Summary
Highlights
The video introduces the anatomy of the radius, one of the two bones in the forearm. The presenter mentions that this is an updated version of a previous video, now with improved explanations. He briefly reviews the regions of the upper limb, focusing on the forearm which contains the ulna (medial) and the radius (lateral).
The presenter stresses the importance of understanding the anatomical position for studying the radius. In supination (palm forward), the radius is lateral and the ulna is medial. He explains that during pronation, the radius rotates over the ulna, which can distort the perception of its anatomy.
The radius, despite being shorter than the ulna, articulates multiple times. Proximally, it articulates with the humerus (humeroradial joint) and the ulna (proximal radioulnar joint). Distally, it articulates again with the ulna (distal radioulnar joint) and with two carpal bones (scaphoid and lunate) to form the wrist joint (radiocarpal articulation).
As a long bone, the radius is divided into a superior epiphysis, an inferior epiphysis, and a central diaphysis. The superior epiphysis is notably less thick than the inferior one.
The superior epiphysis includes the head of the radius, which has a concave surface for articulation with the humeral condyle. Below the head is the neck of the radius. Medially, the head articulates with the ulna at the radial notch of the ulna. Further down, there's a prominence called the radial tuberosity, which faces medially.
The diaphysis (shaft) of the radius has three borders: an anterior border, a posterior border, and a medial or interosseous border. The interosseous border is where the interosseous membrane inserts. Inferiorly, the diaphysis features the pronator crest, where the pronator quadratus muscle attaches, and an area for the interosseous membrane insertion.
The inferior epiphysis is significantly wider. Medially, it has the ulnar notch of the radius, for articulation with the head of the ulna. Laterally, there's a prominent styloid process, which is palpable and crucial in evaluating radius fractures. Posteriorly, there is the dorsal tubercle of the radius, which is a continuation of the posterior border of the diaphysis and has grooves for extensor tendons. The inferior surface forms the carpal articular surface, with two facets for the scaphoid (lateral, triangular) and lunate (medial, quadrilateral) bones, forming the radiocarpal (wrist) joint.