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?
