anatomy of the nervous system

What spinal cord feature is the area where the nerves that supply the lower limb emerge?

Lumbar enlargement

A man presents with median nerve palsy in his left hand. What is the most likely site of injury?

Median Plexus

) What type(s) of axons are wrapped in a protective endoneurium? 1. Myelinated 2. Unmyelinated 3. Only dendrites are surrounded by endoneurium

Myelinated and Unmyelinated

spinal nerves

1. Are parts of PNS. 2. connect the CNS to sensors and effectors in all parts of the body. 3. are named according to the region of the cord from which they emerge.

Identify and describe the function of each of the components of a spinal reflex arc.

1. Receptor: responds to specific changes in body conditions by producing graded potential; 2. Sensory neuron: conducts impulse from receptor to integrating center in gray matter of spinal cord; 3. Integrating center: site of synapse between sensory and other neurons; decision-making area in gray matter of spinal cord; 4. Motor neuron: conducts impulse from integrating center to effector; 5. Effector: is the structure that promotes change in body conditions by responding to motor nerve impulse, such as a muscle or a gland.

In response to a muscle being stretched, a muscle spindle initiates a somatic spinal reflex that causes

1. contraction of the agonist muscle. 2. relaxation of the antagonist muscle.

A typical spinal nerve has how many connections to the spinal cord?

2

In response to a tendon being stretched excessively, a tendon organ initiates a somatic spinal reflex that causes

3. contraction of the antagonist muscle. 4. relaxation of the agonist muscle.

Which branch of a spinal nerve serves the deep muscles and skin of the posterior surface of the trunk?

Posterior ramus

A nerve impulse initiated at a muscle spindle has to travel through which of the following structures to get into the spinal column?

Posterior root of spinal nerve

Which of the following structures contains only sensory axons that conduct nerve impulses from sensory receptors in the skin, muscles and internal organs to the CNS?

Posterior root of spinal nerves

Which region of the spinal cord carries nerve impulses for proprioception?

Posterior white column

Which of the labeled structures contains cerebral spinal fluid?

A

Which white matter tracts of the spinal cord carry sensory information?

Ascending tract

Describe the basic anatomy of a spinal nerve plexus.

Axons from the anterior rami of spinal nerves do not go directly to the body structures they supply. Instead, they form networks called plexuses on both the left and right sides of the body by joining with various numbers of axons from anterior rami of adjacent spinal nerves. Thus, the nerves that emerge from a plexus and innervate body organs contain nerve fibers from multiple spinal nerves.

Which of the labeled structures carries exclusively sensory information towards the spinal cord?

B

Which of the labeled structures carries exclusively motor information away from the spinal cord?

C

Which of the following is NOT a characteristic of the spinothalamic tract?

Carries motor information down the cord

Name and describe the locations of the four major plexuses of spinal nerves.

Cervical: alongside C1 through C4; 2. Brachial: inferior and lateral to C4 through T1 and superior to rib, posterior to clavicle; 3. Lumbar: lateral to L1 through L4 passing obliquely posterior to psoas major and anterior to quadratus lumborum; 4. Sacral: L4-S3; anterior to sacrum.

Which type of descending motor pathway conveys nerve impulses that originate in the cerebral cortex and are destined to cause precise, voluntary movements of skeletal muscles?

Direct pathway

Which of the three spinal meninges is the most superficial?

Dura Mater

Which of following is NOT a function of the spinal reflexes that use muscle spindles and tendon organs as sensors?

Protection of spinal nerves

Which of the following is a degenerative disease of the spinal cord?

amyotrophic lateral sclerosis

Where is the pia mater located?

E

Which of the following is NOT a common characteristic of dermatomes?

Each dermatome is only served by a single spinal nerve

Which of the following parts of a nervous reflex arc is usually a muscle or gland?

Effector

Which of the following regions of the spinal cord contains a conspicuous enlargement?

cervical region

Where is the posterior ramus?

G

Which layer is the dura mater?

I

Which of the following spinal nerves DOES NOT travel through an intervertebral foramen to reach its destination?

cervical spinal nerve 1

Which type of descending motor pathway originates in the brainstem and governs automatic movements that help regulate muscle tone, posture and balance?

Indirect pathway

Which of the following parts of a reflex arc receives sensory information and decides how to respond to a change in the body's condition?

Integration center

Which of the following parts of a reflex arc monitors body conditions?

sensory receptors

Which of the following is a virus infection of the peripheral nervous system caused by herpes zoster, a virus that also causes chickenpox?

shingles

Discuss the clinical significance of dermatomes.

Knowing which spinal cord segments supply each dermatome makes it possible to locate damaged regions of the spinal cord. If the skin in a particular region is stimulated but the sensation is not perceived, the nerves supplying that dermatome are probably damaged.

During childbirth, anesthesia is administered into the epidural space of the spinal column between which of the following vertebrae?

L4 and L5

Which layer of protective connective tissue is the outermost covering surrounding a spinal nerve?

epineurium

Denticulate ligaments are thickenings of

pia mater

The cell bodies of the sensory neurons that carry information from the periphery to the spinal cord are located in the

posterior root ganglion

A somatic spinal reflex that involves one effector muscle being stimulated while the opposing muscle is inhibited is called _____ innervation

reciprocal

Which of the following parts of a reflex arc would have a cell body in the posterior root ganglion?

Sensory neuron

Which of the structures listed below contains cerebrospinal fluid?

Subarachnoid space

Describe the gross external anatomy of the spinal cord.

The spinal cord is roughly cylindrical, but slightly flattened anterior/posterior. It extends from the medulla to the superior border of L2. The length ranges from 42-45 cm and is approximately 2 cm in diameter. There is a cervical enlargement from C4-T1 and a lumbar enlargement from T9-T12. The conus medullaris is the tapered inferior end. The filum terminale is an extension of the pia mater that anchors the cord to the coccyx. The cauda equina is the roots of spinal nerves angling inferiorly in the vertebral canal from the end of the spinal cord. 31 pairs of spinal nerves leave the cord at regular intervals through the intervertebral foramina.

Where is the subarachnoid space?

between arachnoid and pia mater

Where is the subdural space?

between dura mater and arachnoid mater

Where is the arachnoid mater?

between dura mater and pia mater

The area of the skin that provides sensory input to the CNS via one pair of spinal nerve is called

dermatome

intercostal nerves

do not enter into a plexus and directly connect to the structures they supply.

Which of the following lists the connective tissue coverings of the axons, fascicles, and entire nerve in the correct order?

endoneurium, perineurium, epineurium

The thoracic nerves are also called the

intercostals nerves