Chapter 12

Ventral root

Contains the axons of motor neurons that extend into the periphery to control somatic and visceral effectors.

Spinal nerve

Contains the axons of sensory and motor neurons.

Dorsal root

Contains the axons of the neurons whose cell bodies are in the dorsal root ganglion

Dorsal root ganglion

Contains the cell bodies of sensory neurons whose axons carry information to the spinal cord.

Motor nuclei

Issue motor commands peripheral effectors

Acquired reflexes

Learned; enhanced by repetition; driving a car

Receptor, sensory neuron, mortor neuron, peripheral effector

List the components of a reflex arc.

Dorsal, ventral, communicating rami

Major peripheral branches of a spinal nerve

Arachnoid mater

Middle meningeal layer.

Sensory nuclei

Receive and relay sensory information from peripheral receptors

rapid, unconscious, patterned

Common characteristics of reflexes.

Pia mater

Consists of a meshwork of elastic and collagen fibers that is firmly bound to the underlying neural tissue

Dura mater

Contains dense collagen fiber that are oriented along the longitudinal axis of the cord.

White matter

Contains large number of myelinated and unmyelinated axons

Visceral reflexes

Control or adjust the activities of smooth muscle, cardiac muscle, glands, and adipose tissue; vomitting

Spinal reflexes

Occur in nuclei of spinal cord

outer, middle, inner epineurium

Three layer of connective tissue of a spinal nerve

31

A typical spinal cord has how many part of spinal nerves?

Polysynaptic reflexes

3+ neurons

Monosynaptic reflex

2+ neurons

White matter columns

A disease that damages myelin sheaths would affect which portion of the spinal cord?

Anterior gray horns

A person with polio has lost the use of his leg muscles. In which area of his spinal cord would you expect the virus-infected motor neurons to be?

Reflex

A rapid, automatic response triggered by specific stimuli

Spinal reflex

A rapid, automatic response triggered by specific stimuli controlled in spinal cord

Posterior median sulcus

A shallow longitudinal groove on the posterior surface of the spinal cord

Dermatome

A specific bilateral sensory region monitored by a single pair of spinal nerves

Flexor reflex

An example of a withdrawal reflex that contracts the flexor muscles of a limb in response to a painful stimulus

Stretch reflex

Automatically regulates skeletal muscle length

Shingles

Caused by a reactivation of the VZV, the same herpes virus that causes chicken pox

cell bodies of neurons, neuroglia, and unmyelinated axons

Describe the composition of the gray matter of the spinal cord.

over spinal nerves

Describe the direction of sensory input and motor commands relative to the spinal cord.

Innate reflexes

Developmentally programmed; chewing, suckling, tracking objects with eye

Extended; Crossed extensor reflex

During a withdrawal reflex of the foot, what happens to the limb on the side opposite the stimulus? what is this response called?

Cranial reflexes

Important interconnections and processing events occur in nuclei of the brain

more sensitive; quick

In the patellar reflex, how does stimulation of the muscle spindle by gamma motor neurons affect sensitivity and reaction time?

Leg extension; quadriceps femoris muscles

In the patellar reflex, identify the response observed and the effectors involved.

Somatic reflexes

Involuntary control of skeletal muscles; immediate; knee jerk

Polysynaptic reflexes

Involves pools of interneurons, are intersegmental in distribution, involve reciprocal inhibition and have reverberating circuits

Coccyx

Where does the spinal cord end?

Subarachnoid space

Where is the cerebrospinal fluid that surrounds the spinal cord located?