What are the main bones that make up the wrist?

The wrist is composed of the ulna and radius and eight carpal bones: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate.

What role do the carpal bones play in wrist function?

Carpal bones form the complex structure that allows for six directions of movement and grip strength. The trapezium supports the thumb and the capitate supports the middle finger.

What is the triangular fibrocartilage complex (TFCC)?

The TFCC is a pad of cartilage and ligaments between the ulna and carpal bones that cushions and stabilizes the wrist during rotation and load-bearing.

What are the main ligaments that stabilize the wrist?

Key ligaments include the ulnar and radial collateral ligaments, transverse carpal ligament, scapholunate and lunotriquetral ligaments, and the radioscaphocapitate ligament.

What is the purpose of the transverse carpal ligament?

It forms the roof of the carpal tunnel, protecting the flexor tendons and median nerve, connecting triquetrum and hamate to scaphoid and trapezium.

What do the flexor and extensor tendons do?

Flexor tendons bend the fingers and wrist; extensor tendons straighten the fingers, thumb, and wrist.

Which muscles control wrist motion?

Wrist flexors on the forearm’s front bend the wrist; wrist extensors on the back straighten it.

Which nerves provide movement and sensation to the wrist and hand?

The radial, median, and ulnar nerves control wrist and hand movement and sensation.

What arteries supply blood to the wrist and hand?

The radial and ulnar arteries branch from the brachial artery below the elbow to carry blood into the wrist and hand.

What is the function of the wrist’s complex structure of bones, ligaments, and tendons?

They allow fine and powerful movements, balancing stability and flexibility for gripping, rotating, and lifting.

Wrist Anatomy

Q: What is the function of the ulna and radius in wrist movement?

The ulna provides stability on the pinky side, while the radius supports motion on the thumb side and allows rotation, flexion, extension, and side movement.

Q: What are the ulnar and radial styloids?

The ulnar styloid is a projection at the end of the ulna where ligaments attach; the radial styloid is a similar projection on the radius where thumb-side ligaments attach.

BONES

Ulna
The longer of two forearm bones, located on the pinky side of the arm

Radius
The shorter of two forearm bones, located on the thumb side of the arm

Ulnar Styloid
An extension at the bottom of the ulna where the wrist’s pinky-side collateral ligament attaches.

Radial Styloid
An extension at the bottom of the radius where the wrist’s thumb-side collateral ligament attaches.

Scaphoid
A cashew-shaped bone close to the thumb that links the wrist’s two rows of carpal bones.

Lunate
A crescent-shaped bone located in the middle of the first of two rows of carpal bones comprising the wrist.

Triquetrum
A pyramid-shaped bone close to the pinky in the first of two rows of carpal bones comprising the wrist.

Trapezium
A table-shaped bone close to the thumb in the second of two rows of carpal bones comprising the wrist. The trapezium is the foundation of support for the thumb, responsible for pivoting and necessary for opposition, prehension and grasp.

Trapezoid
A wedge-shaped bone located next to the trapezium in the second of two rows of carpal bones comprising the wrist. The trapezoid is the foundation of support for the index finger.

Capitate
The largest wrist bone located at the center of the two rows of carpal bones comprising the wrist. The capitate is the foundation of support for the middle finger.

Hamate
A hook-shaped bone located next to the capitate in the second of two rows of carpal bones comprising the wrist.The hamate is the foundation of support for the ring and little fingers.

Pisiform
A pea-shaped bone close to the pinky in the second of two rows of carpal bones comprising the wrist.

WRIST FIBROCARTILAGE

Triangular Fibrocartilage Complex
A small pad of cartilage similar to the meniscus of the kneethat cushions the wrist joint where the ulna meets the lunate and triquetrum carpal bones.

LIGAMENTS AND TENDONS

Ulnar Collateral Ligament
A cord-shaped ligament that attaches the ulnar styloid on the pinky side of the wrist to the triquetrum carpal bone; also the floor or sub sheath of the extensor carpi ulnaris tendon.

Transverse Carpal Ligament
A strong, fibrous band of ligamentous tissue that crosses over the carpal bones to form the roof of the carpal tunnel through which the flexor tendons and median nerve travel to the hand. It is attached on the pinky side of the wrist to the triquetrum and hamate bones and, on the thumb side, to the scaphoid and trapezium bones.

Radial Collateral Ligament
A ligament that attaches the radial styloid on the thumb side of the wrist to the scaphoid carpal bone.

Flexor Tendons
The tendons that attach the forearm flexor muscles to the finger and hand bones on the palm side of the hand and wrist and serve to curl the fingers and thumb and bend the wrist.

Extensor Tendons
The tendons that attach the forearm extensor muscles to the finger and hand bones on the backside of the hand and wrist and serve to straighten the fingers, thumb and wrist.

MUSCLES

Wrist Flexors
The muscles attaching to the medial epicondyle and running down the front of the forearm that serve to flex the wrist and hand.

