spinal cord and tracts Flashcards
functions of the spinal cord
- highway for information flow between the body and brain - contains neurons involved in local reflex arcs
the spinal cord structure is essentially the ______ along the entire length
same
connective tissue layers
meninges
cross section of spinal cord is the size of
a nickel or dime
anterior is called
ventral
posterior is called
dorsal
the thoracic spinal segment gray matter has a characteristic
lateral form
ventral spinal cord function
motor/efferent
dorsal spinal cord function
sensory.afferent
cell bodies of motor/efferent neurons are in _____ and the axons travel in the _____
- spinal cord gray matter
- nerve
cell bodies of sensory/afferent neurons are in ____ and whose axons ________
dorsal root ganglion enter the spinal cord dorsally
axons that cross the midline
commissures
dorsal horn of butterfly
sensory functions
ventral form of butterfly
motor functions
What region of the spinal cord
cervical
what region of the spinal cord?
thoracic
what region of spinal cord is this?
lumbar
what region of spinal cord?
saccral
in the ventral horn, Neurons innervating _____ muscles are medial
proximal
in the ventral horn, Neurons innervating _____ muscles are lateral
distal
The T1-L2 and S2-4 levels of the spinal cord have an additional enlargement in the ventral (motor) horn : _____ aka _____
lateral horn
intermediolateral column
This is the location of the preganglionic sympathetic and parasympathetic neurons of the ANS.
the lateral horn/intermediolateral column
Axons with similar functions (and destinations) group together into ________. Although these exist, we cannot see most individual tracts within the white matter.
tracts / fasiculus / columns.
Motor tracts arise in the frontal lobe’s ______ aka _____
Precentral gyrus
Primary motor cortex
purpose of the primary motor cortex
Voluntary control over skeletal muscle movement
Somatosensory tracts end in the parietal lobe’s ________ aka _______
Postcentral gyrus
Primary somatosensory cortex
purpose of primary somatosensory complex
Conscious perception of somatosensory input
Location of FIRST neuron in the cerebral cortex to receive sensory information for a given modality from lower CNS region
Primary sensory cortex
Location of LAST neuron in the cerebral cortex before information descends to lower levels of the CNS.
primary motor cortex
The cerebral cortex deals with the ____body/world. Therefore tracts will ____
contralateral
cross
ascending/sensory tracts
spinal thalamic tract (STT)
dorsal column medial lemniscus (DCML)
sensory modalities of spinothalamic tract
pain, temperature, crude touch, tickle, itch
how many neurons make up the chain of sensory/ascending pathways?
3 neuron chain
decussation of spinothalamic tract
level of entry
information is brought to the cerebral cortex of the ________
post central gyrus
ascending/sensory tracts neuron 1
centrally projecting axon that entrers the spinal cord from its dermatome
neuron 2 always _____ but the cell body is located in different areas depending on sensory modality
decussates
in the ascending/sensory tract, neuron 3 cell body is in the _____ and the axon travels in ________
thalamus
posterior limb of internal capsule
in the spinothalamic tract, the nerves run in this area of the white matter
anterolateral system
sensory input in the dorsal column medial lemniscus
fine touch, vibration, proprioception - comes from meissners corpuscles, stretch receptors, etc
decussation in the dorsal column medial lemniscus tract
at medulla
Where do axons carrying information on PAIN from the LEFT toe terminate in the primary somatosensory cortex
RIGHT postcentral gyrus toward the longitudinal fissure
Where do axons carrying information on FINE TOUCH from the LEFT toe terminate in the primary somatosensory cortex?
RIGHT postcentral gyrus toward the longitudinal fissure
desending motor tract is called the
corticospinal tract
the corticospinal tract is a ___ neuron chain
2
in the corticospinal tract, neuron 1 is in the ________ also called the ______
precentral gyrus
upper motor neuron
the upper motorn neuron travels in the _________
posterior limb internal capsule
90% of the neurons in the corticospinal tract decussate in the ________ of the ________
decussate in the medulla (Pyramids) of the Lateral corticospinal tract
in the corticospinal tract, neuron 2 is in the ___________
spinal cord ventral horn
neuron 2 in the corticospinal tract is also called the _______
lower motor neuron
the lower motor neuron exits into _______ and innervates _____ of limbs
spinal nerves
skeletal muscle
descending sympathetic informatoin to lateral horn and then to the face is called the
hypothalamospinal descending motor tract
hyothalamospinal tract neurons arise in the ______ and travel caudally to synapse on the pregnaglionic neuron in the ________
hypothalamus
thoracic spinal cord lateral horn
in facial innervation, the axon jumps onto the _________ and travels to facial structures (pupil, eye lid, sweat glands, skin vessels)
internal carotid artery
hypothalamospinal tract and facial innervation decussation
no decussation!
lesion in sympathetic pathway causes _______
horners syndrome
constriction of pupils
miosis
ptosis
droopy eyelids - loss of sup. tarsal muscle
anhydrosis
lack of sweating
Horners syhdrome is characterized by
miosis, ptosis, anhydrosis, flushing (vasodilation)
spinal cord aterial blood supply - arises in ______ portion of brain
posterior
___ arteries send branches into the interior of the spinal cord. Name them
3
posterior spinal arteries (2)
anterior spinal artery (1)
each posterior spinal artery supplies unilateral _____ area dorsal column
sensory
anterior spinal artery supplies ___ and ___ areas bilaterally
motor and sensory
lower leg axons run through this area in ascending/sensory tract
fasiculus gracilus in the posterior column
