Dr. Mark E. Pruzansky
Dr. Jason S. Pruzansky
975 Park Avenue New York, NY 10028
HandSport Surgery Institute
Schedule Appointment

Hand Anatomy

BONES

Metacarpals
The five bones that form the palm of the hand and connect to each digit.

Proximal Phalanges
The five cylindrical bones closest to the metacarpals that connect the five digits to the palm.

Middle Phalanges
The four cylindrical bones that make up the middle of the fingers. (The thumb does not have a middle phalanx.)

Distal Phalanges
The five cylindrical bones that form the tips of the fingers and thumb.

Wrist Anatomy

ARTICULAR CARTILAGE

The rubbery, slippery substance that covers the ends of bones at the joint. Healthy cartilage enables smooth joint movement and absorbs shock.

JOINTS

Metacarpophalangeal Joint
The base knuckle joints that connect the metacarpal bones to the proximal phalanges.

Proximal Interphalangeal Joint
The middle knuckle joints that connect the proximal phalanges to the middle phalanges.

Distal Interphalangeal Joint
The top knuckle joints that connect the middle phalanges to the distal phalanges.

LIGAMENTS AND TENDONS OF THE HAND

Collateral Ligaments
Ligaments found on each side of each joint on the fingers and thumb that serve to prevent abnormal sideways bending.

Volar Plate
A strong ligament that connects the proximal to the middle phalanges on the palmar side of every joint of the hand and protects the fingers from hyperextension.

Extensor Hood
A broad sheet of interconnected tendons most prominent at the metacarpal-phalangeal joint of the finger that helps straighten the proximal, middle and distal phalanges.

MUSCLES

Intrinsic Muscles
The small muscles of the hand that serve to position and hold fingers steady during fine-tuned activity such as spreading the fingers.

Thenar Eminence
The muscles that form the spongy pad right below the thumb whose main function is opposition.

NERVES

Brachial Plexus
The brachial plexus is the nerve center at the root of the neck and shoulder which is comprised of portions of the nerve roots originating from the cervical spinal cord. This group of nerves criss-crosses and branches and supplies the muscles of the back of the shoulder, chest and the entire upper extremity to the fingertips.

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 that travels near the ulnar nerve into the pinky side of the hand and joins the radial artery in the palm to provide blood to the front of the hand and fingers with branches spreading dorsally.

Radial Artery
The artery that travels across the front of the wrist on the thumb side of the hand and joins the ulnar artery in the palm to provide blood to the front of the hand and fingers with branches spreading dorsally.

BURSAE

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

Learn more about ligament injuries of the hand.

Hand Anatomy FAQs

The hand is made up of metacarpals (five bones forming the palm), proximal phalanges (five bones connecting digits to the palm), middle phalanges (four bones in the middle of the fingers, except the thumb), and distal phalanges (five bones forming the tips of the fingers and thumb).

Articular cartilage is a smooth, rubbery layer that covers the ends of bones at joints. It allows smooth movement between bones and helps absorb shock during hand motion.

The main joints include:
Metacarpophalangeal (MCP) joints – base knuckles connecting metacarpals to proximal phalanges.
Proximal interphalangeal (PIP) joints – middle knuckles connecting proximal to middle phalanges.
Distal interphalangeal (DIP) joints – top knuckles connecting middle to distal phalanges.

Collateral ligaments are located on each side of every finger joint. They prevent sideways bending and help maintain proper finger alignment.

The volar plate is a strong ligament connecting the proximal and middle phalanges on the palm side of the fingers. It prevents hyperextension and protects finger stability during hand movement.

The extensor hood is a sheet of interconnected tendons that helps straighten the fingers by coordinating extension across the proximal, middle, and distal phalanges.

The intrinsic muscles are small muscles within the hand that fine-tune finger movements, allowing for precision tasks like writing or buttoning.

The thenar eminence is the muscular pad beneath the thumb that enables thumb opposition, allowing you to touch the thumb to other fingers.

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

The brachial plexus is a network of nerves originating from the cervical spine that sends signals to the muscles and skin of the shoulder, arm, and hand, coordinating movement and sensation.

The radial artery (thumb side) and ulnar artery (pinky side) form an interconnected network in the palm, providing blood flow to the front and back of the hand and fingers.

Bursae are fluid-filled sacs that reduce friction between tendons and bones or between skin and bone, allowing smoother motion.

You can learn more by visiting the Ligament Injuries of the Hand page linked at the end of the article.