ascending & descending tracts Flashcards
How many neurons are there in conscious and unconscious tracts?
3 in conscious
2 in unsconscious
Where does the corticospinal tract decussate?
Pyramidal medullary decussation. 80% decussate, whereas 20% remain ipsilateral. So you get lateral and anterior corticospinal tracts. Anterior corticospinal decussate at the spinal nerve level at which they exit.
What do the corticospinal tracts control?
Fine motor control of distal muscles e.g. hands, feet, digits. - mostly lateral corticospinal.
Anterior corticospinal ends at cervical and thoracic levels so does head and neck?
Which tracts are ascending/sensory?
Spinothalamic
Dorsal Column Medial Lemniscus
Spinocerebellar
Trigeminal
Where does the spinothalamic tract decussate?
At the spinal level it enters at or above. If travelling up or down first it goes up or down then synapses and decussates.
What’s spinothalamic called once it enters brainstem?
Lateral spinal lemniscus
What the area in a transverse section through which spinothalamic axons travel?
Lissauer’s at dorsal column posterior.
Where does the DCML pathway decussates?
In the medulla, at the nuclei of their own name i.e. nucleus gracilis and nucleus cuneatus.
Where does fascilus cuneatus end?
At T6, above T6 you have both cuneatus and gracilis. Below you only have gracilis
What part of midbrain to all descending tracts go through?
Crus cerebri
What does the trigeminal tract go through?
V1 - opthalmic
V2 - maxillary
V3 - mandibular
All 3 have sensory nuclei
Only mandibular has also motor.
Go into trigeminal nucleus in brainstem. There’s a trigeminal ganglion before the trigeminal nucleus. They synapse at the thalamus. Second order neurons are called trigeminothalamic tracts. and go to the somatosensory cortex. Pain/temp/crude touch.
All come from face + proprioception TM and muscles of mastication.
Where does the corticospinal tract decussate?
80% at pyramids of medulla forming the lateral corticospinal tract and 20% at spinal level forming the anterior corticospinal tract.
What does the corticospinal tract serve?
fine motor of distal limbs
What does rubrospinal tract do?
Fine motor control of hands (flexors).
Where does rubrospinal start and decussate?
Starts from red nucleus of of midbrain and decussates within the tegmentum ‘ventromedial’.
Goes to cervical and lumbar.
