| external respiration | The exchange of respiratory gases in the lungs as distinguished from internal or tissue respiration. (05 Mar 2000) |
|---|---|
| external respiratory nerve of Bell | <anatomy, nerve> Arises from the fifth, sixth, and seventh cervical nerves (roots of brachial plexus), descends the neck behind the brachial plexus, and is distributed to the serratus anterior muscle; it is somewhat unusual in that it courses on the superficial aspect of the muscle is supplies; its paralysis results in "winged scapula". Synonym: nervus thoracicus longus, Bell's respiratory nerve, external respiratory nerve of Bell, posterior thoracic nerve. (05 Mar 2000) |
| external salivary gland | <anatomy> A salivary gland situated in front of and below the ear. (27 Sep 1997) |
| external saphenous nerve | <anatomy, nerve> A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot. (12 Dec 1998) |
| external secretion | A substance formed by a cell and transported outside the cell walls as a means of ridding the cell of the substance or as a messenger to affect the function of other cells. (05 Mar 2000) |
| external semilunar fibrocartilage | A flat disc-shaped ligament which stabilises and supports the outer aspect of the knee joint. Not as commonly injured as the medical meniscus ligament in knee sprains. (27 Sep 1997) |
| external sheath of optic nerve | <anatomy, nerve> The outer sheath around the optic nerve, continuous with the dura mater. Synonym: vagina externa nervi optici, dural sheath of optic nerve. (05 Mar 2000) |
| external spermatic artery | <anatomy, artery> Origin, inferior epigastric; distribution, coverings of spermatic cord; anastomoses, external pudendal, spermatic, and perineal arteria. Synonym: arteria cremasterica, external spermatic artery. (05 Mar 2000) |
| external spermatic fascia | The outer fascial covering of the spermatic cord; it is continuous at the superficial inguinal ring with the fascia covering the external oblique muscle. See: aponeurosis of external abdominal oblique muscle. Synonym: fascia spermatica externa. (05 Mar 2000) |
| external spermatic nerve | <anatomy, nerve> Branch of genitofemoral nerve distributed to skin of anterior scrotum (male) or labia majora (female) and adjacent thigh and supplying a motor branch to the cremaster muscle. Usually passes through deep inguinal ring and canal. Synonym: ramus genitalis nervi genitofemoralis, external spermatic nerve, nervus spermaticus externus. (05 Mar 2000) |
| external sphincter muscle of anus | A fusiform ring of striated muscular fibres surrounding the anus, attached posteriorly to the coccyx and anteriorly to the central tendon of the perineum; it is subdivided, often indistinctly, into a subcutaneous part, a superficial part and a deep part for descriptive purposes. Synonym: musculus sphincter ani externus, external sphincter muscle of anus. (05 Mar 2000) |
| external sphincterotomy | Transurethral incision of external urethral sphincter. (05 Mar 2000) |
| external spiral sulcus | A concavity in the outer wall of the cochlear duct between the prominentia spiralis and the spiral organ. Synonym: sulcus spiralis externus. (05 Mar 2000) |
| external squint | <clinical sign> The outward or temporal deviation of an eye. (27 Sep 1997) |
| external strabismus | An obsolete term for exotropia. (05 Mar 2000) |