Hello, this is Rob Swatsky from the York campus of Harrisburg area community college in York, Pennsylvania. And in this podcast, I'm continuing my review of the Appendicular Skeleton with the bones of the forearm, the radius, and the ulna. The ulna is the largest of the two forearm bones and it's located on the medial side, which is your pinky or little finger side. It's easy to remember because the ulna resembles a crescent wrench in the lateral view. The radius is the smaller of the two bones and it's located on the lateral side or the thumb side of the forearm. When you observe the bones in their side-by-side position, you can see that the ulna is wider at the proximal end at the elbow and narrows towards the distal end at the wrist. The radius is just the opposite. It's narrow at its proximal end and wider at its distal end. Okay, let's look at the bony landmarks of the ulna. The head of the ulna is located at its narrow distal end. It articulates with the carpools but is separated from those bones by a fibrocardal adgenous disc. On the posterior side of the distal end is the styloid process. This is a small spine-like bony projection that serves as an attachment point for the ulnar collateral ligament, connecting it to the wrist. On the proximal end of the ulna is the olecranon, which is the hard bony process that forms the elbow. The olecranon is also called the olecranon process. The olecranon articulates with the humerus by hooking into the olecranon fossa, a deeper depression located at the distal end of the humerus. On the anterior side of the ulna, we'll find the coronoid process. This projection hooks into the coronoid fossa on the anterior distal humerus. The coronoid fossa is a much shallower depression compared to the olecranon fossa. The troclier notch is the larger curved area shaped like the letter U, which identifies this bone as the ulna. It's found between the olecranon and the coronoid process and forms part of the elbow joint. It's named after the troclier of the humerus, the tooth-like process with which it articulates. Located just lateral and below the troclier notch is the radial notch, which articulates with the head of the radius. There is a rough bumpy area called the ulnar tuberosity located inferior to the coronoid process. It serves as an attachment point for the tendons of the biceps brachyimuscle. Okay, now let's examine the bony landmarks of the radius. The head of the radius is located at the proximal end of the bone. It has a round disc shape that resembles a slightly warped hockey puck. The round head of the radius articulates with the capitulum of the humerus as well as the radial notch of the ulna. Just inferior to the head is the narrow neck of the radius. And just inferior to the neck is the radial tuberosity. This is a rough patch of bone that also serves as an attachment point for the tendons of the biceps brachyimuscle. The radius widens at its distal end to form the tooth-like styeloid process on the lateral side, which you can actually feel just proximal to the thumb. This styeloid process is an attachment point for the brachyiradialis muscle as well as the radial collateral ligament to the wrist. The elbow joint is formed through an articulation between the humerus and the ulna and radius. The elbow joint has two points of articulation. One is where the trochlia of the humerus articulates with the trochlia or notch of the ulna, and the other is where the round capitulum process of the humerus articulates with the head of the radius. I'll be reviewing the other articulations between the radius, ulna, and wrist in a future podcast on the joints. Okay, that does it for the bones of the forearm. I hope this podcast has helped you in your review of the bones of the appendicular skeleton. Thanks a lot for watching. Bye.