Elbow and Wrist Anatomy

Elbow Anatomy Overview

Bones

The elbow is composed of three bones. The upper arm bone is known as the humerus. The lower part of the arm is composed of two bones. The larger of these is known as the ulna, the other is the radius. The humerus forms the upper part of the joint and widens as it nears the elbow. There, it forms the medial and lateral epicondyles, which are the two bony structures you can feel on either side of the elbow joint.

Ligaments

There are three main ligaments that support the joints in the elbow: the medial collateral, lateral collateral and annular.

  • Medial collateral ligament - This ligament emanates from the medial epincondyle and passes over the inside of the elbow joint.
  • Lateral collateral ligament: This is a short, narrow band that extends from the base of the lateral epicondyle to the annual ligament.
  • Annular ligament: This band of fibers circles the head of the radius, maintaining contact between the radius and humerus.

 

An Overview of the Wrist's Anatomy

Bones

Fifteen bones form the structure that connects the end of the forearm to the hand. The wrist itself has eight small bones, known as carpal bones. These are grouped in two rows that span the width of the wrist. The proximal row is where the wrist creases as you bend it and it connects the two bones of the forearm - the radius and ulna - to the bones in the hand.

Starting with the thumb side of the wrist, the proximal row of carpal bones is made up of the scaphoid, lunate and triquetrum. The second row, known as the distal row, meets up with the proximal row nearer the fingers. The bones in the distal row include the trapzium, trapezoid, capitate, hamate and pisiform bones.