| lesser trochanter | A pyramidal process projecting from the medial and proximal part of the shaft of the femur at the line of junction of the shaft and the neck; it receives the insertion of the psoas major and iliacus (iliopsoas) muscles. Synonym: trochanter minor, small trochanter, trochantin. (05 Mar 2000) |
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| lesser tubercle of humerus | The anterior of the two tubercles of the neck of the humerus on which the subscapularis is inserted. Synonym: tuberculum minus humeri, lesser tuberosity of humerus. (05 Mar 2000) |
| lesser tuberosity of humerus | The anterior of the two tubercles of the neck of the humerus on which the subscapularis is inserted. Synonym: tuberculum minus humeri, lesser tuberosity of humerus. (05 Mar 2000) |
| lesser tympanic spine | The posterior edge of the tympanic notch (of Rivinus). Synonym: spina tympanica minor. (05 Mar 2000) |
| lesser vestibular glands | A number of minute mucous glands opening on the surface of the vestibule between the orifices of the vagina and urethra. Synonym: glandulae vestibulares minores. (05 Mar 2000) |
| lesser wing of sphenoid bone | One of a bilateral pair of triangular, pointed plates extending laterally from the anterolateral body of the sphenoid bone. Forming the posteriormost portion of the floor of the anterior cranial fossa, their sharp posterior edge forms the sphenoidal ridge separating anterior and middle cranial fossae. The medial end of the lesser wing attaches to the body by means of two pedicles, thus forming the optic canal. The wing itself forms the superior margin of the supraorbital fissure. Synonym: ala minor ossis sphenoidalis, ala orbitalis, Ingrassia's apophysis, Ingrassia's wing. (05 Mar 2000) |
| lesser zygomatic muscle | <anatomy, muscle> Origin, zygomatic bone posterior to zygomaticomaxillary suture; insertion, orbicularis oris of upper lip; action, draws upper lip upward and outward; nerve supply, facial. Synonym: musculus zygomaticus minor, caput zygomaticum quadrati labii superioris, lesser zygomatic muscle. (05 Mar 2000) |
| abdominal sac | The part of the embryonic celom that becomes the abdominal cavity. (05 Mar 2000) |
| air sac | <zoology> Thin-walled sacs or spaces which function as a part of the respiratory system in birds, fishes, insects, and mammals. The sacs are filled with air and connected with the air passages of the lungs; an air cell. Source: Websters Dictionary (04 Jul 1999) |
| allantoic sac | The dilated distal portion of the allantois; it forms part of the placenta in many mammals. (05 Mar 2000) |
| alveolar sac | Terminal dilation of the alveolar ducts that give rise to alveoli in the lung; a small air chamber in the pulmonary tissue from which the pulmonary alveoli project like bays and into which an alveolar duct opens; in birds, air-containing extensions of bronchi that connect with bone cavities. Synonym: sacculus alveolaris, air sac. (05 Mar 2000) |
| amniotic sac | <anatomy, obstetrics> Sac, enclosing the embryo of amniote vertebrates, that provides a fluid environment to prevent dehydration during development of land based animals. See: amnion. (18 Nov 1997) |
| anal sac | A vesicular cutaneous invagination opening by a duct on each side of the anal canal in carnivores (best developed in skunks, but absent in some bears, the raccoon, kinkajou, coati, and sea otter), each lying between the external and internal anal sphincter muscles, which aid in emptying the contents. The sac stores odouriferous scent markers produced by glands that line its wall or duct; frequently the sac becomes impacted in the dog or cat, requiring manual emptying. (05 Mar 2000) |
| aneurysmal sac | The dilated wall of an artery in a saccular aneurysm. (05 Mar 2000) |
| aortic sac | In mammalian embryos, the endothelially lined dilation just distal to the truncus arteriosus; it is the primordial vascular channel from which the aortic arches arise and is homologous to the ventral aorta of gill-bearing vertebrates. (05 Mar 2000) |