- The outer portion of an organ. The outer portion of the adrenal gland is called the adrenal cortex; the outer portion of the cerebrum is the cerebral cortex (a key part of the brain); the outer part of the kidney is the renal cortex (it lies just beneath the capsule surrounding the kidney); etc. The cortex is in contrast to the inner portion of the organ which is called the medulla. Thus, there is the adrenal medulla; the medulla oblongata of the brain; the renal medulla; etc. The word "cortex" is Latin for the bark of a tree. The plural of cortex is cortices. The adjective is cortical.
* * *The outer portion of an organ, such as the kidney, as distinguished from the inner, or medullary, portion. [L. bark]- agranular c. cerebral c..- association c. generic term denoting the large expanses of the cerebral c. that are not sensory or motor in the customary sense, but are involved in advanced stages of sensory information processing, multisensory integration, or sensorimotor integration. SEE ALSO: cerebral c.. SYN: association areas.- auditory c. the region of the cerebral c. that receives the auditory radiation from the medial geniculate body, a thalamic cell group receiving auditory input from the cochlear nuclei in the rhombencephalon; it corresponds approximately to Brodmann areas 41 and 42 and is tonotopically organized. SYN: auditory area.- cerebellar c. the thin gray surface layer of the cerebellum, consisting of an outer molecular layer or stratum moleculare, a single layer of Purkinje cells (the Purkinje cell layer), and an inner granular layer or stratum granulosum. SYN: c. cerebelli [TA].- c. cerebelli [TA] SYN: cerebellar c..- cerebral c. [TA] the gray cellular mantle (1–4 mm thick) covering the entire surface of the cerebral hemisphere of mammals; characterized by a laminar organization of cellular and fibrous components such that its nerve cells are stacked in defined layers varying in number from one, as in the archicortex of the hippocampus, to five or six in the larger neocortex; the outermost (molecular or plexiform) layer contains very few cell bodies and is composed largely of the distal ramifications of the long apical dendrites issued perpendicularly to the surface by pyramidal and fusiform cells in deeper layers. From the surface inward, the layers as classified in K. Brodmann's parcellation are: 1) molecular layer [TA]; 2) external granular layer [TA]; 3) external pyramidal layer [TA]; 4) internal granular layer [TA]; 5) internal pyramidal layer [TA]; and 6) multiform layer [TA], many of which are fusiform. This multilaminate organization is typical of the neocortex (homotypic c.; isocortex [TA] in O. Vogt terminology), which in humans covers the largest part by far of the cerebral hemisphere. The more primordial heterotypic c. or allocortex (Vogt) has fewer cell layers. A form of c. intermediate between isocortex and allocortex, called juxtallocortex (Vogt) covers the ventral part of the cingulate gyrus and the entorhinal area of the parahippocampal gyrus. On the basis of local differences in the arrangement of nerve cells (cytoarchitecture), Brodmann outlined 47 areas in the cerebral c. which, in functional terms, can be classified into three categories: motor c. (areas 4 and 6), characterized by a poorly developed internal granular layer (agranular c.) and prominent pyramidal cell layers; sensory c., characterized by a prominent internal granular layer (granular c. or koniocortex) and comprising the somatic sensory c. (areas 1 to 3), the auditory c. (areas 41 and 42), and the visual c. (areas 17 to 19); and association c., the vast remaining expanses of the cerebral c.. SYN: c. cerebri [TA], pallium [TA], brain mantle, mantle (2).- c. cerebri [TA] SYN: cerebral c..- dysgranular c. the region of the cerebral c. that is transitional between the agranular c. of the precentral gyrus and the granular frontal c. (Brodmann area 8).- fetal adrenal c. an extensive area of the adrenal gland present in primates during fetal life and for a short period after birth; located between the definitive c. and the medulla, it contains large steroid-secreting cells arranged in a reticular pattern; involution of this zone in humans is largely completed by three months after birth. SYN: androgenic zone (2), fetal reticularis (1), fetal zone, provisional c..- frontal c. c. of the frontal lobe of the cerebral hemisphere; 1. originally, the entire cortical expanse anterior to the central sulcus, including the agranular motor and premotor c. (Brodmann areas 4 and 6), the dysgranular c. (area 8), and the granular frontal (prefrontal) c. anterior to the latter; 2. now more often refers to the granular frontal (prefrontal) c.. SYN: frontal area.- c. of hair shaft the principal structural component of the hair shaft, composed of closely packed fusiform keratinized cells and invested by the cuticula pili.- homotypic c. SYN: isocortex.- c. of lens [TA] the softer, more superficial part of the lens of the eye that encloses the central part or nucleus; its refractive power is less than that of the nucleus. SYN: c. lentis [TA].- c. of lymph node [TA] the outer portion of the lymph node underneath its capsule, consisting of fibrous trabeculae separating densely packed masses of lymphocytes arranged in nodules and separated from the trabeculae and capsule by lymph sinuses. SYN: c. nodi lymphatici [TA].