Book Questions Ch 12

How would a transection of the spinal cord at the L1 level affect an individual's bowel and urinary bladder control?

Lose voluntary control of the bowel and urinary bladder, because these functions rely on impulses carried by motor neurons in the brain that must travel down the spinal and synapse with the interneurons and motor neurons involved in reflex

Describe the lumbar plexus and sacral plexus.

Lumbar plexus is a nerve network forms by axons from the ventral rami of spinal nerve segments T12- L4 Sacral plexus is a nerve network formed by the ventral rami of spinal nerve segments L4 -S4

Define nerve plexus, and list the major nerve plexuses.

A nerve plexus is a complex, interwoven network of nerves. The major plexuses are the cervical, brachial, lumbar, and sacral plexuses.

Describe the various classifications of reflexes.

According to their development, the nature of the resulting motor response, the complexity of the neural circuit involved, and the site of information processing

An anesthetic blocks the function of the dorsal rami of the cervical spinal nerves. Which areas of the body will be affected?

Affect the skin and muscles of the back of the neck and of the shoulders

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

Are composed of bundles of myelinated axons

What are common characteristics of reflexes?

Are rapid, unconscious patterned responses to a physical stimulus, which restore or maintain homeostasis

List the major nerves of the sacral plexus.

Are the superior and inferior gluteal nerves, the posterior femoral cutaneous nerve, the sciatic nerve, which branches into the tibial nerve and the fibular nerve, and the pudendal nerve

Explain the etiology (cause) of shingles.

By a reactivation of the varicella-zoster virus, the same herpes virus that causes chickenpox. Once reactivated, the virus stimulates painful inflammation of the nerve ganglia and causes skin eruptions in a pattern that reflects the affected dermatome

Injury to which of the nerve plexuses would interfere with the ability to breathe?

Damage to the cervical plexus, more specifically to the phrenic nerves, which originate in this plexus and innervate the diaphragm, would interfere with the ability to breathe

Which ramus innervates the skin and muscles of the back?

Dorsal ramus of each thoracic or superior lumbar spinal nerve innervates the skin and muscles of the back

Name the major nerves associated with the brachial plexus.

Dorsal scapular, long thoracic, suprascapular, medial and lateral pectoral, subscapular, thoracodorsal, axillary, medial antebrachial cutaneous, radial, musculocutaneous, median, and ulnar nerves

What purpose does reflex testing serve?

Provides information about the nervous system's functional status

What signs and symptoms would you expect Karen to exhibit during her neurological evaluation?

Would expected to have poor control of most muscles of the lower limbs, causing difficulty walking and problems maintaining balance

Identify and describe the three spinal meninges.

Dura mater: outermost component of the cranial and spinal meninges Arachnoid mater: the middle meninx that encloses cerebrospinal fluid Pia mater: the innermost layer of the meninges bound to the underlying neural tissue

Define a nerve plexus trunk and cord.

Trunk is a large bundle of axons contributed by several spinal nerves Cord is a smaller branch of nerves that originates at a trunk.

Identify the three layers of connective tissue of a spinal nerve and identify the major peripheral branches of a spinal nerve.

Epineurium, middle perineurium, and inner endoneurium Dorsal root and ventral root

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

Found in the subarachnoid space, which lies beneath the epithelium of the arachnoid mater and superficial to the pia mater

Postganglionic fibers connecting a sympathetic ganglion in the thoracic or lumbar region with the spinal nerve.

Gray rami

A typical spinal cord has how many pairs of spinal nerves, and where does the spinal cord end?

Has 31 pairs of nerves, and the spinal cord ends at the level of lumbar vertebra 1 or 2

Describe the gross anatomical features of a cross section of spinal cord.

Include the anterior median fissure; the posterior median sulcus; white matter; gray matter; the central canal; dorsal root of each spinal nerve; a ventral root of each spinal nerve; dorsal root ganglia; and spinal nerves.

Identify the basic characteristics of polysynaptic reflexes.

Involve pools of interneurons, are intetsegmental in distribution, involve reciprocal inhibition, and have reverberating circuits

Define gray ramus and white ramus.

Is a bundle of postganglionic sympathetic nerve fibers that are distributed to effectors in the body wall, skin, and libs by way of a spinal nerve; the white ramus is a nerve bundle containing the myelinated preganglionic axons of sympathetic motor neurons in route to sympathetic ganglia

Define stretch reflex.

Is a monosynaptic reflex that provides automatic regulation of skeletal muscle length

Describe the brachial plexus.

Is a network of nerves forms by branches of spinal nerve segments C4- T1 en route to innervating the upper limb.

Define reflex and list the components of a reflex arc.

Is a rapid, automatic response to a specific stimulus A receptor, a sensory neuron, a motor neuron, and a peripheral effector, interneurons may or may not be present as well

Describe a dermatome

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

After injuring her back, 22 year old tina exhibits a positive Babinski reflex. What does this imply about her injury?

Is abnormal adults, it indicates possible damage of descending tracts in the spinal cord

Define reinforcement as it pertains to spinal reflexes.

Is an enhancement of a spinal reflex through the facilitation of motor neurons involved in reflexes

Describe the flexor reflex

Is an example of a withdrawal reflex that contracts the flexor muscles of t a limb in response to a painful stimulus, hence, it has a protective function

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

Is composed of the cell bodies of neurons, neuroglia, and unmyelinated axons

Preganglionic fibers connecting a spinal nerve with a sympathetic ganglion in the thoracic and lumbar region of the spinal cord.

White rami

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?

Would be in the anterior gray horns of the spinal cord, where the cell bodies of somatic motor neurons are located

Differentiate between sensory nuclei and motor nuclei.

Sensory nuclei receive and relay information from peripheral receptors Motor nuclei issue motor commands to peripheral effectors

Compare the effects of a transection of the spinal cord at L1 in an adult with a newborn's inability to control urination.

The descending tracts required for conscious control of urination have not yet fully developed

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

The limb on the opposite side is extended. This response is called a crossed extensor reflex

In the patellar reflex, in what way does stimulation of the muscle spindle by gamma motor neurons affect the speed of the reflex?

The muscle spindles become more sensitive. As a result, little stretching stimulus is needed to stimulate the contraction of the quadriceps muscles. Thus the reflex response would occur more quickly

Name the structures and spinal coverings that would be penetrated during a lumbar puncture procedure.

The needle would penetrate the epidermis, dermis, subcutaneous layer, and then skeletal muscle before reaching the protective spinal covering; the dura mater, then the arachnoid matter and finally the subarachnoid space, which contains cerebrospinal fluid

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

The response observed is leg extension, and the effectors involved are the quadriceps femoris muscles

Compression of which nerve produces the sensation that your lower limb has fallen asleep?

The sciatic nerve