Physical Properties/Structures of 

The Spinal Cord

• 16-18 inches in length

• Cylindrical mass of Nervous Tissue 

• Runs from Foramen Magnum to the level of First or Second Lumbar Vertebrae

The Gray Matter of the

Spinal Cord Primarily

Consists of...

Neuron Cell Bodies 

And

Unmyelinated Axons of Association

and Motor Neurons

The White Matter of

the Spinal Cord

Surrounds...

White Matter of the Spinal Cord

Consists of Mostly...

Myelinated Axons of Motor and

Sensory Neurons

What name does

White Matter

use?

Functions of

the Spinal Cord

Carry Info to/from the Brain

and

Provides some reflexes

Which direction do

Sensory reflexes travel?

Which direction do

Motor reflexes travel?

Meningeal Covering around the 

Brain and Spinal Cord

is composed of...

Duramater

Arachnoid

Pia Mater

Outermost covering

composed of

Dense Fibrous Connective Tissue

Adheres directly to

Nervous Tissue

Cranial Nerves come

directly from...

Two points of attachment of

a Spinal Nerve to

the Spinal Cord

Dorsal Roots(Sensory ONLY)

Ventral Roots(Motor ONLY)

Where do Cell Bodies

reside?

Carry both Sensory and

Motor Impulses

Epineurium

Perineurium

Endoneurium

Connective Tissue surrounding

the Nerve

Connective Tissue surrounding 

the Fascicle

Connective tissue

surrounding

the axon

How many pairs of 

Spinal Nerves are

there?

Where do Spinal Nerves

gain access to the body?

Through the Intervertebral

Foramen

What two branches

do spinal nerves branch into?

Dorsal Ramus

and

Ventral Ramus

8 pairs - Cervical Nerves - C₁ : C₈

12 pairs - Thoracic Nerves - T₁ : T₁₂

5 pairs - Lumbar Nerves - L₁ : L₅

5 pairs - Sacral Nerves - S₁ : S₅

1 pair - Coccygeal Nerves - CO₁

Most Ventral Rami form plexuses

(Where all the spinal Nerves

Run Together)

Complex network of

joining and diverging

nerves

Formed by C₁ - C₄ 

and some of C₅

Formed by C₅ - C₈ 

and most of T₁

Rapid, predictable, involuntary

motor response to a simulus

What is the purpose of

a reflex?

To control Certain Organs

and

To prevent injury

5 Components of a

Reflex Arc

Receptor

Sensory Neuron

Integration Center

Motor Neuron

Effector Organ

Visceral ( Autonomic ) Reflex 

&

Somatic Reflex

Mechanisms that influence the

working of 

Smooth Muscle

Cardiac Muscle

and/or

Glands

Involved with the

Contraction of a

Skeletal Muscle