Palmar Fascia

The palmar fascia is the thick, deep fascia of the palm, consisting of fibrous connective tissue that provides structure, protection, and mechanical support to the palmar region. Its most prominent feature is the palmar aponeurosis, which is centrally located and reinforced by the tendon of the palmaris longus (when present).

Location

The palmar fascia is located in the central palm, lying deep to the skin and superficial to the flexor tendons, lumbricals, and neurovascular bundles. It is continuous proximally with the antebrachial fascia and distally with the fibrous digital sheaths of the fingers.

Structure

The palmar fascia is organized into three regional components:

Function

• Protection: Shields underlying tendons, vessels, and nerves from external trauma
• Support: Stabilizes skin and soft tissue during gripping and digit movement
• Force Distribution: Transmits tension from palmaris longus and muscles to digits
• Tendon Guidance: Anchors fibrous digital sheaths and maintains alignment of flexor tendons

Relations

• Superficial to: Flexor tendons, lumbricals, digital vessels and nerves
• Deep to: Palmar skin, superficial palmar arch, palmaris brevis (in hypothenar area)

Blood Supply

• Branches from the superficial palmar arch (mainly from the ulnar artery)
• Perforating branches from the deep palmar arch

Innervation

While the fascia itself is not directly innervated, nearby skin and structures are supplied by:

• Median nerve: Thenar and lateral palmar skin
• Ulnar nerve: Hypothenar and medial palmar skin

Surface Anatomy

The palmar aponeurosis forms the firm, raised central portion of the palm. The longitudinal bands of the fascia can be palpated and may become visible with strong finger flexion or in pathological thickening.

Development

The palmar fascia develops from deep connective tissue mesenchyme of the upper limb. It begins to organize during fetal hand formation and thickens in early childhood.

Anatomical Variations

• The palmaris longus tendon may be absent (10–15% of people), affecting the aponeurosis's proximal reinforcement
• Accessory slips to digits, skin, or muscle fascia are occasionally present

Clinical Significance

• Dupuytren’s Contracture: Progressive fibrosis and shortening of the palmar aponeurosis leading to flexion deformities, especially of the ring and little fingers
• Palmar Fasciectomy: Surgical excision of diseased fascia in advanced Dupuytren’s cases
• Infection Pathways: Deep space infections may track along fascial planes beneath or around the fascia

Comparative Anatomy

In non-human primates, the palmar fascia is thinner and less functionally differentiated. In humans, it supports enhanced grip strength, skin stabilization, and tendon alignment for fine motor control and complex manual tasks.