Chapter 12: The Central Nervous System Pt. 2

cerebellum

largest part of the hindbrain, right and left cerebellar hemispheres connected by a vermis, three paired cerebella cerebellum to the brainstem

cerebellum pt. 2

modulates and coordinates voluntary movement of limbs, maintains muscle tone and posture, coordinates eye movements, helps in learning motor skills

functional brain systems

limbic, reticular formation, meninges

limbic system

loop of cortical structures surrounding the corpus callosum and thalamus, many important facets of an individual’s personality depend on an intact limbic system, important for emotions such as fear, anger, love, and others

reticular formation

group of 100 nuclei scattered throughout the medulla, midbrains, and pons that function in somatic motor control, autonomic control, arousal, and pain modulation. the RAS (reticular activating system)- filters out the unwanted stimuli

meninges

three protective fibrous coverings that separate the brain and spinal cord from the skull and vertebrae

meninges: three layers

dura matter: tough, protective, outer layer- made of fibrous connective tissue. tough matter

arachnoid matter: mesh like network between the outer and inner layers of the meninges that contains the cerebrospinal fluid (CSF)

pia matter: highly vascular layer that closely follows the contours of the brain. “gentle mother”

cerebrospinal fluid

cerebrospinal fluid (CSF) is a clear, colorless liquid that functions to lend buoyancy, protect, remove wastes, and provide a stable chemical environment. produced by the chordoid plexus within each ventricle, which consists of capillaries covered by simple cuboidal epithelium

blood supply and the blood-brain barrier

brain is very metabolically active, and has a high demand for oxygen and glucose. stopping the blood supply to the brain for as little as 4 minutes can cause irreversible brain damage. CNS is protected by a blood-brain barrier that regulates substances entering the brain. tight junctions within capillaries and astrocytes comprise this barrier

cerebrovascular accidents (strokes)

caused when blood circulation to the brain is blocked and brain tissue dies. most commonly caused by blockage of a cerebral artery. other causes include comprise this barrier

cerebrovascular accidents (strokes)

caused when blood circulation to the brain is blocked and brain tissue dies. most commonly caused by blockage of a cerebral artery. other causes include compression of the brain by hemorrhage or edema, and atherosclerosis. transient ischemic attacks (TIAs)- temporary episodes of reversible cerebral ischemia

spinal cord functions

conduction, locomotion, and control of reflex activity

spinal cord anatomy

begins and the foramen magnum and ends at the first lumbar vertebra. divided into cervical, thoracic, lumbar, and sacral regions. gives rise to 31 pairs of spinal nerves

tracts

ascending tracts carry sensory information up the spinal cord; descending tracts carry motor information down it

spinal cord trauma: paralysis

paralysis- loss of motor function

flaccid paralysis- severe damage to the ventral root or anterior horn cells. lower motor neurons are damaged and impulses do not reach muscle. there is no voluntary control of muscles

spastic paralysis- only upper motor neurons of the primary motor cortex are damaged. spinal neurons remain intact and muscles are stimulated irregularly. there is no voluntary control of muscles