| frontal triangle | A triangle bounded above by the maximum frontal diameter and laterally by lines joining the extremities of this diameter with the glabella. (05 Mar 2000) |
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| frontal tuber | The most prominent portion of the frontal bone on either side. Synonym: tuber frontale, eminentia frontalis, frontal tuber. (05 Mar 2000) |
| frontal veins | The superficial veins draining the frontal cortex and emptying into the superior sagittal sinus. Synonym: supratrochlear veins. (05 Mar 2000) |
| frontal zone contraction theory | Model proposed to account for the movement of giant amoebae in which cytoplasmic contraction at the front of the leading pseudopod (fountain zone) pulls viscoelastic cytoplasm forward in the centre of the cell and forms a tube of more rigid cytoplasm immediately below the plasma membrane behind the active region. The peripheral contracted cytoplasm relaxes into a weaker gel at the rear and is pulled forward in its turn. Contrasts with the ectoplasmic tube contraction model. (18 Nov 1997) |
| abdominal external oblique muscle | <anatomy, muscle> Origin, fifth to twelfth ribs; insertion, anterior half of lateral lip of iliac crest, inguinal ligament, and anterior layer of the rectus sheath; action, diminishes capacity of abdomen, draws thorax downward; nerve supply, thoracoabdominal nerves. Synonym: musculus obliquus externus abdominis, abdominal external oblique muscle. (05 Mar 2000) |
| ambiguous external genitalia | External genitalia not clearly of either sex; most commonly designates external genitalia that are incompletely masculinised. (05 Mar 2000) |
| anterior scrotal branch of external pudendal artery | <anatomy, artery> Distribution, skin of anterior scrotum; anastomoses, posterior scrotal branches from internal pudendal artery. Synonym: rami scrotales anteriores arteriae pudendae externae. (05 Mar 2000) |
| aponeurosis of external abdominal oblique muscle | <anatomy> Broad, flat tendinous portion of the external abdominal oblique muscle. The fleshy fibres of the muscle end in the aponeurosis along a line descending vertically from the costochondral joint of the ninth rib then turning laterally just below the level of the umbilicus toward the anterior superior iliac spine. The fibres of the aponeurosis run medially and inferiorly, contributing to the anterior wall of the sheath of the rectus abdominis muscle and decussating with those of the contralateral aponeurosis at the median linea alba. Inferomedially, the aponeurosis is attached to the upper border of the pubic symphysis, the pubic crest and pubic tubercle. Between the anterior superior iliac spine and the pubic tubercle, it is thickened and turned under, forming the inguinal ligaments. The portion of the aponeurosis attached to the pubic bone forms the superficial inguinal ring by splitting into medial and lateral crura. See: external spermatic fascia, inguinal ligament, lacunar ligament, pectineal ligament, reflected inguinal ligament, superficial inguinal ring, rectus sheath. (05 Mar 2000) |
| bony part of external acoustic meatus | The medial two-thirds of the external acoustic meatus which is formed as the tympanic plate of the temporal bone develops; it extends approximately 16 mm. From its junction with the cartilaginous part to the tympanic membrane. (05 Mar 2000) |
| carotid artery, external | Branch of the common carotid artery which supplies the exterior of the head, the face, and the greater part of the neck. (12 Dec 1998) |
| cartilaginous part of external acoustic meatus | The lateral third of the external acoustic meatus which is continuous with the auricular cartilage and attached to the circumference of the bony part. (05 Mar 2000) |
| chronic progressive external ophthalmoplegia | A specific type of slowly worsening weakness of the ocular muscles, usually associated with a pigmentary retinopathy. See: Kearns-Sayre syndrome, oculopharyngeal dystrophy. Synonym: ocular myopathy. (05 Mar 2000) |
| haemorrhoids, external | Haemorrhoids that occur below the dentate line and are generally painless. They are sometimes called skin tags, or can be seen or felt as extra skin around the anus. External haemorrhoids can become very distressing when the blood in the external haemorrhoid clots and inflammation irritates the nearby pain-sensitive skin. This condition is called a thrombosed external haemorrhoid and is quite painful. (07 Jan 1998) |
| nerve of external acoustic meatus | A branch of the auriculotemporal nerve supplying the lining of the external acoustic meatus. Synonym: nervus meatus acustici externi. (05 Mar 2000) |
| subcutaneous part of external anal sphincter | pars subcutanea musculi sphincteri ani externi, subcutaneous portion of external anal sphincter |