Unit
- Carpal bones: The human hand contains eight carpal bones arranged in two rows. The proximal row includes the scaphoid, lunate, triquetrum, and pisiform. The distal row includes the trapezium, trapezoid, capitate, and hamate. These bones form the carpal arch and provide a stable base for hand movement. Understanding carpal anatomy is critical for planning surgical approaches to fractures or carpal tunnel release.
- Metacarpals: Five metacarpal bones connect the carpus to the phalanges. Each metacarpal has a base, shaft, and head. The first metacarpal is shorter and more mobile, allowing opposition of the thumb. Fractures of the metacarpal neck are common and may require operative fixation if angulated. Surgical planning must consider the extensor tendon anatomy overlying the metacarpals.
- Phalanges: Each finger has three phalanges (proximal, middle, distal) except the thumb which has two. The distal phalanx supports the nail bed and fingertip pulp. Phalangeal fractures often result from crush injuries. Open fractures require urgent irrigation and debridement. Understanding the insertion of flexor and extensor tendons on phalanges guides repair techniques.
- Carpometacarpal joints: The CMC joints connect the distal carpal row to the metacarpal bases. The thumb CMC joint is a saddle joint allowing flexion, extension, abduction, adduction, and opposition. Arthritis at the thumb CMC joint is common and may require reconstruction or arthroplasty. The index and middle CMC joints are relatively rigid, while the ring and little CMC joints have some mobility.
- Metacarpophalangeal joints: The MCP joints are condyloid joints that permit flexion, extension, abduction, adduction, and circumduction. The collateral ligaments are tight in flexion and loose in extension. MCP joint dislocations are common in the index finger. Surgical treatment may involve ligament repair or reconstruction. Understanding the normal range of motion helps in setting rehabilitation goals.
- Proximal interphalangeal joints: The PIP joints are hinge joints that allow only flexion and extension. They are stabilized by collateral ligaments, volar plate, and the extensor mechanism. PIP joint fractures or dislocations can lead to stiffness. Early motion protocols are essential to prevent contracture. Surgical fixation of unstable PIP fractures must restore articular congruity.
- Distal interphalangeal joints: The DIP joints are also hinge joints, with a simpler capsular structure. They are vulnerable to mallet finger injuries due to extensor tendon rupture at the base of the distal phalanx. DIP joint arthrodesis is sometimes performed for painful arthritis. Surgical exposure of the DIP joint requires careful handling of the germinal matrix to avoid nail deformity.
- Longitudinal and transverse arches: The hand has a proximal transverse arch at the carpus, a distal transverse arch at the metacarpal heads, and a longitudinal arch along each finger. These arches are maintained by the intrinsic muscles and ligaments. Collapse of these arches can impair grip strength. Surgical reconstruction of ligamentous injuries aims to restore arch stability for optimal hand function.
Scope of Practice
Role: Hand Surgery Operations Coordinator
Within scope:
- Reviewing patient anatomy knowledge to assist in surgical planning and instrument selection.
- Coordinating imaging studies such as X-rays and CT scans for preoperative assessment.
- Educating patients on hand anatomy and expected surgical outcomes.
- Ensuring proper documentation of anatomical findings in the medical record.
- Collaborating with surgeons to arrange necessary implants and supplies.
Outside scope:
- Performing surgical dissection or osteotomy.
- Interpreting diagnostic imaging independently.
- Making decisions about surgical technique or approach.
- Conducting physical examination for diagnosis.
- Prescribing postoperative therapy protocols.
Quick Revision
- The hand skeleton comprises 27 bones: 8 carpals, 5 metacarpals, and 14 phalanges.
- Joints include CMC (saddle for thumb), MCP (condyloid), PIP and DIP (hinge).
- Arches (transverse and longitudinal) provide structural stability for grip.
- Understanding anatomy guides surgical planning, implant selection, and patient education.
Disclaimer
Educational use only. Not intended for practical surgery, incisions, or other surgical procedures. It does not qualify you to perform physical operations.