test 1: lecture 9 Flashcards
what tracts are found in the cerebral peduncles
corticospinal (voluntary muscle)
corticobular
corticopontine
superior colliculus
inferior colliculus
cerebellar peduncles
two major ascending pathways in the brain stem
dorsal column medial lemniscal (touch vibration proprioception) (1-2 in medulla) (2-3 thalmus) (3→ cerebral cortex)
spinothalamic pathway (pain, temp) (1-2 dorsal horn) (2-3 thalamus) (3→ cerebral cortex)
descending tract in the brain stem
corticospinal tract (voluntary motor)
(from UMN in the brain cross sides at the pyramidal decussation down the lateral funiculus to the dorsal horn) (2nd from dorsal horn out the dorsal root and to muscle)
corticospinal tract
corticospinal tract
voluntary control (2 neuron path)
from the primary motor cortex down through the cerebral peduncles of the midbrain, basilar pons, pyramidal decussation in the caudal medulla, lateral funiculus of the spinal cord, synapse on interneuron or LMN in the dorsal horn
spinothalamic tract
pain and temp
sensory through dorsal root, 1-2 at dorsal horn, 2 switches sides and travels up the anteriolateral tract of the spinal cord. 2-3 in the VPL(ventroposterokateral nucleus) of the thalamus, 3→primary somatosensory cortex
dorsal column medial lemniscus pathway
touch and proprioception
ascending
sensory through dorsal root up through dorsal funiculus (fasiculus cunaetus for the upper body, fasiculus gracilis for the lower body), 1-2 in the arcuate fibers in the medulla, 2 switches sides up through the medial leminscus, 2-3 in ventropostero-lateral nucleus (VPL) thalamus, 3→ primary somatosensory cortex
medial longitudinal fasciculus
Coordinates eye and head movements.
Axons from the abducens nucleus project to the contralateral medial rectus motor neurons in the oculomotor nucleus.
It also is the route of descent for axons of the medial vestibulospinal tract.
___ coordinates eye and head movements.
MLF- Medial Longitudinal Fasciculus
Courses through the brainstem
eyes move together
In the MLF, Axons from the ___ project to the contralateral medial rectus motor neurons in the oculomotor nucleus.
abducens nucleus
(eyes move together)
___ is the route of descent for axons of the medial vestibulospinal tract.
MLF medial longitudinal fasciculus
what is the smaller circle?
medial lemniscus and spinothalamic (lateral to the Medial lemniscus)
vibration, proprioception comes up to medulla by the dorsal columns (fasciculus/nucleus gracilis for hindlimb or fasciculus/nucleus cuneatus for front limb)
1-2 in the medulla then will cross over by the internal arcuate fiber and ascend as the medial lemniscus, 2-3 in the thalamus, 3→ cerebral cortex
caudal medulla (can still see central canal)
internal arcuate fibers (2nd neurons on the dorsal column-medial lemniscus pathway for pressure and proprioception will use these to cross over the medulla and then ascend by the medial lemniscus to the thalamus
RET (reticular formation)
nerve network
fasiculus cuneatus or nucleus cuneatus
of the dorsal column
carries ascending sensory from the upper body from the dorsal column-medial lemniscal tract for vibration and pressure to the medulla
fasiculus gracilis or nucleus gracilis
of the dorsal column
carries ascending sensory from the lower body from the dorsal column-medial lemniscal tract for vibration and pressure to the medulla
where?
middle medulla
choroid plexus of the 4th ventricle in the middle medulla
MLF (medial longitudinal fasciculus)
medial lemniscus (white matter)
(ascending from dorsal column medial lemniscal pathway - touch and proprioception, 1-2 in medulla, cross medulla up through medical leminscus, 2-3 thalamus, 3- cerebral cortex)
spinothalamic (white matter)
ascending pain and temp
(dorsal root to dorsal horn, 1-2, 2 crosses over up through anteriolateral tract, 2-3 in thalamus, 3→ cerebral cortex)
pyramid
descending corticospinal for voluntary to muscles
from cerebral cortex, crosses at the pyramidal decussation, down the lateral corticospinal tract of the spinal cord, 1-2 in the ventral horn, 2→ muscle
pontine nuclei
CST –corticospinal, corticopontine, corticobulbar
medial lemniscal (ascending touch and proprioception from the DCML)
spinothalamic tract (ascending pain and temp)
medial lemniscal (ascending touch and proprioception from the DCML)
spinothalamic tract (ascending pain and temp)
(in the caudal midbrain)
caudal midbrain
CST corticospinal tract (descending voluntary muscle control)
caudal midbrain
inferior colliculus
rostral midbrain
superior colliculus
rostral midbrain
medial lemniscal (ascending touch and proprioception from the DCML)
spinothalamic tract (ascending pain and temp)
rostral midbrain
CST –corticospinal, corticopontine, corticobulbar
cerebral peduncle
if you have a lesion in the long tract of the corticospinal tract
Since a lesion in the brain stem is above the decussation: (corticospinal tract crosses at the pyramidal decussation)
Patient has spastic weakness contralateral and below the lesion (↑tone and ↑reflexes)
if you have a lesion in the long tract in the brain stem of the medial lemniscus?
