Chapter 19 Spinal Cord Flashcards
filum terminale
bundle of connective tissue and glia that connects the end of the cord to the coccyx
cauda equina
horselike tail
long roots exiting the lumbosacral vertebral column
dorsal root
contains sensory axons, brings information into the spinal cord
spinal nerves
carry all of the motor, autonomic, and sensory axons of a single spinal segment
dorsal rami
innervate the paravertebral muscles, posterior parts of the vertebrae, and overlying cutaneous areas
ventral rami
innervate the skeletal, muscular, and cutaneous areas of the limbs and of the anterior and lateral trunk
propriospinal
neurons that begin and end within the spinal cord
adjacent to gray matter
tract cells
cells with long axons that connect the spinal cord with the brain
dorsal horn
primarily sensory, contains endings and collaterals of first-order sensory neurons, interneurons, and dendrites and somas of tract cells
Nucleus Dorsalis
Clarke’s Column
receives proprioceptive info
relays unconscious proprioceptive info to cerebellum
from T1-L3 anterior to dorsal horn
lateral horn
contains cell bodies of preganglionic sympathetic neurons
present only at T1-L2
ventral horn
consists of LMN cell bodies
stepping pattern generators
adaptable neural networks that produce rhythmic output
contribute to stepping by activating LMN, eliciting alternating flexion and extension at the hips and knees
crossed extension reflex
interneuronal circuit that prevents falling when one is standing and lower limb is abruptly withdrawn by adjusting the muscle activity in the stance limb
reciprocal inhibition
decreases activity in an antagonist when an agonist is active, allowing the agonist to act unopposed
recurrent inhibition
inhibition of agonists and synergies, with disinhibition of antagonists
Renshaw cells produce recurrent inhibition
sacral spinal cord controls
urination, bowel function, and sexual function
reflexive bladder function requires
afferents
T1-L2 and S2-S4 cord levels
somatic, sympathetic, and parasympathetic efferents
psychogenic process
involves erotic thoughts and is mediated by L1-L2 sympathetic fibers
reflexogenic erection/engorgement and lubrication results from
direct sensory stimulation of the genitals and is mediated by S2-S4 afferents and S2-S4 parasympathetic fibers
what elicits ejaculation and contraction of pelvic floor
sympathetic nerves L1-L2 and pudendal nerve with cell bodies in S2-S4
vertical tract lesion
results in loss of communication to and from the spinal levels below the lesion
peripheral region lesions
produce deficits in the distribution of a peripheral nerve
-altered or lost sensation in peripheral nerve distr.
-decrease or loss of muscle power in pn distri.
-no vertical tract signs
-decreased or lost phasic stretch reflex
spinal region segmental signs
occurs when a spinal segment, nerve root, and/or spinal nerve is compromised
-altered or lost sensation in a dermatome
-decreased or lost muscle power in a myotome
-decreased or lost phasic stretch reflex
-UMN signs: loss of muscle power, spasticity, hypertonia, babinski sign, clonus