Topic Overview

Skin and Fasciae of the Back

Skin

• Thick, coarse, and pigmented (especially in upper back).

• Rich in sebaceous glands → prone to acne, sebaceous cysts, furuncles.

• Cutaneous innervation:

  • Supplied by posterior (dorsal) rami of spinal nerves.

  • Each nerve supplies a segmental strip (dermatome).

• Clinical:

  • Shingles (Herpes zoster) affects dorsal root ganglion → vesicular eruption along dermatome.

  • Referred pain can localize to back dermatomes.

Fasciae

1. Superficial Fascia

• Thin, contains fat, vessels, and cutaneous nerves.

• Loosely attached → allows skin mobility.

2. Deep Fascia

• Dense fibrous sheath investing muscles.

• In lumbar region → thickened to form thoracolumbar fascia, which has:

  • Posterior layer → attached to spinous processes.

  • Middle layer → attached to transverse processes.

  • Anterior layer → covers quadratus lumborum.

• Provides strong attachment for latissimus dorsi, internal oblique, transversus abdominis.

• Clinical:

  • Thoracolumbar fascia transmits mechanical stresses between upper limb and pelvis.

  • Infections may spread along fascial planes.

Dissection of Back

Step 1: Skin Incision

• Midline incision from external occipital protuberance → coccyx.

• Transverse incisions along scapular spine and iliac crest.

• Reflect skin laterally to expose superficial fascia.

Step 2: Expose Superficial Fascia

• Remove superficial fascia to reveal cutaneous nerves and vessels.

• Identify posterior branches of spinal nerves emerging segmentally.

Step 3: Expose Deep Fascia

• Carefully clear deep fascia to outline trapezius and latissimus dorsi.

• Observe continuity of deep fascia with nuchal ligament (cervical region) and thoracolumbar fascia (lumbar region).

Step 4: Clinical Demonstrations

• Note thickness of skin in upper back (common site for sebaceous cysts).

• Show distribution of cutaneous nerves (dermatomes).

• Demonstrate thoracolumbar fascia as an important structure linking limb and trunk muscles.