Since the ML contains crossed axons of the second neuron, a lesion will result in a loss of touch, vibration, conscious proprioception contralateral
lesion in the brainstem for spinothalamic tract?
Crossed in cord- lesion results in a pain and temperature loss contralateral
3 somatic motor functions of the reticular formation
- Pontine and medullary reticulospinal tracts for Posture and locomotion
- Gaze Centers (PPRF) for coordination of eye movements, particularly horizontal gaze and saccades.
- Central Pattern Generators that produce rhythmic signals to the muscles involved in breathing and swallowing.
Pontine and medullary reticulospinal tracts are for ___ and are in the ___of the brain stem
posture and locomotion
reticular formation
1.Gaze Centers (PPRF) for coordination of ___ and is found where in the brain stem
eye movements, particularly horizontal gaze and saccades.
reticular formation
Central Pattern Generators that produce rhythmic signals to the muscles involved in ___ are found where in the brain stem
breathing and swallowing
reticular formation
the cardiorespiratory center of the reticular formation receives information from ___
Neurons in the caudal part of the solitary nucleus respond to
- Chemoreceptors that monitor levels of carbon dioxide and oxygen in the blood (CN IX, X)
- Baroreceptors that monitor changes in blood pressure (CN IX, X)
- Stretch receptors in the lungs (CN X).
solitary nucleus is found ___ and does what?
the reticular formation of the brain stem
controls blood pressure and heart rate
Neurons in the caudal part of the solitary nucleus respond to
- Chemoreceptors that monitor levels of carbon dioxide and oxygen in the blood (CN IX, X)
- Baroreceptors that monitor changes in blood pressure (CN IX, X)
- Stretch receptors in the lungs (CN X).
Part of the ___ is Pain Modulation – part of descending pain modulation system that can block nociceptive inputs
reticular formation
Reticular formation and small core nuclei in brainstem are part of the ___ - a set of connected nuclei that are responsible for regulating wakefulness, sleep-wake transition and attention
Ascending Reticular Activating system (ARAS)
___ part of the reticular formation maintains consciousness
Ascending Reticular Activating system (ARAS)
4 main functions of reticular formation
sleep and consciousness
pain modulation
Cardiorespiratory Center- blood pressure, heart rate
Somatic Motor function - posture, eye movement, swallowing
red
somatic efferent (3,4,6,12)
yellow
visceral efferent
3,7,9,10
orange
special efferent
5,7,9,10,11 (C1-5) branchiomeric muscle
SE ‑special efferent fibers to skeletal muscle of branchiomeric origin – V, VII, IX, X, IX
purple
special afferent 8
green
blue
red
grey
pink
Somatic Efferent
(skeletal muscle)
Visceral Efferent
(preganglionic parasympathetic)
Special Efferent
(skeletal muscle that develops in the branchial arches)
what kind of nerve fibers?
somatic efferents to skeletal muscle from CN 3,4,6 and 12
CN3 oculomotor nuclei
what is the function of CN 3
oculomotor
Function:
Move the eyeball
Elevate the eyelid
pupillary light reflex - Contricts the pupil
dysfunctions with CN 3 will do what?
oculomotor
Function:
drooping eyelid
dilated, non-responsive pupil
abduction and downward deviation of eye
CN4 trochlear
___ nucleus also contains interneurons that project to contralateral oculomotor nucleus
Abducens
CN12
Damage to hypoglossal nucleus or nerve:
tongue deviates toward the damaged side
Hyperglossal nerve (XII) innervates___ tongue muscles
ipsilateral
function of CN8
vestibulocochlear
hearing and balance
dysfunction in CN8
Deafness
Loss of balance
Ataxia (lack of coordination)
head tilt
falling/ rolling to one side
Nystagmus
Strabismus
Compare Trigeminal Principal (Main) Sensory Nucleus to DC-ML System Touch, vibration
rostral medulla
comes in on trigeminal ganglion, synapse on MO, cross up ML to thalamus (VPM)→ brain
trigeminal principal(main) sensory nucleus
will recieve touch and vibration form CN5(trigeminal) from the face
spinal trigeminal nucleus
pain and temp from the face down to the trigeminal ganglion, synapse and travel back up to the spinal trigeminal nucleus
pain and temp from the face
