| middle cranial fossa | A butterfly-shaped portion of the internal base of the skull posterior to the sphenoidal ridges and limbus and anterior to the crests of the petrous part of the temporal bones and dorsum sellae; it lodges the temporal lobes of the brain in the lateral portions, and the hypophysis centrally. Synonym: fossa cranii media. (05 Mar 2000) |
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| cistern of lateral fossa of cerebrum | An elongated expansion of the subarachnoid space where the arachnoid bridges over the opening of the Sylvian fissure. Synonym: cisterna fossae lateralis cerebri. (05 Mar 2000) |
| Claudius' fossa | A depression in the parietal peritoneum of the pelvis; it is bounded in front by the obliterated umbilical artery, and behind by the ureter and the uterine vessels; it lodges the ovary. Synonym: fossa ovarica, Claudius' fossa. (05 Mar 2000) |
| Mohrenheim's fossa | A triangular depression bounded by the clavicle and the adjacent borders of the deltoid and pectoralis major muscles. Synonym: fossa infraclavicularis, deltoideopectoral triangle, deltoideopectoral trigone, infraclavicular triangle, Mohrenheim's fossa, Mohrenheim's space, regio infraclavicularis, trigonum deltoideopectorale. (05 Mar 2000) |
| piriform fossa | A recess in the anterolateral wall of the nasopharynx on each side of the vestible of the larynx separated from it by the aryepiglottic folds. Synonym: recessus piriformis, piriform recess, piriform sinus. (05 Mar 2000) |
| pituitary fossa | Fossa of the sphenoid bone housing the pituitary gland. See: sella turcica. Synonym: fossa hypophysialis, pituitary fossa. (05 Mar 2000) |
| Morgagni's fossa | The terminal dilated portion of the urethra in the glans penis. Synonym: fossa navicularis urethrae, fossa terminalis urethrae, Morgagni's fossa, Morgagni's fovea. (05 Mar 2000) |
| condylar fossa | A depression behind the condyle of the occipital bone in which the posterior margin of the superior facet of the atlas lies in extension. Synonym: fossa condylaris. (05 Mar 2000) |
| coronoid fossa of humerus | A hollow on the anterior surface of the distal end of the humerus, just above the trochlea, in which the coronoid process of the ulna rests when the elbow is flexed. Synonym: fossa coronoidea humeri. (05 Mar 2000) |
| mylohyoid fossa | A groove on the medial surface of the ramus of the mandible beginning at the lingula; it lodges the mylohyoid artery and nerve. Synonym: sulcus mylohyoideus, mylohyoid fossa. (05 Mar 2000) |
| cranial fossa, posterior | The posterior subdivision of the floor of the cranial cavity, lodging the cerebellum, pons, and medulla oblongata. It is formed by portions of the sphenoid, temporal, parietal, and occipital bones. (12 Dec 1998) |
| popliteal fossa | The diamond-shaped space posterior to the knee joint bounded superficially by the diverging biceps femoris and semimembranosus muscles above and inferiorly by the two heads of the gastrocnemius muscle; deeply, the fossa is bound superiorly by the diverging supracondylar lines of the femur and the soleal line of the tibia inferiorly. Contents: tibial nerve, popliteal artery, vein, fat. Synonym: fossa poplitea, poples, ham, popliteal region, popliteal space, popliteus. (05 Mar 2000) |
| popliteal fossa: the | Hollow behind the knee. (12 Dec 1998) |
| posterior cranial fossa | The internal base of the skull posterior to the crest of the petrous part of the temporal bones and the dorsum sellae and anterior to the grooves for the transverse sinuses, where the cerebellum, pons, and medulla oblongata rest. Synonym: fossa cranii posterior. (05 Mar 2000) |
| posterior fossa tumours | <radiology> Midline, medulloblastoma (hyperdense, enhances), astrocytoma (hypodense, enhances), 4th ventricle, ependymoma (most common, slow-growing, expands ventricle), medulloblastoma (usually obliterates ventricular cavity), choroid plexus papilloma (more common in lateral ventricles) (12 Dec 1998) |