Spinal Cord and Spinal Nerves Flashcards
Spinal Cord Functions
Conduction
- sensory info ascends spinal cord
- motor commands descends spinal cord
Spinal Cord Functions
Neural Integration
- spinal cord receives info from diverse sources
- Processes information
Spinal Cord Functions
Locomotion
central pattern generaters that coordinate simple repetitive movements
(ex. walking doesn’t need much brain activity to do)
Spinal Cord Functions
Reflexes
Involuntary responses to stimuli
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
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
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
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
Arachnoid Mater
Middle layer of Spinal Meninges
Subarachnoid space:
- between Arachnoid Mater and Pia Mater
- filled with cerebral spinal fluid (CSF)
Pia Mater
Delicate, inter layer of Spinal Meninges
Makes up the outer layer of the spinal cord (Gray and white matter)
Name the 3 layers of the Spinal Meninges
- Dura mater
- Arachnoid Mater
- Pia Mater
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
White Matter of the Spinal Cord
Surrounds the gray matter with 3 sections called columns
- Dorsal Column
- Lateral Column
- Ventral Column
Central Canal of Spinal Cord
Directly in center of the Spinal cord
(center of both gray and white matter)
Ascending Spinal Tract
Carries sensory info up to the brain
Descending Spinal Tract
Carry motor commands down from the brain
Decussation
Tracts crossing over the midlnie when passing up or down the spinal cord
Ipsilateral Tracts
Spinal tracts that do not cross the midline
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
