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67 Cards in this Set

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the third deepest layer of the meningeal membrane that Is wound very tightly to the surface of the spinal chord.

The pia mater

What holds the spinal chord in place within the thecal sac? (2)

The denticulate ligaments & the filum terminale

What are the denticulate ligaments?

they are paired connective tissue septa extending from the lateral sides of the spinal chord to the dura mater.

how do the denticulate ligaments attach to the dura mater?

by toothlike processes between the exits of the cervical and thoracic spinal nerves. (denticulate meaning toothlike)

What do the denticulate ligaments limit?

the lateral movement of the spinal cord

What is the filum terminale?

A connective tissue strand that anchors the conus medullaris & the thecal sac to the 1st coccygeal vertebra, limiting their superior movement.

Collections of cell bodies of the sensory neurons forming the dorsal roots of the spinal nerve.

The dorsal root ganglia

the axons of these pseudo-unipolar neurons extend from various parts of the body and ______________________________.

pass through spinal nerves to the dorsal root ganglia

Do the axons synapse in the dorsal root ganglion?

No

The axons pass through the dorsal root into the________

posterior horn of the spinal cord gray matter

Where do the axons synapse?

They synapse w/interneurons in the posterior horn

if they do not synapse in the posterior horn, where to they go?

They pass into the white matter and ascend or descend in the spinal cord.

the simplest stretch in which muscles contract in response to a stretching force applied to them.

Stretch reflex

The sensory receptor of the stretch reflex consisting of 3-10 small, specialized skeletal muscle fibers.

Muscle spindle

Are the muscle fibers of the spindle contractile?

only at their ends

What motor neurons innervate the fibers?

Gamma motor neurons (gamma meaning motor neurons w/small-diameter axons)

What do gamma motor neurons do?

they originate from the spinal cord and control the sensitivity of the muscle spindle cells.

What neurons innervate the noncontractile centers of the muscle spindle cells?

Sensory neurons

Axons of these neurons extend to the ______ and ________ with motor neurons in the spinal cord.


spinal cord


synapse directly

what are the motor neurons in the spinal cord

alpha motor neurons

The alpha motor neurons innervate the muscle _________

in which the muscle spindle Is embedded

Neurons can be classified by the _______ of their ______


diameter


axons

which neurons have the largest diameter?

Alpha motor neurons

Why is the stretch reflex a monosynaptic reflex?
because there is no interneuron between the sensory neuron and the alpha motor neuron

Prevents contracting muscles from applying excessive tension to tendons

The Golgi tendon reflex

Encapsulated nerve endings that have at their ends numerous branches w/small swellings adjacent to bundles of collagen fibers in tendons.

Golgi tendon organs

Where are Golgi tendon organs located?

Near the muscle-tendon junction

As a muscle ________, the attached tendons _____, resulting in increased _______ in the ______.


contracts


stretch


tension


tendon

What does the increased tension do?

It stimulates action potentials in the sensory neurons from the Golgi tendon organs.

Golgi tendon organs have a high threshold and are sensitive only to_______

intense stretch

How is the crossed extensor reflex adaptive?

It helps prevent falls by shifting the weight of the body from the affected to the unaffected limb.

give an example of a withdrawal reflex

stepping on a sharp object would send a stimulus which would lead to you withdrawing your foot (withdrawal rflx) and extend the opposite leg to bear the weight (crossed extensor rflx) (shifting from one leg to the other)

nerves arising from each region of the spinal cord and vertebral column supply ________________

specific regions of the body

The area of skin supplied with sensory innervation by a pair of spinal nerves.

Dermatome

all but what spinal nerve have a specific cutaneous sensory distribution?

All but C1

responsible for diaphragm movement

Cervical nerves C1-C4

Responsible for neck and shoulder movement

Cervical nerves C4-C7
Responsible for upper limb movement

Cervical and Thoracic nerves C5-T2

Responsible for rib movement in breathing, vertebral column movement, & tone in postural back muscles.

Thoracic nerves T1-T12

Resp for hip movement

Thoracic/lumbar nerves T11-L3

Resp for lower limb movement
Lumbar/sacral nerves L2-sacral nerve

one of the most important derivatives of the cervical plexus is the

Phrenic nerve

where does the phrenic nerve originate and derived from?

From spinal nerves C3-C5 and is derived from both the cervical and brachial plexuses.

The phrenic nerves ______ to enter the _____ and then __________ along the sides of the ______ to reach the ________, which they innervate.


descend along each side of the neck, thorax


descend, mediastenium


diaphragm

what is contraction of the diaphragm largely responsible for?

a person's ability to breathe

damage to or compression of (like a tumor at the base of the lung) the phrenic nerve

severely limits breathing

what is the most common type of cancer in men?

cancer of the bronchus, accounting for about %30 of all male cancers (often because of smoking).

Emerges from the posterior cord of the brachial plexus and descends within the deep aspect of the posterior arm.

The radial nerve

where does the radial nerve lay?

midway down the shaft of the humerus, against the bone of the radial groove.

Test question!!!!


This nerve innervates all of the extensor muscles of the upper limb, the supinator muscle, and the brachioradialis.

The Radial Nerve

the cutaneous sensory distribution of the radial nerve is to the

Posterior portion of the upper limb

Test question!!!!

The skin on the back (posterior) surface of the hand is supplied by the


E. none of the above


Should be Radial nerve.

Originate from spinal segments L4-S3 and are bound together within a connective tissue sheath for the length of the thigh

The tibial and common fibular nerves

These two nerves, combined within the same sheath, are referred jointly as the

Sciatic nerve or ischiadic nerve

What is the largest peripheral nerve in the body?

The sciatic nerve

describe the rout of the sciatic nerve
passes through the greater sciatic notch in the pelvis & descends in the posterior thigh to the popliteal fossa, where the 2 portions of the sciatic nerve separate.

The structure that anchors the inferior end of the spinal cord to the coccyx is the

Filum terminale

Axons of sensory neurons synapse with the cell bodies of interneurons in the _____ of spinal gray matter

posterior horn

A reflex response accompanied by the conscious sensation of pain is possible because of ____

divergent pathways

______ are responsible for regulating the sensitivity of the muscle spindle.

Gamma motor neurons

Which of these events occur when a person steps on tack with the right foot?

The flexor muscles of the right thigh contract, and the extensor muscles of the right thigh relax because of reciprocal innervation.

Damage to the dorsal ramus of a spinal nerve results in

loss of sensation and loss of motor function

A collection of spinal nerves that join together after leaving the spinal cord is called a

plexus

A dermatome


1. is the area of skin supplied by a pair of spinal nerves


2. exists for each spinal nerve except C1


3. can be used to locate the site of spinal cord or nerve root damage

which of these nerves arises from the cervical plexus?

The phrenic nerve

The sciatic nerve is actually 2 nerves combined within the same sheath. They are the_____

common fibular (peroneal) and tibial

The muscles of the anterior compartment of the thigh are supplied by the ______

femoral nerve