MODULE 3 (A)

brain and spinal cord

connects the brain and spinal cord to the rest of the body

consists of the axons conveying messages from the sense organs to the CNS and from the CNS to the muscles

controls the heart, intestines, and other organs

human brain; spinal cord

horizontal, sagittal, and coronal (frontal)

• Communicates with all the sense organs and muscles except those of the head • A segmented structure, and each segment has on both the left and right sides a sensory nerve and a motor nerve • Dorsal roots (axon bundles) carry sensory information, and the exiting ventral roots carry motor information

cell bodies of the sensory neurons are in clusters of neurons outside the spinal cord

motor neurons

• H-shapes gray matter in the spinal cord is densely packed with the cell bodies and dendrites • White matter: containing myelinated axons

• A network of nerves that prepare the organs for a burst of vigorous activity • Consists of chains of ganglia just to the left and right of the spinal cord’s central regions (the thoracic and lumbar areas) • Prepares the organs for “fight or flight” • Sweat glands, adrenal glands, the muscles that constrict blood vessels, and the muscles that erect the hairs of the skin have sympathetic input

• Sometimes called the “rest and digest” system, facilitates vegetative, nonemergency responses • Para means “beside” or “related to” • Opposite of sympathetic activities • Aka. the craniosacral system because it consists of the cranial nerves and nerves from the sacral spinal cord

• The most prominent part of the mammalian brain • Aka. Prosencephalon (“forward brain”), Diencephalon (“between brain”), Telencephalon (“end-brain”) • Major structures in Prosencephalon: Thalamus, hypothalamus • Major structures in Telencephalon: Cerebral cortex, hippocampus, basal ganglia

• In adult mammals it is dwarfed and surrounded by the forebrain • Aka. Mesencephalon (“middle brain”) • Major structures: Tectum, tegmentum, superior colliculus, inferior colliculus, substantia nigra

• Posterior part of the brain • Aka. Rhombencephalon (literally, “parallelogram brain”) • Major structures: Medulla, pons, cerebellum

• Enlarged extension of the spinal cord • The head and the organs connect to the medulla and adjacent areas by 12 pairs of cranial nerves • Cranial nerves originating in the medulla control vital reflexes such as breathing, heart rate, vomiting, salivation, coughing, and sneezing

• Lies anterior and ventral to the medulla • Contains nuclei for several cranial nerves • In the pons, axons from each half of the brain cross to the opposite side of the spinal cord so that the left hemisphere controls the muscles of the right side of the body and the right hemisphere controls the left side

• Large hindbrain structure with many deep folds • Contributes to the control of movement • Important for “balance and coordination” • Ppl w/ damage to the cerebellum have trouble shifting their attention back and forth between auditory and visual stimuli; also have difficulty w/ timing

roof of the midbrain

• The swellings on each side of the tectum • Both are important for sensory processing–inferior colliculus for hearing, superior colliculus for vision

is under the tectum and is the intermediate level

gives rise to a dopamine-containing pathway that facilitates readiness for movement

• Each hemisphere is organized to receive sensory information, mostly from the contralateral (opposite) side of the body • Controls muscles, mostly on the contralateral side • The outer portion is the cerebral cortex • Under the cerebral cortex are other structures, including the thalamus and the basal ganglia

• Several interlinked structures form a border around the brainstem • Includes the olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate gyrus of the cerebral cortex