anatomy and physiology martini chapter 13

fibular nerve and tibial nerve

as it approaches the knee, the sciatic nerve divides into two branches, which are?

meningitis

bacterial or viral infection can cause _, or inflammatin of the meningeal membranes.

ascending tracts

carry sensory information toward the brain

posterior gray horns

contain somatic and visceral sensory nuclei.

anterior gray horns

contain somatic motor nuclei.

descending tracts

convey motor commands to the spinal cord.

polysynaptic reflexes

have a longer delay between stimulus and response. can produce far more complicated responses than monosynaptic reflexes, because the interneurons can control motor neurons that activate several muscle groups simultaneously.

plantar reflex

in adults, stroking the lateral sole of the foot produces a curling of the toes, called a _, or negative Babinski reflex, after about a 1sec delay.

intersegmental reflex arcs

in the most complicated spinal reflexes, called _, many segments interact to produce a coordinated, highly variable motor response.

monosynaptic reflex

in the simplest reflex arc, a sensory neuron synapses directly on a motor neuron, which serves as the processing center. such a reflex is called _.

nuclei

masses of gray matter within the central nervous system.

tendon reflex

monitors the external tension produced during a muscular contractions and prevents tearing or breaking of the tendons.

acquired reflexes

more complex, learned motor patterns are called _.

gamma motor neurons

motor neurons innervating intrafusal fibers are called _.

gamma efferents

motor neurons innervating intrafusal fibers are called gamma motor neurons, their axons are called _.

withdrawal reflexes

move affected body parts of the body away from a stimulus. the strongest ones are triggered by painful stimuli, but these reflexes are sometimes initiated by the stimulation of touch receptors or pressure receptors.

intrafusal muscle fibers

muscle spindles each consist of a small bundle of specialized skeletal muscle fibers called _.

reverberation

one of five circuit patterns: collateral branches of axons somewhere along the circuit extend back toward the source of an impulse and further stimulate the presynaptic neurons.

serial processing

one of five circuit patterns: information is relayed in a stepwise fashion, from one neuron to another or from one neuronal pool to the next.

parallel processing

one of five circuit patterns: occurs when several neurons or neuronal pools process the same information simultaneously.

convergence

one of five circuit patterns: several neurons synapse on a single postsynaptic neuron.

divergence

one of five circuit patterns: the spread of information from one neuron to several neurons, or from one pool to multiple pools. this permits the broad distribution of a specific input.

visceral reflexes

or autonomic reflexes, control the activites of other systems.

sciatic nerve

passes posterior to the femur, deep to the long head of the biceps femoris muscle.

gray commissures

posterior to and anterior to the central canal contain axons that cross from one side of the cord to the other before they reach an area in the gray matter.

patellar reflex

when a physician taps your patellar tendon with a reflex hammer, receptors in the quadriceps muscle are stretched.

reinforcement

when many of the excitatory synapses are chronically active, the postsynaptic neuron can enter a state of generalized facilitation. this can result it _, an enhancement of spinal reflexes.

cauda equina

when seen in gross dissection, the filum terminale and the long ventral and dorsal roots resemble a horse's tail.

coccygeal ligament

within the sacral canal, the spinal dura mater tapers from a sheath to a dense cord of collagen fibers that blends with components of the filum terminale to form the _.

horns

are the areas of gray matter on each side of the spinal cord.

endoneurium

(innermost layer), extend from the perineurium and surround individual axons.

perineurium

(middle layer), extend inward from the epineurium.

Babinski sign

(or positive Babinski reflex). stroking an infant's foot on the lateral sole produces a fanning of the toes known as _. this response disappears as descending motor pathways develop.

epineurium

(outermost layer), consists of a dense network of collagen fibers.

tract or fasciculus

a bundle of axons in the CNS that is somewhat uniform with respect to diameter, myelination, and conduction speed.

nerve plexus

a complex, interwoven network of nerves.

anterior median fissure

a deeper groove along the anterior (ventral) surface.

ventral roots

a pair of _ contains the axons of motor neurons that extend into the periphery to control somatic and visceral effectors.

epidural space

a region that contains areolar tissue, blood vessels, and a protective padding of adipose tissue.

anterior white commissure

a region where axons cross from one side of the spinal cord to the other.

flexor reflex

a representative withdrawal reflex, affects the muscles of a limb. if you grab an unexpected hot pan, a dramatic _ will occur.

filum terminale

a slender strand of fibrous tissue, extends from the inferior tip of the conus medullaris.

denticulate ligaments

along the length of the spinal cord, paired _ extend from the pia mater through the arachnoid mater to the dura mater.

major nerves of the lumbar plexus

answer: major nerves of the lumbar plexus. genitofemoral nerves, lateral femoral cutaneous nerve, femoral nerve.

major nerves of the sacral plexus

answer: major nerves of the sacral plexus. sciatic nerve and pudendal nerve.

