Chapter 10 Flashcards
Where is Broca’s area located?
A: In the dominant, usually left hemisphere, it lies in the inferior frontal gyrus, just anterior to the articulatory areas of the primary motor cortex.
Where is Wernicke’s area located?
A: In the superior temporal gyrus, adjacent to the primary auditory cortex and is involved in language processing.
The arterial supply to the cerebral hemispheres is derived from…?
A: The anterior circulation provided by the bilaterally paired internal carotid arteries, as well as by the posterior circulation provided by the bilateral vertebral arteries
The vertebral arteries, which supply the posterior circulation, arise from the subclavian arteries and then ascend through where?
A: Through foramina in the transverse processes of the cervical vertebrae before entering the foramen magnum.
What is the Circle of Willis?
A: Where the anterior and posterior circulations meet in an anastomotic ring from which all major cerebral vessels arise.
What are the main arteries supplying the cerebral hemispheres?
A: The main arteries supplying the cerebral hemispheres are the: 1. anterior 2. middle 3. posterior
- The anterior cerebral arteries (ACAs) and middle cerebral arteries (MCAs) are the terminal branches of the internal carotid arteries
How are the anterior and posterior circulations are linked to each other via what arteries?
A: The anterior and posterior circulations are linked to each other via the posterior communicating arteries, the PComm’s, which connect the internal carotids to the posterior cerebral arteries.
The posterior cerebral arteries (PCAs) are formed by the top of what artery?
A: The top of the basilar artery, which in turn is formed by the convergence of two vertebral arteries.
Anterior circulation arises from the____ arteries while posterior circulation arises from the ______ arteries
A: Internal carotid arteries; vertebral arteries
Anterior circulation arises from the INTERNAL CAROTID ARTERIES
Posterior circulation arises from the VERTEBRAL arteries
What vascular territory in the brain does the anterior cerebral artery cover?
A: The ACA passes forward to travel in the interhemispheric fissure as it sweeps back and over the corpus callosum. The ACA supplies most of the cortex on the anterior medial surface of the brain, from the frontal to the anterior parietal lobe, including the medial sensorimotor
The anterior cerebral artery (depicted in yellow on the diagrams) is a terminal branch of the internal carotid artery. It is divided into 2 or 3 segments, depending on the author.
A1 segment: from origin to anterior communicating artery and gives rise to medial lenticulostriate arteries (inferior parts of the head of the caudate and the anterior limb of the internal capsule)
A2 segment: from anterior communicating artery to bifurcation in pericallosal artery and callosomarginal artery
A3 segment: major branches, excluding terminal branches, which supply the medial portions of FRONTAL lobes, superior medial part of PARIETAL lobes, anterior part of the CORPUS COLLOSUM
What 2 major arteries branch off from the ACA?
A: The callosomarginal artery and pericallosal artery
What vascular territories do the MCA cover?
A: The MCA turns laterally to enter the depths of the Sylvian fissure. Within the Sylvian fissure, it usually bifurcates into the SUPERIOR division and the INFERIOR division. The superior division supplies the cortex above the Sylvian fissure, including the lateral frontal lobe and usually includes the Rolandic cortex. The inferior division supplies the cortex BELOW the Sylvian fissure, including the lateral temporal lobe and a variable portion of the parietal lobe.
The MCA supplies most of the cortex on the dorsolateral convexity of the brain.
The cortical branches of the MCA (depicted in red on the diagrams) supply the lateral surface of the hemisphere, EXCEPT for the medial part of the frontal and the parietal lobe, which are supplied by the ACA, and the inferior part of the temporal lobe, which is supplied by the PCA.
What vascular territory does the PCA cover?
A: The PCA curves back after raising from the top of the basilar and sends branches over the inferior and medial temporal lobes and over the medial occipital cortex. Therefore, it includes the inferior and medial temporal and occipital cortex.
The vascular territory of the PCA is depicted in blue. The P1 segment extends from the PCA origin to the posterior communicating artery, contributing to the circle of Willis. Posterior thalamoperforating arteries branch off the P1 segment to supply blood to the midbrain and thalamus. Cortical branches of the PCA supply the inferomedial part of the temporal lobe, occipital pole, visual cortex, and splenium of the corpus callosum. In addition, the arterial supply of hippocampus usually arise from PCA, including:
anterior hippocampal artery, which usually arises from the PCA and less commonly from the anterior choroidal artery
larger middle hippocampal artery, most commonly arising from the PCA
posterior hippocampal artery, usually arising from the splenial artery or the PCA
What are the lenticulostriate arteries?
