BIO 240 Lecture Notes - Lecture 7: Obturator Foramen, Iliac Crest, Pelvic Brim
Document Summary
The pectoral (shoulder) girdles attach the bones of the upper extremities to the axial skeleton. Each girdle consists of a clavicle and a scapula. The clavicle (collarbone) forms the anterior component of the pectoral girdle. It articulates medially with the manubrium of the sternum at the sternoclavicular joint and articulates laterally with the acromion of the scapula at the acromioclavicular joint. The clavicle receives forces from the upper extremity and transfers them to the axial skeleton. As the only attachment of the upper extremity to the axial skeleton, excessive forces, such as falling on one"s outstretched arms, causes all force to be moved into the clavicle. As a result, this is the most broken bone in the body. The scapula is the posterior component of the pectoral girdle. It is freely positioned over the upper posterior rib cage by complex muscular attach- ments. There are no bony attachments between the scapula and the axial skeleton.
