Hand/Wrist/Elbow

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 backwards bending of the PIP joint (hyperextension).

Muscles are fibrous tissues that help produce movement. Muscles work by contracting.

There are two types of muscles in the hand, intrinsic and extrinsic muscles.

Intrinsic muscles are small muscles that originate in the wrist and hand. They are responsible for fine motor movement of the fingers during activities such as writing or playing the piano.

Extrinsic muscles originate in the forearm or elbow and 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 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 help in straightening the fingers, and are called extensor tendons.

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 are the ulnar nerve, radial nerve and median nerve. All three nerves originate at the shoulder and travel down the arm to the hand. Each of these nerves has sensory and motor components.

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.

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 are small fluid- filled sacs that decrease friction between tendons and bone or skin. Bursae contain special cells called synovial cells that secrete a lubricating fluid.

There are several muscles extending across the elbow joint that help in various movements. These include the following:

• Biceps brachii: upper arm muscle enabling flexion of the arm
• Triceps brachii: muscle in the back of the upper arm that extends the arm and fixes the elbow during fine movements
• Brachialis: upper arm muscle beneath the biceps which flexes the elbow towards the body
• Brachioradialis: forearm muscle that flexes, straightens and pulls the arm at the elbow
• Pronator teres: this muscle extends from the humeral head, across the elbow, and towards the ulna, and helps to turn the palm facing backward
• Extensor carpi radialis brevis: forearm muscle that helps in movement of the hand
• Extensor digitorum: forearm muscle that helps in movement of the fingers

The elbow joint is supported by ligaments and tendons, which provide stability to the joint.

Ligaments are a group of firm tissues that connect bones to other bones. The most important ligaments of the elbow joint are the:

• Medial or ulnar collateral ligament: comprised of triangular bands of tissue on the inner side of the elbow joint.
• Lateral or radial collateral ligament: a thin band of tissue on the outer side of the elbow joint.

Together, the medial and lateral ligaments are the main source of stability and hold the humerus and ulna tightly in place during movement of the arm.

• Annular ligament: It is a group of fibers that surrounds the radial head, and holds the ulna and radius tightly in place during movement of the arm.

The ligaments around a joint combine to form a joint capsule that contains synovial fluid.

Any injury to these ligaments can lead to instability of the elbow joint.

Tendons are bands of connective tissue fibers that connect muscle to bone. The various tendons which surround the elbow joint include:

• Biceps tendon: attaches the biceps muscle to the radius, allowing the elbow to bend
• Triceps tendon: attaches the triceps muscle to the ulna, allowing the elbow to straighten

The main nerves of the elbow joint are the ulnar, radial and median nerves. These nerves transfer signals from the brain to the muscles that aid in elbow movements. They also carry the sensory signals like touch, pain, and temperature back to the brain.

Any injury or damage to these nerves causes pain, weakness or joint instability.

Arteries are blood vessels that carry oxygen-pure blood from the heart to the hand. The main artery of the elbow is the brachial artery that travels across the inside of the elbow and divides into two small branches below the elbow to form the ulnar and the radial artery.