Posterior trochleas laterally articulate with ulnas' olecranon processes. Posterior capitulums medially articulate with radial heads. Olecranon fossas lie between trochleas and capitulums. While most shoulder joint muscles attach between scapulas and humeruses, some muscles attach to sternums, vertebral columns and hips. Sternum Manubriums, bodies and xiphoid processes make up sternums.
First ribs attach to sternums' manubriums.
Ribs' two through seven attach to sternums' bodies. Xiphoid processes are cartilaginous tips that hang from sternums' bodies. Shoulder Joint Kinesiological Joint Actions Humeral movements define shoulder joint kinesiological actions. Humeruses move forward and backward, up from and down to sides, forward and backward from shoulder high positions and rotate inwardly and outwardly. Abductions occur when shoulder joint muscles contract to laterally move humeruses upward from side positions.