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112 terms

Gross Brain Structures and CNS vasculature

What are the two cerebral hemispheres separated by?
A deep fissure known as the longitudinal fissure
What are Sulci?
What are gyri?
What are the five lobes of the cerebral cortex?
Frontal, Parietal, Occipital, Temporal, and Limbic
What is the Central Sulcus?
an important landmark sperating the somatic motor and sensory cortical regions
What serves as the boundary between the frontal and parietal lobes?
The central sulcus
What is the central sulcus aka?
the rolandic sulcus
What separates the temporal and frontal lobe?
The lateral fissure
What is the lateral fissure aka?
the sylvian fissure
Where is the precentral gyrus located?
just rostral to the central sulcus
What does the precentral gyrus contain?
the motor areas of the cerebrum
What does the precentral sulcus seperate?
The precentral gyrus from the three horizontal gyri of the frontal lobe
What are the three horizontal gyri of the frontal lobe?
The superior, middle, and inferior frontal gyri
What sulci serperate the horizontal gyri of the frontal lobe?
the superior, and inferior frontal sulci
What is Broca's speech area?
It is the motor region for speech formulation and defines the dominant hemisphere
Where is Broca's Speech area located?
It is a region located in the inferior frontal lobe near the prefrontal cortex at the posterior part of the inferior frontal gyrus of ONE hemisphere
What is the parietal lobe involved in?
somatosensory information and with making associations among the varied snesory inputs arriving in the cerebrum
Where is the parietal lobe located?
it extends from the central sulcus caudally to an imaginary line drawn between the parietal-occipital sulcus and the preoccipital notch
What is the postcentral gyrus aka?
The primary somatosensory cortex
Where is the postcetnral gyrus located?
just caudal to the central sulcus
What is the postcentral gyrus primarily concerned with?
the initial cortical processing of tactile and proprioceptive information
What is the portion of the parietal lobe divided into that lies jst caudal to the postcentral sulcus?
the superior and inferior parietal lobes
What does the inferior parietal lobe consist of?
the supramarginal gyrus and the anguluar gyrus
What is the inferior parietal lobe particularly involved in along with portions of the temporal lobe?
The comprehension of language
What is the remaining portion of the parietal lobe involved with?
spacial orientation and perception
What are the four major functions that the temporal lobe is associated with?
Primary auditory cortex, language comprehension, higher order visual processing, learning and memory
How many gyri does the lateral surface of the temporal lobe have?
Three gyri, known as the superior, middle, and inferior temporal gyri
What are the three gyri of the lateral surface of the temporal lobe separated by?
Two sulci, known as the superior and inferior temporal sulci
What structure located on the ventral surface of the brain is part of the temporal lobe?
The parahippocampal gyrus
What is the medial projection off the anterior parahippocampal gyrus?
The uncus
What is the primary auditory cortex?
an area for hearing, located in the superior surface of the temporal lobe and superior temporal gyrus
What is the language comprehension area of the temporal lobe?
Wernicke's area
What is Wernicke's are responsible for?
the sense of hearing which functions in the interpretation of speech.
Where is the Wernicke's are located?
the posterior part of the superior temporal gyrus and in parts of the adjacent parietal and occipital lobes (in the dominant, usually the left, hemisphere)
Much of the temporal lobe is associated with higher order visual proecessing, but this are is of particular importance.
The inferior surface of the temporal lobe
This part of the temporal lobe is involved in learning and memory and is actually part of the limbic system and is related to underlying limbic structures.
The medial portion of the temporal lobe, aka the medial temporal lobe
Where is the occipital lobe located?
in the cerebral hemispheres, caudal to the imaginary line drawn between the parieto-occipital fissure and the preoccipital notch
What is the ossipital lobe aka?
The visual cortex
What is unique about the lateral surface of the occipital lobe?
Its lateral surface is variable and contains the lateral occipital gyri
What is the cuneate gyrus?
a wedge shaped portion of the occipital lobe between the parieto-occipital fissure and the calcarine sulci
What lies inferior to the cuneate gyrus?
