing breathing and the heart rate

Lobes of the Lateral Cerebellar Hemispheres

Anterior Lobe, Middle/Posterior Lobes

3 Major Regions/Lobes in the Cerebellum

Flocculonodular lobe, Anterior lobe, Posterior lobe

Cerellar Peduncles

connect the cerebellum to the brainstem; midbrain, pons, and medulla oblongata, respectively

The Cerebellar Peduncles has:

Superior, Middle, Inferior

Cerebellum - What is number 1?

Vermis

Cerebellum - What is number 2?

Anterior Lobe

Cerebellum - What is number 3?

Primary Fissure

Cerebellum - What is number 4?

Posterior Lobe

Purkinje cells

functional unit of the cerebellar cortex

Mossy fibers

ascending tracts from elsewhere in the brain that will branch within the cerebellum

Dentate nucleus

largest intracerebellar nuclei

Fastigial nucleus

intracerebellar nuclei that lies near the midline in the vermis

Diencephalon

forms a central core of brain tissue superior to the midbrain. It contains numerous nuclei involved in a wide variety of sensory and motor processing between higher and lower brain centers. Surrounded by the third ventricle.

The Diencephalon consists of:

Thalamus, Hypothalamus, Epithalamus, Subthalamus

Thalamus

“sensory relay station/center for information” coming into cerebral cortex. It consists of bilateral nuclei and forms the superolateral wall of 3 rd ventricle

The Thalamus is the largest part of diencephalon (makes up __ of it).

80%

Hypothalamus

central controller of endocrine system and major coordinating center of the autonomic nervous system forming the most inferior portion of the diencephalon

Infundibulum

a stalk that connects the pituitary gland to the base of hypothalamus

Subthalamus

small area immediately inferior to the thalamus containing subthalamic nuclei involved in controlling motor function

Epithalamus

small area superior and posterior to the thalamus consisting of the habenula and pineal gland

Habenula / Habenular nucleus

involved in motivational control of behavior

Pineal gland / body

involved in modulation of sleep-wake cycle and other biorhythms