the spinal cord

Question 1

explain the protection and covering of the spinal cords structure

Answer 1

Spinal cord in vertebral cavity-
Surrounded by bone (protection)

Wrapped in meninges (3 layers of connective tissue) – additional protection
1. Outer - dura mater,
2. Middle - arachnoid mater
3. Inner - pia mater

The spinal cord meninges are continuous with the brain meninges

Question 2

describe the dura mater structure

Answer 2

tough, dense C.T.

Epidural space (filled with fat and C.T.) lies between dura mater and vertebral column

Question 3

describe the arachnoid mater structure

Answer 3

web-like arrangement of collagen and elastic fibres

The sub-arachnoid space lies blow this layer and contains cerebrospinal fluid

Question 4

describe the pia mater structure

Answer 4

transparent layer of collagen and elastic fibres

Adheres to surface of spinal cord and brain

Contains numerous blood vessels

Question 5

describe the length of the spinal cord

Answer 5

Ranges from 42-45 cm in length

Extends from medulla oblongata to 2nd lumbar vertebra

Question 6

how is the cauda equina part of the spinal cord formed

Answer 6

Nerves from lumbar, sacral and coccygeal regions form the cauda equina

Question 7

explain the internal structure of the spinal cord

Answer 7

Two grooves divide the left & right halves

• Anterior median fissure &
• posterior median sulcus

Grey matter

(H shaped) - 3 horns on each side
- Anterior, posterior, lateral

Question 8

explain the 3 parts to the H shape in the internal part of the spinal cord structure

Answer 8

Anterior- somatic motor neurons

Posterior- sensory neurons (somatic & Autonomic)

Lateral- autonomic motor neurons

Question 9

how is white mater organised in the internal structure of the spinal cord

Answer 9

organised into columns:

Anterior, posterior & lateral white columns

Sensory = ascending tracts
Carry information toward brain

Motor = descending tracts
Carry information down spinal cord

Question 10

what do spinal nerves contain

Answer 10

2 bundles of axons = roots

Question 11

name and describe the 2 bundles of axons

Answer 11

axons = roots

Dorsal root- only sensory axons
- Swelling called dorsal root ganglion- Contains Cell bodies of sensory neurons

Ventral root- axons of somatic & autonomic motor neurons

Question 12

what are the 2 types of nerve

Answer 12

motor nerve
sensory nerve

Question 13

how are spinal nerves named and numbered

Answer 13

according to level of vertebra they emerge from i.e. C1-8, T1-12, L1-5, S1-5 & 1 coccygeal

Cauda equina (horses tail) - arrangement of nerves at lower end of spine.

Question 14

what are the functions of the spinal cord

Answer 14

Routes signals along pathways

Grey matter integrates signals

Reflex = fast involuntary sequence of actions in response to a stimulus

Inborn reflex e.g. withdrawal reflex

newborn reflexes

Can also have learned reflexes,
e.g. driving skills

Can be spinal or cranial integration

Question 15

describe the process of Reflex arc (patellar reflex)

Answer 15

1. Sensory receptor- responds to stimulus
   - Tap below patella
2. Sensory neuron- to dorsal horn & brain
3. Integrating centre- e.g. single synapse
   - Sensory to motor neurons
4. Motor neuron- from centre to effector
   - Via ventral horn
5. Effector- responder (muscle)