Flashcards in Exam 2: Brainstem and Cerebellum Deck (25)
1
Brainstem
-consists of mesencephalon (midbrain), pons, medulla oblongata
-relay center for sensory input and motor output
-also responsible for many basic reflex actions
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Pyramids
-bilateral ridges on anterior (ventral) side of medulla oblongata
-motor axons
-most of these axons desussate (cross over to opposite side)
-so in most instances each side of brain controls opposite side of body
3
Autonomic Nervous System Centers (part of what)
-part of medulla oblongata
-cardiac center: regulates heart rate
-vasomotor center: constricts and dialates arterioles so it regulates bp (constrict=increased bp, dialate=decreased bp)
-respiratory center: regulates breathing rate
-other centers
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Inferior Part of 4th Ventricle
-space inside medulla oblongata
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Pons
-chiefly composed of groups of axons (nerve fiber tracts)
-middle portion of brainstem
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Respiratory Centers
-in pons help to control rate and depth of breathing
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Superior Part of Fourth Ventricle
-part of pons
-continuous with cerebral aqueduct
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Tectal Plate
-on posterior side of mesencephalon
-divided into superior colliculi and inferior collicui
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Superior Colliculi
-(2) visual reflex centers
-coordinate head and eye movements to sudden image
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Inferior Colliculi
-(2) auditory reflex centers
-coordinate head and eye movements to sudden sound
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Cerebral Peduncles
-part of mesencephalon
-groups of axons (nerve fiber tracts) on anterior side of mesencephalon
-conduct nerve impulses between cerebrum and brainstem
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Cerebellum
-right and left cerebellar hemispheres
-not part of brainstem
-higher motor and sensory functions
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Cerebral (Mesencephalic) Aqueduct
-connects 4th ventricle to 3rd ventricle
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Cerebellar Peduncles Definition
-groups of axons (nerve fiber tracts)
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Inferior Cerebellar Peduncle
-connect medulla oblongata to cerebellum
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Middle Cerebellar Peduncle
-connect pons to cerebellum
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Superior Cerebellar Peduncle
-connect midbrain to cerebellum
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Functions of Cerebellum
-coordinates and fine tunes skeletal muscle movement (cerebrum initates the movement, but the cerebellum makes it pretty)
-maintains balance and posture in response to info from proprioceptors (sensory nerve endings in muscles, joints, and tendons)
-DOES NOT START SKELETAL MUSCLE MOVEMENT
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Cranial Meninges
-Pia Mater
-Subarachnoid space
-Arachnoid matter
-Dura Mater-outermost layer
-Inner Meningeal Layer
-Outer periosteallayer
-(in order from deepest to most superficial)
-in some areas the layers are separated and form dural venous sinuses
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Dural Venous Sinuses
-large veins that drain blood away from vein
-between inner menigeal and outer periosteal layers of dura mater
-vein walls formed from dura mater
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CSF
-cerebrospinal fluid
-provides buoyency for brain and spinal cord
-maintains CNS chemical environment
-produced continuously (approx 500 mL/day)
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Ventricular System Consists of
-1 & 2) left and right lateral ventricles: found in each cerebral hemisphere
-3) third ventricle: space in diencephalon connects to each lateral ventricle via an interventricular foramen
-4) cerebral aqueduct: in mesencephalon
-5) fourth ventricle: in pons and medulla oblongata.
-(CSF flows from 1-5)
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CSF Circulation Process
-CSF produed by choroid plexus in ventricles
-CSF flows from third ventricle to cerebral aqueduct to 4th ventricle
-CSF leaves 4th ventricle and enters subarachnoid space
-CSF circulates in subarachnoid space
-Excess CSF removed from subarachnoid space by arachnoid villi
-Pressure in subarachnoid space opens 'flap' in a villus so excess CSF leaves the subarachnoid space and enters dural venus sinuses (bloodstream)
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Arachnoid Villi
-extensions of arachnoid mater that project int dural venous sinus
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