Bone formation occurs through endochondral or intramembranous processes. Intramembranous ossification forms flat bones directly from mesenchyme. Endochondral ossification creates long and short bones from cartilage model
Acromion is cartilage at birth, identifiable by 5-6 weeks. Two ossification centers appear during puberty, fuse between 18-25. Positioned above shoulder as lateral extension of scapula spine. Anterior tip attaches coracoacromial ligament
Rare genetic disorder causing premature skull bone fusion. Named after German geneticist Rudolf Arthur Pfeiffer (1931-2012). Caused by mutations in FGFR1 or FGFR2 genes. Affects about 1 in 100,000 people
Scapula connects humerus with clavicle, forming back of shoulder girdle. Flat, triangular bone located on posterolateral thoracic cage. Contains cancellous tissue in head and processes, thin compact tissue elsewhere
The sphenoid bone is an unpaired bone located in the middle of the skull. It resembles a butterfly or bat with wings, hence the name "sphenoid". The bone consists of a body containing the sella turcica and paired paranasal sinuses. It has two greater wings and two lesser wings, with pterygoid processes
Two quadrilateral bones forming sides and roof of neurocranium. Located near midline of skull, posterior end. Each bone has two surfaces, four borders, and four angles