UNIT 2: Brain Stems and Supporting Systems Flashcards
what does the diencephalon include
thalamus, epithalamus, subthalamus, hypothalamus, plus mammillary bodies
describe the thalamus
- contains multiple nuclei that are part of motor, sensory, and associative pathways
- receives ALL sensory feedback (except olfactory), and relays to the cortex (i.e. thalamus decides whether the info is worthwhile - like a gate keeper/amplifier … decides what is worthwhile and also whether the the dial needs to be turned up or down)
- motor contribution –> transmits info from cerebellum and BG to primary motor cortex (involved in motor planing and initiation of speech)
- axons that connect thalamus and cerebral cortex pass thru the internal capsule
what is the thalamus made up of
many nuclei - each do something specific and talk to specific systems (ex. vision)
Connection bw limbic sys and thalamus
limbic sys will tell the thalamus whether it needs to focus on something in relation to memories associated w a sensory or motor signal
hypothalamus functions
- controls many body activities - major regulator of homeostasis
- sensory input related to somatic, visceral, and special (taste, smell, vision) senses arrive here
- important connections w pituitary gland; produces a variety of hormones
- controls and integrate activities of the ANS - major regulator of visceral activities (contraction of smooth and cardiac muscle, gland secretion)
- regulates emotion + behaviour, eating and drinking, body temp, circadian rhythms, and consciousness
describe the composition of the cerebellum
- external portion is gray matter (cortex)
- internal core is comprised of white matter (tracts) and deep nuclei (subcortical nuclei)
- communicates w pons via cerebellar peduncles (afferent and efferent tracts)
- each hemisphere has 3 lobes: anterior, posterior, flocculonodular
- vermis = central cortex that connects the 2 cerebellar hemispheres (analogous to corpus callosum)
- more neurons than cortex!
function of cerebellum
- primary structure responsible for coordination of fine movement: integrates somatic info related to vestibular function (balance), muscle and joint sense, and perception of the body in space
- works w cerebrum to fine tune the motor plan for optimal execution
- i.e. helps us compare what I thought i was gonna do to what I actually did (motor learning ) - whereas the BG helps us select a motor plan
what are the 3 functional divisions of the cerebellum?
- vestibulocerebellum (flocculonodular lobe)
- spinocerebellum (anterior lobe and posterior lobe)
- cerebrocerebellum (posterior lobe)
vestibulocerebellum (flocculonodular lobe) of cerebellum
integrates vestibular info about body position w motor plan
spinocerebellum (anterior lobe and posterior lobe) of cerebellum
integrates proprioceptive info (body sense of position and movement in space) and controls gait and stance
cerebrocerebellum (posterior lobe) of cerebellum
execution of voluntary motor plans initiated by cerebral cortex - feedback to smooth movements, correct errors, coordinate complex sequences of muscle contraction
3 anatomic divisions of the brainstem
mesencephalon = midbrain
metencephalon = pons (minus cerebellum)
myelencephalon = medulla oblongata
all pathways to and from cerebrum pass through…
the brainstem (afferent and efferent)
the brainstem contains what types of nuclei
- many autonomic regulatory nuclei
- nuclei associated w cranial nerves II thru XII
what does the midbrain contain
aqueduct, fibre tracts, nuclei
the midbrain’s aqueduct connects to…
the 3rd ventricle above w the 4th ventricle below
the fibre tracts of the midbrain are also called “___” and contain “___” and “____”
- cerebral peduncles (pair of vertical fibre tracts)
- corticopsinal, corticobular, and corticopontine motor neuros (refer to where they go)
- sensory neurons from medualla to thalamus
what are the 4 nuclei of the midbrain
superior colliculi, inferior colliculi, substantia nigra, red nuclei
superior colliculi
- nuclei in the midbrain
- central visual pathway nuclei
inferior colliculi
- nuclei in the midbrain
- central auditory pathway nuclei
substantia nigra
- nuclei in the midbrain
- subconscious muscle activity (functionally part of the basal ganglia)
red nuclei
- nuclei in the midbrain
- minor role in motor function (i.e. limb flection) in association w cerebellum
which cranial nerves are associated w the midbrain
oculimotor nerve (III) (motor), trochlear nerve (IV) (motor), mesencephalic nerve of trigeminal tract (V) (sensory)
what and where is the pons
- enlarged section of the brainstem bw the midbrain (above) and medulla (below)
- bridge to the cerebellum (anterior to it)
the pons contains
- fibre tracts
- CN nuclei
on the ventral side of the pons you can see what type of fibre tracts?
- cerebral peduncles –> horizontal fibre tracts allowing communication bw cerebrum, brainstem, and cerebellum (maximizes efficiency of voluntary motor control)
- basilar sulcus –> cradles the basilar artery (a depression)
on the dorsal side of the pons there are fibre tracts similar to the…
medulla - carry both sensory and motor info - corticobular and corticospinal tracts
which cranial nuclei are in the pons
- trigeminal motor nuclei
- principal sensory nuclei of the trigeminal tract
-abducent nuclei (motor) - facial motor nuclei
- superior salivatory nuclei (motor)