| septum lucidum | A thin plate of brain tissue, containing nerve cells and numerous nerve fibres, that is stretched like a flat, vertical sheet between the column and body of fornix below, the corpus callosum above and anteriorly; it is usually fused in the median plane with its partner on the opposite side so as to form a thin, median partition between the left and right frontal horn of the lateral ventricles; in less than 10% of humans there is a blind, slitlike, fluid-filled space between the two transparent septa, the cavity of septum pellucidum. The transparent septum is continuous ventralward through the interval between the corpus callosum and the anterior commissure with the precommissural septum and subcallosal gyrus. See: cavity of septum pellucidum, septal area. Synonym: septum pellucidum, septum lucidum. (05 Mar 2000) |
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| septum mediastinale | <anatomy> The space in the thoracic cavity behind the sternum and in between the two pleural sacs (containing the lungs). (27 Sep 1997) |
| septum membranaceum ventriculorum | Part of the fibrous skeleton of the heart which is seen as a small, thin, round or oval nonmuscular area at the superior end of the interventricular septum; it lies just below and is continuous with the portion of the fibrous ring of the aortic valve supporting the anterior and posterior cusps, and with the right fibrous trigone; the atrioventricular bundle of conducting tissue courses along its dorsal margin and bifurcates at its inferior margin into the right and left crura. Synonym: pars membranacea septi interventricularis, membranous septum, septum membranaceum ventriculorum. (05 Mar 2000) |
| septum mobile nasi | The anterior movable part of the nasal septum formed by the medial crus of the greater alar cartilage on each side. Synonym: pars mobilis septi nasi, septum mobile nasi. (05 Mar 2000) |
| septum musculare ventriculorum | The thick muscular portion which comprises most of the interventricular septum of the heart. Synonym: pars muscularis septi interventricularis cordis, septum musculare ventriculorum. (05 Mar 2000) |
| septum, nasal | The dividing wall that runs down the middle of the nose so that there are normally two sides to the nose, each ending in a nostril. (12 Dec 1998) |
| septum nasi | The dividing wall that runs down the middle of the nose so that there are normally two sides to the nose, each ending in a nostril. (12 Dec 1998) |
| septum nasi osseum | The bones supporting the bony part of the nasal septum; these are the perpendicular plate of the ethmoid, the vomer, the sphenoidal rostrum, the crest of the nasal bones, the frontal spine, and the median crest formed by the apposition of the maxillary and palatine bones. Synonym: septum nasi osseum. (05 Mar 2000) |
| septum of auditory tube | A very thin horizontal plate of bone forming two saemicanals, the upper, smaller, for the tensor tympani muscle, the lower, larger for the auditory tube; its termination in the middle ear is the processus cochleariformis. Synonym: septum canalis musculotubarii, septum of musculotubal canal, septum tubae. (05 Mar 2000) |
| septum of frontal sinuses | The bony partition between the right and left frontal sinuses; it is often deflected to one side of the middle line. Synonym: septum sinuum frontalium. (05 Mar 2000) |
| septum of glans penis | A fibrous partition extending through the glans penis from the lower surface of the tunica albuginea to the urethra. Synonym: septum glandis. (05 Mar 2000) |
| septum of musculotubal canal | A very thin horizontal plate of bone forming two saemicanals, the upper, smaller, for the tensor tympani muscle, the lower, larger for the auditory tube; its termination in the middle ear is the processus cochleariformis. Synonym: septum canalis musculotubarii, septum of musculotubal canal, septum tubae. (05 Mar 2000) |
| septum of sphenoidal sinuses | The bony partition between the two sphenoidal sinuses, often deflected to one side of the mid line. Synonym: septum sinuum sphenoidalium. (05 Mar 2000) |
| septum of testis | A mass of fibrous tissue continuous with the tunica albuginea, projecting into the testis from its posterior border. Synonym: corpus highmori, corpus highmorianum, Highmore's body, septum of testis. (05 Mar 2000) |
| septum of tongue | The median vertical fibrous partition of the tongue merging posteriorly into the aponeurosis of the tongue. Synonym: septum linguae, septum of tongue. (05 Mar 2000) |