Spinal Nerves

How long is the spinal cord?

45 cm (18 inches)

Where does the spinal cord end?

At vertebra L1

Name the regions of the spinal cord.

Cervical, thoracic, lumbar, sacral, coccygeal

What is the cauda equina?

Long dorsal and ventral roots below L1

How many spinal segments are there?

31 segments

What do dorsal roots carry?

Sensory input

What do ventral roots carry?

Motor output

What are the 3 layers of meninges

Dura mater, arachnoid matter, pia mater

Where is CSF found in the spinal cord

In the central canal

What is white matter made of

axons

What is gray matter made of

Cell bodies (somas) and glial cells

Name the horns of gray matter

posterior, lateral anterior

name the horns of gray matter

posterior, lateral, anterior

how many pairs of spinal nerves are there

31 pairs

are spinal nerves sensory, motor, or mixed

mixed

what forms nerve plexuses

ventral rami of spinal nerves

name the 4 nerve plexuses

cervical, brachial, lumbar, sacral

what nerve innervates the diaphragm

phrenic nerve (from cervical plexus)

what is the largest nerve from the sacral plexus

sciatic nerve

what is a reflex

fast, automatic motor response

what is the reflex arc sequence

receptor → sensory neuron → CNS → motor neuron → effector

how many spinal nerves are there

31 pairs

what part of the spinal cord contains axons

white matter

what is the outmost layer of the meninges

dura mater

what does the dorsal root carry

sensory input

what does the ventral root carry

motor output

what nerve plexus supplies the upper limbs

brachial plexus

what nerve controls the diaphragm

phrenic nerve

what is the name for the lower bundle of nerves under L1

Cauda equina

What is the function of a reflex

Fast, automatic motor response

What structure runs down the center of the spinal cord containing CSF

Central Canal