Chapter 13
There are ___________ pairs of spinal nerves
31
What is the gray commissure of the spinal cord?
A band of gray matter connecting the gray matter of the left side to the right side
What is a nerve?
A cord of nerve fiber bundles bound together by CT
Reflex Arc
A simple neural pathway that mediates a reflex; involves a receptor, an afferent nerve fiber, one or more interneurons, an efferent nerve fiber, and an effector
What is a fascicles in the spinal cord?
A tract of nerve fibers within a funiculus
The ___________ median fissure is a longitudinal groove on the ventral surface of the spinal cord
Anterior
The ______________ horns of the spinal cord contain the cell bodies of outgoing somatic motor neurons
Anterior
What is made of gray matter?
Anterior, posterior, and lateral horns
The ___________ mater is just below (deep to) the dura mater
Arachnoid
The neural pathway that mediates a reflex is called a reflex ______________
Arc
What is the white matter of the spinal cord?
Bundles of myelinated and unmyelinated axons found superficial to the gray matter
In the spinal cord, what is the space within the gray commissure that contains CSF?
Central Canal
Place the spinal cord regions in order from superior to inferior
Cervical, Thoracic, Lumbar, and Sacral
Which tracts will have its origin and destination of opposite sides of the body?
Contralateral
Which reflex is contralateral?
Crossed extension
Because the nerve tracts of the spinal cord undergo _______________, the right side of the brain communicates with the left side of the brain, and vice versa
Decussation
Within the spinal cord, which tracts carry motor signals down from the brain?
Descending/Efferent
The dural sheath around the spinal cord is formed from the ______________ mater
Dura
Meninges superficial to deep
Dura mater, arachnoid mater, pia mater
A quick contraction of flexor muscles in response to a painful stimulus is called a ____________ reflex
Flexor
What structure marks the beginning of the spinal cord?
Foramen magnum
where are the neuron cell bodies, dendrites, and synapses found in the CNS?
Gray Matter
Which nerve tracts do not decussate and have their origin and destination on the same side of the body?
Ipsilateral
In an adult, the spinal cord ends at vertebrae ______________
L1
In an adult, the spinal cord ends at which vertebrae?
L1
What are the three columns of white matter found in the spinal cord?
Lateral, AnteRior, Posterior
The end of the spinal cord indicated by the arrow is
Medullary cone
The ____________ are a series of fibrous CT membranes covering the CNS
Meninges
What are intrafusal fibers?
Modified muscle fibers within a muscle spindle
Which type of reflex arc consists of only afferent neuron and an efferent neuron?
Monosynaptic
What is hemiplegia?
Paralysis of one side of the body
Within a nerve, each fascicle is wrapped in a layer called a(n) _________________
Perineurium
Which meninx is closely associated with he contours of the spinal cord?
Pia Mater
What is a reflex involving one or more interneurons called
Polysynaptic
The _______________ median sulcus is a longitudinal groove on the dorsal surface of the spinal cord
Posterior
Within the spinal cord, an ascending tract will carry ________________ information up to the brain
Sensory
What are the four components of a monosynaptic somatic reflex arc?
Skeletal muscle, efferent nerve fiber, receptor in skin, muscle or tendon, and afferent nerve fiber
What are four possible effectors of a reflex?
Smooth muscle, gland, cardiac muscle, and skeletal muscle
The typical location for muscle _________________ is at the ends of a muscle, near the tendons
Spindles
In the spinal cord, where is the white matter in relation to the gray matter?
Superficial
A ____________ reflex occurs in response to excessive tension on a tendon
Tendon
Which fibrous structure is indicated in the figure?
Terminal Filum
What is the lumbar enlargement of the spinal cord?
The area of the spinal cord that gives rise to the nerves of the lower limbs and pelvis
What is the arachnoid layer?
The middle layer of meninges
What is the subarachnoid space?
The space between the arachnoid and Pia mater
Which of the following best describes the medullary cone of the spinal cord?
The tapered end
Identify the regions of the spinal cord
Thoracic, Lumbar, Cervical, Sacral
It takes ___________ neurons for a somatic sensation nerve signal to complete the sensory pathway
Three (ascending)
What is a bundle of nerve fibers within the white matter of the spinal cord?
Tract
The number of neurons in a. descending pathway is __________
Two
What does bilateral 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 the __________ motor neurons have their somas in the cerebral cortex or the brainstem
Upper