Spinal Cord Anatomy Flashcards
gray matter =
cell bodies
gray matter is composed mostly of
neuronal cell bodies, capillaries, and some support cells
dorsal white matter column boundaries
medially - dorsal median sulcus
laterally - dorsolateral sulcus
dorsal white matter column consists of
fasciculus gracilis and fasciculus cuneatus
dorsal white matter column contains
only sensory ascending tracts
lateral white matter column location
between dorsal and ventral roots
lateral white matter column contains
ascending and descending fiber tracts
both sensory and motor fibers
ventral white matter column location
between ventral roots and ventral median fissure
ventral white matter column contains
both ascending and descending sensory and motor tracts
how many pairs of spinal nerves
31 pairs
spinal cord segments
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
which spinal cord segments are part of the lumbar and cervical enlargements
cervical - C5-T1
lumbar - L2-S2
4 types of neurons found in spinal cord gray matter
- interneurons
- motor neurons
- sensory neurons
- preganglionic autonomic neurons
location of interneurons
everywhere
characteristics of interneurons
short axons, receive info, send info a short distance, help shape CNS function
location of motor neurons
ventral horn only
characteristics of motor neurons
alpha - striated
gamma - special receptors in muscle
innervate skeletal muscle fibers
location of sensory neurons
dorsal horn only
characteristics of sensory neurons
axons form ascending sensory white matter tracts
others integrate
location of preganglionic motor neurons
lateral horns (T1-L2 and S2-S4)
characteristics of preganglionic motor neurons
axons form part of output pathway of autonomic nervous system
4 types of dorsal horn nuclei
- substantia gelatinosa
- nucleus proprius
- nucleus dorsalis
- visceral afferent nucleus
location/function of substantia gelatinosa
location - apex of dorsal horn function - pain modulation
location/function of nucleus proprius
location - dorsal horn (largest nucleus) function - transmission of pain and temperature
location/function of nucleus dorsalis (clark’s nucleus)
location - medial base of dorsal horn, spinal cord segments C8-L3 function - related proprioceptive info
location/function of visceral afferent nucleus
location - lateral to nucleus dorsalis in dorsal horn, spinal cord segments T1-L2, S2-4 function - receives visceral sensory dorsal root fibers (input part of ANS)
which spinal cord segments contain a lateral horn
T1-L2 and S2-S4 (forms intermediolateral cell column)
what kind of neurons are located in the lateral horn
visceral preganglionic motor neurons
function of visceral preganglionic motor neurons
part of the ANS
why kind of neurons are located in the ventral horn
- alpha motor neurons (large)
- gamma motor neurons (small)
- interneurons
function of ventral horn neurons
motor
names of 3 white matter bundles not part of 3 major white matter columns
- ventral white commissure
- dorsolateral tract of lissauer
- fascicles proprius
function of ventral white commissure
pain and temperature
allows sensory pain info to cross midline of spinal cord
function of dorsolateral tract of lissauer
short ascending and descending fibers carrying info relating to pain
function of fasciculus proprius
short ascending and descending fibers that connect spinal segments and are important for intersegmental reflexes
syringomyelia
Causes a lesion around the central canal of the spinal cord
Usually present in the cervical cord region (The lesion starts centrally affecting medial structures then grows out laterally)
syringomyelia destroys
ventral white commissure and the alpha and gamma motor neurons in the ventral gray matter
spina bifida
Congenital malformation of neural tube development
Results in incompletely formed spinal cord and sometimes malformations of vertebral segments
signs/symptoms of spina bifida
varying degrees of paralysis,
absence of skin sensation,
poor or absent bowel and/or bladder control
Curvature of spine (scoliosis)
4 presentations of spina bifida
- spina bifida occulta
- meningocele
- meningomyelocele
- rachischisis/anencaphalic
beginning/end of spinal cord
Begins: foramen magnum
Ends: approximately L2 in adults
Spinal Cord Neural Segment
Part of spinal cord which receives or gives dorsal and ventral rootlets for a single pair of spinal nerves
Lesion in Gray Matter
Impairments are segmental:
only affecting structures innervated by that particular section of grey matter
Ex) Lesion in gray matter of C5 → you impair ONLY the muscles innervated by C5
Lesion in White Matter
The lesion in white matter affects all functions of all structures below the level of the lesion
Destroys function of cell bodies that they originated from
White matter spreads
Ex) Complete lesion of C5 → paralysis in every section the tract is heading to below