A&P Final

conduction

nerve fibers conduct sensory and motor
information up and down the spinal cord

neural integration

spinal neurons receive input from multiple
sources, integrate it, and execute appropriate output (for
example, bladder control)

locomotion

spinal cord contains central pattern generators:
groups of neurons that coordinate repetitive sequences of
contractions for walking

reflexes

involuntary responses to stimuli that are vital to
posture, coordination and protection

conduction, neural integration, locomotion, reflexes

what are the four functions of the spinal cord?

spinal cord

cylinder of nervous tissue that arises from the brainstem at the
foramen magnum of the skull; Occupies the upper two-thirds of vertebral canal

cervical enlargement

nerves to upper limb

lumbosacral enlargement

nerves to pelvic region and lower limbs

medullary cone

cord tapers to a point inferior to
lumbosacral enlargement

cauda equina

bundle of nerve roots that occupy the vertebral canal from L2 to S5

meninges

three fibrous membranes that enclose the
brain and spinal cord

dural sheath

surrounds spinal cord and is separated from vertebrae by epidural space

arachnoid membrane

adheres to dura and is separated from pia by fibers spanning the subarachnoid space that is filled with cerebrospinal fluid

pia membrane

follows contours of spinal cord and continues inferiorly as a fibrous terminal filum that fuses with dura to form coccygeal ligament

gray matter

neuron cell bodies with little myelin; site of information processing, synaptic integration

white matter

abundantly myelinated axons; carry signals from one part of the CNS to another

decussation

crossing of the midline that occurs in many tracts so that brain senses and controls contralateral side of body

contralateral

when the origin and destination of a tract are on opposite sides of the body

ipsilateral

when the origin and destination of a tract are on the same side of the body; does not decussate

ascending

_ tracts carry sensory information

descending

_ tracts carry motor information

endoneurium

loose connective tissue external to neurilemma

perineurium

layers of overlapping squamous cells that wrap fascicles

epineurium

dense irregular connective tissue that wraps entire nerve

sensory nerves

Carry signals from sensory receptors to the CNS

motor nerves

Carry signals from CNS to muscles and glands

mixed nerves

Consists of both afferent and efferent fibers

ganglion

cluster of neurosomas outside the CNS

skull; atlas

first cervical nerve exits between _ and _

cervical

spinal nerves C1-C8

thoracic

spinal nerves T1-T12

lumbar

spinal nerves L1-L5

sacral

spinal nerves S1-S5

coccygeal

spinal nerve Co1

posterior root ganglion

contains the neurosomas of sensory neurons carrying signals to the spinal cord

posterior ramus

innervates the muscles and joints in that region of the spine and the skin of the back

meningeal branch

reenters the vertebral canal and innervates the meninges, vertebrae, and spinal ligaments

cervical plexus

in the neck, C1 to C5: supplies neck and phrenic nerve to the diaphragm

brachial plexus

near the shoulder, C5 to T1: supplies upper limb and some of shoulder and neck

lumbar plexus

in the lower back, L1 to L4: supplies abdominal wall, anterior thigh, and genitalia

sacral plexus

in the pelvis, L4, L5, and S1 to S4: supplies remainder of lower trunk and lower limb

sciatica

sharp pain that travels from gluteal region along the posterior side of the thigh and leg to ankle

dermatome

a specific area of skin that conveys sensory input to a spinal nerve

reflexes

quick, involuntary, stereotyped reactions of glands or muscle to stimulation

somatic reflexes

reflexes involving the somatic nervous system innervating skeletal muscle

afferent nerve fibers

carry information from receptors to
posterior horn of spinal cord or to the brainstem

integrating center

a point of synaptic contact between neurons
in gray matter of cord or brainstem

efferent nerve fibers

carry motor impulses to muscles

effectors

the muscles that carry out the response

muscle spindle

stretch receptors embedded in skeletal muscles

proprioceptors

specialized sense organs to monitor position
and movement of body parts

stretch reflex

when a muscle is stretched, it “fights back” and contracts

reciprocal inhibition

reflex phenomenon that prevents muscles from working against each other by inhibiting antagonist when agonist is excited

