Lab Manual - Hand

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Describe the position of tendons, associated bursae, nerves, and vessels beneath the palmar carpal ligament.
  2. Identify the prominent features of carpals, metacarpals and phalanges associated with the hand as listed in the lab manual.
  3. Define the thenar, hypothenar, central, and adductor-interosseous compartments of the hand and the functional significance of each.
  4. Correlate any fractures or deep cuts of the hand with functional disruptions of associated muscular and neurovascular structures.
  5. Describe the movements of the fingers and thumb.
  6. Describe the collateral circulation of the hand.

Procedure:

1. Open the hand, look at creases, and skin the palm (do not cut the recurrent branch of median n.). (Play movie; View images: N 447, 448, 459, 460, 461, 465, 466, 468, 472A, 472B, 476, 477, 479, TG 2-24, 2-25, 2-33A, 2-33B, 2-34A, 2-34B, 2-38A, 2-38B, 2-40)

PALM OF THE HAND. Remove the skin from the palm of the hand. If the digits are more than slightly flexed, it is difficult if not impossible to dissect the digits and palm. To make the dissection easier, the flexor digitorum superficialis and profundus and flexor pollicis longus should be transected in the forearm. Sever them at different levels (proximal to distal) so that their tendons can be distinguished from each other. Be careful not to cut the median nerve directly beneath flexor digitorum superficialis. It should then be possible to straighten the digits, thus making the dissection easier. Note the dense attachment to deep fascia and dense subcutaneous tissue.

Bones of the hand
Bones of the hand
Wrist bones

Locate the palmar digital branches of the median and ulnar nerves along the borders of the digits. Determine area of distribution. Do they supply any portion of the dorsal side of the digit? How much? Significance? What do they accompany?

Scrape the subcutaneous fat from the deep fascia of the palm. In the thenar eminence do not clean completely down to the muscle until the recurrent (motor) branch of the median nerve has been located. Define the parts of the deep fascia: thenar fascia, hypothenar fascia, palmar aponeurosis and fibrous flexor digital sheaths. Characterize each, define boundaries and extent.

Palmar aponeurosis. Using a sharp scalpel, clean its surface thoroughly to display fibrous structure and orientation of fibers. What is its relation to palmaris longus, the palmar carpal ligament and the flexor retinaculum? Identify the superficial transverse metacarpal ligament and transverse fasciculi; note the gaps between them. What can be seen in these gaps? Note the digital fibers extending to the sides of the digits and the flexor digital sheaths.

2. Reflect the palmar aponeurosis distalward and identify neurovascular structures. (Play movie; View images: N 447, 448, 459, 460, 461, 462, 465, 466, 468, 472, 476, 477, 479, TG 2-33, 2-34, 2-36, 2-37A, 2-37B, 2-38, 2-39, 2-40)

Clean the subcutaneous fat from the digits and expose the fibrous flexor digital sheaths. Note attachments and structures.

Reflect the palmar aponeurosis distalward, separating it from the palmaris longus and the flexor retinaculum, defining the distal border of the latter. As you reflect, note the septa at its medial and lateral margins that extend to the second and fifth metacarpals. Continue reflecting and note septa extending to metacarpals II-V. These form compartments for the flexor tendons in the central compartment of the palm. What is the carpal tunnel and its associated syndrome?

Pick up the median nerve at the proximal border of the flexor retinaculum then cut the retinaculum following the median nerve to the distal border of the flexor retinaculum. Identify the recurrent (motor) branch of the median nerve at the distal border of the flexor retinaculum; trace it into the thenar muscles. Trace the superficial palmar branch of the radial artery to the thenar compartment. Does it continue beyond? Where? Define the common and proper digital branches of the median nerve, and areas of distribution. How do median and ulnar nerves share in the cutaneous innervation of the digits (review)? Note the change in relationship of palmar nerves and arteries as they reach the digits.

Trace the ulnar artery and nerve into the palm across the flexor retinaculum to the interval between the hook of the hamate and the pisiform. Note their bifurcation here. Trace the superficial ulnar artery into the superficial palmar arterial arch; note its position, relation, and distribution (common and proper digital arteries). What artery completes the superficial palmar arterial arch? Trace the superficial ulnar nerve into common and proper digital nerves. (Review pattern of distribution.)

