Upper Limb - Hand & Wrist

UPPER LIMB - HAND & WRIST

1. Overview of Chapters Related to Upper Limb

• Chapter 4: Focuses on the Hand and Wrist

• Chapter 5: Covers the Shoulder Girdle and Arm (Humerus)

• The structure and functions of the upper limb are essential for various activities, providing mobility and dexterity.

2. Bony Anatomy of the Right Hand and Wrist

• Total of 27 bones in the hand and wrist.

  1. Phalanges (14 total)

  • Bones of the fingers and thumb.

  1. Metacarpals (5 total)

  • Long bones that form the palm of the hand.

  1. Carpals (8 total)

  • Bones of the wrist.

2.1. Phalanges

• Each digit consists of 2 or 3 separate bones called phalanges (singular = phalanx).

  • Each of the four digits (2nd, 3rd, 4th, and 5th) has three phalanges: proximal, middle, and distal.

  • The thumb (1st digit) is composed of 2 phalanges (proximal and distal).

• Each phalanx has three parts:

  • Distal Rounded Head

  • Body (Shaft)

  • Expanded Base

2.2. Metacarpals

• Five metacarpals, numbered from the thumb to the 5th digit.

• Each metacarpal consists of:

  • Distal Rounded Head

  • Body (Shaft)

  • Concave Base

  • The base of each metacarpal articulates with the associated carpals.

2.3. Carpals

• Eight carpal bones that form the wrist.

• These bones enable movement of the wrist and stability for hand functions.

3. Joints of the Hand and Wrist

• Different types of joints facilitate various movements:

  • Inter-phalangeal joints (DIP and PIP): Ginglymus/hinge joints allow flexion and extension.

  • Metacarpo-phalangeal joints (MCP): Ellipsoidal/condyloid joints allow flexion, extension, abduction, adduction, and circumduction.

  • Carpo-metacarpal joints (CMC): Varies depending on thumb (saddle joint) and other fingers (plane/gliding joints).

  • Inter-carpal joints: Plane/gliding joints between carpals.

3.1. Specific Joint Identification

• DIP: Distal Inter-phalangeal joint

• PIP: Proximal Inter-phalangeal joint

• MCP: Metacarpo-phalangeal joint

• CMC: Carpo-metacarpal joint

• When labeling anatomy, specify which digit on which hand is being referenced.

4. Imaging Techniques and Radiologic Evaluation

4.1. PA Hand Projection

• Positioning:

  • Patient should have hand and forearm extended, with palm pronated on the imaging receptor (IR).

  • Fingers should be spread slightly for clarity.

• Technical Factors:

  • CR (Central Ray) is perpendicular to the 3rd MCP joint.

  • SID: 40 inches, Field Size: 10x12 inches, kV: 55-65.

• **Evaluation Criteria: **

  • Entire hand, carpals, and 1 inch of distal radius/ulna must be demonstrated.

  • Ensure no rotations of phalanges or metacarpals evidenced by symmetrical positioning.

  • Open joints and optimal image quality marked by sharp soft tissue margins and trabecular markings.

4.2. PA Finger Projection (Digits 2-5)

• Positioning:

  • Center the affected finger to the long axis of the IR; CR perpendicular to PIP joint.

  • Collimate to include distal metacarpal per protocol.

4.3. PA Oblique Hand Projection

• Positioning:

  • Pronate hand; rotate laterally 45 degrees while ensuring digits are separated.

  • CR directed to the 3rd MCP joint.

• Evaluation Criteria:

  • Should show entire hand, carpals, and distal forearm with appropriate positioning and exposure factors.

4.4. AP Thumb Projection

• Rotate hand internally to supinate, with CR directed to the 1st MCP joint.

4.5. Lateral Hand and Finger Projection

• Rotate hand and wrist into a lateral position, separating fingers with CR to 2nd MCP joint.

4.6. Evaluation Criteria for Lateral Projections

• Entire hand visible, with open joints and clear superimpositions where required.

5. Summary Evaluation Criteria for All Imaging Protocols

• Entire area of interest must be well captured with appropriate positioning.

• Open joints with clear margins indicating no motion.

• Relevant anatomical areas must be demonstrated based on specific imaging protocols.