gray matter consists of (1) and is divided into .. (2)
(1) neuronal cell bodies
(2) dorsal horn, ventral horn and lateral horn
white matter consists of (1) and is divided into.. (2)
(1) neuronal fibers
(2) dorsal funiculus, ventral funiculus and lateral funiculus
ventral median fissure is related to..
anterior spinal artery
dorsal intermediate septum
present only at and above vertebra T6 --> distinguishes ascending fibers within the gracile fasciculus (lower extremity) from cuneate fasciculus (upper extremity)
L1 in adult
L3 in newborns
dorsal and ventral nerve roots of spinal nerves L1 through coccygeal 1
extension of pia mater that reaches from the conus medullaris to the end of the dursal sac at the vertebral level S2
what is contained with epidural space?
fat and internal vertebral venous plexuses
lateral extensions of pia mater that attach to dura mater, thereby suspending the spinal cord w/in the dural sac
which artery supplies the ventral 2/3 of the spinal cord?
anterior spinal artery (arises from vertebral arteries)
which artery(s) supplies the dorsal 1/3 of the spinal cord?
posterior spinal arteries (2 of them) that arise from vertebral arteries or the PICA
significance of great radicular artery (artery of Adamkiewicz)
this artery makes a major contribution to the anterior spinal artery and provides the main blood supply to lower part of spinal cord
anterior spinal artery syndrome -- cause?
ligation of great radicular artery during resection of an abdominal aortic aneurysm
anterior spinal artery syndrome - symptoms
paraplegia - bilateral spastic paresis w/ pyramidal signs below lesion
loss of voluntary control of bladder and bowel
bilateral loss of pain and temperature sensation
bilateral Horner syndrome
bilateral flaccid paralysis
how many spinal nerves are there?
8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal
dorsal primary ramus
innervates skin and deep muscles of the back
ventral primary ramus
innervates remainder of the body
white communicating rami
contain myelinated preganglionic SNS nerve fibers
present only in spinal nerves T1-L3
gray communicating rami
contain unmyelinated POST-SNS nerve fibers
present in all spinal nerves
which tract mediates tactile discrimination, vibration sensation, form recognition and proprioception?
dorsal column medial lemniscus pathway
which tract mediates pain and temperature sensation?
lateral spinothalamic pathway
which tracts transmit info about proprioceptive and muscle reflex activity from the spinal cord to the cerebellum?
dorsal and ventral spinocerebellar tracts
interruption of which tract above T1 results in Horner's syndrome?
poliomyelitis and Werdnig-Hoffman disease
caused by damage to alpha motor neurons w/in ventral gray horn --> LMN lesion
clinical findings in LMN lesion
fasciculations and fibrillations
absent Babinski sign
amyotrophic lateral sclerosis (Lou Gehrig's disease)
damage to alpha motor neurons within the ventral gray horn and the lateral corticospinal tract; both UMN and LMN lesion
clinical findings in combined LMN/UMN lesion
spastic paralysis or paresis
no fasciculations or fibrillations
positive Babinski sign
caused by damage to sensory pathways of dorsal columns
CF = loss of tactile discrimination, vibration sensation and proprioception
hemisection of spinal cord - caused by a penetrating blow
clinical findings in Brown-Sequard syndrome
loss of tactile discrimination, vibration, proprioception
spastic paresis with pyramidal signs below lesion
loss of pain and temp one segment below the lesion
what causes damage to dorsal columns, lateral corticospinal tracts and spinocerebellar tracts?
vitamin B12 neuropathy - deficiency
clinical findings in vitamin B12 neuropathy
bilateral loss of tactile discrimination, vibration, proprioception
bilateral spastic paresis with pyramidal signs
bilateral arm and leg dystaxia
central cavitation of cervical spinal cord whose etiology is unknown but results in damage to ventral white commissure (involving decussating lateral spinothalamic axons) and ventral gray horns
clinical findings in syringomyelia
bilateral loss of pain and temperature
flaccid paralysis of the intrinsic muscles of the hand
what are some complications of spinal cord injury?
renal stones, pyelonephritis, renal failure
MC intramedullary tumor of spinal cord
common locations of ependymomas
- cervical region - near obliterated central canal
- lumbosacral region associated with conus medullaris
where do astrocytomas commonly occur in spinal cord?
cervical and thoracic regions
MC location of meningioma of spinal cord
MC type of extradural tumors of spinal cord
metastasis (lung, breast and prostate) MC metastasize to the body of vertebrae
arises from remnants of embyronic notochord; usually occur in sacral or clival regions
where is lumbar puncture performed?
above or below the spinous process of vertebra L4 (i.e. L3-L4 or L4-L5 interspace)
produced by injected anesthetic into subarachnoid space
up to spinal nerve T10 for vaginal delivery, and up to T4 in cesarean section