Ulna – Left/Right. Locate the anterior aspect of Ulna. A good landmark is the trochlear notch. When viewed anteriorly, the radial notch point to the side the bone is from, i.e. left ulna will have the radial notch (see below) on the left side of the bone.
Head of radius. The radius and ulna of the left forearm, posterior surface. The top is proximal (elbow) and bottom is distal (wrist). The head of the radius has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum of the humerus.
The radius is located on the lateral side of the forearm between the elbow and the wrist joints. It forms the elbow joint on its proximal end with the humerus of the upper arm and the ulna of the forearm.
Its base is continuous with the body of the bone, and of considerable strength. Its apex is pointed, slightly curved upward, and in flexion of the forearm is received into the coronoid fossa of the humerus. Its upper surface is smooth, concave, and forms the lower part of the semilunar notch.
The ulna is a long bone in the forearm. It lies medially and parallel to the radius, the second of the forearm bones. The ulna acts as the stabilising bone, with the radius pivoting to produce movement. Proximally, the ulna articulates with the humerus at the elbow joint.
The radius' main functions are to articulate with the ulna and humerus at the elbow to provide supination and pronation. Then to articulate with the lunate and scaphoid to provide all the movements of the wrist.
Radius – Left/Right
- Locate the anterior aspect of the radius bone.
- When viewed anteriorly, the radial tubercle towards the proximal end will point the direction as per the side of the body it is from, i.e. right radius will have the radial tubercle on the right side.
It joins with the humerus on its larger end to make the elbow joint, and joins with the carpal bones of the hand at its smaller end. Together with the radius, the ulna enables the wrist joint to rotate. The ulna is 50 percent larger in diameter than the radius at 4 to 5 months of age.
The "funny bone" got its nickname because of that funny feeling you get after you hit it. But your funny bone isn't actually a bone at all. Running down the inside part of your elbow is a nerve called the ulnar nerve. The ulnar nerve lets your brain know about feelings in your fourth and fifth fingers.
The head of the radius is discoid and fits with the radial neck within the circular annular ligament, that attaches the proximal radius to the ulna. The wheel like rotation of the head of the radius enables supination (palm facing upwards), and pronation (palm facing downwards).
The trochlear notch (also semilunar notch, or greater sigmoid cavity) is a large depression in the upper extremity of the ulna that fits the trochlea of the humerus (the bone directly above the ulna in the arm) as part of the elbow joint. It is formed by the olecranon and the coronoid process.
1. olecranon process - process of the ulna that forms the outer bump of the elbow and fits into the fossa of the humerus when the arm is extended. olecranon. appendage, outgrowth, process - a natural prolongation or projection from a part of an organism either animal or plant; "a bony process"
The humerus is the long bone in the upper arm. It is located between the elbow joint and the shoulder. At the elbow, it connects primarily to the ulna, as the forearm's radial bone connects to the wrist. At the shoulder, the humerus connects to the frame of the body via the glenoid fossa of the scapula.
The radioulnar joints: Two separate joints exist between the radius and the ulna. The distal radioulnar joint is down by the wrist. The proximal radioulnar joint is a synovial pivot joint that allows the head of the radius to move as it articulates in the radial notch of the ulna.
Ulnar head (caput ulnae) is a small rounded eminence at the distal end of the ulna.
The ulna extends through the forearm from the elbow to the wrist, narrowing significantly towards its distal end. At its proximal end it forms the elbow joint with the humerus of the upper arm and the radius of the forearm. The ulna extends past the humerus to form the tip of the elbow, known as the olecranon.