flexor reflex

the quick contraction of flexor muscles resulting in the withdrawal of a limb from an injurious stimulus

polysynaptic reflex arc

pathway in which signals travel over many synapses on their way to the muscle

crossed extension reflex

contraction of extensor muscles in limb opposite of the one that is withdrawn

intersegmental reflex

one in which the input and output occur at different levels (segments) of the spinal cord

rostral

toward the forehead

caudal

toward the spinal cord

longitudinal fissure

deep groove that separates cerebral hemispheres

gyri

thick folds on brain surface; elevated

sulci

shallow grooves in brain surface; depressed

corpus callosum

thick nerve bundle at bottom of longitudinal
fissure that connects hemispheres

outer periosteal

_ layer of dura mater: Equivalent to periosteum of cranial bones

outer periosteal and inner meningeal

what are the two layers of the dura mater?

dural sinuses

collect blood circulating through the brain; separate the two layers of the dura mater

false

T or F: there is an epidural space in the dura mater

falx cerebri

part of dura mater that separates the two cerebral hemispheres

tentorium cerebelli

part of dura mater that separates cerebrum from cerebellum

falx cerebelli

part of dura mater that separates right and left halves of cerebellum

arachnoid mater

Transparent membrane over brain surface; contains CSF instead of blood

subarachnoid space

separates arachnoid mater and pia mater

pia mater

Very thin membrane, not usually visible without microscope; Follows all contours of brain; Follows arteries as they penetrate into cerebrum

meningitis

inflammation of the meninges

ventricles

four fluid-­filled chambers within brain

interventricular foramen

pore that connects lateral ventricles to third ventricle

cerebral aqueduct

tube running through midbrain that connects third ventricle to fourth ventricle

central canal

tube that connects to fourth ventricle and runs through center of spinal cord

cerebrospinal fluid

Clear, colorless liquid; Fills the ventricles and canals of CNS; Surrounds brain and bathes its external surface

choroid plexus

spongy mass of blood capillaries on the floor of each ventricle

ependymal

type of neuroglia that lines ventricles and covers choroid plexus

arachnoid granulation

Cauliflower­shaped extensions of the arachnoid meninx; Protrude through dura mater into superior sagittal sinus; CSF penetrates the walls of the villi and mixes with the blood in the sinus

stroke

interruption of blood supply causes death of brain tissue

medulla oblongata, pons, midbrain

what are the three parts of the brainstem?

medulla oblongata

All ascending and descending fibers connecting brain and spinal cord pass through _; begins at foramen magnum

pons

anterior bulge in brainstem, rostral to medulla

cerebellar peduncles

thick stalks on posterior pons that connect it (and the midbrain) to the cerebellum

midbrain

Short segment of brainstem that connects
hindbrain to forebrain; Contains cerebral aqueduct

tectum

roof­-like part of the midbrain posterior to cerebral aqueduct

superior colliculi

visual attention, tracking moving objects, and some reflexes

inferior colliculi

relays signals from inner ear to thalamus and other parts of the brain

cerebral peduncles

two anterior midbrain stalks that anchor the cerebrum to the brainstem

central pattern generators

neural pools that produce rhythmic signals to the muscles of breathing and swallowing

gaze centers

allow eyes to track and fixate on objects

somatic motor control

reticular formation: Adjust muscle tension to maintain tone, balance, and posture, especially during body movements; Relay signals from eyes and ears to cerebellum

cardiovascular control

reticular formation: Cardiac and vasomotor centers of medulla oblongata

pain modulation

reticular formation: Some pain signals ascend through the reticular formation; Some descending analgesic pathways begin in the reticular formation

sleep and consciousness

Reticular formation: plays a central role in consciousness, alertness,
and sleep; Injury here can result in irreversible coma

habituation

Reticular formation: activating system modulates activity in cerebral cortex so that it ignores repetitive, inconsequential stimuli

vermis

right and left hemispheres of cerebellum are connected by