The lingual gyrus
What is the limbic lobe primarily composed of?
the cingulate and parahippocampal gyri
Where is the cingulage gyrus located?
immediately superior to the corpus callosum and proceeds posteriorly to become continuous with the parahippocampal gyrus
What is the limbic system of structures important for?
emotional responses, drive-related behavior and memory
What is the corpus callosum?
It is composed of fibers interconnecting the two cerebral hemispheres that is large and consists of four parts
What are the four parts of the corpus callosum?
The rostrum, genu, body, and splenium
What are the two major commissures visible from the medial aspect of the brain?
the anterior commissure and the posterior commissure
Where is the anterior commissure located?
just in front of the columns of the fornix
What is the fornix part of?
The limbic system
Where is the posterior commisure located?
near the base of the pineal body
What is located caudal to the corpus callosum?
A thin sheet of gray matter known as the septum pellucidum which occupies the midline
What is located caudal and posterior to the septum pellucidum?
the thalamus
What frequently results when the medial thalamus fuses with its contralateral counterpart?
The massa intermedia (aka interthalamic adhesions)
What is the thalamus seperated from the hypothalamus by?
The hypothalamic sulcus
How far does the hypothalamus extend rostrally?
To the optic chiasm
How far does the hypothalamus extend caudally?
to the mamillary bodies
What is the infundibulum?
The stalk that attaches to the pituitary (aka hypohysis) to the hypothalamus
Cerebral circulation is provided by which four vessels?
2 internal carotids and 2 vertebrals
Which vessel provides the PRIMARY blood supply to the brain?
The internal carotid artery
What does the internal carotid artery anastomes with?
the vertebral artery and the contralateral internal carotid a.
What is the pathway of the internal carotid artery?
It enters the cranium adjacent to foramen lacerum and traverses the cavernous sinus which is adjacent to the hypophysis (pituitary)
What are the branches of the internal carotid artery?
The opthalamic artery, the posterior communicating a., the anterior chorodial artery,
the anterior cerebral artery, the middle cerebral artery,
What does the opthalamic artery supply?
the optic nerve, the optic chiasm, the optic tract, the retina, the extraocular muscles, the eyelids, the forehead, the ethmoidal air cells, the lateral nasal wall and dorsum of the nose.
Where does the opthalamic artery branch?
adjacent to the hypophysis (pituitary) at the posterior margin of the orbit
What is the posterior communicating artery?
A branch of the internal carotid artery that connects to the posterior cerebral a.
What is the posterior communicating artery a part of?
The circle of Willis
What does the anterior choroidal artery follow?
The optic tract
What does the anterior choroidal artery supply?
The optic nerve, chiasm, and tract, the hippocampal formation, parts of the basal ganglia, the thalamus, and the posterior limb of the internal capsule, and the choroid plexus
Where does the anterior cerebral artery travel?
Between the 2 hemispheres and is joined in the midline by the anterior communicating artery
What does the anterior cerebral artery supply?
The midline cortical structures, the medial and inferior portions of the frontal lobes (lower extremity regions of motor cortex), medial portions of parietal lobes (lower extremity regions of sensory cortex), rostral corpus callosum and limbic lobe, parts of basal ganglia, anterior limb of internal capsule, olfactory bulb and tract, parts of the optic nerve, chiasm, and tract
What are the major branches of the anterior cerebral artery?
The orbital, frontopolar, the pericallosal, and the callosomarginal
Which artery is the largest and most complex cerebral arteries and is a direct continuation of the internal carotid artery?
The middle cerebral artery
How does the middle cerebral artery travel?
Laterally within the lateral and central sulci between the frontal, parietal, and temporal lobes
What are the branches of the middle cerebral artery?
The lenticulostriate arteries, and the superior and inferior trunks
What does the lenticulostriate do?
Penetrates the anterior perforated substance known as the striate
What does the lenticulostriate primarily supply?
The basal ganglia structures and internal capsule (anterior and posterior limbs)
What can happen when the lenticulostriate arteries are occluded?
It can cause major deficits if the internal capsule is affected
What arteries are subdivided into multiple branches to supply most of the convexity of the cerebral hemisphere, including the frontal, parietal, temporal, and occipital lobes?
The superior and inferior trunks
What areas specifically are supplied by the superior and inferior trunks?
