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34 terms

18.3 Brain Stem and Reticular Formation

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Reticular Formation
Netlike region of interspersed gray and white matter extending throughout the brainstem.
Medulla Oblongata
Begins at the foramen magnum and extends to the inferior border of the pons.
Pyramids
Bulges of white matter on the anterior aspect of the medulla. Formed by the largest motor tracts that pass from the cerebrum to the spinal cord.
Decussation of Pyramids
Crossing of axons just superior to the junction of the medulla and the spinal cord.
Nuclei
Masses of gray matter where neurons form synapses with one another.
Cardiovascular Center
In the medulla, regulates rate and force of heartbeat and diameter of blood vessels.
Medullary Rhythmicity Area
In the medulla, adjusts basic rhythm of breathing.
Medulla
nuclei from this part of the brain control reflexes for vomiting, coughing, and sneezing.
Olive
In the medulla, where neurons relay impulses from proprioreceptors to the cerebellum.
Gracile Nucleus
In the medulla, controls proprioception and sensation of fine touch in lower body.
Cuneate Nucleus
In the medulla, controls proprioception and sensation of fine touch in the upper body.
Medial Lemniscus
Band of white matter composed of ascending sensory axons; extends through the medulla, pons and midbrain.
Vestibulocochlear
Nerves that convey impulses related to hearing.
Glossopharyngeal
Nerves that control muscles during swallowing and tastebuds of posterior 1/3 of tongue.
Vagus
Nerves that recieve signals from viscera, control cardiac and smooth muscle of visceral organs, controls secretion of digestive fluids.
Accessory
Nerves whose cranial portion arise in the medulla; controls skeletal muscles of soft palate.
Hypoglossal
Nerves that control muscles of tongue while speaking or swallowing.
Pons
Part of brain located directly superior to the medulla and anterior to the cerebellum. Bridge that connects parts of the brain with one another.
Pontine Nuclei
Large synaptic relay station consisting of scattered gray centers; forms the ventral region of the pons.
Pneumotaxic and Apneustic
Areas of the pons that control inhaling, exhaling, and rhythm of breathing.
Trigeminal
Control muscels involved in chewing.
Facial
Motor part of these nerves goes to facial muscles, salivary glands, tear ducts, and nasal mucus sinuses. Sensory part controls anterior 2/3 of taste buds.
Abducens
Control lateral eye muscles.
Midbrain
Extends from the pons to the diencephalon.
Cerebral Peduncles
Pair of tracts in the anterior part if the midbrain. Contain corticospinal, corticobulbar, and corticopontine motor neurons which conduct nerve impulses from the cerebrum to the spinal cord. Also contain axons of sensory neurons that extend from the medulla to the thalamus.
Tectum
Posterior part of the midbrain.
Superior Colliculi
Two superior elevations of the tectum; coordinates eye movements with visual stimuli.
Inferior Colliculi
Two inferior elevations of the tectum; coordinates head movement response to auditory stimuli.
Substantia Nigra
Left and right nuclei in the midbrain that secrete dopamine.
Red Nuclei
Left and right nuclei in the midbrain that function with the cerebellum to coordinate muscle movement.
Mesencephalic Nucleus
Only nucleus in the CNS that is not a synaptic relay station between neurons. Contains cell bodies of snesory neurons carrying proprioceptive signals from skeletal muscles of the head.
Oculomotor
Motor part of these nerves controls movement of eyeballs and constriction of pupils and shape of lens. Goes to intrinsic and extrinsic eye muscles.
Trochlear
Control movement of eyeball via trochlear nerves.Goes to superior oblique eye muscle.
Reticular Activating System
Consist of sensory axons that project into cerebral cortex. Functions in arousal and consciousness. Prevents sensory overload.