3. Examine the muscles of the thenar and hypothenar compartments. (Play movie; View images: N 461, 462, 465, 466, TG 2-34A, 2-34B, 2-35, 2-37, 2-38)

Consider the basic compartmental structure of the hand and dissect each compartment separately (thenar compartment, hypothenar compartment, central compartment, adductor-interosseous compartment).

Examine the thenar fascia; open and remove. Dissect abductor pollicis brevis and flexor pollicis brevis. Does the flexor pollicis brevis have a deep head? Examine opponens pollicis (deep to the other thenar muscles) and the insertion of adductor pollicis (not a thenar compartment muscle). Note the position of the tendon of flexor pollicis longus surrounded by the radial bursa.

Examine the hypothenar fascia; open and remove. Dissect abductor digiti minimi, flexor digiti minimi (brevis), and opponens digiti minimi. Innervation of hypothenar muscles? Note relations of the deep ulnar nerve and artery to the origins of these muscles.

4. Cut the flexor retinaculum and pull the long flexor tendons toward the fingertips. (Play movie; View images: N 433, 450, 460, 461, 462, 463, 464, 465, 466, 475, TG 2-21, 2-31, 2-34A, 2-34B, 2-35, 2-37A, 2-37B, 2-38, 2-45, 2-48)

Examine the flexor retinaculum. Determine its attachments and extent. Review its relationships with the palmar carpal ligament, palmaris longus and palmar aponeurosis. Examine the contents of the carpal tunnel. How is it formed? Examine tendons of flexor digitorum superficialis and profundus; note their relative positions in the canal and the ulnar bursa. Into which digital sheath does the bursa continue distally? If you have not already done so, cut the tendons of flexor digitorum superficialis and profundus near the wrist (but at different distances from the retinaculum), pull distally and separate. Identify the lumbrical muscles, noting origin; trace to their insertion into extensor expansions; innervation? Consider function.

Pull the long flexor tendons toward the fingers from beneath the superficial palmar arterial arch and trace the tendons of the long flexors to the flexor digital sheaths. Incise a sheath longitudinally, noting the synovial lining and the manner of insertion of flexor digitorum superficialis and profundus tendons into the middle and distal phalanges, respectively. What are vincula?

Return to the carpal tunnel and trace the flexor pollicis longus tendon to its insertion. Note the radial bursa. Locate the flexor carpi radialis tendon. Is it in the carpal tunnel? What happens to it? Trace it to its insertion. Trace the median nerve and bring all of its branches in the hand into continuity (motor and sensory).

Clean the adductor pollicis muscle and identify its oblique and transverse heads. Clear the anterior interosseous fascia from interosseous muscles and identify the deep palmar arterial arch; note the accompanying deep branch of the ulnar nerve.

5. Follow the radial artery through the anatomical snuffbox and through the 1st dorsal interosseous m. (Play movie; View images: N 464, 465, 466, 469, TG 2-35A, 2-35BC, 2-37A, 2-37B, 2-41, 2-45, 2-46, 2-48, 2-49, 2-50, 2-52)

Return to the wrist and pick up the radial artery in the "anatomical snuff box". Identify dorsal metacarpal arteries and dorsal digital branches.

Trace the radial artery to the interval between the first and second metacarpal bones. Reflect the first dorsal interosseous muscle from its attachment to the first metacarpal and continue tracing the radial artery into the deep palmar arterial arch. Identify princeps pollicis and radialis indicis arteries.

Angiogram of the wrist and hand

Reflect the origin of adductor pollicis. Dissect dorsal and palmar interosseous muscles; determine position, structure, dual insertion, and action. Observe these muscles on both the palmar and dorsal sides of the hand. Follow these muscles to their insertions on proximal phalanges and extensor expansions.

Consider the complete blood supply to the hand: sources, arches (how many and how formed?). How do the dorsal and palmar proper digital arteries differ in their formation? What are perforating arteries? Where are they found? Function?

Organize the motor innervation to intrinsic muscles of the hand and review sensory distribution. Organize the actions of both the intrinsic and extrinsic muscles of the hand.

Growth plates at the wrist
Colles' fracture