Session 4: Hands

Question 1

Carpal Tunnel

Answer 1

Carpal tunnel:

• Passage between the forearm and the hand
• —Anterior wall: Flexor retinaculum
• —Posterior wall: Carpal arch formed by 6 carpal bones

—Contents – 9 tendons, 1 nerve

1. —4 FDS tendons
2. —4 FDP tendons
3. —Flexor pollicis longus tendon
4. —Median nerve

• —Palmaris longus, ulnar nerve and ulnar artery pass superficially to flexor retinaculum
  
  • —Ulnar nerve is medial to ulnar artery
    
    • —They both pass through Guyon’s canal*
• —Radial artery curls around to enter the hand through posterolateral aspect of wrist

Roof of the carpal tunnel:

Flexor Retinaculum:

Ligament which forms the roof of the carpal tunnel.

Anchors to 4 bony points:

Laterally

1. Tubercle of scaphoid
2. Tubercle of trapezium

Medially

1. .Pisiform
2. Hook of hamate

Question 2

Name the joints of the hand

Answer 2

1. —Distal radio-ulnar joint
2. —Wrist joint – radiocarpal joint
3. —Intercarpal joints

• —Between individual carpal bones
• —Between proximal and distal row bones – midcarpal joint

1. —Carpo-metacarpal joints
2. —Intermetacarpal joints (between II-V)
3. —Metacarpophalangeal joints
4. —Proximal and distal interphalangeal joints

Question 3

Radiocarpal (wrist) Joint

Answer 3

• —Synovial joint between the distal end of radius, the scaphoid and lunate
• —Numerous fibrous ligaments*:
  
  • —Palmar and dorsal radio-carpal ligaments
  • —Ulnar and Radial collateral ligaments (of the wrist)
• —Movements:

1. —Flexion, Extension
2. —Abduction and adduction
3. —Circumduction

Question 4

Intercarpal Joints:

Answer 4

—Gliding movement

—Augment other movements of the hand

—

—Joints between the proximal row

—Scaphoid, lunate, triquetrum, pisiform

—Joints between the distal row

—Trapezium, trapezoid, capitate, hamate

—

—Joints between the proximal and distal rows

—The midcarpal joint

Question 5

Carpo-metacarpal Joints:

Answer 5

Between the distal row of carpal bones and the bases of metacarpals I to V

—1st carpo-metacarpal joint

—The joint between the metacarpal I and the trapezium

—It is a saddle joint which permits all movements of the thumb

—Often becomes osteoarthritic

—2nd-5th carpo-metacarpal joints

—Less mobile than the joint for the thumb

Question 6

Inter-Metacarpal Joints:

Answer 6

—Made of deep transverse metacarpal ligaments

—Bind together the 2nd and 5th metacarpals

—No attachment to metacarpal I, allowing the thumb to act more independently

Question 7

Metacarpo-phalangeal (MCP) Joints:

Answer 7

Between the metacarpal heads and the bases of the proximal phalanges.

—Allow flexion, extension, adduction, abduction

—Reinforced by…

—Palmar ligament

—Medial and lateral MCP collateral ligaments

Question 8

Interphalangeal Joints:

Answer 8

—There are proximal and distal IPJs for all digits except thumb

—Allow flexion and extension only

—Reinforced by medial and lateral collaterals

Question 9

Describe the position and function of the retinacula and tendon sheaths of the wrist and hand.

Answer 9

The Fascia of the Palm

The palmar fascia is the deep fascia of the palm. It condenses into the:—

• —Palmar aponeurosis
  
  • —Overlies the long flexor tendons of the hand
    
    • —Which are contained in a common synovial sheath
  • —Proximally continuous with the flexor retinaculum
  • —Distally continuous with the fibrous digital sheaths
• —Fibrous digital sheaths
• —This fascia further condenses into annular and cruciate ligaments

Osseo-fibrous Tunnels:

• —The osseo-fibrous tunnels are present on the palmar aspect of the hand
• —They are tunnels which are formed by the fibrous digital sheaths and the underlying bone
• —Within the tunnels run the

1. —Long flexor tendons
2. —And their digital synovial sheaths

• —The picture on the bottom right shows the fibrous digital sheath and its annular (A) and cruciate (C) condensations

Describe the Path of a tendon

—With knowledge of the palmar fascia, describe the path of the flexor digitorum tendons from the wrist to their phalangeal attachments. (4 marks, 2 choc reward)

1.Pass into the hand under the flexor retinaculum

—And enters a common synovial sheath…

2.Passes through an osseo-fibrous tunnel

—Within a digital synovial sheath

3. The FDS splits around the FDP
4. The FDS attaches to the middle phalanx and FDP attaches to the distal phalanx

Dorsal Tendinous Anatomy:

• —The extensor tendons will pass under the extensor retinaculum
• —They are connected by intertendinous bands
• —Covered by synovial sheaths