The inferior and middle frontal gyri, most of the pre and post cenral gyri, the superior and inferior parietal lobules, the superior and middle temporal gyri, and the rostral portions of the occipital lobe
The rolandic (central sulcal) branches are the most common branches to experience what?
What are the branches of the superior and inferior trunks?
The rolandic (central sulcal), prerolandic, orbitofrontal, temporal, angular, parietal
How do the vertebral arteries enter the cranial vault?
Through ascending in the transverse foramina of C6 and above then entering through the foramen magnum
Because of this tortuous route of the vertebral arteries, what might some patients experience during extension and rotation of the head?
vertebrobasilar insufficiency
What are the branches of the vertebral arteries?
Anterior spinal artery, posterior spinal artery, and posterior inferior cerebellar artery (PICA)
What does the anterior spinal artery supply?
Roughly 2/3 of the anterior spinal cord
How is the anterior spinal artery formed?
Two arteries unite to form one single artery descending mid line vessel
How does the posterior spinal artery traverse?
It sometimes remains as paired descending vessels on the posterior surface of the spinal cord
What does the posterior spinal artery supply?
The posterior 1/3 of the spinal cord
What does the posterior inferior cerebellar artery (PICA) supply?
parts of the medulla and inferior aspect of the cerebellum
What is occlusion of the PICA known as?
Lateral medullary syndrome
What is the artery that is the result of two arteries uniting at the caudal border of the pons?
The basilar artery
What does the basilary artery split into at the level of the midbrain?
The posterior cerebral arteries
What are the branches of the basilar artery?
The anterior inferior cerebellar artery, the labyinthine artery, the prontine branches, the superior cerebellar arteries, the posterior cerebral arteries
What does the anterior inferior cerebellar artery?
parts of the pons and anterior portions of the inferior cerebellum
What does the labryinthine artery supply?
the inner ear, NOT THE BRAIN STEM
What do the pontien branches supply?
The pons
What does the superior cerebellar artery supply?
The superior parts of the cerebellum, caudal midbrain, and rostral pons
What does the posterior cerebral artery supply?
Parts of the midbrain and thalamus, inferior surface of the temporal lobe, and the medial aspect of the occipital lobe, including the primary visual cortex, and splenium of corpus callosum
What is the circle of Willis?
A region of overlapping blood supply in the brain and anastomotic connections to protect the brain when part of its vascular supply is blocked
What is the circle of willis composed of?
Two posterior cerebral arteries, 2 posterior communicating arteries, 2 internal carotid arteries, 2 anterior cerebral arteries, and 1 anterior communicating arteries
What is vascular insufficiency?
A disruption of blood flow to a region of tissue
What is a stroke or CVA?
An abrupt incident of vascular insufficiency. Most are typically due to blocked blood flow (ischemic stroke) or to bleeding from a vessel (hemorrhagic stroke)
What is the most common cause of ischemic strokes?
thrombus or embolus
What is the result of reduced blood flow to a region of brain tissue?
Neurological damage ranging from decreased neuronal activity to necrosis depending upon the length of time blood flow is lost
What is the size of an infarct related to?
The size of the occluded vessel. Blockage of smaller perforating arteries have smaller areas of necrosis than that of larger vessels
Does that mean that small infarcts cannot produce sever symptoms?
No, even very small infarcts can produce severe neurological deficits depending of location
Hemorrhagic strokes are often the result from the rupture of small perforating arteries, what is the most common cause of the rupture?
What is an aneurysm?
A ballon-like swelling in the wall of an artery, it can occure anywhere but most often at or near an arterial bifurcation
Where are aneurysms most likely to occur in cerebral circulation?
at or near the anterior half of the circle of Willis, but they can occur other places
What causes the pathological symptoms of aneurysms?
Pressure on nearby structures or rupture causing subarachnoid hemorrhage
Is the diagnosis of aneurysm always a death sentence?
No, many can be corrected surgically if detected in time
What is Arteriovenous Malformation (AVM)?
Congenital malformation in which there is an abnormal direct connection between the arteries and veins without normal intervening capillary bed. This condition makes sufferes prone to bleeding and results in neurological symptoms