Hand & Wrist
Treatment of the Hand and Wrist is a highly specialized field that addresses a broad set of conditions and symptoms. Nonsurgical approaches to treatment such as medications, injections, and therapy are common, although when surgery is indicated, advanced and minimally invasive procedures are performed on an outpatient basis.
The human hand is made up of the wrist, palm, and fingers and consists of 27 bones, 27 joints, 34 muscles, over 100 ligaments and tendons, and many blood vessels and nerves.
The hands enable us to perform many of our daily activities such as driving, writing and cooking. It is important to understand the normal anatomy of the hand to learn more about diseases and conditions that can affect our hands.
Bones of the Hand
The wrist is comprised of 8 carpal bones. These wrist bones are attached to the radius and ulna of the forearm to form the wrist joint. They connect to 5 metacarpal bones that form the palm of the hand. Each metacarpal bone connects to one finger at a joint called the metacarpophalangeal joint (MCP joint). This joint is commonly referred to as the knuckle joint.
The bones in our fingers and thumb are called phalanges. Each finger has 3 phalanges separated by two interphalangeal joints, except for the thumb, which has only 2 phalanges and one interphalangeal joint.
The first joint close to the knuckle joint is called the proximal interphalangeal joint (PIP joint). The joint closest to the end of the finger is called the distal interphalangeal joint (DIP joint).
The MCP and PIP joint act like hinges when the fingers bend and straighten.
Soft Tissues of the Hand
Our hand bones are held in place and supported by various soft tissues. These include: articular cartilage, ligaments, muscles and tendons.
Articular cartilages are smooth material that act as shock absorbers and cushion the ends of bones at each of the 27 joints, allowing smooth movement of the hand.
Muscles and ligaments function to control the movement of the hand.
Ligaments are tough rope-like tissues that connect bones to other bones, holding them in place and providing stability to the joints. Each finger joint has two collateral ligaments on either side, which prevents the abnormal sideways bending of the joints. The volar plate is the strongest ligament in the hand. It joins the proximal and middle phalanx on the palm side of the joint and prevents backward bending of the PIP joint (hyperextension).
Muscles of the Hand
Muscles are fibrous tissues that help produce movement. They work by contracting.
There are two types of muscles in the hand:
- Intrinsic muscles are small muscles that originate in the wrist and hand. They are responsible for fine motor movements of the fingers during activities such as writing or playing the piano.
- Extrinsic muscles that originate in the forearm or elbow control the movement of the wrist and hand. These muscles are responsible for gross hand movements. They position the wrist and hand while the fingers perform fine motor movements.
Each finger has six muscles controlling its movement: three extrinsic and three intrinsic muscles. The index and little finger each have an extra extrinsic extensor.
Tendons of the Hand
Tendons are soft tissues that connect muscles to bones. When muscles contract, tendons pull the bones, causing the finger to move. The extrinsic muscles are attached to finger bones through long tendons that extend from the forearm through the wrist. Tendons located on the palm side help in bending the fingers and are called flexor tendons, while tendons on top of the hand called extensor tendons help in straightening the fingers.
Nerves of the Hand
Nerves of the hand carry electrical signals from the brain to the muscles in the forearm and hand, enabling movement. They also carry the senses of touch, pain and temperature back from the hands to the brain.
The three main nerves of the hand and wrist include:
- Ulnar nerve : The ulnar nerve crosses the wrist through an area called Guyon’s canal and branches to provide sensation to the little finger and half of the ring finger.
- Median nerve : The median nerve crosses the wrist through a tunnel called the carpal tunnel. The median nerve provides sensation to the palm, thumb, index finger, middle finger and part of the ring finger.
- Radial nerve : The radial nerve runs down the thumb side of the forearm and provides sensation to the back of the hand from the thumb to the middle finger.
All three nerves originate at the shoulder and travel down the arm to the hand. Each of these nerves has sensory and motor components.
Blood Vessels of the Hand
Blood vessels travel beside the nerves to supply blood to the hand. The main arteries are the ulnar and radial arteries, which supply blood to the front of the hand, fingers, and thumb. The ulnar artery travels next to the ulnar nerve through the Guyon’s canal in the wrist. The radial artery is the largest artery of the hand, traveling across the front of the wrist, near the thumb. Pulse is measured at the radial artery.
