septum primum(redirected from Primary septum)
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1. a wall or partition dividing a body space or cavity. Some are membranous, some are osseous, and some are cartilaginous; each is named according to its location. See also septal defect. adj., adj sep´tal.
2. nasal septum.
alveolar septum interalveolar septum.
atrial septum (septum atrio´rum cor´dis) interatrial septum.
atrioventricular septum the part of the membranous portion of the interventricular septum between the left ventricle and the right atrium.
deviated septum an injury or malformation of the nasal septum so that one part of the nasal cavity is smaller than the other; this is fairly common and seldom causes complications. Occasionally the deviation may handicap breathing, block the normal flow of mucus from the sinuses during a cold, or prevent proper drainage of infected sinuses. In some cases surgery (called partial or complete submucous resection) may be necessary to relieve the obstruction and reduce irritation and infection in the nose and sinuses.
1. one of the thin plates of bone separating the alveoli of the teeth in the mandible and maxilla. Called also interradicular septum.
2. one of the thin septa that separate adjacent pulmonary alveoli, containing connective tissue and the capillary network of the blood supply of the lung. Defs. 1 and 2 called also alveolar septum.
interatrial septum (septum interatria´le cor´dis) the partition separating the right and left atria of the heart; called also atrial septum.
interradicular septum interalveolar septum (def. 1).
interventricular septum (septum interventricula´re cor´dis) the partition separating the right and left ventricles of the heart; called also ventricular septum.
nasal septum a plate of bone and cartilage covered with mucous membrane that divides the nasal cavity.
septum lu´cidum septum pellucidum.
pellucid septum (septum pellu´cidum) the triangular double membrane separating the anterior horns of the lateral ventricles of the brain; called also septum lucidum.
septum pri´mum a septum in the embryonic heart, dividing the primitive atrium into right and left chambers. See also congenital heart defect.
rectovaginal septum the membranous partition between the rectum and vagina.
rectovesical septum a membranous partition separating the rectum from the prostate and urinary bladder.
septum of ventricles of heart (ventricular septum) (septum ventriculo´rum cor´dis) interventricular septum.
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.
In the embryonic heart, a septum between the right and left chambers.
See also: septum
pl. septa [L.] a wall or partition dividing a body space or cavity.
Some septa are membranous, some are composed of bone, and some of cartilage. The wall separating the atria of the heart, for instance, is called the interatrial septum.
the part of the membranous portion of the interventricular septum between the left ventricle and the right atrium.
a septum, formed by merging of the bulbar cushions, divides the bulbus cordis into aortic and pulmonary outflows.
cystic septum pellucidum
an embryonic malformation resulting in the formation of a fluid-filled cavity in the septum between the two lateral ventricles, instead of the normal glial raphe.
in the avian body cavity there is no diaphragm but the cavity is divided into three compartments; this is one of the divider organs; thin and membranous for the most part, the septum forms the ventral boundary of paired cavities containing the lungs.
the bony partition between adjacent tooth sockets.
the partition separating the right and left atria of the heart.
a septum that converts an organ into lobes.
fascial septum separating muscle masses.
bony partition between the large orbital cavities of birds.
the partition separating the right and left ventricles of the heart. See also ventricular septum.
septum pellucidum (below).
membranous partition in the ventral median fissure of the spinal cord.
a partition which divides the lower part of the bird's body cavity; the part of the cavity cranial to this septum contains the thoracic air sacs and the thoracic parts of the cervical and clavicular air sacs. The part of the body cavity caudal to this septum contains heart, liver, spleen, gastrointestinal, urinary and reproductive tracts and abdominal air sacs.
a fold which detaches from the periorbital fascia at the orbital rim, and which leads into the tarsi, the thickened margins of the eyelids.
septum pellucidum, pellucid septum
the triangular double membrane separating the anterior horns of the lateral ventricles of the brain. Called also septum lucidum, telencephalic septum.
a transitory partition between the mouth and pharynx in the embryo.
a septum in the embryonic heart, dividing the primitive atrium into right and left chambers.
the membranous partition between the rectum and vagina.
a membranous partition separating the rectum from the prostate and urinary bladder.
develops during embryonic life to contribute to the formation of the foramen ovale between the cardiac atria.
see septum pellucidum (above).
a major contributor to the development of the diaphragm and the liver.
a partition which develops from truncal cushions within the truncus arteriosus and contributes to the separation of cardiac outflow into pulmonary and systemic circulations.
a septum which divides the urinary passages from the hindgut in the embryo by horizontally partitioning the cloaca.