Proximal Region of the Radius
The proximal end of the radius articulates in both the elbow and proximal radioulnar joints. Important bony landmarks include the head, neck and radial tuberosity: Head of radius – A disk shaped structure, with a concave articulating surface.The radius permits the forearm and hand to pronate and supinate, flex and extend at the elbow, and adduct, abduct, extend, flex, and circumduct the wrist. The distal radius crosses over the distal ulna and inverts to allow the wrist and hand to pronate. A reversal of this movement allows for supination.
The ulna is located on the opposite side of the forearm from the thumb. 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.
It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore the radius is considered to be the larger of the two.
Ulna. The ulna is a long thin bone with a small distal head that bears the styloid process, and an expanded proximal end. The proximal end terminates in the olecranon process and bears the semilunar notch on its upper surface. In man, the head of the ulna does not articulate with any of the bones of the carpus.
Muscle attachments
| Muscle | Direction |
|---|
| Brachialis muscle | Insertion |
| Pronator teres muscle | Origin |
| Flexor carpi ulnaris muscle | Origin |
| Flexor digitorum superficialis muscle | Origin |
The distal end of the humerus has two articulation areas, which join the ulna and radius bones of the forearm to form the elbow joint. The more medial of these areas is the trochlea, a spindle- or pulley-shaped region (trochlea = “pulley”), which articulates with the ulna bone.
Proximal then refers to something closer to the torso while distal refers to parts and places away from the torso. So a finger is distal to the wrist, which is distal to the elbow, which is distal to the shoulder.
Proximal and Distal
They describe the position of a structure with reference to its origin – proximal means closer to its origin, distal means further away. Examples: The wrist joint is distal to the elbow joint. The knee joint is proximal to the ankle joint.Proximal: Closer to the point of attachment with the torso. In other words, closer to the shoulder or the hip. The elbow is proximal to the wrist. Distal: Farther from the point of attachment.
The knee is proximal to the foot. Moving distally from the hip brings you to the thigh. The foot is distal to the knee.
Proximal - toward or nearest the trunk or the point of origin of a part (example, the proximal end of the femur joins with the pelvic bone). Distal - away from or farthest from the trunk or the point or origin of a part (example, the hand is located at the distal end of the forearm).
The Humerus. The humerus is a long bone of the upper limb, which extends from the shoulder to the elbow. The proximal aspect of the humerus articulates with the glenoid fossa of the scapula, forming the glenohumeral joint.
Tracing proximally from the hand brings you to the shoulder. The knee is proximal to the foot. Moving distally from the hip brings you to the thigh. The foot is distal to the knee.
Proximal means nearer to the center (trunk of the body) or to the point of attachment to the body. If another reference point is given, such as the heart, the proximal point of another organ or extremity is the point closest to the heart, central rather than peripheral. Proximal is the opposite of distal.
Medical Definition of Proximal
Proximal: Toward the beginning, the nearer of two (or more) items. For example, the proximal end of the femur is part of the hip joint, and the shoulder is proximal to the elbow. The opposite of proximal is distal.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.
Cause. The cause of trochleitis is often unknown (idiopathic trochleitis), but it has been known to occur in patients with rheumatological diseases such as systemic lupus erythematosus, rheumatoid arthritis, enteropathic arthropathy, and psoriasis.
The trochlea has the capitulum located on its lateral side and the medial epicondyle on its medial. It is directly inferior to the coronoid fossa anteriorly and to the olecranon fossa posteriorly.
Medical Definition of trochlea
: an anatomical structure resembling a pulley: as. a : the articular surface on the medial condyle of the humerus that articulates with the ulna. b : the fibrous ring in the inner upper part of the orbit through which the tendon of the superior oblique muscle of the eye passes.The distal end of the humerus has two articulation areas, which join the ulna and radius bones of the forearm to form the elbow joint. The more medial of these areas is the trochlea, a spindle- or pulley-shaped region (trochlea = “pulley”), which articulates with the ulna bone.
It is the smallest nerve to service the eye. CN-IV passes through the superior orbital fissure, and it provides motor function, or movement. It serves the superior oblique eye muscle and connects to the annular tendon. As a result, it processes brain signals to move the eyes up and down, and also outwards.
The trochlea of superior oblique is a pulley structure in the eye. The tendon of the superior oblique muscle passes through it. Situated on the superior nasal aspect of the frontal bone, it is the only cartilage found in the normal orbit.
The carrying angle is acute angle between median axis of the upper arm with fully extended and supinated forearm. This angle can also be used to calculate lateral obliquity of arms1. It is said that females have more carrying angle than males because of variations in secondary sexual characters in females2 3 4 5 6.
The ulna is located on the opposite side of the forearm from the thumb. 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.
Fractures of the distal portion of the ulna occur in isolation as a result of a rotational force applied to the wrist or as a result of a direct blow to the ulnar aspect of the distal forearm (nightstick fracture). Isolated ulnar styloid fractures are mostly benign and are treated by nonoperative means.
The main feature of the proximal end of the ulna is this large curved articular surface. The curve that it forms is called the trochlear notch. It articulates with the trochlea of the humerus. The very proximal end of the ulna is the olecranon.
Many muscles in the arm and forearm attach to the ulna to perform movements of the arm, hand and wrist. Movement of the ulna is essential to such everyday functions as throwing a ball and driving a car. The ulna extends through the forearm from the elbow to the wrist, narrowing significantly towards its distal end.
The term forearm is used in anatomy to distinguish it from the arm, a word which is most often used to describe the entire appendage of the upper limb, but which in anatomy, technically, means only the region of the upper arm, whereas the lower "arm" is called the forearm.
Trapezium bone
The trapezium is the first and most lateral of the distal row of carpal bones when the hand is viewed from its palmar surface.Carrying angle is a small degree of cubitus valgus, formed between the axis of a radially deviated forearm and the axis of the humerus. It helps the arms to swing without hitting the hips while walking.
The proximal end of the ulna resembles a crescent wrench with its large, C-shaped trochlear notch. This region articulates with the trochlea of the humerus as part of the elbow joint. The inferior margin of the trochlear notch is formed by a prominent lip of bone called the coronoid process of the ulna.
The proximal end of the ulna articulates with the trochlea of the humerus. To enable movement at the elbow joint, the ulna has a specialised structure, with bony prominences for muscle attachment.