Wrist Extensors

The muscles attaching to the lateral epicondyle and running down the back of the forearm that serve to extend the wrist and hand.

NERVES

Radial Nerve
One of three nerves originating at the shoulder that carry signals from the skin and joints to the brain and back again to the muscles of the upper extremities to coordinate movement and position sense. The radial nerve begins from the inside of the upper arm, travels diagonally across to the outer elbow and then again crosses to the thumb side of the forearm and into the back of the thumb, index and half of the middle finger. Muscles controlled by the Radial Nerve include the triceps and wrist and finger extensors.

Median Nerve
One of three nerves originating at the shoulder that carry signals from the skin and joints to the brain and back again to the muscles of the upper extremities to coordinate movement and position sense. The median nerve begins from the outside of the upper arm and travels down the inner side of the upper arm before moving to the center of the forearm and into the palmar side of the thumb, index, middle and half of the ring finger and distal segment of the thumb, index, middle and ring fingers. Muscles controlled by the Median Nerve include the wrist and finger flexors.

Ulnar Nerve
One of three nerves originating at the shoulder that carry signals from the skin and joints to the brain and back again to the muscles of the upper extremities to coordinate movement and position sense. The ulnar nerve begins from the inside of the upper arm and travels down the inside of the forearm and into the palmar and dorsal sides of the pinky and half of the ring finger. Muscles controlled by the Ulnar Nerve include the wrist and finger flexors, as well as the small muscles in the hand that coordinate fine movements.

BLOOD VESSELS

Ulnar Artery
The artery branching off the brachial artery below the elbow that brings oxygenated blood down the pinky side of the forearm and into the wrist and hand.

Radial Artery
The artery branching off the brachial artery below the elbow that brings oxygenated blood down the thumb side of the forearm and into the wrist and hand.

BURSAE

Sacs containing lubricating fluid that serve to reduce friction between tendons and bones and skin and bones.

Learn about ligament injuries of the wrist.

Wrist Anatomy FAQs

The wrist is composed of two forearm bones (ulna on the pinky side and radius on the thumb side) and eight carpal bones arranged in two rows: scaphoid, lunate, triquetrum, pisiform, trapezium, trapezoid, capitate, and hamate.

The ulna provides stability on the pinky side of the wrist, while the radius supports motion on the thumb side and allows the wrist to rotate, flex, extend, and move side-to-side.

The ulnar styloid is a small projection at the end of the ulna where the wrist’s pinky-side ligaments attach. The radial styloid is a similar projection at the end of the radius where the thumb-side ligaments attach.

The carpal bones form the complex structure of the wrist that allows for six directions of movement and potentiate grip strength. Four carpal bones serve as foundations for one or more fingers—for example, the trapezium supports the thumb and the capitate supports the middle finger.

The TFCC is a small pad of cartilage and ligaments located between the ulna and the carpal bones (lunate and triquetrum). It acts like a cushion and stabilizer—similar to the meniscus in the knee—protecting and guiding the wrist during rotation and load-bearing.

The ulnar collateral ligament supports the pinky side of the wrist, the radial collateral ligament stabilizes the thumb side, and the transverse carpal ligament forms the roof of the carpal tunnel through which the median nerve and flexor tendons pass. The scapholunate and lunotriquetral ligaments stabilize the proximal row of carpal bones. The radioscaphocapitate ligament links the radius to both carpal bone rows.

The transverse carpal ligament forms the roof of the carpal tunnel, protecting and guiding the flexor tendons and median nerve as they travel from the forearm into the hand. It connects the triquetrum and hamate on the pinky side to the scaphoid and trapezium on the thumb side.

Flexor tendons attach to the front of the hand and wrist, enabling bending of the fingers and wrist.
Extensor tendons attach to the back of the hand and wrist, allowing straightening of the fingers, thumb, and wrist extension.

Wrist flexors run along the front of the forearm, beginning at the medial epicondyle of the elbow, and help bend the wrist and hand.
Wrist extensors run along the back of the forearm, attaching to the lateral epicondyle of the elbow, and help straighten the wrist and hand.

Three main nerves control the wrist and hand:
Radial nerve: controls extension and sensation on the back of the thumb, index, and middle finger.
Median nerve: controls flexion, thumb opposition, and sensation on the palm side of the thumb, index, middle, and half of the ring finger.
Ulnar nerve: controls fine finger movements, coordination, and sensation in the pinky and half of the ring finger.

The radial artery (thumb side) and ulnar artery (pinky side) branch from the brachial artery below the elbow and carry oxygenated blood into the wrist and hand.

Bursae are small, lubricating sacs that reduce friction between tendons, bones, and muscles, allowing smooth wrist and hand motion.

Together, these structures allow the wrist to perform fine and powerful movements, maintaining balance between stability and flexibility for gripping, rotating, and lifting.

You can explore more on the site’s Ligament Injuries of the Wrist page linked at the end of the article.