SPINAL CORD

Question 1

The Spinal Cord Composition

Answer 1

Located within the
vertebral column
which extends from
cervical vertebrae to
coccygeal vertebrae
* Divided into 5
regions: 31 Spinal
nerves
* Cervical (8)
* Thoracic (12)
* Lumbar (5)
* Sacral (5)
* Coccygeal (1)

Question 2

Spinal Cord Gross Anatomy

Answer 2

31 pairs of spinal nerves emerge from spinal cord:
One pair at each vertebral disc
* Not as long as vertebral column: Ends around L1-L2
vertebral discs

Question 3

Motor and Sensory Activity

Answer 3

Afferent:
– spinal/cranial nerves
– spinal cord
– __Brainstem___________
– thalamic bodies
– primary sensory cortex
– sensory association
areas
* Efferent
– Primary motor cortex
– premotor cortex
– __Basal Ganglia___________
– __Brainstem___________
– ____Cerebellum_________
– spinal cord
– spinal/cranial nerves

Question 4

Basic Structure – Function relationship
Spinal Cord and Spinal Nerves

Answer 4

Nerve relay to/from periphery and CNS
* Transmits incoming sensory information from spinal nerves
via sensory nuclei
* Transmits outgoing motor information from brain to
muscles, organs, glands, etc. via motor nuclei
* Generates sensorimotor reflexes

Question 5

Spinal Cord Internal Anatomy
* Outer ring of

Answer 5

Outer ring of white
matter [ ascending
(_Afferent________) and
descending (__Efferent______)
fibers]
* Butterfly shaped gray
area in center – nerve
cell bodies

Question 6

anterior and posterior roots

Answer 6

Spinal nerves: carry both sensory and motor
information
* Each nerve is connected to spinal cord by 2 roots
* Anterior root (Ventral): Contains _Efferent (motor)_____________ fibers
* Posterior root (Dorsal): Contains __Afferent (sensory)______________ fibers

Question 7

White Matter Tracts
Columns

Answer 7

White matter arranged into 3 bundles of fasciculi
* Dorsal column: __Ascendina fibers_______________
* Lateral column: ___Both ascending and descending_______________________
* Ventral column: ___Both ascending and descending_________

Question 8

Spinal Cord Internal Anatomy
* Motor and sensory roots exit

Answer 8

Motor and sensory roots exit spinal cord at
intervertebral foramina
* Here, roots unite to form spinal nerve
* So, motor and sensory fibers mix together

Question 9

Ascending tracts

Answer 9

Carry _sensory________information
* Names of afferent tracts
* Dorsal Column-Medial Lemniscal System
* Spinothalamic tract

Question 10

Descending Tracts

Answer 10

Carry
_____motor_____information
* Names of efferent tracts
* Corticospinal tract
* Corticobulbar tract

Question 11

Motor Units
* 4 Components

Answer 11

4 Components
* Motor Cell Bodies
* Efferent Fibers (axons)
* Motor End Plate; neuromuscular junction (NMJ)
* Innervated Muscle Fibers

• Several motor units per muscle
• Muscles will degenerate if neuromuscular junction is
  damaged

Question 12

Spinal Reflex

Answer 12

Sensory-motor nerve pathway without brain influence
Example:
* Withdrawal reflex
* Knee-jerk
* Eliminates the extra time for routing to higher neural
structures – with reflexes you want quick action!
* REFLEX ARC (= Pathway)
Sensory Neuron in periphery -> Interneuron (Relay
Neuron) in the spinal cord-> Motor Neuron in periphery

Question 13

Brainstem

Answer 13

All ascending and descending longitudinal fiber tracts
pass through the brainstem
* Contains
* __Pons__________
* ___Misbrain_________
* ___Medulla_________
* (Reticular formation)

Question 14

Brainstem: Reticular Formation

Answer 14

Composes most of the brainstem, but functionally
interconnected with thalamus and spinal cord
* Important for
* Cortical arousal
* Pain processing
* Vital life functions independent of cortical input
* Cardiovascular function
* Coughing yawning
* Swallowing, vomiting, sucking
* Respiration

Question 15

Brainstem

Answer 15

Midbrain
* Pons
* Medulla

Question 16

Brainstem: Midbrain, Pons, Medulla
* Vital Functions

Answer 16

Vital Functions
* Essential to human survival
* Involved in regulation of cardiac and respiratory
function, consciousness, alertness, consciousness,
eating (swallowing), and the sleep cycle.
* Continuous with the spinal cord (SC)
* Location of 4th ventricle
* Contains nuclei of cranial nerves III ~ XII located in
the brainstem