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  ULNA The ulna is the medial bone of the forearm. It is homologous with the fibula of the lower limb. It has an upper end, a shaft and a lower end. Features: Upper End: The upper end presents the olecranon and coracoid processes, and the trochlear and radial notches. The olecranon process projects upwards from the shaft. It has superior, anterior, posterior, medial and lateral surfaces. The anterior surface is articular, it forms the upper part of the trochlear notch. The posterior surface forms a triangular sub cutaneous area which is separated from the skin by a bursae. The medial surface is continuous inferiorly with the medial surface of the shaft. The lateral surface is smooth, continues as posterior surface of shaft. The superior surface in its posterior part shows a roughened area. 2. The Coracoid process projects forwards from the shaft just below the olecranon and has four surfaces. The superior surface forms the lower part of the trochlear notch. The anterior surface is tria

  RADIUS The radius is the lateral bone of the forearm. It is homologous with the tibia of the lower limb. It has an upper end, a lower end and a shaft. Features: It has an upper end, shaft and a lower end. Upper End: The head is disc-shaped and is covered with hyaline cartilage. It has a superior concave surface which articulates with the capitulum of the humerus at the elbow joint.  The neck is enclosed by the narrow lower margin of the annular ligament. The head and neck are free from capsular attachment and can rotate freely within the socket. The tuberosity lies just below the medial part of the neck. It has a rough posterior part and a smooth anterior part. Shaft: It has three borders and three surfaces. Borders: The anter ior border extends from the anterior margin of the radial tuberosity down close to the styloid process. It is oblique in the upper half of the shaft, and vertical in the lower half. The oblique part is called the anterior oblique line. The posterior border is t

  SCAPULA The Scapula is a thin bone placed on the posterolateral aspect of the thoracic cage.It has two surfaces, three borders , three angles and three processes.  Features of Scapula: Surfaces: The Costal Surface is concave and is directed medially and forwards.It is marked by three longitudinal ridges.The part of the bone is rod-like.It acts as a lever for the action of seratus anterior. The Dorsal Surface gives attachment to the spine of scapula which divides the surface into Supraspinous and Infraspinous fossa. Borders: The Superior border is thin and shorter.It presents the suprascapular notch. The Lateral border is thick. It presents the infraglenoid tubercle. The Medial border is thin.It extends from the superior angle to the inferior angle. Angles: The Superior angle is covered by the trapezius. The Inferior angle is covered by latissimus dorsi. The Lateral  or glenoid angle is broad and bears the glenoid cavity or fossa. Processes: The spinous process is a triangular plate o