Note: There are two transverse bands that help to stabilize the wrist joint anteriorly. The palmar carpal ligament is wider and extends more proximally, whereas the transverse carpal ligament (flexor retinaculum) is narrower, deeper, more distal, and more dense. The palmar carpal ligament is a condensation of distal antebrachial fascia that is continuous with the extensor retinaculum (posteriorly) and (when present) the tendon of the palmaris longus m. The palmar carpal ligament lies superficially to the ulnar a. & n. and the transverse carpal ligament (with the carpal tunnel, deep). The transverse carpal ligament in the roof to the carpal tunnel.

Note: The ulnar a. and ulnar n. are in close proximity in the medial wrist region. The ulnar a. forms the majority supply to the superficial palmar arch. The ulnar n. provides afferent innervation to medial palmar and medial dorsal surfaces of the hand and 1.5 digits, and efferent supply to all intrinsic hand muscles (except those in the thenar compartment and half of the lumbrical mm.). The ulnar a. & n. pierce the transverse carpal ligament (flexor retinaculum) to enter the hand region - they do not travel through the carpal tunnel.

Photo 2. Ulnar n. in the wrist

Photo 3. Ulnar & radial aa.

Note: The transverse carpal ligament surrounds the tendon for the flexor carpi radialis m. (the lateral flexor and abductor of the radiocarpal joint).  

3.) Using scissors, incise the transverse carpal ligament sagittally.

Note: The carpal tunnel transmits median n., the tendons of muscles responsible for flexing the metacarpophalangeal (MCP), and interphalangeal (PIP & DIP) joints for all digits and the bursae which surround the tendons.

Photo 4. Carpal tunnel & contents

Note: The ulnar bursa surrounds and protects three layers of tendons, from superficial-to-deep, which are:

• • 1st layer: tendons of flexor digitorum superficialis m., to digits 3 & 4

  • 2nd layer: tendons of flexor digitorum superficialis m., to digits 2 & 5

  • 3rd layer: tendons of flexor digitorum profundus m., to digits 2-5

The radial bursa surrounds and protects the tendon of flexor pollicis longus m., to digit 1.  

Observe structures of the anterior (palmar) side of the digits

Find these structures:

• • Thenar compartment

    • Abductor pollicis brevis m.

    • Flexor pollicis brevis m.

    • Opponens pollicis m.

    • Tendon of flexor pollicis longus m.

  • Hypothenar compartment

    • Abductor digiti minimi m.

    • Flexor digiti minimi brevis m.

    • Opponens digiti minimi m.

  • Central compartment

    • Palmar aponeurosis

    • Tendons from the digital flexor mm. of the anterior forearm

  • Adductor / interosseous compartment

    • Adductor pollicis m.

    • Palmar interossei mm.

  • Radial a., & deep palmar (arterial) arch

  • Ulnar a., & superficial palmar (arterial) arch

  • Median n.

    • Recurrent br.

  • Ulnar n.

Note: The hand is comprised of the palmar region, the dorsal region, and the digits (1-5, thumb = digit 1). The palmar region is divided into 5 compartments: thenar, hypothenar, central, and the adductor and interosseous compartments.

 4.) Locate the thenar eminence. Clean and identify structures of the thenar compartment.

Note: The thenar compartment is the most lateral compartment of the hand on the palmar side. This compartment is at the base of the thumb. The three intrinsic muscles in this compartment control the thumb: abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis mm. In addition to these intrinsic muscles, the tendon from the flexor pollicis longus m. resides in this compartment.

Note: The muscles of the hand are all innervated by the ulnar n. with the exception of the thenar mm. (which are innervated by the recurrent br. of the median n.) and the radial half of the lumbrical mm. (also innervated by the median n.). Upon exiting the carpal tunnel, the recurrent br. of the median n. branches laterally from the median n., and enters the thenar mm. between the abductor pollicis brevis m. and flexor pollicis brevis m. If there is an anastomosis between the superficial palmar (arterial) arch with the radial a., you may see the superficial palmar br. of the radial a. in the vicinity of the recurrent br. of the median n.

Photo 5. Thenar compartment, superficial

Photo 6. Thenar compartment, deep

5.) Clean and identify structures of the hypothenar compartment.

Note: The hypothenar compartment is the most medial compartment of the hand on the palmar side, and this compartment is at the base of the little finger. The three intrinsic muscles in this compartment control the little finger (digit 5): abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi mm.

Photo 7. Hypothenar compartment

 6.)  Clean and identify structures of the central compartment.

