Chapter 12: Spinal Cord and Spinal Nerves

Name the plexus which supplies innervation to the muscles acting on the scapula and innervates the skin of the medial arm and forearm

Brachial plexus

Identify the major plexuses that have similar distribution and are thus considered as one plexus

- Lumbar plexus - Sacral plexus

Identify the structures innervated by the cervical plexus

- Muscles of the hyoid - Diaphragm - Skin of the neck - Posterior portion of the head

Identify the five major nerves of the brachial plexus

- Musculocutaneous nerve - Median nerve - Ulnar nerve - Axillary nerve - Radial nerve

What is a plexus?

An intermingling of nerves

What are the spinal nerves that give rise to the brachial plexus?

C5-T1

The spinal cord is divided into 4 segments; they are the...

Cervical, Thoracic, Lumbar, Sacral

Which is a nerve of the lumbosacral plexus?

Pudendal nerve

The nerve plexus that innervates the muscles of the pelvic floor and the skin over the coccyx is the

coccygeal plexus

The ________ rami of spinal nerves innervate most of the deep muscles of the back and muscles of the trunk responsible for moving the vertebral column

dorsal

The most superficial layer of the meninges is the _____ mater and the deepest layer of the meninges is the _____ mater.

dura; pia

The lumbar and sacral plexuses have similar distribution, thus are often considered as one plexuses know as the ______ plexus

lumbosacral

The obturator, femoral, tibial and common fibular nerves arise from the _____ plexus

lumbosacral

Twelve pairs of cranial nerves and 31 pairs of spinal nerves with their ganglia make up the ______

peripheral nervous system

An intermingling of nerves is called a(n)

plexus

Major branches of a spinal nerve are called

rami

Dorsal (posterior) roots consist of only ______ fibers (axons)

sensory

The reflex where muscles contract in response to stretching within the muscle is called a

stretch reflex

The space between the dura mater and arachnoid mater is the

subdural space

The space related to the meninges that contains a small amount of serous fluid is the

subdural space

The coccygeal plexus innervates

the muscles of the pelvic floor

The _____ rami of spinal nerves innervate the ribs, the intercostal muscles and the skin of the thorax

ventral

Musculocutaneous nerve

- Anterior arm muscles and the skin of the lateral surface of the forearm - The anterior portion of arm - Anterior portion of arm

Identify the nerves that combine to form the sciatic nerve

- Common fibular nerve - Tibial nerve

Axillary nerve

- Deltoid, teres minor and skin of the shoulder - Inferior lateral shoulder - Part of the shoulder

Identify characteristics of stretch reflexes

- Does not involve an interneuron - Helps to control posture - Promotes muscle contraction - Monosynaptic

Radial nerve

- Extensor muscles of the arm and forearm and skin of the posterior surface of the arm, forearm and hand - Posterior surface of arm, forearm and lateral two-thirds of dorsum of hand - Posterior portion of arm, forearm and hand

Identify the major nerves of the lumbosacral plexus

- Femoral nerve - Obturator nerve - Tibial nerve - Common fibular nerve

List actions of nerves from the brachial plexus

- Innervate the skin of the medial arm and forearm - Supply muscles acting on the scapula and arm

Which are characteristics of reflexes?

- Integrated within the CNS - Can be influenced by higher brain centers - Automatic responses - Produce consistent results - Are homeostatic

Ulnar nerve

- Intrinsic muscles of the hand muscles and the skin on the medial side of the hand - Medial one-third of hand, little finger and middle half of ring finger - Anterior portion of forearm and hand

Median nerve

- Pronator and most of the flexor muscles of the forearm, most of the thenar muscles, and the skin of the lateral side of the palm of the hand - Lateral two-thirds of palm, anterior thumb, index, and middle fingers, dorsal tips of thumb, index, middle, and ring fingers - Similar to the ulnar nerve

Which of the following statements correctly describe spinal reflexes

- Spinal reflexes can be influenced by descending tracts. - Spinal reflexes can interact with ascending tracts.

Indicate the correct order of meninges from superficial at the top to deep at the bottom.

1. Dura Mater 2. Arachnoid mater 3. Pia mater

Identify the three layers of meninges

1. Dura mater 2. Arachnoid mater 3. Pia mater

Identify the layers of meninges and the related spaces from most superficial to deepest.

1. Epidural space 2. Dura mater 3. Subdural space 4. Arachnoid mater 5. Subarachnoid space 6. Pia mater

List the layers of connective tissue surrounding nervous tissue starting with the most superficial layer and ending with innermost layer surrounding an individual Schwann cell sheath.

1. Epineurium 2. Perineurium 3. Endoneurium

Place the events of a stretch reflex in chronological order

1. Muscle spindles detect stretch 2. Sensory neurons conduct action potential to spinal cord 3. Sensory neurons synapse with an alpha motor neuron 4. Alpha motor neuron conducts action potential to muscle 5. Muscle contracts and resists stretching

The PNS consists of ______ pairs of cranial nerves and ______ pairs of spinal nerves

12, 31

Epineurium

A layer of dense connective tissue surrounding a nerve

Endoneurium

Delicate layer of connective tissue surrounding a single axon and its Schwann cell sheath

Identify the function of Golgi tendon organs

Detect intense stretching of tendons

What are Golgi tendon organs?

Encapsulated nerve endings in tendons

True or false: Spinal nerves are named for the region of the body that they innervate

False: Spinal nerves are named for the region of the vertebral column from which they emerge

True or False: Spinal reflexes operate as isolated entities

False: Spinal reflexes can interact with ascending tracts to the brain and can be influenced by descending tracts from the brain.

Which matter of the spinal cord contains neuron cell bodies?

Gray

List the functions of the spinal cord

It serves as the link between the brain and the PNS. It integrates incoming information. It produces responses through reflex mechanisms.

Perineurium

Layer of connective tissue surrounding a nerve fascicle

Name the structure that serves as the link between the brain and the PNS

Spinal Cord

Explain how spinal nerves are named

Spinal nerves are named for the region of the vertebral column from which they emerge

True or false: The radial and musculocutaneous nerves are major nerves of the brachial plexus

True: These are two major nerves of the brachial plexus.

True or false: The gluteal nerve is a nerve of the lumbosacral plexus

True: This is a major nerve of the lumbosacral plexus

The central canal of the spinal cord is

a hollow space

A dermatome is the area of skin supplied with sensory innervation by

a pair of spinal nerves

The ventral and dorsal rami are branches of

a spinal nerve

The muscles of the hyoid, skin of the neck, the posterior portion of the head and the diaphragm are innervated by the

cervical plexus

An area of the skin supplied with sensory innervation is called a(n)

dermatome

The space between the dura mater and the periosteum of the vertebral canal is the

epidural space

The space related to the meninges that contains spinal nerve roots, blood vessels and areolar and adipose tissue is the

epidural space

The space related to the meninges that contains spinal nerve roots, blood vessels and areolar and adipose tissue is the _____

epidural space

The ________ matter of the spinal cord consists of myelinated axons, and the ________ matter consists of neuron cell bodies

white, grey

Pain receptors are the sensory receptors of a

withdrawal reflex