Segmentation

Question 1

There are how mnay pairs of spinal nerves?

Answer 1

31(32):

Cervical: 8

Thoracic: 12

Lumbar: 5

Sacral: 5

Coccygeal: 1(2)

Question 2

During development of the cord the segmental arrangement is obscure; with the only evidence remaining being what?

Answer 2

The rootlets of the spinal nerves

Question 3

What matter (gray or white), is the central butterfly?

–What does it consist of?

Answer 3

gray matter

Consists of neuron cell bodies and glial cells

Question 4

What is the white matter made up of?

Answer 4

Myelinated axons

Question 5

White matter contains both ascending and decending fiber tracts that can be divided into three general locations, named funiculi: what are they?

Answer 5

1. ) Dorsal funiculis
2. ) Lateral funiculus
3. ) Ventral Funiculus

Question 6

Gray Matter is composed of what?

Answer 6

Nerve cell bodies and their dendritic processes and glial cells

Question 7

Aside from the Dorsal Horn (sensory) and Ventral horn (motor) there is a lateral horn also called what and present where?

Answer 7

Intermediolateral cell column

–Present T1-L2

Question 8

Where can you find preganglionic sympathetic neurons, a component of the Autonomic Nervous System

Answer 8

Lateral horn of gray matter

–aka Intermediolateral cell column

Question 9

Sacral segments S1-S3 also have a lateral horn that contains what?

Answer 9

Preganglionic parasympathetic neurons for the lower body parts, the other part of the ANS

Question 10

Gray matter is divided into sevearl nuclei or divisons, the Roman Numerals are reffered to as what?

Answer 10

Lamina of Rexed

Question 11

What regions of gray matter are important? (6)

Answer 11

1. ) Lissauer’s Tract
2. ) Dorsal Horn: Substantia gleatinosa
3. ) Dorsal Horn: Nucleus proprius
4. ) Dorsal Nucleus of Clarke (segs T2-L2)
5. ) Intermediolatearl cell column (lateral horn)
6. ) Ventral horn

Question 12

When viewed from a transverse perspective describe fibers that lie Medially, Laterally, and Intermediate

Answer 12

Medailly: Large Diameter, Heavily myelinated (Ia, Ib, A-alpha, II)

Laterally: Small diameter, non-myelinated C fibers

Intermediate: Finely myelinated, A delta fibers

Note: type A delta fibers and C fibers travel in Lissauers tract

Question 13

The Final Common Pathway refers to what?

Answer 13

The ventral horn containing lower motor neurons

(a-alpha, gamma motor neurons)

Question 14

How are the cell bodies of Lower motor neurons arranged in the ventral horn

Answer 14

Most medially: axial (trunk, neck etc.) muscles

Laterally: Extremity Muscles (largest Ventral Horns)

Posteriorly: Flexion muscles

Anterior: Extension muscles

Question 15

What forms the spinal nerve (component of PNS)?

Answer 15

merging of the dorsal and ventral roots away form the spinal cord

note: after merging Spinal nerve is both sensory and motor

Question 16

Each spinal nerve does what?

Answer 16

Branches into a number of branches to reach its spefic dermatomal segment or muscle of innervation

Question 17

What is associated with the spinal nerves at T1-L2

Answer 17

Autonomic ganglia

—they are the location of the postganglionic cell bodies for the sympathetic nervous system

note: preganglionic cell bodies are located in the Lateral horn