Exam II Flashcards
what is the function of the PCML / DCML?
somatosensory pathway: vibration, proprioception, light touch
where is the origin and termination of the PCML / DCML?
(1) origin: dorsal root ganglion (synapse at nucleus gracilis / cuneatus
(2) termination: VPL / Somatosensory cortex
where does decussation of the PCML / DCML occur?
internal arcuate fibers (cauda medulla)
what is the function of the Lateral Spinothalamic tract?
somatosensory tract: pain, temperature, crude touch, itch, tickle, and some visceral sensations
where is the origin and termination of the Lateral Spinothalamic tract?
(1) origin: immediate synapse in gray matter of the spinal cord
(2) termination:
- A-pain: VPL to somatosensory cortex
- C-pain: intralaminar and mediodorsal nuclei to limbic and somatosensory cortex
where does decussation of the Lateral Spinothalamic tract occur?
anterior commissure (spinal cord)
what are the 2 lateral motor tracts?
(1) Lateral Corticospinal tract
(2) Rubrospinal tract
what are the 4 medial motor tracts?
(1) Anterior Corticospinal tract
(2) Vestibulospinal tracts
(3) Reticulospinal tracts
(4) Tectospinal tract
what is the function of the Lateral Corticospinal tract?
movement of the contralateral limb (voluntary, fine, skilled movements)
where is the origin and termination of the Lateral Corticospinal tract?
(1) origin: primary motor cortex
(2) termination: entire cord
where does decussation of the Lateral Corticospinal tract occur?
pyramidal decussation (cervicomedullary junction)
what is the function of the Rubrospinal tract?
movement of contralateral limb? (not fully understood in humans)
where is the origin and termination of the Rubrospinal tract?
(1) origin: red nucleus, magnocellular (midbrain)
(2) termination: cervical cord
where does decussation of the Rubrospinal tract occur?
ventral tegmental decussation (midbrain)
what is the function of the Anterior Corticospinal tract?
control of bilateral axial / girdle movements; postural control of head and neck (proximal muscles, neck, trunk)
where is the origin and termination of the Anterior Corticospinal tract?
(1) origin: primary motor and supplementary motor cortex
(2) termination: cervical and upper thoracic cord
where does decussation of the Anterior Corticospinal tract occur?
DOESN’T DECUSSATE
what is the function of the LATERAL Vestibulospinal tract?
balance for whole body
where is the origin and termination of the LATERAL Vestibulospinal tract?
(1) origin: lateral vestibular nucleus (Pons)
(2) termination: entire cord
what is the function of the MEDIAL Vestibulospinal tract?
maintains head and neck tone
where is the origin and termination of the MEDIAL Vestibulospinal tract?
(1) origin: medial (and inferior) vestibular nucleus (medulla)
(2) termination: C/S and T/S cord
what is the function of the PONTINE & MEDULLARY reticulospinal tracts?
posture and gait
where is the origin and termination of the PONTINE reticulospinal tract?
(1) origin: pontine reticular formation
(2) termination: entire cord
where is the origin and termination of the MEDULLARY reticulospinal tract?
(1) origin: medullar recticular formation
(2) termination: entire cord
what is the function of the tectospinal tract?
head and eye movement
where is the origin and termination of the tectospinal tract?
(1) origin: superior colliculus (midbrain)
(2) termination: cervical cord
where does decussation of the tectospinal tract occur?
dorsal tegmental decussation (midbrain)
what are separations of the dura membranes important for?
create sinuses; important to venous drainage
what structure can be damaged by the falx cerebri?
corpus callosum
what can be damaged by the tentorium cerebrelli?
midbrain, brainstem, occulomotor nerve
what artery is in the epidural space?
middle meningeal artery
what commonly causes rupture of the middle meningeal artery?
fracture of the temporal bone
what does the subdural space contain?
bridging veins
what can rupture of the bridging vein cause?
subdural hematoma
what does the subarachnoid space contain?
CSF and major arteries of the brain
what makes up the choroid plexus? what is the function of the choroid plexus?
