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
