brain and spinal cord

spinal cord

from the brain stem to the 1st lumbar vertebrae, 17 inches long

conus medullaris

end of the spinal cord, containing nerve roots called cauda equina, runs to the coccyx

filum terminale

extension of the pia mater, runs from the conus medullaris to the coccyx, inferior anchor for the spinal cord

spinal tap

removing spinal fluid for testing, done inferior to the L1 vertebrae

grooves in the spinal cord surface

the anterior median fissure and the shallower posterior median sulcus

central canal

an opening that runs the length of the spinal cord and is filled with cerebrospinal fluid

white matter

composed of myelinated and unmyelinated nerve fibers organized into regions called columns

tract

a bundle of axons, cross over to the opposite side

dorsal root

carries incoming sensory neurons

dorsal root ganglion

contains the cell bodies sensory neurons from the dorsal root

ventral root

contains the axons of motor neurons

spinal nerve

the dorsal and ventral roots on either side coming together

gray matter

composed of a mixture of the cell bodies of neurons

anterior horns

connected by a crossbar called the gray commissure, contain motor neurons to act as a pathway to skeletal muscles by the ventral roots

posterior horns

serve as a sensory pathway by way of the dorsal root

lateral horns

mostly at the thoracic level, contains autonomic sympathetic motor neurons serving as a motor pathway to the visceral organs, exit via the ventral root

brain divisions

cerebrum, brainstem, diencephalon, and the cerebellum

ventricles

4 cavities in the brain filled with cerebrospinal fluid

meninges

three layers of connective tissue membrane, covering and protecting the CNS organs and enclosing cerebrospinal fluid

dura mater

leathery, double layered outer meninx

arachnoid meninx

loose, middle layer, separated from the dura mater by the subdural space

subarachnoid space

contains blood vessels and is filled with cerebrospinal fluid

pia mater meninx

thin connective tissue tightly attached to the brain

cerebrospinal fluid

fluid formed in the walls of the ventricles from blood plasma by permeating through the choroid plexus

CSF function

cushions the brain and spinal cord by providing buoyancy, allowing the brain to float

choroid plexus

formed from a network of blood vessels within the ventricles

blood brain barrier function

diffusion barrier to prevent most particles from entering the CNS tissues, keeps the brain and spinal cord separate from general blood circulation

blood brain barrier

formed by the relatively impermeable brain capillaries, (due to astrocytes)

cerebrum

largest part of the brain, split into two hemispheres that control opposing sides of the body

cerebrum controls

consciousness, governs intelligence, reasoning, and higher level thinking, controls lower parts of the brain and can override their functioning

median longitudinal fissure

separates the left and right hemisphere

gyri

raised ridges of tissue marking the cerebral cortex

sulci

shallow grooves separating the gyri

transverse fissure

separates the cerebrum from the cerebellum

corpus callosum

white nerve fibers connecting the left and right hemisphere

cerebral cortex

the outer portion of the cerebrum, grey in color

frontal lobe

controls higher level executive functions, such as reasoning and decision making, and controls motor functions and allows control over voluntary muscle actions

parietal lobe

receives sensory info from receptors in the mouth (for taste), and from the skin (for touch, pressure, and pain)

occipital lobe

interprets visual input

temporal lobe

has sensory areas for hearing and smelling

primary areas

receive or send information for one type of sensory or motor information

association areas

act mainly to integrate more than one type of sensory information for purposeful action

Broca’s area

responsible for speech production

Wernicke’s area

responsible for speech comprehension

brainstem

contains the medulla oblongata, pons, and midbrain

medulla oblongata

lies between the spinal cord and pons, contains vital centers for regulating heartbeat, breathing, and vasoconstriction, also contains reflex centers for vomiting, coughing, sneezing, hiccupping, and swallowing

pons

contains bundles of axons traveling between the cerebellum and the rest of the CNS, helps the medulla regulate breathing and head movements in response to auditory and visual stimuli

midbrain

relay station for tracts passing between the cerebrum and spinal cord or cerebellum, also has reflex centers for higher

superior and inferior colliculi

on the posterior portion of the midbrain, controls reflexes for the head and neck in response to sudden visual or auditory stimuli

diencephalon

consists of the hypothalamus, thalamus, and epithalamus

hypothalamus

forms the floor of the third ventricle, maintains homeostasis, regulates basic body functions, and controls the pituitary gland

thalamus

in the roof of the third ventricle, last portion of brain for sensory input, serves as a central relay station

epithalamus

forms the roof of the third ventricle, mostly composed of the pineal gland

cerebellum

divided into two hemispheres and three lobes, made of white and grey matter, coordinates body movements by relaying info, maintains balance, muscle tone, and posture, and controls eye movements

muscle tone

the degree at which muscles remain partially contracted while at rest

anterior and posterior lobes

receive information from the body trunk and influence the motor activities of the trunk, shoulder, and pectoral girdle muscles

vermis

middle of the cerebellum, coordinates limb movements

cerebellar peduncles

on the anterior portion of the cerebellum, connect the cerebellum to other parts of the brain

limbic system

involves both conscious and unconscious brain, contains neural pathways to connect portions of the brain, “feeling brain”, involved in memory

cingulate gyrus

(limbic lobe), connects the different lobes of the cerebrum

hippocampus

involved in the retrieval and storage of memories

amygdala

involved in emotions such as rage and anger

fornix

bundle of nerve fibers that serves as a connection to the hippocampus

mamillary bodies

contain fibers that project into the thalamus and assist with the memory of smell

basal nuclei/ganglia

masses of gray matter deep within the cerebrum, work with the cerebellum to regulate planning motor movements and motor learning (mostly to slow and control precise movements)

parts of the basal ganglia

putamen, caudate nucleus, and Globus pallidus