epidermis
The Dermis.
The reticular layer.
reticular layer is responsible for tension lines in the skin
reticular layer
The deeper part of the dermis is responsible for markings on our skin surface called Flexure lines. These lines are easily observed as the deep skin creases on the palms. Flexure lines result from a continual folding of the skin, often over joints, where the dermis attaches tightly to underlying structures. Flexure lines are also visible on the wrists, soles of the feet, fingers, and toes.
NO CLEAVAGE LINES SHOULD BE MADE PARALLEL. When and incision is made parallel to the cleavage lines, the skin gapes less and heals more readily than when the incision is made across the cleavage lines
Light coming up from the centre of the Sun goes through the outer layer where it encounters absorbtion by elements in the outer layer, and this gives rise to absorbtion lines in the spectrum.
cleavage lines
Cleavage occurs naturally between the tissue of the two breasts. We think mostly of well-endowed females as having cleavage, but overweight boys and men can have cleavage too. The "lines of cleavage" are, as a simple description, the line between the clothing or bra and the exposed area of the breast and the "line" or separation between the breasts. So, if a woman wears an ill-fitting bra or one that is too small, the area of cleavage can be pronounced. In smaller bosoms, cleavage is less pronounced or noticeable.
Here are some vocabulary for the integumentary system: Epidermis Dermis Papillary layer Reticular layer Subcutaneous layer Hair Shaft Sweat Gland Tactile Corpuscle Sebaceous Gland Arrector Pili Muscle Hair Follicle Nerve Fibers Artery Vein Stratum Germinitivum Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum Albino Lines of Cleavage Hypodermis Apocrine Glands Merocrine Sweat Glands
flexure lines
These are called striations.
That is cleavage.