"Hair (TA: pilus/pili) remains important physiologically and psychologically for humans. The hair shaft develops from a structure known as the hair follicle. Each hair has an arrector pili muscle and both sensory and sympathetic neural connections."
"The hair shaft (TA: stipes pili) arises within hair follicles (TA: folliculus pili), which are tubular epidermal structures that penetrate deep into the dermis. At their deepest point, the follicle expands to form the hair bulb. The hair root is the portion of the hair shaft deep to its exit point from the skin surface."
"The hair shaft (TA: stipes pili) arises within hair follicles (TA: folliculus pili), which are tubular epidermal structures that penetrate deep into the dermis. At their deepest point, the follicle expands to form the hair bulb. The hair root is the portion of the hair shaft deep to its exit point from the skin surface."
"The hair shaft (TA: stipes pili) arises within hair follicles (TA: folliculus pili), which are tubular epidermal structures that penetrate deep into the dermis. At their deepest point, the follicle expands to form the hair bulb. The hair root is the portion of the hair shaft deep to its exit point from the skin surface."
"The hair shaft (TA: stipes pili) arises within hair follicles (TA: folliculus pili), which are tubular epidermal structures that penetrate deep into the dermis. At their deepest point, the follicle expands to form the hair bulb. The hair root is the portion of the hair shaft deep to its exit point from the skin surface."
"The hair shaft (TA: stipes pili) arises within hair follicles (TA: folliculus pili), which are tubular epidermal structures that penetrate deep into the dermis. At their deepest point, the follicle expands to form the hair bulb. The hair root is the portion of the hair shaft deep to its exit point from the skin surface."
"The hair shaft (TA: stipes pili) arises within hair follicles (TA: folliculus pili), which are tubular epidermal structures that penetrate deep into the dermis. At their deepest point, the follicle expands to form the hair bulb. The hair root is the portion of the hair shaft deep to its exit point from the skin surface."
"The base of the bulb is turned in on itself, forming a depression in which the vascular dermal papilla sits. The papilla contains multiple supplying and draining capillaries and specialised mesenchymal cells that regulate the growth of the hair shaft."
"Encasing the papilla within the bulb of the follicle is a matrix comprising the germination cells, which undergo rapid division (fastest mitosis of any tissue in the body) to form the new hair cells. These developing cells ascend to form the hair shaft and internal root sheath. Melanocytes are interspersed throughout the matrix releasing melanin to be incorporated into the growing hair cells."
"An arrector pili muscle originates from the dermis and inserts into the hair follicle at the bulge. Contraction of this smooth muscle, under sympathetic control, causes hair to become erect and also compresses an associated sebaceous gland which secretes its sebum onto the shaft. Sebum, a fat-rich substance has a protective function for the hair."
Expected headings
"Arterial supply and venous drainage"
"Distribution of hair is further modified by age, sex and ethnicity 3."