Anatomy of the Hand and Wrist – Structure, Function, and Mobility of the Hand

The hand and forearm together form a functional unit and are connected at the wrist. Hand movements are largely initiated by muscles originating in the forearm. Only the slender tendons of these muscles are located directly in the hand. Some of the tendons are surrounded by tendon sheaths, which protect them and reduce friction.

The three major nerves of the hand are the radial nerve (nervus radialis), the median nerve (nervus medianis), and the ulnar nerve (nervus ulnaris).

The hand can be divided into three regions:

The carpus, consisting of 8 carpal bones (ossa carpi, carpalia):

The carpal bones are connected to one another by ligaments and arranged in two rows:

• Carpal bones in the proximal row: scaphoid (Os scaphoideum), lunate (Os lunatum), triquetrum (Os triquetrum), pisiform (Os pisiforme)
• Carpal bones in the distal row: trapezium (Os trapezium), trapezoid (Os trapezoideum), capitate (Os capitatum), hamate (Os hamatum).

The metacarpus, consisting of 5 metacarpal bones (ossa metacarpi):

The metacarpal bones are connected to the distal row of carpal bones via joints. These long bones can be divided into a base, shaft, and head.

The 5 fingers (digiti manus) with 14 finger bones:

The five fingers are called the thumb (Pollex), index finger (Index), middle finger (Digitus medius), ring finger (Digitus anularis), and little finger (Digitus minimus). The fingers (with the exception of the two-segmented thumb) consist of a proximal phalanx (Phalanx proximalis), a middle phalanx (Phalanx media), and a distal phalanx (Phalanx distalis).

Like the metacarpal bones, the finger bones are long bones with a base, shaft, and head. The thumb is connected to the carpal bones by the thumb saddle joint and can therefore assume an opposable position relative to the other fingers, enabling the pincer grip. The remaining four fingers each have three finger joints, which are connected by collateral ligaments.

The wrist consists of partial joints that function together as a single unit. The human wrist comprises the proximal wrist joint between the radius and the proximal row of carpal bones, as well as the distal wrist joint between the proximal and distal rows of carpal bones.

Common disorders affecting the hand include Dupuytren’s disease (Morbus Dupuytren, Dupuytren’s contracture —a condition affecting the connective tissue of the palm, in which nodules and cords form on the palm side of the hand) and carpal tunnel syndrome (carpal tunnel syndrome). Carpal tunnel syndrome is a type of nerve compression syndrome (entrapment syndrome); in this case, the median nerve is compressed within the flexor side of the wrist canal (carpal tunnel).

Another condition that can affect the hand is Raynaud’s syndrome, in which the fingers or toes suddenly become cold or numb. The fingers are more commonly affected. Due to disturbances in the small blood vessels, blood flow to the extremities is reduced in this condition.

Common fractures in the hand include a scaphoid fracture, which is often caused by breaking a fall with an outstretched hand but is frequently misinterpreted by the patient as a sprain, as well as a fracture of the radius near the hand (radius fracture).

Nerve injuries to the hand and forearm are also not uncommon. They are most often caused by cuts. Tendon disorders also occur frequently in the hand (trigger finger or De Quervain’s tenosynovitis, a specific form of tendon sheath inflammation).

The hand can be affected by both osteoarthritis (especially osteoarthritis of the thumb saddle joint, or rhizarthrosis) and rheumatism.

The anatomy of the hand demonstrates how the human hand is structured as a highly sophisticated system. The hand consists of 27 bones, including eight carpal bones, which are arranged in two rows, along with structures such as the triquetrum. Together with 14 finger bones and the finger phalanges, the bones of the hand form the movable part of the human hand. Anatomically, the hand can be divided into three sections, with the metacarpus connecting to the carpal bones and the fingers of the hand complementing its function.

The muscles of the hand work closely with the muscles, joints, and tendons of the extensor muscles to enable movement. The robust tendon plate and groups of stronger muscles ensure a powerful grip, while the hand’s mobility is finely tuned. The grasping function, along with finger flexion, is crucial for everyday activities. The hand is highly complex, as approximately 17,000 sensory receptors enable precise sensory perception.

Vascular and nervous structures such as the radial artery, ulnar artery, and ulnar nerve supply the hand and are essential for its function. The palm and the pad of the little finger further contribute to stability and fine motor skills. Movements from the forearm to the hand are initiated by muscles in the forearm. Overall, the hand and wrist form a functionally coordinated system that is indispensable for precision and control.

What is the anatomy of the hand?

The anatomy of the hand includes the carpal bones, metacarpal bones, and phalanges. In total, the hand consists of 27 bones connected to one another by joints.

What is the function of the hand?

The hand’s function lies in precise movement and the ability to grasp. The fingers and thumb enable both delicate and powerful movements.

What role do tendons play in the hand?

Tendons connect muscles to bones and transmit force to the fingers. Flexor and extensor tendons enable finger movement.

What is carpal tunnel syndrome?

Carpal tunnel syndrome is a condition in which the median nerve is compressed within the carpal tunnel. This causes pain and numbness in the hand.

What conditions can affect the hand?

The most common conditions include osteoarthritis, tendonitis, and carpal tunnel syndrome. These can limit the mobility of the hand.