Lecture 2

Dorsal View

1. Pertaining to the back or to any dorsum. 2. Denoting a position more toward the back surface than some other object of reference; a synonym of posterior in human anatomy and of superior in the anatomy of quadrupeds.

Corticalspinal Tract

A collection of about a million axons that originate in the cerebral cortex, descend through the internal capsule, cerebral peduncle, basal pons, and medullary pyramid, then reach the spinal cord, where they terminate, via the lateral and anterior corticospinal tracts. Roughly half of then originate I primary motor cortex, the rest arising from premotor and supplementary motor areas and the parietal lobe (especially somatosensory cortex). Corticospinal axons end in the spinal cord on cells of the posterior horn, intermediate gray, and anterior horn, where some synapse directly on alpha and gamma motor neurons. A single function role is difficult to specify, but this is the principal pathway for the production of skilled voluntary movements.

Parahippocampal Gyrus

A fold of tissue near the hippocampus that is often included in the limbic system § The gyrus immediately adjacent to the hippocampus. Its anterior region contains the entorhinal cortex, a meeting ground for cortical projections from multiple areas and the source of most afferents to the hippocampus. § Uncus A medial protuberance from the anterior end of the parahippocampal gyrus caused by the underling amygdala. The proximity of its surface to the adjacent cerebral peduncle can cause clinical problems during cerebral edema or as a result of space-occupying masses, because the uncus can herniate through the tentorial notch and compress the midbrain.

Temporal Lobe

A region of the cerebral cortex responsible for hearing and language. The most inferior lobe of each cerebral hemisphere, inferior to the lateral sulcus and anterior to the occipital lobe. The temporal lobe includes auditory sensory and association cortex, part of posterior language cortex, visual and higher-order association cortex, primary and association olfactory cortex, the amygdala, and the hippocampus.

Occipital Lobe

A region of the cerebral cortex that processes visual information The most posterior lobe of each cerebral hemisphere. The occipital lobe includes the primary visual cortex in the banks of the calcarine sulcus and adjoining areas of visual association cortex.

Parietal Lobe

A region of the cerebral cortex whose functions include processing information about touch. § A cerebral lobe bounded by the frontal, temporal, and occipital lobes on the lateral surface of each hemisphere, and by the frontal, limbic, and occipital lobes on the medial surface. The parietal lobe contains primary somatosensory cortex in the precentral gyrus, areas involved in language comprehension (in the inferior parietal lobule, usually on the left), and regions involved in complex aspects of spatial orientation and perception. Parietal lobe has two parts which are separated by a sulcus that run through it called the intraparietal sulcus (Superior Parietal Lobule; Inferior Parietal Lobule)

Cingulate Gyrus

A strip of limbic cortex lying along the lateral walls of the groove separating the cerebral hemispheres, just above the corpus callosum A broad belt of cortex partially encircling the corpus callosum. The cingulate gyrus forms the upper part of the limbic lobe and has extensive limbic connections. Anterior cingulate cortex is closely related to the amygdala, posterior cingulate cortex to the hippocampus.

Scotomas

Blind or partially blind areas in the visual field An area of lost or depressed vision within the visual field, surrounded by an area of less depressed or of normal vision.

Quadrantanopia

Blindness of one quadrant of the visual field Patient is unable to see in the upper or lower contralateral quadrant

Fusiform Gyrus

Brain area of the inferior temporal cortex that recognizes faces A long gyrus, beginning just lateral to the uncus and running posteriorly along the inferior surface of the temporal lobe the occipitotemporal gyrus is bounded laterally by the inferior temporal gyrus and medially by the Parahippocampal gyrus.

Precentral Gyrus (primary motor cortex)

Controls movements A vertically oriented convolution of the frontal lobe immediately anterior to the central sulcus. The precentral gyrus is the site of primary motor cortex (Brodmann's area 4).

Collateral Sulcus

Divides lingual and parahippocampal gyri from fusiform gyrus A deep infolding of the inferior surface of the temporal lobe, bulging into the wall of the inferior horn of the lateral ventricle as the collateral eminence. It separates the occipitotemporal gyrus from the parahippocampal gyrus.

lateral sulcus (sylvian fissure)

Divides the temporal lobe from the frontal and anterior parietal lobes A long, deep sulcus on the lateral aspect of each cerebral hemisphere resulting from downward and forward expansion of the temporal lobe during fetal development. The insula lies hidden within the depths of this sulcus, which separates the temporal lobe from the frontal and parietal lobes and provides a route by which the middle cerebral artery accesses the lateral convexity.

Sigmoid "hook"

Hooklike configuration of the posterior surface of the precentral gyrus the "hook" corresponds to the motor hand area. Also called the hand "knob".

