Meninges

connective tissues surround spinal cord and brain

What are the layers of the meninges?

-Dura Mater: dense irregular connective tissue
-Arachnoid layer: avascular; delicate collagen and elastic fibers; looks like a spiderweb
-Pia Mater: thin transparent connective tissue; adheres to brain or spinal cord; composed of collagen and elastic fibers; vascular

What are the spaces between the meninges?

-Epidural space: above the dura mater; filled with fat and connective tissue
-Subdural space: filled with interstitial fluid
-Subarachnoid space: filled with cerebrospinal fluid

List the layers of the meninges along with the spaces in the meninges.

-Bone
-Epidural Space: filled with fat and connective tissue
-Dura Mater: dense irregular connective tissue
-Subdural Space: filled with interstitial fluid
-Arachnoid layer: avascular; delicate collagen and elastic fibers; looks like a spiderweb
-Subarachnoid space: filled with cerebrospinal fluid
-Pia Mater: thin transparent connective tissue; adheres to brain or spinal cord; composed of collagen and elastic fibers; vascular

From what to what does the spinal cord extend to?

from the Medulla to the level of L2

What is the Conus Medullaris?

The tapering of the spinal cord at the L2 location

Cauda Equina

"horse's tail" which forms the inferior of spinal cord; made of pia mater

Where are the enlargements of the spinal cord?

C4-T1 for upper limbs; T9-T12 for lower limbs

What is the deep, wide, groove in the ventral surface?

Anterior Median Fissure

What is the shallow narrow groove on dorsal side?

Posterior Median Sulcus

How many pairs of spinal nerves are there?

31 pairs

What are the the roots of the spinal cord?

-where axons connect spinal cord to nerves
-posterior sensory root
-anterior motor root

What are a group of myelinated axons called when inside the CNS and when outside the CNS?

-Group of myelinated axons inside the CNS= Tract/Column (one way street)
-Group of myelinated axons outside the CNS= Nerve (two way street)

Describe the Dorsal and Ventral horns of gray matter in the spinal cord

Dorsal: somatic and autonomic sensory nuclei (comes into the spinal column)
Ventral: cell bodies for skeletal muscle (going out of the spinal cord, to the effectors)

Describe the Lateral horns of the gray matter of the spinal cord

Only in the thoracic, upper lumbar and sacral regions; cell bodies of autonomic (involuntary) motor neurons for smooth, cardiac, and glandular tissue. Not in lower lumbar and cervical.

Gray Commissure

Forms the small little bit of gray matter above and below the central canal

Describe Ascending tracts and Descending tracts

Ascending (sensory) tracts: always bring information up from the body to the CNS
Descending (motor) tracts: always send information from the CNS down to the body

What are the types of Sensory tracts??

- Spinothalamic: lateral and anterior; pain, temperature, crude touch, and deep pressure (not very distinct)
- Posterior column tract: right and left; body position, discriminative touch, two-point discrimination; light pressure and vibration (more precise)

What are the types of Motor tracts?

- Direct: travel directly from the brain to the skeletal muscle for very precise, voluntary movement
- Indirect: impulses from brain stem and brain for automatic movements, muscle tone (take an indirect route throughout the body)

What are Association neurons?

neurons that integrate sensory input to all parts of the CNS