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Because the brain is confined to the skull, brain size is limited. Ridges and depressions create folds allowing a larger cortical surface area, and greater cognitive function, to exist in the confines of a smaller cranium .
Patients show visible folds, ridges or creases on the surface of the top of the scalp. [2] The number of folds can vary from two to roughly ten and they are typically soft and spongy. The condition typically affects the central and rear regions of the scalp, but sometimes can involve the entire scalp.
In neuroanatomy, a sulcus (Latin: "furrow"; pl.: sulci) is a shallow depression or groove in the cerebral cortex.One or more sulci surround a gyrus (pl. gyri), a ridge on the surface of the cortex, creating the characteristic folded appearance of the brain in humans and most other mammals.
The periaqueductal gray (PAG), also known as the central gray, is a brain region that plays a critical role in autonomic function, motivated behavior and behavioural responses to threatening stimuli. [1] [2] PAG is also the primary control center for descending pain modulation. It has enkephalin-producing cells that suppress pain.
The middle frontal gyrus makes up about one-third of the frontal lobe of the human brain. (A gyrus is one of the prominent "bumps" or "ridges" on the cerebral cortex.. The middle frontal gyrus, like the inferior frontal gyrus and the superior frontal gyrus, is more of a region in the frontal gyrus than a true gyrus.
This narrow layer is found only on the palms and soles. The epidermis of these two areas is known as "thick skin" because with this extra layer, the skin has 5 epidermal layers instead of 4. granular layer (stratum granulosum) Confocal image of the stratum granulosum Keratinocytes lose their nuclei and their cytoplasm appears granular.
The skin weighs an average of four kilograms, covers an area of two square metres, and is made of three distinct layers: the epidermis, dermis, and subcutaneous tissue. [1] The two main types of human skin are: glabrous skin , the hairless skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. [ 3 ]
Merkel cells are found in the skin and some parts of the mucosa of all vertebrates. In mammalian skin, they are clear cells found in the stratum basale [2] [3] (at the bottom of sweat duct ridges) of the epidermis approximately 10 μm in diameter. They are oval-shaped mechanoreceptors essential for light touch sensation and found in the skin of ...