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-referred to as the "little brain"
-attaches posteriorly to the brainstem and occupies the posterior cranial fossa
-coordination center for motor funcitons
-does not initiate actual motor functions, it uses the brainstem to connect with the cerebrum to execute a variety of movements, including maintenance of muscle tone, posture, balance, and coordination of movement
cerebellum
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-the cerebellum consists of two ... (lateral hemispheres)
-these hemispheres have an interesting appearance because the folds of gray matter resemble a cauliflower
cerebellar hemispheres
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a midline structure called the ... connects the two cerebellar hemispheres
vermis
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on the inferior surface of the cerebellar hemispheres are two rounded prominences called the
cerebellar tonsils
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-three pairs of nerve fiber tracts, the cerebellar peduncles, connect the cerebellum to the brainstem
-the ... connect the cerebellum to the midbrain
-the ... serve as attachments to the pons, and the ... attach to the medulla oblongata
- superior cerebellar peduncles
- middle cerebellar peduncles
- inferior cerebellar peduncles
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-deep within the center of each cerebellar hemisphere is a collection of nuclei called the ...
-the largest and most lateral of the deep cerebellar nuclei
-fibers of this project to the thalamus via the superior cerebellar peduncles. from here, the fibers travel to the motor areas of the cerebral cortex, namely the precentral gyrus thus influencing motor control
dentate nucleus
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-supply the frontal, parietal, and temporal lobes of the brain and orbital structures
-these arteries arise from the bifurcation of the carotid arteries in the neck and can be divided into 7 segments. they ascend through the base of the skull and enter the carotid canals of the temporal bones
internal carotid arteries
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the internal artery then turns forward within the cavernous sinus, then up and backward through the dura mater, forming an S shape referred to as the ... before it reaches the base of the brain
carotid siphon
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as the internal carotid artery exits the cavernous sinus, it branches into the ... just inferior to the anterior clinoid process
ophthalmic artery
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the ... and its branches supply the anterior frontal lobe and the medial aspect of the parietal lobe
anterior cerebral artery
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the main segments and branches of the anterior cerebral artery are the
horizontal (A1) segment, the vertical (A2) segment, and the distal (A3) segment
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-the horizontal segment of the anterior cerebral artery extends from the internal carotid artery (ICA) bifurcation to the...
-this artery joins the two anterior cerebral arteries just anterior to the optic chiasm
anterior communicating artery
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-the vertical segment of the anterior cerebral artery, an extension of the horizontal segment, courses superiorly toward the rostrum of the corpus callosum
-major branches are the
orbitofrontal, frontopolar, pericallosal, callosomarginal, and splenial arteries
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the distal segment of the anterior cerebral artery curves around the genu of the corpus callosum and continues as the
pericallosal artery
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-the ... is by far the largest of the cerebral arteries and is considered a direct continuation of the internal carotid artery
-gives off many branches, as it supplies much of the lateral surface of the cerebrum, insula, and anterior and lateral aspects of the temporal lobe; nearly all the basal ganglia; and the posterior and anterior internal capsule
middle cerebral artery
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four major segments of the middle cerebral artery are the
horizontal (M1), insular (M2), opercular (M3), and cortical (M4)
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the horizontal segment of the middle cerebral artery courses from the origin at the internal carotid artery bifurcation laterally toward the insula and branches into the ... which supply to the lentiform nucleus, parts of the internal capsule, and caudate nucleus
lateral lenticulostriate
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-begin in the neck at the subclavian artery ans ascend vertically through the transverse foramina of the cervical spine
-can be divided into four segments
-curve around the atlanto-occipital joints to enter the cranium through the foramen magnum
vertebral arteries
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the two vertebral arteries course along the medulla oblongata and unite ventral to the pons to form the
basilar artery
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four major pairs of arteries in order from inferior to superior
posterior inferior cerebellar (PICA), anterior inferior cerebellar (AICA), superior cerebellar (SCA), and posterior cerebral (PCA)
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the posterior cerebral arteries can be divided into four major segments
precommunicating or peduncular (P1), ambient (P2), quadrigeminal (P3), and calcarine (P4)
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forms a connection between the posterior cerebral artery and the internal carotid artery
posterior communicating artery
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-critically important anastomosis among the four major arteries feeding the brain
-formed by the anterior and posterior cerebral, anterior and posterior communicating, and the internal carotid arteries
