septum, gen. septi, pl. septa (sep´tum, -tI, -ta)
1. [NA] A thin wall dividing two cavities or masses of softer tissue. See septal area, transparent s. 2. In fungi, a wall; usually a cross-wall in a hypha. [L. saeptum, a partition]
s. accesso´riuman additional ridge forming the lower border of the limbus fossae ovalis.
alveolar s.interalveolar s
aortopulmonary s.the spiral s. which, during development, separates the truncus arteriosus into a ventral pulmonary trunk and dorsal aorta. See also bulbar ridge.
atrioventricular s.the small part of the membranous s. of the heart just above the septal cusp of the tricuspid valve that separates the right atrium from the left ventricle.s. atrioventriculare [NA] , pars membranacea septi atriorum;
s. atrioventricula´re [NA] atrioventricular s
s. of auditory tubea very thin horizontal plate of bone forming two semicanals, 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.s. canalis musculotubarii [NA] , s. of musculotubal canal, s. tubae;
Bigelow's s.calcar femorale
bony nasal s.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.s. nasi osseum [NA] ;
bulbar s.obsolete term for spiral s.
s. bul´bi ure´thraea fibrous s. in the interior of the bulb of the penis which divides it into two hemispheres.
s. cana´lis musculotuba´rii [NA] s. of auditory tube
cartilaginous s.nasal septal cartilage
s. cervica´le interme´dium [NA] intermediate cervical s
s. clitor´idisan incomplete fibrous s. between the corpora cavernosa of the clitoris.s. corporum cavernosorum clitoridis [NA] ;
Cloquet's s.femoral s
comblike s.pectiniform s
s. cor´porum cavernoso´rum clitor´idis [NA] s. clitoridis
crural s.femoral s
distal spiral s. See spiral s.
endovenous s., s. endoveno´suma remnant of the primitive separation between veins which fused to form a definitive trunk, such as the trunk leading to the left common iliac and the left renal veins.
femoral s.the delicate fibrous membrane that closes the femoral ring at the base of the femoral canal.s. femorale [NA] , Cloquet's s., crural s;
s. femora´le [NA] femoral s
s. of frontal sinusesthe bony partition between the right and left frontal sinuses; it is often deflected to one side of the middle line.s. sinuum frontalium [NA] ;
gingival s.interdental papilla
s. glan´dis [NA] s. of glans penis
s. of glans penisa fibrous partition extending through the glans penis from the lower surface of the tunica albuginea to the urethra.s. glandis [NA] ;
hanging s.the deformity caused by an abnormal width of the septal portion of the alar cartilages.
interalveolar s. 1. the tissue intervening between two adjacent pulmonary alveoli; it consists of a close-meshed capillary network covered on both surfaces by very thin alveolar epithelial cells; 2. one of the bony partitions between the tooth sockets.s. interalveolare [NA] , alveolar s., septal bone;
s. interalveola´re, pl. sep´ta interalveola´ria [NA] interalveolar s
interatrial s.the wall between the atria of the heart. See also s. primum, s. secundum.s. interatriale [NA] ;
s. interatria´le [NA] interatrial s
interdental s.the bony portion separating two adjacent teeth in a dental arch.
interlobular s.the connective tissue between pulmonary lobules, usually containing a vein and lymphatics; seen radiographically when thickened as a Kerley B line.
intermediate cervical s.a thin s. composed of glia fiber and leptomeningeal connective tissue in the cervical spinal cord marking the border between the gracile fasciculi and cuneatus of the dorsal funiculus.s. cervicale intermedium [NA] ;
s. interme´diumold term for the s. of the atrioventricular canal of the embryonic heart formed by the fusion of the dorsal and ventral atrioventricular canal cushions.
