Anatomy of the Upper Limb Part 2 PDF

IV- The Ulna  IV-The Ulna The ulna is one of the two forearm long bones that, in conjunction with the radius, make up the antebrachium. The bone spans from the elbow to the wrist on the medial side of the forearm when in anatomical position. The ulna acts as the stabilising bon...

IV- The Ulna  IV-The Ulna The ulna is one of the two forearm long bones that, in conjunction with the radius, make up the antebrachium. The bone spans from the elbow to the wrist on the medial side of the forearm when in anatomical position. The ulna acts as the stabilising bone, with the radius pivoting to produce movement. IV.1 The proximal Ulna The proximal end of the ulna articulates with the trochlea of the humerus, it’s sometimes referred to as the head of the ulna. It contains the: Olecranon: is the tip of the ulna and serves as the insertion point for the triceps Coronoid process: this ridge of bone projects outwards anteriorly Trochlear notch: formed by the olecranon and coronoid process Radial notch: located on the lateral surface of the trochlear notch IV.2 The shaft and distal ulna The shaft is the long middle portion of the ulna. It is the site of attachment for the interosseous membrane, which spans the distance between the two forearm bones. The distal end of the ulna ends in a rounded head, with distal projection – the ulnar styloid process. The head articulates with the ulnar notch of the radius to form the distal radio-ulnar joint. V- The Radius V- The Radius The radius is one of two long bones that make up the human antebrachium. It lies laterally and parallel to ulna. The radius pivots around the ulna to produce movement at the proximal and distal radio-ulnar joints. V.1 The proximal Radius The proximal end of the radius articulates in both the elbow and proximal radioulnar joints. It contains the: Head of radius: A disk shaped structure, with a concave articulating surface Distal to the radial head is the neck of the radius and radial tuberosity - an oval prominence that is the site of attachment of the biceps brachii muscle. Distal to the radial tuberosity is the shaft, it expands in diameter as it moves distally. V.2 The distal Radius In the distal region, the radial shaft expands to form a rectangular end. The lateral side projects distally as the styloid process; In the medial surface, there is a concavity, called the ulnar notch, which articulates with the head of ulna. The distal radius articulates with the scaphoid and lunate carpal bones. This makes up the wrist joint. Fractures of the distal radius account for some of the most common fractures. Distal radius fractures  VI- The Carpal Bones VI- Carpal Bones The carpal bones are bones of the wrist that connect the distal aspects of the radial and ulnar bones to the bases of the five metacarpal bones of the hand. There are eight carpal bones, which divide into two rows: a proximal row and a distal row. Proximal Row (lateral to medial): the scaphoid, lunate, triquetrum, and pisiform Distal Row (lateral to medial): the trapezium, trapezoid, capitate, and hamate. Collectively, the carpal bones form an arch in the coronal plane. Proximally, the scaphoid and lunate articulate with the radius to form the wrist joint. In the distal row, all of the carpal bones articulate with the metacarpals. VII- The metacarpal bones VII- The metacarpal bones The metacarpal bones are five bones that form the middle part of the skeleton of the hand. They are numbered, and each associated with a digit: First metacarpal or metacarpal I - associated with a thumb; Second metacarpal (II) - with an index finger; Third metacarpal (III) - associated with a middle finger; Fourth metacarpal (IV) - with a ring finger; Fifth metacarpal (V) - associated with a little finger. Each metacarpal consists of a base, shaft and a head. The medial and lateral surfaces of the metacarpals are concave, allowing attachment of the interossei muscles. VII- The metacarpal bones VIII-The phalanges  The phalanges are the bones of the fingers. VIII- The phalanges The thumb has a proximal and distal phalanx, while the rest of the digits have proximal, middle and distal phalanges. IX-Sesamoid A sesamoid bone is a small bone commonly found embedded within a muscle or tendon near joint surfaces Bones functioning as a pulley to alleviate stress on that particular muscle or tendon.