A & P Chapter 13

The anterior rami of the spinal nerves form which nerve plexuses.

cervical, lumbar, sacral

also known as a motor nerve fiber, a(n) _____ fiber is a nerve fiber carrying nerve signals away from the central nervous system

efferent

spinal nerves are described as ______ nerves because they carry both afferent and efferent signals

mixed

which viral disease results i the destruction of motor neurons

poliomyelitis

the anterior horns of the spinal cord contain the somas of which neurons

somatic motor

the number of neurons in a descending pathway is _____

two

What does contralateral mean?

two points on the opposite side of the body

What does ipsilateral mean?

two points on the same side of the body

Consider the two motor neurons that form descending pathways. The neurons called _______ motor neurons have their somas in the cerebral cortex or brainstem

upper

_______ fibers are nerve fibers that innervate blood vessels, glands, and internal organs.

visceral

_____ matter is composed of myelinated and unmyelinated axons and is superficial to the gray matter of the spinal cord

white

a general fiber innervates which of the following?

widespread organs such as muscles, skin, glands, viscera, and blood vessels

how many spinal nerves are in each region of the spinal cord in order from superior to inferior?

8,12,5,5,1

Which horns of the spinal cord contain the cell bodies of outgoing somatic motor neurons?

anterior

the larger _____ ramus of a spinal nerve innervates the anterior and lateral skin and muscles of the trunk and gives rise to the nerves of the limbs

anterior

external to the neurilemma of a nerve fiber is the layer of loose connective tissue that surrounds a nerve fiber called a(n)

endoneurium

the ___ motor neurons (which are the motor neurons connecting the brainstem and spinal cord to muscle fibers) of the descending pathway innervate skeletal muscle

lower

in descending pathways, the upper motor neurons synapse with which neurons in the brainstem of spinal cord?

lower motor

in a sensory pathway, which neurons run from the spinal cord or brainstem to the thalamus ?

second order

in a sensory pathway, which neurons run from the spinal cord or brainstem to the thalamus?

second order

within the spinal cord, an ascending tract will carry ______ information up the brain

sensory

what is an afferent fiber?

sensory nerve fiber

a somatic fiber innervates which of the following?

skin, skeletal muscles, bones and joints

How many pairs of spinal nerves are there?

31

in a sensory pathway, the ____ order neuron runs from the thalamus to the sensory cerebral cortex

3rd

the central canal of the spinal cord contains ____ fluid

CSF

in an adult, the spinal cord ends at vertebra

L1

the lateral gray horns of the spinal cord are found in which segments of the spinal cord?

T2 to L1

What is the gray commissure of spinal cord?

a band of gray matter connecting the right and left sides together

what is a fasciculus in the spinal cord?

a tract of nerve fibers within a funiculus

which horns of the spinal cord contain the cell bodies of outgoing somatic motor neurons?

anterior

where does the spinal cord arise from the medulla oblongata?

at the foramen magnum

a nerve fiber refers to which part of a neuron?

axon

in the spinal cord, the ______ canal is lined with ependymal cells and contains cerebrospinal fluid

central

which describes a mixed nerve?

containing both sensory and motor nerve fibers; afferent and efferent fibers

because the nerve tracts of the spinal cord undergo ______, the right side of the brain communicates with the left side of the body, and vice versa

decussation

within the spinal cord, which tracts carry motor signals down the brain?

descending

Within a nerve, nerve fibers are gathered into bundles called:

fascicles

a ____ is a tract of nerve fibers within a column of the spinal cord

fasciculus

a _____ is a tract of nerve fibers within a column of the spinal cord

fasciculus

in a sensory pathway , the _____ order neuron detects the stimulus and transmits the signal to the spinal cord or brainstem

first

in a sensory pathway, which neuron detects the stimulus and transmits the signal to the spinal cord or brainstem?

first order

all spinal nerves except c1 pass through which structure to emerge from the vertebral column?

intervertebral foramen

which nerve tracts do not decussate and have their origin and destination on the same side of the body

ipsilateral

a special fiber innervates which of the following?

localized organs in the head (eyes, ears, olfactory and taste receptors, etc.)

which are the functions of the spinal cord?

locomotion, conduction, reflexes

the anterior root of a spinal nerve contain axons of which neurons?

motor

a ______ is a cordlike organ composed of numerous nerve fibers (fascicles) bound together by connective tissue

nerve

Within a nerve, each fascicle is wrapped in a layer called a ________

perineurium

the ______ ramus of spinal nerve innervates the muscles, joints, and skin of back

posterior

which spinal cord areas are composed of gray matter?

posterior, anterior, and lateral horns

what are the three pairs of funiculi in the spinal cord

posterior, lateral, anterior

which tracts carry signals that control muscles of the upper and lower limbs, especially for posture and balance?

reticulospinal

which of these structures is closest to the spinal cord

rootlet

moving peripherally from the spinal cord the anterior and posterior ____ form the spinal nerve

roots

in an amyotrophic lateral sclerosis, motor neurons are destroyed and ____ (scarring) if the lateral regions of the spinal cord occurs

sclerosis

the posterior root of a spinal nerve carries _____ nerve fibers

sensory

the somas of ______ neurons are found within the posterior root ganglion

sensory

where is the white matter in the spinal cord?

superficial to the gray matter

the lateral horns of the spinal cord contain somas of ____ motor neurons

sympathetic

what is the anterior median fissure of the spinal cord?

the longitudinal groove on the ventral surface of the spinal cord

in a sensory pathway, which neurons run from the thalamus to the sensory cerebral cortex?

third order

it takes _____ neurons for a somatic sensation nerve signal to complete the sensory pathway

three