Anterior Neck and Thorax - LO 1

1. Describe the location and composition of the integumentary and fascial layers one encounters when dissecting from superficial to deep.

During any early dissection, the first step is typically the removal of the most superficial layers, starting with the skin.

The skin (or integumentary system) is composed of two divisions:

• Epidermis

  • Most superficial (we can see the most superficial components of the epidermis)

  • Avascular

  • Mostly composed of dead, keratinized, flattened cells

  • Contains afferent nerve endings

    • Afferent nerve endings conduct signals back to the central nervous system; cutaneous sensation (sensations include pain, temperature, pressure, etc.)

• Dermis

  • The larger division & deep to the epidermis

  • Highly vascular

    • Supplies blood to deep portions of the epidermis

  • Significantly more contents than epidermis, including:

    • Afferent nerve endings

    • Sudoriferous (sweat) glands

    • Complexes of hair follicles, sebaceous (oil) glands, and arrector pili mm. (smooth muscle)

Fascia is the term for grossly visible connective tissue collections or sheaths deep to the skin.

The superficial fascia (i.e. hypodermis, subcutaneous tissue) is deep to the dermis. This layer is often colloquially referred to as the fatty layer due to high loose areolar connective tissue content. The thickness of the layer varies between individuals and different areas of the body.

• Functions:

  • Principal site of energy storage

  • Layer of insulation

Deep fascia is more dense than superficial fascia, and is devoid of adipose tissue (fat). This fascia is important in surrounding and supporting muscles, organs (viscera), and neurovasculature (investing fascia).