Unit 2 : spinal cord and spinal nerves

anatomy of spinal cord and its functions

what are the functions of the spinal cord?

1. spinal reflexes

2. integration center

3. pathway for sensory impulses to travel to brain

4. pathway for motor impulses to travel from brain

what is a meninges

a connective tissue covering that surrounds brain and spinal cord

What are the layers and spaces of the meninges

1. Epidurmal

• between the dura mater and the vertebrae

• contains some fat and connective tissue

• epidural anesthetic

• only around the spinal cord

2. Dura Mater = “tough mother”

• layer composed of dense, irregular CT

3. subdural space

• between the dura mater and the arachnoid mater

4. Arachnoid mater

• delicate, cobweb-like layer

5. Subarachnoid space

• between the arachnoid and the pia mater

• contains cerebrospinal fluid

• spina anesthetic (L4-5) spinal tap

6. Pia Mater

• thin delicate layer

• adheres to the spinal cord and brain

meningitis is the inflammation of the menings

The spinal cord ends at L1-L2 in adults and L3-L4 in children

what is the cauda equine

Lumbar, sacral, and coccygeal nerves continue through vertebral foramina to exit from lumbar and sacral intervertebral foramen even though the cord has ended

what is the filum terminal

extension of pia mater, continues to coccyx

What doe sthe dorsal root do = sensory

dorsal root gangliom contains cell bdies of sensory meurons (unipolar)

What doe sthe ventral root do = motor

axons of neurons

multipolar cell bodies in grey mater

anterior horn = skeletal muscle

lateral horn = cardiac and smooth musle

what are the grooves in the interior spinal cord?

anterior median fissure - deep wide hgrrove on anterior side

posterior median sulcus - shallow, narrow groove on posterior side

Whe is gray mater and what does it contribute to?

unmyelinated, many cell bodies and unmyelinated axons

1. Gray commissure - H bar of the spinal cord, neurons which cross from one side of the cord to the other

2. central canal - small opening in the center of the cord, contains CSF, continuous with 4th vetricle of the brain

3. gray horns - contains many cell bodies, anterior, posterior and lateral

What is white matter and what does it do?

Myelinated, surrounds gray matter, anterior white commissure

1. White columns

• anterior, posterior, and lateral white columns

• contains tracts = bundle of neurons going to / coming from a common location

• Some tracts are ascending = sensory

• Some tracts are descending = motor

what are the sensory tracts

spinothalamic tract and spinocerebellar tract

what are the motor tracts withign the spinal cord

corticospinal tract

integration center for spinal reflexes is on gray mater of teh spinal cord

somatic reflexes result in skeletal muscle contraction

autonomic (visceral) reflexes involove smoothe and cardiac muscle and glands

What are the 5parts of the spinal reflex arc

1. receptors

2. sensory neuron

3. integrating center

4. motor neuron

5. effector

How many spinal nerve pairs are there?

31

What are the spinal nerve pair groups, and how many are in each group?

1. Cervical (8)

2. Thoracic (12)

3. Lumbar (5)

4. Sacral (5)

5. Coccygeal (1)

What are the stuctures and connective tissue coverings

1. endometrium - covers individual neurons

2. Perineurium - covers fascicles (bundles of neurons)

3. Epineurium - covers the entire nerve

What are the branches or ramus of the spinal cord?

1. dorsal ramus - branches to skin and deep back muscles

2. ventral ramus - branches to limbs and the ventral body

3. Rami Communications - part of ANS

What is a Plexus Braid?

nerve fibers in anterior rami from various levels join and form networks

1. cervical plexus

2. brachial plexus

3. lumbosacral plexus

what are demotomes?

Areas of skin whose sensory nerves are supplied by certain spinal nerves

overlap somewhat

used clinically to map sites of potential cord injury and disease