Lateral View Brain

In anatomy, the side of the body or a body part that is farther from the middle or center of the body. Typically, lateral refers to the outer side of the body part, but it is also used to refer to the side of a body part. For example, when referring to the knee, lateral refers to the side of the knee farthest from the opposite knee. The opposite of lateral is medial.

Gyri (gyrus)

Large folds of tissue covering the surface of the cerebrum

Postcentral Gyrus (primary somatosensory cortex)

Lies posterior to the central sulcus; the primary target for touch sensations and information from muscle-stretch receptors and joint receptors. A vertically oriented convolution of the parietal lobe immediately posterior to the central sulcus. The postcentral gyrus is the site of primary somatosensory cortex (Brodmann's areas 3, 1, and 2).

Ventral View

Of or relating to the underside of an organism, or that side which is normally directed downwards in the usual stance or resting position. In bipedal primates such as humans, the ventral side is the front, which would become the underside if a four-legged gait were assumed.

Medial View Brain

Pertaining to the middle; in or toward the middle; nearer the middle of the body. Medial is as opposed to lateral. For example, the medial side of the knee is the side closest to the other knee whereas the lateral side of the knee is the outside of the knee.

Cingulate Sulcus

Separates frontal and parietal lobes from cingulate gyrus A more or less continuous, curved infolding of each cerebral hemisphere clearly demarcating the outer margin of the cingulate gyrus; posteriorly, a branch (the marginal branch) ascends to the superior margin of the parietal lobe immediately behind the upper end of the central sulcus).

Central Sulcus

Separates frontal lobe from parietal lobe An anatomically and functionally important infolding of the cerebral hemisphere, beginning just medial to the superior border of the hemisphere, proceeding over its superior margin, and descending obliquely forward almost to the lateral sulcus. The central sulcus is the boundary between the frontal and parietal lobes, and the transition zone between primary motor and primary somatosensory.

Calcarine Sulcus

Separates the occipital lobe into superior and inferior halves A prominent, deep cerebral infolding, originating anteriorly in the temporal lobe near the splenium of the corpus callosum and continuing posteriorly into the occipital lobe, where it terminates at the occipital pole. Its upper and lower banks contain the primary visual cortex (Brodmann's Area 17). Anteriorly along this course the parietooccipital sulcus branches off from it.

Parietooccipital Sulcus

Separates the parietal lobe from the occipital lobe § A deep fissure separating the parietal and occipital lobes on the medial aspect of the cerebral hemisphere. Inferiorly the parietooccipital sulcus joins the calcarine sulcus, which continues into the temporal lobe as a common stem for both these sulci.

Superior Frontal Sulcus

Separates the superior frontal gyrus from the middle frontal gyrus

Sulci (sulcus)

Shallow grooves separating the gyri Divides the cerebral hemispheres into lobes

Inferior Parietal Lobule

The area of the parietal lobe on the lateral surface of the cerebrum lying inferior to the interparietal sulcus; it contains the angular and the supramarginal gyri.

Frontal Lobe

The lobe at the front of the brain associated with movement, speech, and impulsive behavior. The most anterior lobe of each cerebral hemisphere. The frontal lobe includes motor, premotor, and supplementary motor cortex, an extensive prefrontal region, and a large expanse of orbital cortex. The latter two regions have access via long association fibers to all other lobes and also to the limbic system, and are important (in a poorly understood way) in working memory, regulating emotional tone, prioritizing bodily/environmental demands, and stabilizing short- and long-range goal-directed activity.

hindbrain, midbrain, forebrain

The major subdivisions of the human brain

Superior Parietal Lobule

The superior parietal lobule contains Brodmann's areas 5 and 7. Behind it is the lateral part of the parietooccipital fissure, around the end of which it is joined to the occipital lobe by a curved gyrus , the arcus parietooccipitalis.

Paracentral Lobule

U shaped continuation of pre and post central gyri The extensions of the precentral and postcentral gyri onto the medial surface of the hemisphere, forming a lobule that surrounds the end of he central sulcus.

Lingual Gyrus

Visual processing The gyrus forming the inferior bank of the calcarine sulcus. The lingual gyrus overlaps the posterior portion of the occipitotemporal gyrus, separated from it by the collateral sulcus.

Hemianopia

blindness in one half of the visual field of one or both eyes Patient is unable to see in the contralateral visual field

Insula

regions of cortex located at the junction of the frontal and temporal lobes The original lateral surface of the embryonic telencephalic vesicle overlying an area of fusion with the diencephalon, forming in the adult a central lobe of the cerebral hemisphere, typically convoluted into about three short gyri (located more anteriorly) and two long gyri. With rapid cerebral expansion during fetal development, the insula is overgrown and by birth concealed by frontal, parietal, and temporal opercula. It includes gustatory and autonomic areas, but is less well understood than other cortical areas due to its hidden location.