Nerve Supply of the Back Flashcards
functions of spinal cord
relay center for incoming sensory info through dorsal roots & horn
conduit for ascending (afferent) and descending (efferent) pathways
origin of LMNs = commands to muscles of body from ventral horn
What are meninges?
connective tissue membrane
Name the meninges from inside out
pia, arachnoid, dura
Subarachnoid space is filled with…
cerebrospinal fluid and arteries
Subdural space is the location of:
veins
The epidural space contains:
fat
Describe Bell-Magendie Law
Sensory info goes into the spinal cord via dorsal (posterior) roots of spinal nerves
Motor “commands” leave the spinal cord via ventral (anterior) roots of spinal nerves
Ventral horn contains:
cell bodies of alpha & gamma motor neurons (LMN)
Dorsal horn contains:
sensory cell bodies
How are spinal nerves numbered?
numbered for vertebrae above, except in cervical region
(i.e., C2= between C1-C2; C8 between C7-T1; T1 between T1-T2)
Describe the dorsal root
Sensory (afferent) route
Formed by union of smaller dorsal rootlets which emerge from dorsal side of spinal cord
Larger than ventral root
*located inside vertebral canal
what type of neuron is the dorsal root ganglion part of?
pseudounipolar
what does each ramus carry?
mixed motor and sensory fibers from both ventral and dorsal horns
spinal nerves are formed by union of…
dorsal and ventral roots in intervertebral foramen
Describe the ventral root
Motor (efferent) route
Formed by union of smaller ventral rootlets from ventral side of spinal cord
*located inside vertebral canal
Dorsal rami is divided into…
medial and lateral branches
Dorsal rami motor innervation
intrinsic muscles of the back
Medial branch of dorsal ramus function
all levels supply muscles, only levels T6 and up are also cutaneous (sensory to skin) to upper back
Lateral branch of dorsal ramus function
all levels supply muscles, only levels T6 and below are also cutaneous to lower back and medial gluteus region