(1) ependymal cells
(2) produces CSF
how does CSF exit and create a pressure gradient?
arachnoid granulations
the fasciculus gracilis carries what type of information? where is it located in the brain?
LE infromation; medial
the fasciculus cuneatus carries what type of information? where is it located in the brain?
UE information; lateral
what is the difference between Spinothalamic, Spinoreticular, Spinomesencephalic pathways?
(1) Spinothalamic: identifying noxious stimuli (stepping on something sharp)
(2) Spinoreticular: adds the emotional component (ouch, that hurts!)
(3) Spinomesencephalic: Pain modulation (that feels better!)
what is the function of A-alpha (I) receptors? what pathway uses these fibers?
(1) proprioception (muscle spindle and GTO)
PATHWAY
Spinocerebellar
what is the function of A-beta (II) receptors? what pathway uses these fibers?
(1) proprioception (muscle spindle)
(2) light touch (Meissner’s corpuscle)
(3) 2-point discrimination (Merkel’s receptors)
(4) vibration (Pacinian corpuscle)
(5) vibration (Ruffini ending)
(6) light touch / vibration (hair receptors)
PATHWAY
PCML
what is the function of A-delta (III) receptors? what pathway uses these fibers?
(1) acute pain
(2) cool temperature
(3) itch
PATHWAY
Lateral Spinothalamic (A-pain)
what is the function of C (IV) receptors? what pathway uses these fibers?
(1) chronic pain
(2) warm temperature
(3) touch
PATHWAY
Lateral Spinothalamic (C-pain)
which fibers have the highest conduction fibers? which have the lowest?
Highest: Alpha-A
Lowest: C
what relay nuclei of the thalamus send information to sensory and motor areas?
mainly lateral thalamus, VPL, PN, LGN, MGN, interior nucleus
what relay nuclei of the thalamus send information to association cortices?
non-specific (found in pulvinar and MD)
what relay nuclei of the thalamus send information to the basal ganglia?
intralaminar (lie within intermedullar lamina)
what relay nuclei of the thalamus do not project into the cortex and deal with communication within the thalamus?
reticular nuclei (thin sheet lateral to thalamus and medial to internal capsule)
A lesion above the medulla will prevent what sided deficits for the DCML tract?
-Contralateral
A lesion in the lower medulla will present what sided deficits for the DCML Tract?
-Ipsilateral
A lesion at the brainstem will cause what sided symptoms of the anterolateral spinal thalamic tract?
-Contralateral
Polyneuropathy is associated with what disease?
-Diabetes; “sock and glove” syndrome
A spinal nerve lesion will follow what pattern?
-Dermatome/Myotome
Posterior cord damage will affect what ascending tract?
-DCML
Anterior Spinal Cord damage will affect what tract?
-ALS Tract
A narrow central cord lesion will affect what ascending tract?
-ALS Tract; cannot deccusate either way, bilateral loss caudal to lesion
Why is there more white matter in the cervical segments?
-They house all tracts
What is associated with a lower motor neuron lesion?
-Atrophy, decreased tone, twitching, decreased reflexes
What is associated with a upper motor neuron lesion?
-increased tone, increased relfexes
A left MCA superior division infarct will cause what type of aphasia?
-Brocas
A left MCA inferior division infact with cause what type of aphasia?
-Wernickes
How do motor deficits usually present with a left inferior division of the MCA infarct?
-no deficits
What is a major deficit associated with a right MCA inferior division infarct?
-Left hemineglect
A left MCA deep territory infarct will cause what type of deficit?
-Right hemiparesis
Non dominant ACA strokes can cause what?
-Contralateral neglect
An occlusion of the internal carotid will cause what type of infarct?
-ACA-MCA Watershed
An ACA-MCA watershed infarct of the dominant hemisphere will cause what?
-Transcortical aphasia syndromes
Watershed infarcts cause what type of motor deficits?
-Proximal arm and leg weakness (regions of the humunculus involved include trunk and proximal limb)
What are the 4 D’s of a vertebral basillar stroke?
-Dysarthria, dysphagia, diplopia, dizziness