-located mainly in the suprasellar cistern at the base of the brain
-functions as a means of collateral blood flow between cerebral hemisphere in the event of blockage
circle of willis
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-relatively small mass of tissue packed with motor and sensory nuclei, making it vital for normal brain function
-10 of the 12 cranial nerves originate from nuclei located here
-major segments are the midbrain, pons, and medulla oblongata
-as a whole acts as a conduit among the cerebral cortex, cerebellum, and spinal cord
brainstem
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located within the central portion of the brainstem and common to all three segments is the ..., an area that provides integrative functions, such as complex motor patterns, aspects of respiratory and cardiovascular activity, and regulation of consciousness
tegmentum
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the central core of the tementum contains the ..., an area containing the cranial nerve nuclei and ascending and descending tracts to and from the brain
reticular formation
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-located above the pons at the junction of the middle and posterior cranial fossae
-smallest portion of the brainstem
-primarily composed of massive bundles of nerve fiber tracts and can be divided into two major segments: CEREBRAL PEDUNCLES and the TECTUM "QUADRIGEMINAL PLATE"
-surrounds the cerebral aqueduct, which contains CSF and connects the third and forth ventricles
midbrain
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-large oval-shaped expansion of the brainstem centrally located between the midbrain and medulla oblongata
-creates a prominent bulge as it lies just posterior to the clivus and anterior to the cerebellum
-literally means bridge
-pontine fibers relay signals between the spinal cord and the cerebral and cerebellar corices
pons
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-extends from the pons to the foramen magnum, where it continues as the spinal cord
-contains all fiber tracts between the brain and spinal cord, as well as vital centers that regulate internal activities of the body
-these centers are involved in the control of heart rate, respiratory rhythm, and blood pressure
medulla oblongata
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-the center of the anterior and posterior surfaces of the medulla oblongata is marked by the ... and ...
-these two fissures divide the medulla oblongata into two symmetric halves
anterior and posterior median fissures
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-located on either side of the anterior median fissure are two bundles of nerve fibers
-these contain nerve tracts that contribute to voluntary motor control
-at the lower end of these, some of the nerve tracts cross over to the opposite side (accounts for the fact that each half of the brain controls the opposite half of the body)
medullary pyramids
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-largest portion of the brain
-divided into left and right hemispheres
cerebrum
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each cerebral hemisphere contains neural tissue arranged in numerous folds called
gyri
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the gyri are separated by shallow grooves called ... and deeper grooves called ...
sulci and fissures
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the main sulcus that can be identified on CT and MRI images of the brain is the ..., which divides the PRECENTRAL GYRUS of the frontal lobe and POSTCENTRAL GYRUS of the parietal lobe
central sulcus
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-considered the motor strip of the brain
-divided by the central sulcus in the frontal lobe
precentral gyrus
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-considered the sensory strip of the brain
-divided by the central sulcus in the parietal lobe
postcentral gyrus
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-one of the main fissures of the cerebrum
-long, deep furrow that divides the left and right cerebral hemispheres
-located here is the falx cerebri and superior sagittal sinus
longitudinal fissure
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-one of the main fissures of the cerebrum
-deep furrow that separates the frontal and parietal lobes from the temporal lobe
-numerous blood vessels, primarily branches of the middle cerebral artery, follow the course of this fissure
lateral (Sylvian) fissure
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neuron cell bodies
gray matter
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myelinated axons
white matter
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-outermost portion of the cerebrum
-composed of gray matter approx. 3-5 mm. thick
-not only receives sensory input but also sends instructions to the muscles and glands for control of body movement and activity
-deep in this is white matter, which contains fibers that create pathways for the transmission of nerve impulses to and from the ...
cerebral cortex
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-the largest and densest bundle of white matter fibers within the cerebrum if the
-this midline structure forms the roof of the lateral ventricles and connects the right and left cerebral hemispheres
corpus callosum
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four parts of the corpus callosum
rostrum, genu, body, and splenium
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-another important bundle of white matter
-crosses the midline within the lamina terminalis and connects the anterior portions of each temporal lobe
anterior commissure
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-another important bundle of white matter
-pathway made of several fibers that transmit nerve impulses for pupillary (consensual) light reflexes
-this pathway crosses the midline posterior to the third ventricle, immediately above the cerebral aqueduct and inferior to the pineal body
posterior commissure
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