Your hand consists of your wrist, palm, and fingers. The wrist has many smaller bones and joints, allowing the hand to move in different directions. It also includes the distal ends of the forearm bones. The palm has 5 bones that connect with 14 finger bones.
Let’s take a closer look.
Your wrist is made up of eight small bones called the carpal bones, or the carpus. These irregularly shaped bones join your hand to the two long forearm bones: the radius and ulna.
The carpal bones are small square, oval, and triangular bones. The cluster of carpal bones in the wrist makes it both strong and flexible. Your wrist and hand wouldn’t work the same if your wrist joint were only made up of one or two larger bones.
The eight carpal bones are:
- scaphoid, a long boat-shaped bone under your thumb
- lunate, a crescent-shaped bone beside the scaphoid
- trapezium, a rounded-square shaped bone above the scaphoid and under the thumb
- trapezoid, a wedge-shaped bone beside the trapezium
- capitate, an oval or head-shaped bone in the middle of the wrist
- hamate, a wedge-shaped bone under the pinky finger side of the hand
- triquetrum, a pyramid-shaped bone under the hamate
- pisiform, a small, pea-shaped sesamoid bone (a bone embedded in a tendon or muscle) that sits on top of the triquetrum
The wrist has three main joints. This makes the wrist more stable than if it had only one joint. It also gives your wrist and hand a wide range of movement, allowing for many different motions and positions.
The wrist joints let your wrist move your hand up and down, like when you lift your hand to wave. These joints allow you to rotate your hand and bend your wrist forward and backward as well as side to side.
- Radiocarpal joint. The radiocarpal joint is where the radius — the thicker forearm bone — connects with the bottom row of wrist bones: the scaphoid, lunate, and triquetrum bones. This joint is mainly on the thumb side of your wrist.
- Ulnocarpal joint. This is the joint between the ulna — the thinner forearm bone — and the lunate and triquetrum wrist bones. This is the pinky finger side of your wrist.
- Distal radioulnar joint. This joint is in the wrist but doesn’t include the wrist bones. It connects the bottom ends of the radius and ulna.
The metacarpals are the five long hand bones between your wrist and fingers. They make up the palm of your hand and are visible through the skin on the back of your hand. Each metacarpal bone corresponds to a digit (finger) and consists of a base, shaft or body, and head.
Slightly thicker and shorter, the first metacarpal has the most mobility and can move on its own. The second through fifth metacarpals move alongside each other and are similar in size and shape. Of these four bones, the fourth and fifth are the most mobile.
The five metacarpal bones are:
- First (thumb) metacarpal: thickest, shortest metacarpal bone, moves along with with the trapezium
- Second (index) metacarpal: longest metacarpal bone with the largest base that connects to the trapezium, trapezoid, and capitate
- Third (middle) metacarpal: articulates with the capitate
- Fourth (ring) metacarpal: articulates with the capitate and hamate
- Fifth (pinky) metacarpal: smallest metacarpal bone, articulates with the hamate
The finger bones are made up of 14 narrow bones called phalanges. Each of the four fingers consists of a proximal, middle, and distal phalanx. The thumb has a proximal and distal phalanx only.
The three phalanges of the fingers are:
- Proximal phalanx. The proximal phalanx, the largest of the phalanges, forms joints with the metacarpal bone and middle phalanx.
- Middle (intermediate) phalanx. The middle phalanx forms joints with the proximal phalanx and distal phalanx.
- Distal phalanx. The distal phalanx supports the fingernail and sensitive skin of the fingertip and forms a joint with the middle phalanx.
The finger joints provide movement and allow you to perform activities such as pinching and grasping, according to the American Society for Surgery of the Hand (ASSH).
Per the ASSH, the four finger joints are:
- Carpometacarpal (CMC): joint at the distal carpal bone and base of the metacarpal bone
- Metacarpophalangeal (MCP): knuckle joining the metacarpal bone to the proximal phalanx, allows pinching, gripping, and finger movement in multiple directions
- Proximal interphalangeal (PIP): joint between the proximal and middle phalanges, allows finger to bend and extend
- Distal interphalangeal (DIP): joint at the fingertip near the nail bed
The three thumb joints are:
- Trapeziometacarpal (TMC) joint: CMC joint of the thumb, is more specialized and has the most movement and flexibility
- Metacarpophalangeal (MCP): joint connecting the metacarpal bone and the proximal phalanx, used for pinching and gripping
- Interphalangeal (IP): fingertip joint near the nail bed
It’s possible to injure or damage the ligaments, tendons, muscles, and nerves of your wrist, hand, and fingers. Several health conditions can also occur in this area.
Common wrist, hand, and finger injuries and conditions include:
- Sprain. A sprain occurs when you tear or stretch a ligament. This could be due to overstretching, physical impact, or a fall.
- Impaction syndrome. Also called ulnocarpal abutment, this wrist condition happens when the ulna arm bone is slightly longer than the radius. This usually occurs after a wrist fracture has healed in a malunited (atypical) fashion, and makes the ulnocarpal joint between this bone and your wrist bones less stable.
- Arthritis pain. Arthritis can happen in any of the wrist, hand, or finger joints, including the MCP joint. You can get wrist joint pain from arthritis. This can happen from usual wear and tear or an injury to the wrist. You can also get rheumatoid arthritis from an immune system imbalance.
- Fracture. You can fracture any of the bones in your wrist, hand, or fingers from a fall or other injury.
- Repetitive stress injuries. Common injuries to the wrist, hand, and fingers happen from repetitive movements. This includes typing, texting, writing, and playing tennis. Symptoms include swelling, numbness, and pain.
- Carpal tunnel syndrome. This syndrome occurs when the median nerve is compressed. Carpal tunnel syndrome can result from repeated overextension of the wrist, high blood pressure, or diabetes.
- Boxer’s fracture. This impact injury usually affects the fourth and fifth metacarpals. Often, a boxer’s fracture occurs when you use a closed fist to hit a hard object.
- Jersey finger. This common sports injury often occurs in the ring finger, when the tendon near the fingertip pulls away from the bone. Surgery is sometimes necessary.
- Mallet finger. Also called baseball finger, mallet finger is an impact injury that affects the tendon that straightens your finger or thumb. The tendon may tear or detach from the finger bone, causing pain, bruising, and swelling.
- Trigger finger. Also called stenosing tenosynovitis, this condition often affects the thumb and ring finger. It may happen after forceful hand use and is common in people with diabetes and rheumatoid arthritis. Symptoms of trigger finger include pain, stiffness, and a locking or catching sensation when you bend or straighten your finger.
Your hand is made up of 27 bones in the wrist, palm, and fingers. It consists of 8 carpal bones, 5 metacarpal bones, and 14 phalanges.
Along with the hand joints, these bones provide support, flexibility, and dexterity, so you can perform a range of activities and movements.