Spinal Cord and Spinal Nerves Flashcards by Daniel Lim

Spinal Cord Functions

Conduction

sensory info ascends spinal cord
motor commands descends spinal cord

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Spinal Cord Functions

Neural Integration

spinal cord receives info from diverse sources
Processes information

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Spinal Cord Functions

Locomotion

central pattern generaters that coordinate simple repetitive movements
(ex. walking doesn’t need much brain activity to do)

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Spinal Cord Functions

Reflexes

Involuntary responses to stimuli

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How many pairs of spinal nerves are there?

How many pairs does each region of the spine have?

31 pairs of spinal nerves

Cervical has 8 pairs (C1 to C8)
Thoracic has 12 pairs (T1 to T12)
Lumber has 5 pairs (L1 to L5)
Sacral has 5 pairs (S1 to S5)
Coccyx has 1 pair

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What are the 4 major regions of the spinal cord and it’s 2 enlargements?

4 Major Regions:
Cervical
Thoracic
Lumbar
Sacral

Enlargements:
Cervical
Lumbosacral

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Where is the Medullary Cone and Cauda Equine located?

The Medullary Cone is found inferior to the Lumbosacral Enlargement

The Cauda Equine is found inferior to the Medullary Cone

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Dura Mater

Tough outer layer of the spinal meninges

Epidural space:
Superfical space in between duramater and bone

Subdural space:
Deep space in between dura mater and arachnoid mater

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Arachnoid Mater

Middle layer of Spinal Meninges

Subarachnoid space:
- between Arachnoid Mater and Pia Mater
- filled with cerebral spinal fluid (CSF)

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Pia Mater

Delicate, inter layer of Spinal Meninges

Makes up the outer layer of the spinal cord (Gray and white matter)

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Name the 3 layers of the Spinal Meninges

Dura mater
Arachnoid Mater
Pia Mater

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Gray Matter of the Spinal Cord

Most deepest layer found in the spinal cord

H shape:
- Dorsal Gray Horn
- Ventral Gray Horn
- Lateral Gray Horn
- Gray Commissure

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White Matter of the Spinal Cord

Surrounds the gray matter with 3 sections called columns

Dorsal Column
Lateral Column
Ventral Column

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Central Canal of Spinal Cord

Directly in center of the Spinal cord
(center of both gray and white matter)

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Ascending Spinal Tract

Carries sensory info up to the brain

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Descending Spinal Tract

Carry motor commands down from the brain

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Decussation

Tracts crossing over the midlnie when passing up or down the spinal cord

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Ipsilateral Tracts

Spinal tracts that do not cross the midline

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Ascending (sensory) Tracts

Gracile Fasciculus

Located in the Posterior Funiculus
Decussation: in Medulla

Function:
Sensation of body position, discrimative touch, and pressure of lower body (below T6)

Ascending (sensory) Tracts

Cuneate Fasciculus

Located in Posterior Funiculus
Decussation: In Medulla

Functions:
Sensation of body position, discrimative touch, and pressure of upper body (Level T6 up)

Ascending (sensory) Tracts

Spinothalamic Tract

Located in Lateral and Anterior Funiculus
Decussation: In Spinal Cord

Functions:
carries info of pain and temperture

Descending (Motor) Tracts

Lateral Corticospinal

Located in Lateral Funiculus
Decussation: In medulla

Functions:
Fine motor control of limbs

Descending (Motor) Tracts

Anterior Corticospinal

Located in Anterior Funiculus
Decussation: in Spinal Cord

Functions:
Fine motor control of limbs

Posterior Median Sulcus and Anterior Median Fissure

Posterior Median Sulcus: groove on the dorsal surface of the spinal cord

Anterior Median Fissure: groove on the ventral surface of the spinal cord

Where do the Cervical Enlargement supply nerves to?

Gives rise to upper limbs

Where do the Lumbosacral enlargement supply nerves to?

Gives rise to the pelvis and lower limbs

Another name for a pair of spinal nerves

Spinal segment

What is the tapering end of the spinal cord called?

Medullary cone

What makes up a nerve?

Several axons wrapped by connective tissue

What are the 3 components that make up a nerve?

From deep to superifical: - Endoneurium: wraps one axon - Perinerium: wraps a fascicle of axons - Epineurium: wraps entire nerve

What makes up a ganglion?

Cluster of nerve cell bodies outside the CNS

Where and What are the Proximal Branches in a spinal cord?

Proxminal branches are interior roots and are found in the dural sac Dorsal Root: Posterior branch of the spinal nerve with a dorsal root ganglion attached Ventral Root: Anterior branch of the spinal nerve

Where and what are the Distal branches located in spinal cord?

Distal branches are found exterior of the spinal vertebrae Posterior Ramuses branch out posteriorly of the vertebrae Anterior Ramus are lateral to the spinal vertebrae

What are Nerve Plexuses?

They receive fibers from anterior rami and give rise to lateral nerves

Cervical Plexus

Found in neck C1 to C5

Brachial Plexus

Found in shoulders Gives rise to all nerves that supply the upper limbs (C5 to T1)

Lumbar Plexus

In lower back L1 to L4

Sacral and Coccygeal Plexuses

Below lumbar for Sacral Plexus L4 to S4 contains both lumbar and sacral vertebrae

Dermatome

Area of skin innervated by a particular nerve

Dermatome Map

Diagram of areas of skin innverated by each spinal nerve

What are properties of a reflex?

- Requires a simulation - Quick - Involuntary - Sterotyped (very predictable movement)

What do Visceral Reflexes control?

- Control Glands, cardiac muscle, and smooth muscle - Controlled by Autonomic Nervous system (VMD)

What do Somatic Reflexes control?

- Control Skeletal Muscles - Controlled by somatic nervous system

Description of General Fibers

Innervate widespread organs such as muscles, skin, glands, viscera, and blood vessels

Description of Special Fibers

What are mixed nerves?

Nerves containing both afferent and efferent nerve fibers Can conduct signals in two directions