Human Anatomy - Kotsan I. Y. 2009

Skin
Vessels and Nerves of the Skin

The Blood Vessels of the Skin originate partly from local and partly from proper cutaneous Arteries. By anastomosing with one another, they form a deep cutaneous arterial network (rete arteriosum cutaneum) at the border between the subcutaneous adipose tissue and the skin proper (dermis). From this network, arterial branches extend to the glomeruli of the Sweat Glands, Hair papillae, and subcutaneous tissue. In the vertical direction, vessels also branch off from the cutaneous network into the overlying layers of the skin, where they branch, anastomose with each other, and form the subpapillary arterial network (rete arteriosum subpapillare). The subpapillary arterial network supplies the hair follicles, sweat gland ducts, and Sebaceous Glands, and sends small arteries to the papillae, where they divide into arterial capillaries. These capillaries transition into wider venous capillaries, which subsequently form the Veins OF THE skin.

The arterial networks of the skin are unevenly developed across different body regions, reaching their greatest development on the soles, palms, and buttocks.

Venous blood flows from the capillaries into veins that form superficial subpapillary and, subsequently, deep subpapillary venous plexuses located at the border of the dermis and subcutaneous adipose tissue. From this plexus, venous blood flows into the deep dermal venous plexus and then into the subcutaneous venous plexus.

The lymphatic capillaries of the skin form two networks: a superficial network in the reticular layer of the dermis—receiving capillaries originating in the papillae—and a deep network located at the border with the subcutaneous adipose tissue. The Lymphatic vessels formed by the deep network connect with the Vessels of the fasciae and Muscles before draining into regional Lymph Nodes.

Innervation of the skin is provided by both somatic sensory nerves (cranial and spinal) and NERVES OF THE Autonomic Nervous System. The skin contains numerous structurally diverse nerve endings that perceive sensations of Touch, pressure, pain, and Temperature (see above, "Skin Receptors"). The innervation of the arrector pili muscles, glands, and Blood and Lymphatic vessels is supplied by postganglionic sympathetic fibers that reach the skin as part of somatic nerves and alongside blood vessels. Nerve fibers form plexuses within the subcutaneous adipose tissue and the papillary layer of the dermis, as well as around glands and hair roots.

The cutaneous analyzer, like any sensory analyzer, consists of three divisions: the receptive (receptor), the central (cortical), and the conducting pathway.

The receptive division of the cutaneous analyzer is represented by receptors located in the epidermis, dermis, and subcutaneous adipose tissue throughout the skin (see above, "Skin Receptors").

The central division of the cutaneous analyzer comprises subcortical centers (thalamic nuclei) and the cortical center for general sensitivity, located in the postcentral gyrus and the superior parietal lobule of the parietal lobe.

The conducting pathway of the cutaneous analyzer is represented by sensory nerve pathways for pain, temperature, tactile, and spatial cutaneous sensitivity (see above, "Conducting Pathways");

All Sensory Organs in a unified Organism are interconnected, particularly within the Cerebral Cortex, where the cortical ends of all analyzers link via associative pathways. This interrelation and mutual influence of sensory organs ensure compensatory development of certain analyzers when others are impaired.

Basic Latin Terms

Skin — cutis

Epidermis — epidermis; Basal layer — stratum basale

Spiny layer — stratum spinosum

Granular layer — stratum granulosum

Clear layer — stratum lucidum

Horny layer — stratum corneum

Dermis — dermis (corium)

Papillary layer — stratum papillare

Papillae — papillae

Skin ridges — cristae cutis

Skin sulci — sulci cutis

Reticular layer — stratum reticulare

Subcutaneous adipose tissue — tela subcutanea

Sweat glands — glandulae sudoriferae

Sebaceous glands — glandulae sebaceae

Mammary gland — glandula mammaria

Areola — areola mammae

Hair — pili

Nail — unguis

Nail matrix — matrix unguis

ROOT of nail — radix unguis

Nail body — corpus unguis

Free margin — margo liber

Hidden margin — margo occultus

Lateral margin — margo lateralis

Nail sinus — sinus unguis

Nail wall — vallum unguis

Lunula — lunula

Hyponychium — hyponychium

Eponychium — eponychium

Cutaneous arterial network — rete arteriosum cutaneum

Subpapillary arterial network — rete arteriosum subpapillare