Other blood vessels travel across the back of the wrist to supply blood to the back of the hand, fingers and thumb.
Bursae of the Hand
Bursae are small fluid-filled sacs that decrease friction between tendons and bone or skin. They contain special cells called synovial cells that secrete a lubricating fluid.
The wrist joint is one of the most complex joints in the human body. Numerous joints and bones contribute to the strength and stability of the wrist. The wrist is made up of eight separate small bones called carpal bones. The carpal bones connect the two bones of the forearm, the radius and the ulna, to the bones of the hand. The metacarpal bones are the long bones that lie within the palm and attach to the phalanges, the bones in the fingers and thumb.
Arthritis is an inflammatory condition of the joints. There are several types of arthritis and the most common type is osteoarthritis or wear-and-tear arthritis. Arthritis affects various joints in the body and the arthritis in the hand affects the joint at the base of the thumb. Arthritis may also affect the joints of other digits.
Tendons in your fingers connect the finger bones to finger muscles and help bend and straighten the finger at the joint when the muscles contract. Boutonnière deformity is a condition in which a tendon injury to the middle joint of the finger results in the inability to straighten the affected finger.
Carpal tunnel syndrome is a common, painful, progressive condition that is caused by compression of the median nerve at the wrist area.The common symptoms of carpal tunnel syndrome include numbness and tingling sensation in all the fingers except the little finger, pain and burning sensation in your hand and wrist that may radiate up the arm and elbow, and weakness in your hand with diminished grip strength.
The muscles and bones of your hand are connected by thick flexible tissue called tendons. Tendons are covered by a thin soft sheath of tissue known as synovium. Extensor pollicis brevis and abductor pollicis longus are two tendons located on the thumb side of the wrist.
Dupuytren’s contracture is a hand condition where thickening of the underlying fibrous tissues of the palm causes the fingers to bend inward. This makes it difficult to fully straighten the affected fingers. It commonly occurs in the ring finger and little finger. Occasionally, the middle finger is affected, but the thumb and index finger are rarely affected.
Ganglion cysts are swellings that most commonly develop along the tendons or joints of wrists or hands. They can be found either at the top of the wrist, palm side of the wrist, end joint of a finger or at the base of a finger. A ganglion cyst is not cancerous and will not spread to the other parts of the body. It looks like a water balloon on a stalk and contains a clear fluid or jelly material. Ganglion cysts can be found in people of all ages.
Gamekeeper's thumb, also known as skier's thumb, is a tear of the ulnar collateral ligament, a band of tissue that supports the joint at the base of the thumb. Damage to the ulnar collateral ligament may lead to chronic instability of the thumb, creating problems in its normal functioning.
Triceps tendonitis is inflammation of the triceps tendon, the tissue that connects the triceps muscle on the back of the upper arm to the back of the elbow joint, allowing you to straighten your arm back after you have bent it.
Fractures of the Hand and Fingers
Carpal tunnel syndrome can be treated with carpal tunnel release surgery. The traditional surgery involves an incision of up to 2 inches in the palm and wrist area, whereas endoscopic surgery involves one or two half-an-inch incisions and the use of an endoscope. During the surgery, the transverse carpal ligament will be dissected to release the pressure on the median nerve and enlarge the carpal tunnel.
The wrist is a complex joint made up of 8 carpal bones aligned in two rows with four bones present in each row. The carpal bones are further connected to 5 metacarpal bones that form the palm of the hand. Each small bone forms a joint with the bone next to it. Thus, the wrist joint is made up of many small joints. The two bones of the forearm, radius and ulna, also form a joint with the first row of carpals.
Trigger Finger, also known as stenosing tenosynovitis or flexor tendonitis, is a condition where one of the fingers or the thumb of the hand is caught in a bent position. The affected digit may straighten with a quick snap, similar to pulling and releasing the trigger on a gun, hence the name trigger finger.
The hand is one of the most flexible and useful parts of our body. Because of overuse in various activities, the hands are more prone to injuries, such as sprains and strains, fractures and dislocations, lacerations and amputations while operating machinery, bracing against a fall and sports-related injuries.