Linton, Christina P.
Christina P. Linton, PhD, FNP-BC, Department of Dermatology, Central Utah Clinic, Provo, Utah.
The author declares no conflict of interest.
Correspondence concerning this article should be addressed to Christina P. Linton, PhD, FNP-BC, Central Utah Clinic, 1055 North 500 West, Suite 111, Provo, UT 84604. E-mail: email@example.com
ALOPECIA – Hair loss, usually on the scalp.
ANAGEN – Phase of hair growth; lasts for variable periods of time depending on body site. Hairs in this phase have pigmented, malleable proximal ends.
ARRECTOR PILI MUSCLE – Bundles of smooth muscle fibers that are attached to the deep part of the hair follicles and act to pull the hairs erect.
BULB – Lowermost portion of the hair follicle.
CANITIES – Graying of hair.
CASTS – Remnants of the inner root sheath that may mimic nits. Unlike nits (which are firmly attached), hair casts slide freely along the shaft. Also called pseudonits.
CATAGEN – Regression phase in between the telogen and anagen phases; driven by massive keratinocyte apoptosis, which leads to involution of the lower two thirds of the hair follicle.
CICATRICIAL ALOPECIA – Irreversible loss of hair follicles with disappearance of follicular ostia. Also called scarring alopecia.
CORTEX – Comprises the bulk of the hair shaft and contains melanin; situated between the medulla (in larger hairs) and cuticle.
CLUB HAIR – Hair characteristic of the telogen phase in which the bulb has become a club-shaped mass.
CUTICLE – Covers the hair shaft to provide protection; may be completely lost at the end of long hairs. The integrity and properties of the cuticle greatly impact the appearance of the hair.
EFFLUVIUM – Process of increased daily hair shaft shedding (more than 25–100 hairs per day).
EXCLAMATION POINT HAIR – Short broken hairs whose distal ends are broader than the proximal ends; indicative of alopecia areata.
EXOGEN – Phase of active hair shaft shedding.
HIRSUTISM – Excessive growth of terminal hairs in a “male pattern” in a female patient that is related to hormonal factors (androgen overproduction or increased end-organ sensitivity to androgens). The “male pattern” may involve the upper lip, chin, cheeks, central chest, breasts, lower abdomen, and/or groin.
HYPERTRICHOSIS – The growth of excessive amounts of hair on any area of the body; may be generalized or localized and congential or acquired and involve lanugo, vellus, or terminal hairs.
LANUGO HAIR – Fine, pigmented hair on the fetal body that is shed in utero or during the first weeks of life; somewhere between vellus and terminal hair in length and form; occurrence in postnatal life (hypertrichosis lanuginosa) may indicate a serious problem.
MADAROSIS – Loss of eyelashes and/or eyebrows.
MATRIX – Rapidly proliferating keratinocytes that terminally differentiate to produce the hair shaft.
MEDULLA – The central axis of some hairs; contains a column of large vacuolated and keratinized cells; surrounded by the cortex.
MINIATURIZATION – Terminal-to-vellus hair conversion in conditions such as androgenic alopecia. The miniaturized follicles still display an arrector pili muscle.
OPHIASIS – Confluent hair loss along the temporal and occipital scalp; usually a feature of alopecia areata.
POLIOSIS – Circumscribed patches of white or gray hair. May be associated with several syndromes, including vitiligo, regressing melanoma, and alopecia areata. Migrating patches without hair loss may represent a forme fruste of alopecia areata.
PILOERECTION – Erection of the hair shaft due to the action of the arrector pili muscle.
PILOMOTOR REFLEX – Contraction of the smooth muscle of the skin resulting in “gooseflesh” appearance; caused by mild application of tactile stimulus or by local cooling.
PILOSE – Hairy.
ROOT – The part of the hair that is embedded in the hair follicle.
SHAFT – The visible hair that arises from the bulb. Made up of the medulla (in the center of larger hairs) and the cortex and covered by the cuticle.
SCHIZOTRICHIA – Splitting of the hairs at their ends.
TELOGEN – Period of relative quiescence; lasts for variable periods of time depending on body site. Hairs in this phase are clubbed with depigmented, rounded-up proximal ends (also called club hairs).
TERMINAL HAIR – Produced by large hair follicles located in the subcutis; hairs are generally pigmented, medullated, and >0.03 mm in diameter.
TRICHOLOGIA – A nervous habit of plucking at the hair.
TRICHOPHAGIA – Habitual biting of the hair or swallowing of plucked hairs.
TRICHORRHEXIS – A condition in which the hairs tend to break or split.
TRICHOTILLOMANIA – A compulsion to pull out one’s own hair from the scalp, eyebrows, or eyelashes.
TUFTING – Doll’s hair–like bundling of follicular units; usually a feature of cicatricial alopecia.
VELLUS HAIR – Produced by very small (but functionally active, cycling) hair follicles located in the dermis; thin (≤0.03 mm diameter), short, often depigmented, and usually nonmedullated hair shaft; arrector pili muscle absent.
© 2012 Lippincott Williams & Wilkins, Inc.