| septum primum | A crescentic septum in the embryonic heart that develops on the dorsocephalic wall of the originally single atrium and initiates its partitioning into right and left chambers; the tips of the septum grow toward and fuse with the atrioventricular canal cushions. (05 Mar 2000) |
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| septum rectovaginale | The fascial layer between the vagina and the lower part of the rectum. Synonym: septum rectovaginale. (05 Mar 2000) |
| septum rectovesicale | A fascial layer that extends superiorly from the central tendon of the perineum to the peritoneum between the prostate and rectum. Synonym: septum rectovesicale, Denonvilliers' aponeurosis, rectovesical fascia, Tyrrell's fascia. (05 Mar 2000) |
| septum scroti | An incomplete wall of connective tissue and nonstriated muscle (dartos fascia) dividing the scrotum into two sacs, each containing a testis. Synonym: septum scroti. (05 Mar 2000) |
| septum secundum | The second of two major septal structures involved in the partitioning of the atrium, developing later than the septum primum and located to the right of it; like the septum primum, it is crescentic, but its tips are directed toward the sinus venosus, and it is more heavily muscular; it remains an incomplete partition until after birth, with its unclosed area constituting the foramen ovale. (05 Mar 2000) |
| septum sinuum frontalium | 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 sinuum sphenoidalium | 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 spurium | A septum in the right atrium of the embryonic heart formed by the right venous valve and its continuation onto the dorsocephalic wall of the atrium; in human embryos, it reaches its fullest development during the third month and then undergoes regression, taking no part in atrial partitioning (hence its designation as false); reduced portions persist as the valve of the inferior vena cava and the valve of the coronary sinus. (05 Mar 2000) |
| septum tubae | 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, ventricular | The wall between the two lower chambers (the right and left ventricles) of the heart. (12 Dec 1998) |
| sinus septum | A small fold forming the medial end of the valve of the inferior vena cava; it is developed from the dorsal wall of the embryonic sinus venosus. (05 Mar 2000) |
| spiral bulbar septum | See: spiral septum. (05 Mar 2000) |
| spiral septum | A septum dividing the embryonic bulbus cordis into pulmonary and aortic outflow tracts from the developing heart; the distal spiral septum is derived from the right and left endocardial cushions and so separates the pulmonary and aortic orifices; the proximal spiral septum is the portion of the septum that is incorporated into the membranous part of the interventricular septum. (05 Mar 2000) |
| nasal septum | 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) |
| depressor muscle of septum | <anatomy> A vertical fasciculus from the orbicularis oris musculus passing upward along the median line of the upper lip, and inserted into the cartilaginous septum of the nose; action, depresses septum; nerve supply, facial. Synonym: musculus depressor septi, depressor muscle of septum. (05 Mar 2000) |