(sŭl'kŭs , sŭl'kī‵, sŭl'sī‵)

Plural: sulci

[L. sulcus, a groove]

A furrow, groove, or fissure, esp. on the surface of the brain.

alveololingual s.The sulcus in the floor of the mouth between the base of the tongue and the alveolar ridge, on each side extending from the frenulum of the tongue back to the retromolar wall.

atrioventricular s.Atrioventricular groove

bicipital s.Atrioventricular groove.

calcarine s.Calcarine fissure.

callosal s.On the medial side of each cerebral hemisphere, the sulcus that runs parallel to the top of the corpus callosum, separating the corpus callosum from the overlying cingulate gyrus.

central s.The sulcus on the lateral aspect of the cerebral hemisphere, separating the parietal and frontal lobes. The central sulcus lies approx. midway along the lateral surface of the cerebral hemisphere, between the frontal and occipital poles of the brain. The gyrus anterior to the central sulcus (the precentral gyrus) is the primary motor cortex, and the gyrus posterior to the central sulcus (the postcentral gyrus) is the primary sensory cortex. Occasionally, the central sulcus is interrupted and is not a continuous sulcus from top to bottom. SYN: sulcus centralis.

s. centralis Central sulcus.

cingulate s.A sulcus curving transversely along the anterior medial surface of the cerebral hemisphere. It parallels the callosal sulcus, from which it is separated by the cingulate gyrus. It forms the lower edge of the medial frontal gyrus and the paracentral lobule.

circular s.The sulcus that almost entirely encircles the insula (of the cerebral hemisphere).

collateral s.A sulcus running longitudinally on the inferior (under) surfaces of the occipital and temporal lobes of the brain. In the occipital lobe, the collateral sulcus forms the lower edge of the lingual gyrus; in the temporal lobe, it forms the lower edge of the posterior two thirds of the parahippocampal gyrus.

coronary s.Atrioventricular groove

s. cutis Any of the sulci on the skin of the palmar surface of the fingers and toes. These sulci form the fingerprints.

frontal s.

SEE: inferior frontal sulcus; superior frontal sulcus.

gingival s.The sulcus between the free gingiva and the tooth surface. Normal sulcus depth is between 0.5 and 1.5 mm. Inflammation in the sulcus is the first sign of gingivitis. When enlarged by disease, the gingival sulcus deepens and becomes a periodontal pocket.

SEE: periodontal pocket.

hippocampal s.Hippocampal fissure

hypothalamic s.A transverse sulcus along the inside of each lateral wall of the third ventricle of the brain. The sulcus runs from the interventricular foramen back to the cerebral aqueduct, and it marks the boundary of the thalamic nuclei (dorsally) and the hypothalamic nuclei (ventrally).

inferior frontal s.A sulcus running from front to back along the lateral surface of the frontal lobe of the brain. It separates the middle frontal gyrus from the inferior frontal gyrus.

inferior temporal s.A sulcus that runs from front to back along the lower lateral surface of the temporal lobe of the brain. It runs under and parallel to the superior temporal sulcus, from which it is separated by the middle temporal gyrus. The inferior temporal sulcus is usually interrupted and not a continuous groove.

intertubercular s.Bicipital groove.

interventricular s.Bicipital groove.

intraparietal s.A sulcus branching from the postcentral sulcus and running transversely and posteriorly along the lateral surface of the parietal lobe of the brain. It divides the posterior portion of the parietal lobe into two parts, superior and inferior; it terminates at the midpoint of the transverse occipital sulcus. SYN: interparietal fissure.

lateral s.Sylvian fissure.

lateral occipital s.A short transverse sulcus on the lower lateral surface of the occipital lobe of the brain. It separates the superior and the inferior occipital gyri.

s. limitans A shallow sulcus running transversely halfway down each inner wall of the neural tube of the embryo. It divides the alar (dorsal, sensory precursor) neural tube cells from the basal (ventral, motor precursor) neural tube cells.

malleolar s.Malleolar groove.

median s.On the dorsal surface of the tongue, the midline sulcus that separates the surface into right and left halves.

Monro s.

SEE: under Monro, Alexand er (secundus).

nasolabial s.Nasolabial groove

nymphocaruncular s.The sulcus between the caruncula of the hymen and the labium minus.

nymphohymenal s.The sulcus between the labium minus and the hymen on either side.

occipital s.

SEE: transverse occipital sulcus.

occipitotemporal s.A sulcus running longitudinally on the inferior surface of the temporal lobe of the brain. It is parallel to the collateral sulcus, from which it is separated by the medial occipitotemporal gyrus.

olfactory s.The most medial sulcus running longitudinally on the orbital surface of the frontal lobe of the brain, separating the gyrus rectus from the medial orbital gyrus. The olfactory bulb and olfactory tract lie along the olfactory sulcus.

olfactory nasal s.An anterior-posterior sulcus in the wall of the nasal cavity. It passes from the anterior area to the lamina cribrosa. SYN: nasal carina.

parieto-occipital s.An oblique sulcus on the medial surface of the brain, marking the boundary between the parietal and the occipital lobes. The calcarine fissure intersects the middle of the parieto-occipital sulcus.

postcentral s.The sulcus that runs down the lateral surface of the parietal lobe of the brain, parallel to the central sulcus. Between the central and the postcentral sulci lies the postcentral gyrus.

precentral s.A sulcus on the lateral surface of the frontal lobe of the brain, parallel to the central sulcus. Between the precentral and the central sulci lies the precentral gyrus. The precentral sulcus is usually interrupted and not a continuous groove.

s. precentralis An interrupted sulcus generally parallel to the central sulcus and anterior to it.

s. pulmonalis A sulcus for the posterior lung adjacent to the bodies of the thoracic vertebrae.

s. spiralis cochleae A sulcus between the labium tympanicum and labium vestibulare.

subparietal s.A sulcus that continues the path of the cingulate sulcus posteriorly. The subparietal and the cingulate sulci are not directly connected

superior frontal s.A sulcus running from front to back along the upper surface of the frontal lobe of the brain, separating the superior frontal gyrus from the middle frontal gyrus.

s. superior auricular The groove above the auricle in which one's glasses, mask straps, and earphones ride. SYN: dangler's ridge.

superior temporal s.A sulcus that runs from front to back along the lateral surface of the temporal lobe of the brain. It runs under and parallel to the sylvian (lateral) fissure, from which it is separated by the superior temporal gyrus.

sylvian s.Sylvian fissure.

temporal s.

SEE: inferior temporal sulcus; superior temporal sulcus.

s. terminalis 1A shallow sulcus along the outside surface of the right atrium of the heart marking the junction of the venae cava and the atrium. The crista terminalis is found at the corresponding location inside the right atrium.2A V-shaped sulcus on the dorsal surface of the tongue separating the anterior two thirds of the tongue from the posterior one third. The anterior (oral) part of the tongue receives different innervation and has different embryological origins from the posterior (pharyngeal) part.

transverse occipital s.A sulcus running transversely along the lateral surface of the occipital lobe of the brain.