What bones make up the elbow joint?

The elbow is formed by the humerus, ulna, and radius, which work together to allow bending and rotation of the forearm.

What are the lateral and medial epicondyles?

The lateral epicondyle is on the outside of the elbow and anchors wrist extensor tendons; the medial epicondyle is on the inside and anchors wrist flexor tendons.

What is the function of articular cartilage in the elbow?

Articular cartilage covers bone ends in the elbow, allowing smooth, shock-absorbing motion.

What are the main ligaments that stabilize the elbow?

The medial and lateral collateral ligaments connect the humerus to the ulna and radius, maintaining joint stability.

What is the annular ligament and what does it do?

The annular ligament encircles the radial head, keeping it aligned with the ulna and allowing forearm rotation.

What are the distal biceps and triceps tendons?

The distal biceps tendon connects to the radius for flexion and supination; the distal triceps tendon connects to the ulna for extension.

Which muscles move the elbow?

Biceps flex the elbow, triceps extend it, and wrist flexors and extensors assist in forearm movement.

Which nerves pass through or near the elbow?

The radial, median, and ulnar nerves run near the elbow, controlling movement and sensation in the arm, wrist, and hand.

What arteries supply blood to the elbow and forearm?

The brachial artery divides into the ulnar and radial arteries, supplying oxygenated blood to the forearm, wrist, and hand.

What are bursae and what is their role in the elbow?

Bursae are small sacs that reduce friction between tendons, bones, and skin to help smooth elbow movement.

What is the normal range of motion for the elbow?

A healthy elbow flexes up to 145°, extends to 0°, and rotates about 80° in both pronation and supination.

Where can I learn more about elbow ligament injuries or pain conditions?

Visit the 'Ligament Injuries of the Elbow' or 'Elbow Pain' pages on the Hand Surgeons NYC website.

Elbow Anatomy

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

Lateral Epicondyle
The outside bump just above the elbow where the tendons connecting muscles that straighten the fingers and wrist attach.

Medial Epicondyle
The inside bump just above the elbow where the tendons connecting muscles that bend the fingers and wrist attach.

ARTICULAR CARTILAGE

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

LIGAMENTS AND TENDONS

Medial Collateral Ligament
One of two ligaments that connect the humerus to the ulna. The medial side refers to the position on the inside edge of the elbow.

Lateral Collateral Ligament
One of two ligaments that connect the humerus to the radius and ulna. The lateral side refers to the position on the outside edge of the elbow.

Annular Ligament
The ring-shaped ligament that wraps around the head of the radius and keeps it snugly in place against the ulna.

Distal Biceps Tendon
The tendon that attaches the biceps muscle at the front of the upper arm to the radius that allows the elbow to bend and supinate.

Distal Triceps Tendon
The tendon that attaches the triceps muscle at the back of the upper arm to the ulna that allows the elbow to straighten.

MUSCLES

Biceps
One of themuscles at the front of the upper arm that allows the elbow to bend and supinate.

Triceps
The muscle at the back of the upper arm that allows the elbow to straighten.

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.

Right Elbow Normal Anatomy (Medial View)

BLOOD VESSELS

Brachial Artery
The main artery leading from the upper arm down to the front crease of the elbow, where it branches into the ulnar artery and radial artery.

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.

Elbow Movement and Normal Range of Motion

Elbow Anatomy FAQs

The elbow joint is formed by three bones: the humerus (upper arm bone), the ulna (on the pinky side of the forearm), and the radius (on the thumb side). These bones work together to allow bending and rotation of the forearm and elbow.

The lateral epicondyle is the bony bump on the outside of the elbow where the tendons that straighten the fingers and wrist attach, including those responsible for forearm pronation and supination. The medial epicondyle is the bump on the inside of the elbow where the tendons that bend the fingers and wrist attach.

Articular cartilage covers the ends of the bones in the elbow joint, providing a smooth, lubricated surface that allows easy movement and absorbs shock during arm and elbow motion.

The medial collateral ligament (on the inner side) connects the humerus to the ulna, while the lateral collateral ligament (on the outer side) connects the humerus to both the radius and ulna. These ligaments maintain joint stability during motion.

The annular ligament is a ring-shaped band that wraps around the head of the radius, holding it tightly against the ulna. It allows the forearm to rotate smoothly when turning the hand palm up or down.

The distal biceps tendon connects the biceps muscle to the radius and enables elbow bending (flexion) and forearm rotation (supination).
The distal triceps tendon connects the triceps muscle to the ulna and allows elbow straightening (extension).

The biceps at the front of the upper arm bend the elbow, while the triceps at the back straighten it. The wrist flexors (attached to the medial epicondyle) and wrist extensors (attached to the lateral epicondyle) also cross the elbow and assist in wrist and hand motion.

Three major nerves run near the elbow:
Radial nerve: runs on the outer side and controls extension of the wrist and fingers and sensation on the back of the thumb side.
Median nerve: runs on the front and controls flexion and sensation on the palm side of the thumb, index, and middle fingers.
Ulnar nerve: runs along the inner side of the elbow (the “funny bone”) and controls fine motor movements and sensation in the pinky and half of the ring finger.

The brachial artery runs down the upper arm to the front of the elbow, where it divides into the ulnar artery (pinky side) and radial artery (thumb side). These arteries provide oxygenated blood to the forearm, wrist, and hand.

Bursae are small, lubricating sacs that reduce friction between tendons, bones, and skin—helping the elbow move smoothly during flexion and extension.

A healthy elbow typically bends (flexes) up to about 145 degrees, straightens (extends) to 0 degrees, and rotates the forearm approximately 80 degrees in both pronation (palm down) and supination (palm up).

The elbow’s design—with interlocking bones, strong ligaments, tendons, and muscles—provides stability for lifting while maintaining flexibility for precise arm and hand movements.

You can find additional information by visiting the Ligament Injuries of the Elbow or Elbow Pain sections on the Hand Surgeons NYC website.