Segmentation of Spinal Cord - Lecture 5 Flashcards
31 spinal cord segments
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
even after the vertebral column grows much longer…
each pair of spinal nerves still exits at its original location
now several segments away
by intervertebral foramen
C1-C8 exit
above the corresponding numbered vertebra
(C8 will be above T1)
T1-12, L1-L5, S1-S5, Co1 esit
below the corresponding numbered vertebrae
what is a spinal segment
region of the spinal cord associated with a particular pair of spinal nerves
spinal cord roots
2 branches of spinal nerves
ventral root
dorsal root
ventral root
contains axons of motor neurons
efferent
dorsal root
contains axons of sensory neurons
afferent
dorsal root ganglia
dorsal root ganglia
contain cell bodies of sensory neurons
pseudo unipolar neurons
a kind is sensory neuron in the PNS
contain an axon that has split into 2 branches
2 branches of pseudo unipolar neurons
one branch runs to the periphery
one branch runs to the spinal cord
general somatic afferent
sensory info
touch, pressure, pain, temp, proprioception
general visceral afferent
sensory info perceived by the viscera
glands, organs, membranes
general somatic efferent
fibers work to provide innervation to skeletal muscles that arise from somatic origin
general visceral efferent
provide innervation to the glands, cardiac muscle and smooth muscle
