Topic Overview

✋ Palmar Aspect of Wrist and Hand

Introduction

• The palm forms the anterior aspect of the hand, specialized for grip and precision.

• It contains muscles, tendons, nerves, arteries, and fascia arranged in distinct compartments.

• The structures passing from forearm into the palm are protected by the flexor retinaculum at the wrist.

Dissection of Palmar Aspect of Wrist and Hand

Steps

1. Place the hand supine and make an incision along the wrist crease and another along the mid-palmar line.

2. Reflect the skin and superficial fascia to expose:

   • Palmar cutaneous branches of median and ulnar nerves.

   • Superficial veins and superficial palmar arch.

3. Note palmar fascia – thin over thenar and hypothenar areas, thick centrally forming the palmar aponeurosis.

4. Divide the palmar aponeurosis to reveal flexor tendons and lumbricals.

5. Observe the flexor retinaculum at the wrist – forming the roof of the carpal tunnel.

6. After incising the retinaculum, identify structures deep to it (in the carpal tunnel).

Flexor Retinaculum (Transverse Carpal Ligament)

Definition

A strong fibrous band bridging the anterior concavity of the carpus, converting it into the carpal tunnel.

Attachments

• Medially: Pisiform and hook of hamate.

• Laterally: Tubercle of scaphoid and crest of trapezium.

Relations

Superficial (Above)

• Palmar cutaneous branch of median nerve.

• Palmaris longus tendon (if present).

• Ulnar artery and nerve (pass superficial to it, through Guyon’s canal).

Deep (Below)

• Forms the roof of carpal tunnel enclosing:

  • Median nerve.

  • Four tendons of flexor digitorum superficialis.

  • Four tendons of flexor digitorum profundus.

  • Tendon of flexor pollicis longus.

Function

• Converts the carpal groove into a tunnel, preventing “bow-stringing” of tendons.

• Maintains proper alignment and provides mechanical efficiency for flexor tendons.

• Protects the median nerve and tendons from displacement during wrist movement.

Structures Superficial to Flexor Retinaculum

• Palmaris longus tendon (when present).

• Ulnar nerve and artery (in Guyon’s canal).

• Palmar cutaneous branches of median and ulnar nerves.

Structures Deep to Flexor Retinaculum (Within Carpal Tunnel)

• Median nerve.

• Tendons of FDS, FDP, and FPL enclosed in synovial sheaths.

Clinical Anatomy of Palmar Aspect and Flexor Retinaculum

1. Carpal Tunnel Syndrome

• Cause: Compression of median nerve beneath the flexor retinaculum.

• Symptoms:

  • Numbness and tingling in lateral 3½ fingers.

  • Weakness and wasting of thenar muscles.

  • Difficulty in thumb opposition.

• Tests:

  • Phalen’s test (wrist flexion reproduces symptoms).

  • Tinel’s sign (tapping over tunnel causes tingling).

• Treatment: Surgical decompression by incising flexor retinaculum.

2. Guyon’s Canal Syndrome (Ulnar Tunnel Syndrome)

• Compression of ulnar nerve in canal superficial to retinaculum → causes hypothenar weakness and sensory loss in medial 1½ fingers.

3. Palmaris Longus Variations

• Absent in about 10–15% of individuals.

• Commonly used for tendon grafting (e.g., facial reanimation, thumb reconstruction).

4. Synovial Sheath Infections

• Infection of ulnar or radial bursae can spread rapidly due to continuity with digital synovial sheaths.

• Ulnar bursa: Surrounds tendons of FDS and FDP.

• Radial bursa: Surrounds tendon of FPL.

• Clinical sign: swelling and tenderness along palm and wrist → may require drainage.

5. Flexor Retinaculum in Surgery

• Must be carefully divided during carpal tunnel release.

• Palmar cutaneous branch of median nerve lies superficial, hence preserved.

6. Pulsations at Wrist

• Radial pulse: lateral to tendon of flexor carpi radialis.

• Ulnar pulse: lateral to pisiform bone.