Lecture 14-The Spinal Cord

L1-L2

where does the spinal cord end?

Conus medullaris

ending of the spinal cord that forms a cone shape

Cauda equina

many nerves that branch out of the end of the spinal cord

31

how many segments make up the spinal cord?

dorsal root, dorsal root ganglia, ventral root, spinal nerve

what makes up a segment of the spinal cord

mixed, afferent and efferent

Spinal nerves are ______ nerves consisting of ___________ fibers

spinal meninges

Specialized membranes that provide protection, physical stability, and shock absorption

no

do the meninges help with transmission?

dura mater

Tough, fibrous outermost layer of the meninges

arachnoid mater

middle layer of the meninges

pia mater

Innermost layer meninges layer, adjacent to spinal tissue or brain tissue

epidural space

space between the dura mater and the lining of the vertebral bones, often filled with adipose tissue

coccygeal ligament

formed where dura mater blends with the filum terminale

subarachnoid space

what separates the arachnoid mater from the pia mater?

arachnoid trabeculae

extend from the arachnoid to the outer layer of the pia mater

subdural

In a cadaver, there is a _________ space (between the dura mater and arachnois) but is not found in living people

cerebrospinal fluid

what is found in the subarachnoid space?

pia mater

what meninges layer contains blood vessels?

denticulate ligaments

Extensions of the pia mater called __________ attach the pia mater and arachnoid mater to the dura mater

somas and glial cells

what makes up gray matter?

horns that surround the central canal

what is the shape of gray matter in the spinal cord?

myelinated and unmyelinated axons organized in tracts and columns

what makes up white matter?

Gray commissure

central connection between greater an lesser horns

Somatic sensory and visceral nuclei

what makes up the posterior (dorsal) horns?

visceral motor nuclei

what makes up the lateral horns?

somatic motor nuclei

what makes up the anterior (ventral) horns

8, 12, 5, 5, 1

__ cervical nerves
__ thoracic nerves
__ lumbar nerves
__ sacral nerves
__ coccygeal nerves

epineurium

Outer layer of nerve—becomes continuous with the dura mater

perineurium

Layer surrounding a fascicle—a fascicle (fasciculus) is a bundle of axons

endoneurium

Layer surrounding a single axon

rami communicantes

White and gray rami are collectively called _______________

dermatomes

Spinal nerves supply specific regions of the skin known as ______________

4

there are _______ nerve plexuses

nerve plexus

Each __________ is associated with an interwoven network of nerves

Cutaneous and muscular

what are the branches of the crevical plexus?

cervical plexus

what nerve plexus is formed by these major nerves?

lesser occipital, supraclavicular, great auricular, transverse cervical, ansa cervicalis, phrenic

lumbar plexus

what nerve plexus is made up of these major nerves?

Iliohypogastric, Ilio-inguinal, Lateral femoral cutaneous, Genitofemoral, Femoral, Obturator

sacral plexus

what nerve plexus is made up of these major nerves?

Superior gluteal, inferior gluteal, sciatic, posterior femoral cutaneous, pudendal

reflex

An immediate involuntary motor response

reflex arc

The neural “wiring” of a single reflex
– Begins at a sensory receptor and ends at a peripheral effector

development, the site where information is processed, resulting motor response, complexity

How are reflexes classified

monosynaptic

involves a single segment of the spinal cord

polysynaptic

Integrates motor output from several spinal segments

• conus medullaris

The tapered, inferior portion of the spinal cord is called the _____.
• cauda equina
• conus medullaris
• filum terminale
• sacral prominens

• dura mater, arachnoid mater, pia mater

Which of the following is the correct sequence regarding the meninges going from superficial to deep?
• dura mater, arachnoid mater, pia mater
• pia mater, dura mater, arachnoid mater
• arachnoid mater, dura mater, pia mater
• pia mater, arachnoid mater, dura mater

• conducting impulses

Which of the following is NOT a function of the spinal meninges?
• protection
• providing stability
• shock absorption
• conducting impulses

• epineurium

Which connective tissue covering of a peripheral nerve is composed of a tough fibrous sheath forming the outmost layer of a peripheral nerve?
• epineurium
• endoneurium
• perineurium
• dura mater

a.2-5-1-3-4

Which of the following is the correct sequence of steps in a stretch reflex, an example of spinal reflexes?
1.Information processing at motor neuron
2.Stretching of muscle stimulates muscle spindle
3.Activation of motor neuron
4.Contraction of muscle
5.Activation of a sensory neuron

a.2-5-1-3-4 c. 5-2-1-3-4
b.2-5-4-1-3 d. 2-1-5-4-3

brachial plexus

what nerve plexus is made up of these major nerves?

Radial nerve, Ulnar nerve, Median nerve, Musculocutaneous nerve