A: They are part of the ‘deep cerebral structures’; they are the most penetrating vessels at the base of the brain. They are small vessels which arise from the initial portions of the MCA, before it enters the Sylvian fissure and before it penetrates the anterior perforated substance to supply large regions of the basal ganglia and internal capsule.
In hypertension, what arteries are prone to narrowing?
A: The lenticulostriate arteries and other small vessels are prone to narrowing, which, can lead to lacunar infarction, as well as rupture, causing intracerebral hemorrhage.
What other vessels supply deep structures?
A: The anterior choroidal artery arises from the interal carotid artery.
What territory does the anterior choridal artery cover?
A: Its territory covers portions of the basal ganglia ( the globus pallidus, putamen, thalamus, part of the LGN, and the posterior limb of the internal capsule extending up to the lateral ventricle.
What is the recurrent artery of Heubner?
A: It comes off the portion of the anterior cerebral artery (ACA) to supply portions of the head of the caudate, anterior putamen, globus pallidus, and internal capsule ( eg, structures of the basal ganglia).
What are the thalamoperforator arteries?
A: Small penetrating arteries that arise from the proximal posterior cerebral arteries near the top of the basilar artery. They supply the thalamus and sometimes extend to a portion of the posterior limb of the internal capsule.
What deep structures are supplied by the ACA?
A: The putamen; branches of the ACA, the recurrent ACA also supply the putamen.
What deep structures are supplied by the MCA?
A: Caudate nucleus
What deep structures are supplied by the anterior choroidal artery?
A: Globus pallidus
Where do most infarcts and ischemic events occur?
A: In the MCA, because of the relatively largey territory supplied by the MCA.
In what 3 regions do MCA infarcts occur?
A: The superior div., inferior div., and deep territory
What are the deficits associated with a left MCA superior division infarct?
A: Right face and arm weakness of the upper motor neuron type, and a nonfluent, or Broca’s aphasia. In some cases, there may also be some right face and arm cortical type sensory loss.
What are the deficits associated with a left MCA inferior division infarct?
A: Fluent, or Wernicke’s aphasia, and a right visual field deficit. There may also be some right face and arm cortical type sensory loss. Motor findings are usually absent, and patients may seem initially confused or crazy, but otherwise intact. Some mild right sided weakness may be present.
What are the deficits associated with a left MCA deep territory infarct?
A: Right pure motor hemiparesis of the upper motor neuron type. Larger infarcts may produce “cortical” deficits, as well as aphasia.
What are the deficits associated with a left MCA stem infarct?
A: Combination of the above, eg, right pure motor hemiparesis of the upper motor neuron type, with right hemiplegia, right hemianesthesia, right homonymous hemianopia, and global aphasia. There is often a left gaze preference especially at the onset, caused by damage to left hemisphere cortical areas important for driving the eyes to the right.
What deficits are associated with a right MCA superior division infarct?
A: Left face and arm weakness of the upper motor neuron type. Left hemi neglect is present. In some cases there is left face and arm cortical type sensory loss.
What deficits are associated with a right MCA inferior division infarct?
A: Profound left hemineglect. Left visual field and somatosensory deficits are often present; however, there may be difficult to test because of the neglect. Motor neglect with decreased voluntary or spontaneous initiation of movements on the left side can occur.
What deficits are associated with a right MCA deep territory infarct?
A: Left pure hemiparesis of the upper motor neuron type. Larger infarcts may produce cortical deficits, such as left hemi neglect.
What deficits are associated with a right MCA stem infarct?
A: Combination of the above, with left hemiplegia, left hemianesthesia, left homonymous hemianopia, and profound left hemi neglect.
What deficits are associated with a left ACA infarct?
A: Right leg weakness of the upper motor neuron type and right leg cortical type sensory loss. Grasp reflex, frontal lobe behavioral abnormalities, and transcortical aphasia can also be seen. Large infarcts may cause right hemiplegia.
What are the deficits associated with a right ACA infarct?
A: Left leg weakness of the upper motor neuron type and left leg cortical type sensory loss. Grasp reflex, frontal lobe behavioral abnormalities, and left hemineglect can also be seen. Larger infarcts may cause hemiplegia.
What are the deficits associated with a left PCA infarct?
A: Right homonymous hemiaopia. Extension to the splenium of the corpus callosum can cause alexia without agraphia. Larger infarcts including the thalamus and internal capsule may cause aphasia, right hemisensory loss, and left hemiparesis.
What is alexia without agraphia?
A: Pure word blindness. Inability to read but can name, have intact oral repetition, auditory comprehension, or writing are intact.