- motor c. the region of the cerebral c. most nearly immediately influencing movements of the face, neck and trunk, and arm and leg; it corresponds approximately to Brodmann areas 4 and 6 of the precentral gyrus and immediately adjacent portions of the superior and middle frontal gyri; its effects upon the motor neurons innervating the skeletal musculature are mediated by corticospinal fibers (pyramidal tract) and corticonuclear fibers and are particularly essential for the human capacity to perform finely graded movements of arm and leg. SYN: excitable area, motor area, Rolando area.- orbitofrontal c. the cerebral c. covering the basal surface of the frontal lobes. SYN: fronto-orbital area.- ovarian c. [TA] the layer of the ovarian stroma lying immediately beneath the tunica albuginea, composed of connective tissue cells and fibers, among which are scattered primary and secondary (antral) follicles in various stages of development; the c. varies in thickness according to the age of the individual, becoming thinner with advancing years. SYN: c. ovarii [TA], c. of ovary.- c. ovarii [TA] SYN: ovarian c..- parastriate c. visual c..- peristriate c. visual c..- piriform c. the olfactory c., corresponding to the rostral half of the uncus; receiving its major afferents from the olfactory bulb, it is classified as allocortex. SEE ALSO: cerebral c.. SYN: olfactory c., piriform area.- premotor c. a somewhat ill-defined term usually referring to the agranular c. of Brodmann area 6. SYN: premotor area.- renal c. [TA] the part of the kidney consisting of renal lobules in the outer zone beneath the capsule and also the lobules of the renal columns that are extensions inward between the pyramids; contains the renal corpuscles and the proximal and distal convoluted tubules. SYN: c. renalis [TA].- c. renalis [TA] SYN: renal c..- secondary sensory c. a cortical region occupying the parietal operculum (upper lip of the lateral sulcus) closely posterior to the foot of the postcentral gyrus; like the primary somatic-sensory c. of the postcentral gyrus, this region receives sensory impulses originating in face, trunk, and limbs; projections to the s.s.c. are from the ventral basal complex (ventral posteromedial and posterolateral thalamic nuclei) and from the primary somesthetic c..- sensory c. formerly denoting specifically the somatic sensory c., but now used to refer collectively to the somatic sensory, auditory, visual, and olfactory regions of the cerebral c..- somatic sensory c., somatosensory c. the region of the cerebral c. receiving the somatic sensory radiation from the ventrobasal nucleus of the thalamus; it represents the primary cortical processing mechanism for sensory information originating at the body surfaces (touch) and in deeper tissues such as muscle, tendons, and joint capsules (position sense); it corresponds approximately to Brodmann areas 1, 2, 3 on the postcentral gyrus. SYN: somesthetic area.- supplementary motor c. a region from which, by electrical stimulation, the musculature of all bodily parts can be activated, as it also can by stimulation of the motor c. of the precentral gyrus; the region corresponds approximately to the expansion of Brodmann area 6 over the medial surface of the cerebral hemisphere; this area has largely a bilateral representation and is concerned primarily with tonic and postural motor activities.- c. of suprarenal gland [TA] the outer part of the adrenal gland, consisting of three zones from without inward: zona glomerulosa, zona fasciculata, and zona reticularis; this part of the adrenal c. yields steroid hormones such as corticosterone, deoxycorticosterone, and estrone. SYN: c. glandulae suprarenalis [TA], adrenal c., suprarenal c..- tertiary c. SYN: paracortex.- c. of thymus [TA] the outer part of a lobule of the thymus; it surrounds the medulla and is composed of masses of closely packed lymphocytes. SYN: c. thymi [TA].- visual c. the region of the cerebral c. occupying the entire surface of the occipital lobe, and composed of Brodmann areas 17–19. Area 17 (which is also called striate c. or area because the line of Gennari is grossly visible on its surface) is the primary visual c., receiving the visual radiation from the lateral geniculate body of the thalamus. The surrounding areas 18 (parastriate c. or area) and 19 (peristriate c. or area) are probably involved in subsequent steps of visual information processing; area 18 is referred to as the secondary visual c.. SYN: visual area.
* * *1 a) the outer or superficial part of an organ or body structure (as the kidney, adrenal gland, or a hair) esp cerebral cortexb) the outer part of some organisms (as paramecia)2 a) a plant bark or rind (as cinchona) used medicinallyb) the peel of any of several fruits used esp. in the writing of medical prescriptions
* * *cor·tex (korґteks) gen. corґticis, pl. corґtices [L. â€œbark, rind, shellâ€] 1. an external layer, as the bark of a tree or the rind of a fruit. 2. the outer layer of an organ or other body structure, as distinguished from the internal substance. 3. the region of the cytoplasm adjacent to the plasma membrane, containing a network of actin fibers.
Medical dictionary. 2011.