A ridge or a crevice formed when a flexible surface doubles back on itself. Synonym: plica
2. A bend, e.g., one of the bends in a polypeptide that determines its in situ three-dimensional structure.
3. A particular three-dimensional folded shape assumed by a polymer, such as a protein.
4. A thin, doubled sheet extending from a tissue or a cell.
In the gastrula stage of the embryo, a small bulge of embryonic ectoderm and mesoderm that begins extending into the proamniotic cavity; it eventually gives rise to the amnion and the chorion.
Each of the two lateral rims of the inlet to the larynx, which are the top edges of the quadrate membranes. These folds are ridges composed of mucosa-covered muscle fibers and fibrocartilage ligaments; they lie behind the thyroid cartilage and extend downward from the sides of the epiglottis anteriorly to the tops of the arytenoid cartilages posteriorly. Near their posterior ends, each fold surrounds a small cuneiform cartilage and then a corniculate cartilage (which sits atop the arytenoid cartilage).
Two ridges of skin-covered muscle along the sides of the chest where the under side of each arm meets the shoulder. The anterior axillary fold is formed by the lateral edge of the pectoralis major muscle; the posterior axillary fold is formed by the lateral edges of the latissimus dorsi and teres major muscles.
Transverse ruffles that ring the inner wall of the small intestine. The circular folds (plicae) are soft ridges of mucosa that protrude into the intestinal lumen. These folds are largest and closest together in the duodenum distal to the major duodenal papilla, they decrease in height and number through the distal jejunum, and they disappear in the distal ileum. See: circular plica
A ligament, arising from the peritoneum, that attaches the splenic flexure of the colon to the diaphragm.
Douglasfold See: Douglas, James
Any of the mostly longitudinal folds of mucosa found in the empty stomach. See: ruga
A fold of skin in the embryo on each side of the genital tubercle that develops into the labia minora in females.
One of three mucous membrane folds between the base of the tongue and the epiglottis.
The linear crease in the skin that separates the buttocks from the thighs. This fold marks the lower limits of the gluteus maximus muscle.
The lower border of the breast where it meets the chest wall. Synonym: submammary fold
A line that forms in the skin under the swollen eyelids of patients with atopic dermatitis. Synonym: atopic pleat; Dennie–Morgan fold
A valvelike fold in the lower part of the nasolacrimal duct.
Along the back wall of the mouth, the ridge of oral mucosa that runs from the maxilla (superiorly) or the mandible (inferiorly) to the cheek.
The line of flexure where the oral mucosa passes from the maxilla or mandible to the lip.
A fold of mucosal tissue.
A groove in the skin surrounding the margins and proximal edges of the nail.
In the early embryo, the raised lateral edges of the neural plate. The neural folds are thickened ridges of epithelium that are pushed up and that meet in the midline as the neural plate curls into a longitudinal tube. These folds, transition zones between the neural tissue in the neural plate and the surrounding surface ectoderm, give rise to the neural crest cells and to ectodermal placodes.
palmate fold of the uterus
Any of the longitudinal ridges along the cervical canal of the uterus.
semilunar fold of conjunctiva
The fold of conjunctiva at the inner angle (inner canthus) of the eye.
sentinel foldSentinel pile.
skin fold, skinfold
A doubling of skin and its underlying adherent subcutaneous tissue. To assess a person's body fat, a skin fold is pinched at a standard site, and the thickness of the doubled skin is measured, using skin fold calipers; a body fat estimate is then calculated using a table or a computer program. There are 6-12 standard locations for measuring skin fold thickness, including over the triceps muscle along the back of the arm and just above the iliac crest of the hip.
submammary foldInframammary fold.
transverse fold of rectum
Any of the three permanent folds projecting into the lumen of the rectum. Synonym: Houston valve
urogenital fold See: urogenital ridge
ventricular fold of the larynx
The upper pair of ridges that project into the midsection of the larynx; these define the upper boundary of the laryngeal vestibule. Each fold is composed of pinkish mucosa covering a thin ligament (the vestibular ligament), which runs from the thyroid cartilage anteriorly to the arytenoid cartilage posteriorly, roughly parallel to the vocal ligament below it. The ventricular vocal folds contribute to certain types of sound production. Synonym: false vocal cordvestibular fold
vestibular foldVentricular fold of the larynx.
The ligament of the left side of the superior vena cava.
Synonym: true vocal cord
The lower pair of ridges that project into the midsection of the larynx; these define the lower boundary of the laryngeal vestibule, a disk shaped subcavity of the laryngeal cavity. The protruding vocal folds create the narrowest cross-section of the larynx, and they are the edges of the glottis, i.e., rima glottidis, where phonation is produced.
Each vocal fold is composed of whitish, stratified squamous epithelium covering a thin ligament (the vocal ligament), which runs from the thyroid cartilage anteriorly to the arytenoid cartilage posteriorly. The vocal ligament is the medial edge of the vocalis muscle.
During a strong inspiration, the vocal folds are pulled farther apart to widen the opening into the trachea. During swallowing, the vocal folds are pulled together to protect the trachea. During phonation, the vocal folds are pulled together and airflow causes them to vibrate and make a sound; the pitch of this sound can be changed by varying the tension on the vocal ligaments.