spinal nerve

distal to each dorsal root ganglion, the sensory and motor roots are bound together into a single _.

dorsal root ganglia

every spinal segment is associated with a pair of _, located near the spinal cord.

neuronal pools

functional groups of interconnected neurons. it may be scattered, involving neurons from in several regions of the brain, or localized, with neurons restricted to one specific location in the brain or spinal cord.

reciprocal inhibition

in theory, the contraction of a flexor muscle should trigger a stretch reflex in the extensors that would cause them to contract, opposing the movement. interneurons in the spinal cord prevent such competition through _.

conus medullaris

inferior to the lumbar enlargement, the spinal cord becomes tapered and conical, this region is called _.

brachial plexus

innervates the pectoral girdle and upper limb, with contributions from the ventral rami of spinal nerves C5-T1.

crossed extensor reflex

involves a contralateral reflex arc, because the motor response occurs on the side opposite the stimulus. this reflex complements the flexor reflex, and the two occur simultaneously.

lumbar puncture or spinal tap

involves the insertion of a needle into the subarachnoid space in the inferior lumbar region.

motor nuclei

issue motor commands to peripheral effectors.

trunks

large bundles of axons contributed by several spinal nerves.

anterior white columns

lie between the anterior gray horns and the anterior median fissure.

posterior white columns

lie between the posterior gray horns and the posterior median sulcus.

lateral gray horns

located only in the thoracic and lumbar segments, contain visceral motor nuclei.

somatic reflexes

provide a mechanism for the involuntary control of the muscular system.

lumbar enlargement

provides innervation to structures of the pelvis and lower limbs.

sensory nuclei

receive and relay sensory information from peripheral receptors.

cranial reflexes

reflexes processed in the brain.

postural reflexes

reflexes that help us maintain a normal upright posture. standing for example.

peripheral neuropathies

regional losses of sensory and motor function most often resulting from nerve trauma or compression.

innate reflexes

results from the connections the form between neurons during development. such reflexes generally appear in a predictable sequence, from the simplest reflex responses (withdrawal from pain) to more complex motor patterns (chewing, suckling, tracking objects with eyes).

enlargements

segments are expanded, forming the _ of the spinal cord.

subdural space

separates the dura mater from deeper meningeal layers.

cords

smaller branches that originate at trunks.

mixed nerves

spinal nerves contain both afferent(sensory) and efferent (motor) fibers.

cervical enlargement

supplies nerves to the shoulder and upper limbs.

spinal meninges and cranial meninges

surround the brain.

lumbar plexus and sacral plexus

the _ and _ arise from the lumbar and sacral segments of the spinal cord.

subarachnoid space

the arachnoid mater includes this epithelium, called the arachnoid membrane, and the arachnoid trabeculae, a network of collagen and elastic fibers that extends between the arachnoid membrane and the outer surface of the pia mater. the region between is called the _.

dorsal roots

the axons of the neurons form the _, which being sensory information into the spinal cord.

stretch reflex

the best known monosynaptic reflex is the _, which provides automatic regulation of skeletal muscle length. patellar reflex is an example.

central canal

the gray matter, dominated by the cell bodies of neurons, neuroglia, and unmyelinated axons, surround the narrow _ and forms an H or butterfly shape.

spinal reflexes

the important interconnections and processing events occur in the spinal cord.

arachnoid

the inner surface of the dura mater is in contact with the outer surface of the _.

musculocutaneous nerve

the lateral cord forms the _ exclusively and, together with the medial cord, contributes to the median nerve.

extrafusal muscle fibers

the muscle spindle is surrounded by larger skeletal muscle fibers, called _. responsible for resting muscle tone and, at greater levels of stimulation, for the contraction of the entire muscle.

ulnar nerve

the other major nerve of the medial cord.

axillary nerve and radial nerve

the posterior cord gives rise to the _ and the _.

posterior median sulcus

the posterior(dorsal) surface of the spinal cord has a shallow longitudinal groove.

muscle spindles

the sensory receptors involved in the stretch reflex are _.

dermatome

the specific bilateral region of the skin surface monitored by a single pair of spinal nerves is known as a _.

pia mater

the subarachnoid space extends between the arachnoid epithelium and the innermost meningeal layer called the _.

cerebrospinal fluid (CSF)

the subarachnoid space is filled with _, which acts as a shock absorber and a diffusion medium for dissolved gases, nutrients, chemical messengers and waste products.

lateral white column

the white matter between the anterior and posterior columns on each side makes up the _.

columns

the white matter on each side of the spinal cord can be divided into three regions called _.

reflex arc

the wiring of a single reflex. begins at a receptor and ends at a peripheral effector, such as a muscle fiber or a gland cell.

dura mater

tough and fibrous, it's a layer that forms the outermost covering of the spinal cord. layer contains dense collagen fibers, oriented along the longitudinal axis of the cord.