Note: The central compartment makes up most of the palmar surface of the hand between the thenar and hypothenar eminences. The central compartment is covered anteriorly (superficially) by the palmar aponeurosis. The central compartment contains the tendons of the extrinsic digital flexor muscles (muscles of the anterior forearm) and lumbrical mm.

 Photo 8. Central compartment

Note: Located superficial in the central compartment, the superficial palmar arch is an arterial arch that supplies the common palmar digital aa. The superficial palmar arch is primarily supplied by the ulnar a., but frequently draws blood also from the radial a.

Photo 9. Superficial palmar arch

Note: Located deep in the central compartment, the deep palmar arch is an arterial arch that supplies the palmar metacarpal aa. The deep palmar arch is primarily supplied by the radial a., but frequently draws blood also from the ulnar a.

7.) Clean and identify structures of the adductor / interosseous compartment.

Note: The adductor / interosseous compartment is posterior (deep) to the central compartment, and contains the muscles of the palm of the hand. Tendons are the large adductor pollicis and the interosseous muscles. The adductor pollicis m. adducts the thumb, the palmar interossei mm. adduct the digits toward midline – the middle (digit 3) finger, and the dorsal interossei mm. abduct the digits away from the midline. A useful mnemonic is PAD, DAB: Palmar interossei ADduct, Dorsal interossei ABduct.

Photo 10. Adductor / interosseous compartment

Remove the skin of the dorsal surface of the foot and ankle, and identify tendons and associated neurovasculature

Find these structures:

Structures associated with medial malleolus:

• • Posterior tibial a.

  • Tendons

  • Tibial n.

Structures associated with lateral malleolus:

• • Tendons of fibular mm.

Dorsalis pedis a.

8.) Locate the anterior tibial a. in the anterior leg compartment, and follow the artery as it transitions into the dorsalis pedis a. Locate the tendons of the anterior compartment of the leg (dorsiflexors).

Note: The dorsalis pedis a. is the continuation of the anterior tibial a. The name transition occurs at the level of the ankle. The dorsalis pedis a. is in close association with the deep fibular n. on the dorsal foot. This artery supplies the two main muscles of the dorsum of the foot: extensor digitorum brevis m. and extensor hallucis brevis m. The dorsalis pedis a. transitions into the deep plantar a. (dives between the 1st and 2nd digits), which contributes to the plantar arterial arch.

Photo 11. Dorsal foot with dorsalis pedis a.

9.) Locate structures directly posterior to the medial malleolus: posterior tibial a., tendons, and tibial n.

Note: The tendons of the deep posterior leg (tibialis posterior m., flexor digitorum longus m., and flexor hallucis longus m.), along with neurovasculature (tibial n. and posterior tibial a.) enter the plantar foot by coursing posterior to the medial malleolus. The tendons are surrounded by synovial sheaths like the tendons in the carpal tunnel, and are held down by the flexor retinaculum.

Note: The tibial n. is a one of the terminal branches of the sciatic n., and this nerve bifurcates into the medial and lateral plantar nn., which provide efferent innervation to intrinsic muscles of the plantar foot.

Note: The posterior tibial a. supplies the muscles of the posterior leg. This artery travels posterior to the medial malleolus and bifurcates around the calcaneus to become the medial and lateral plantar aa. The lateral plantar a. with the deep plantar a. will create the deep plantar (arterial) arch.

10.) Locate structures directly posterior to the lateral malleolus: tendons of the fibularis mm.

Note: The tendons of the fibularis (peroneal) mm. (fibularis longus & fibularis brevis mm.) travel to the foot from the lateral side of the leg posterior to the lateral malleolus. The superior and inferior fibular retinacula hold the tendons in place. The tendon of the fibularis brevis m. travels posterior to the lateral malleolus and inserts on the base of the fifth metatarsal. In forceful inversion sprains, this tendon can pull on and fracture the 5th metatarsal bone.

Photo 12. Fibularis tendons posterior to lateral malleolus

Remove the skin of the plantar surface of the foot, and identify the plantar aponeurosis

Find this structure:

• • Plantar aponeurosis

11.) Carefully skin the plantar surface of the foot to identify the plantar aponeurosis. The skin and subcutaneous layer here are very thick, so dissect carefully to the plantar aponeurosis.

Note: On the plantar surface of the foot, the central portion of the deep fascia (plantar aponeurosis/fascia) is significantly thicker than the surrounding areas, and is distinctly longitudinally arranged. The plantar aponeurosis holds intrinsic plantar muscles of the foot in place and helps support the longitudinal arches of the foot. It arises posteriorly from the calcaneus, courses across the midfoot, and divides into five longitudinal bands distally that course into the digits.

Photo 13. Plantar aponeurosis