intermuscular s.a term applied to aponeurotic sheets separating various muscles of the limbs; these are anterior and posterior crural, lateral and medial femoral, lateral and medial humeral.s. intermusculare [NA] ;
s. intermuscula´re [NA] intermuscular s
interpulmonary s.mediastinum (2)
interradicular septathe bony partitions that project into the alveoli between the roots of the molar teeth.septa interradicularia [NA] , intra-alveolar septa;
sep´ta interradicula´ria [NA] interradicular septa
interventricular s.the wall between the ventricles of the heart.s. interventriculare [NA] , ventricular s;
s. interventricula´re [NA] interventricular s
s. lin´guae [NA] lingual s
lingual s.the median vertical fibrous partition of the tongue merging posteriorly into the aponeurosis of the tongue.s. linguae [NA] , s. of tongue;
s. lu´cidumtransparent s
s. mediastina´lemediastinum (2)
s. membrana´ceum ventriculo´rummembranous part of interventricular septum
membranous s. 1. membranous part of nasal septum 2. membranous part of interventricular septum
s. mo´bile na´simobile part of nasal septum
s. muscula´re ventriculo´rummuscular part of interventricular septum of heart
s. of musculotubal canals. of auditory tube
nasal s.the wall dividing the nasal cavity into halves; it is composed of a central supporting skeleton covered on each side by a mucous membrane.s. nasi [NA] ;
s. na´si [NA] nasal s
s. na´si oss´eum [NA] bony nasal s
orbital s.a fibrous membrane attached to the margin of the orbit and extending into the lids, containing the orbital fat and constituting in great part the posterior fascia of the orbicularis oculi muscle.s. orbitale [NA] ;
s. orbita´le [NA] orbital s
pectiniform s., s. pectinifor´methe anterior portion of the s. penis which is broken by a number of slitlike perforations.comblike s;
s. pellu´cidum [NA] transparent s
s. pe´nis [NA] the portion of the tunica albuginea incompletely separating the two corpora cavernosa of the penis.
placental septaincomplete partitions between placental cotyledons; they are covered with trophoblast and contain a core of maternal tissue.
precommissural s. See septal area.
s. pri´muma crescentic s. 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 s. grow toward and fuse with the atrioventricular canal cushions.
proximal spiral s. See spiral s.
rectovaginal s.the fascial layer between the vagina and the lower part of the rectum.s. rectovaginale [NA] ;
s. rectovagina´le [NA] rectovaginal s
rectovesical s.a fascial layer that extends superiorly from the central tendon of the perineum to the peritoneum between the prostate and rectum.s. rectovesicale [NA] , Denonvilliers' aponeurosis, rectovesical fascia, Tyrrell's fascia;
s. rectovesica´le [NA] rectovesical s
scrotal s.an incomplete wall of connective tissue and nonstriated muscle (dartos fascia) dividing the scrotum into two sacs, each containing a testis.s. scroti [NA] ;
s. scro´ti [NA] scrotal s
s. secun´dumthe second of two major septal structures involved in the partitioning of the atrium, developing later than the s. primum and located to the right of it; like the s. 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.
sinus s.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.
s. sin´uum fronta´lium [NA] s. of frontal sinuses
s. sin´uum sphenoida´lium [NA] s. of sphenoidal sinuses
s. of sphenoidal sinusesthe bony partition between the two sphenoidal sinuses, often deflected to one side of the mid line.s. sinuum sphenoidalium [NA] ;
spiral s.a s. dividing the embryonic bulbus cordis into pulmonary and aortic outflow tracts from the developing heart; the distal spiral s. is derived from the right and left endocardial cushions and so separates the pulmonary and aortic orifices; the proximal spiral s. is the portion of the s. that is incorporated into the membranous part of the interventricular s.
spiral bulbar s. See spiral s.
s. spu´riuma s. 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.
s. of testismediastinum testis
s. of tonguelingual snucleus fibrosus linguae;
transparent s.a thin plate of brain tissue, containing nerve cells and numerous nerve fibers, 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 s. pellucidum. The transparent s. is continuous ventralward through the interval between the corpus callosum and the anterior commissure with the precommissural septum and subcallosal gyrus. See also cavity of septum pellucidum, septal area.s. pellucidum [NA] , s. lucidum;
transverse s. 1. ampullary crest 2. the mesodermal mass separating the pericardial and peritoneal cavities; it is covered with mesothelium except where intimately associated with the liver, which originally develops within it; the s. is definitively incorporated into the diaphragm as the central tendon.
s. tu´baes. of auditory tube
urogenital s.the coronally placed ridge formed by the caudal portion of the urogenital ridges fusing in the midline of the embryo; it lies between the hindgut dorsally and the bladder ventrally.
urorectal s.in embryos, a partition dividing the cloaca into a dorsal, rectal portion and a ventral portion called the urogenital sinus; reaching the cloacal membrane at about the time of its disintegration, the urorectal s. divides the cloacal exit into an anal and a urogenital orifice.urorectal fold;
ventricular s.interventricular s
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