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