Human A&P Ch.13 CNS Spinal Cord

Spinal cord

• Integrates & processes information (for simple, somatic reflexes)

• Functions w/ brain

The spinal cord stops developing around age ____.

4 years

The spinal cord terminates at ___ or ___ at _______.

L1 or L2; Conus medullaris

Cauda equina

Extensions of dorsal & ventral roots towards lumbar & sacral segments

• “Horse’s tail”

Enlargements

Cervical & lumbar; Expanded areas to control limbs

There are ___ spinal segments

31

Spinal meninges are specialized membranes that provide _______, _______, & _______.

Protection, physical stability, & shock absorption

The spinal meninges are _______ with cranial meninges.

Continuous

• Dura mater

• Arachnoid mater

• Pia mater

Dura mater

Tough fibrous outermost layer or meninges

• Stabilizes spinal cord within vertebral canal

• Cranial & sacral attachments stabilize longitudinal axis of spinal cord

The Epidural space is the space b/w dura mater & lining of _______ bones.

Vertebral

The coccygeal ligament is where dura mater blends with _____ _______.

Filum terminale

Arachnoid mater

Middle meningeal layer

Arachnoid mater is separated from pia mater by the _______ space.

Subarachnoid

• CSF flows through this space

_______ _______ extend from arachnoid to outer layer of pia mater.

Arachnoid trabeculae

Pia mater

Deepest meningeal layer

• Blood vessels are found here

• Firmly bound to brain & spinal cord tissue

Denticulate ligaments

Extensions of pia mater that attach pia & arachnoid mater to dura mater

Gray matter

• Surrounds a central canal

• Called “horns” due to shape

• Consists of somas (cell bodies)

• Consists of glial cells

Organization of gray matter

Somas are organized into groups called nuclei

Sensory nuclei

Transmit sensory info

Motor nuclei

Transmit “orders”

• Effectors

Dorsal (post.) horns

Somatic sensory & visceral nuclei

Lateral (intermediate) horns

Visceral motor nuclei

Ventral (ant.) horns

Somatic motor nuclei

Spinal nerves form 2 branches

1. Dorsal (post.) ramus

2. Ventral (ant.) ramus

White matter

Sensory information

• Consists of axons (mostly myelinated)

• Axons are organized into tracts or columns

• Located outside gray matter

Organization of white matter

• Consists of columns of axons (funiculi)

• Anterior white commissure

Within the _____ matter of the spinal cord, sensory information enters the _____ root, while motor commands travel through the _____ root. 

Gray; dorsal; ventral

A reflex arc ____ ____ require conscious thought. _____ reflexes control skeletal muscle. 

Does not; Somatic