Spinal Cord (CNS) Flashcards
What is the spinal cord?
terminal cord-like part of CNS located in vertebral canal
How long is the spinal cord?
43-45 cm (occupies 2/3 of vertebral canal)
Where does the spinal cord start and end?
start: medulla oblongata (at level of foramen magnum)
end: level of LI-LII intervertebral disc
Where does the spinal cord end in infants?
as low as level of LIII
Why is there a difference between the end of the spinal cord in adults and infants?
elongation of spinal cord stops at age 4-5, but growth of vertebral column continues
External Features of the Spinal Cord
What does the spinal cord look like when viewed externally?
cylinder with 2 enlargements in its cervical and lumbar regions
External Features of the Spinal Cord
What does the cervical enlargement give rise to?
nerves innervating the upper limbs
External Features of the Spinal Cord
What does the lumbar (lumbosacral) enlargement give rise to?
nerves innervating the lower limbs
External Features of the Spinal Cord
How does the conus medullaris form?
spinal cord tapers down inferior to lumbar enlargement
External Features of the Spinal Cord
What are the 2 main longitudinal grooves on the surface of the spinal cord?
ventral (anterior) median fissure
dorsal (posterior) median sulcus
External Features of the Spinal Cord
What emerges from the ventral (anterior) median fissure?
on either side, ventral (motor) rootlets of the spinal nerves
External Features of the Spinal Cord
What emerges from the dorsal (posterior) median sulcus?
on either side, dorsal (sensory) rootlets of the spinal nerves
External Features of the Spinal Cord
What do ventral rootlets join to form
ventral (motor) root of the spinal nerves
External Features of the Spinal Cord
What do dorsal rootlets join to form?
dorsal (sensory) root of spinal nerves
External Features of the Spinal Cord
What is each dorsal root of the spinal nerve associated with?
dorsal root ganglion
External Features of the Spinal Cord
What does the dorsal root ganglion house?
cell bodies of the sensory neurons
External Features of the Spinal Cord
What is each spinal nerve formed by?
union of ventral and dorsal roots
External Features of the Spinal Cord
What is the spinal cord segment?
section of spinal cord that gives rise to a pair of spinal nerve
External Features of the Spinal Cord
How many spinal cord segments are there? Name the types and how many there are.
31 spinal cord segments
- 8 cervical segments (C1-C8)
- 12 thoracic segments (T1-T12)
- 5 lumbar segments (L1-L5)
- 5 sacral segments (S1-S5)
- 1 coccygeal segment (Co)
Internal Features of the Spinal Cord
Describe the gray matter of the spinal cord.
H-shaped, with ventral (anterior) horn and dorsal (posterior) horn
Internal Features of the Spinal Cord
What is the gray commissure?
narrow strip that connect right and left halves of gray matter, and contains central canal
Internal Features of the Spinal Cord
What is the lateral horn?
a third horn between ventral and dorsal horns in some segments (T1 to L2, and S2 to S4)
Internal Features of the Spinal Cord
What do the lateral horns of T1 to L2 carry?
cell bodies of sympathetic neurons
Internal Features of the Spinal Cord
What do the lateral horns of S2 to S4 carry?
cell bodies of parasympathetic neurons
Internal Features of the Spinal Cord
What do ventral horns contain?
cell bodies of motor neurons
Internal Features of the Spinal Cord
What do the axons of motor neurons form?
motor (ventral) roots of spinal nerves
Internal Features of the Spinal Cord
What do dorsal horns contain?
cell bodies of sensory neurons
Internal Features of the Spinal Cord
What do the axons of sensory neurons form?
form dorsal root of spinal nerves - when neurons receive info from sensory neurons in dorsal root ganglia
**unsure of this question
Internal Features of the Spinal Cord
Where is the white matter and how is it organized?
surrounds gray matter
organized as ventral, lateral, and dorsal columns (funiculi) on each half of spinal cord
Internal Features of the Spinal Cord
What do the ventral, lateral, and dorsal columns of white matter contain?
tracts (bundles of myelinated nerve fibers) that travel along length of spinal cord