138Anatomy and physiology of domestic animals associated with bone formation, it can occur in other tissues. There are two general classes of bone formation. Intramembranous ossiﬁ cation occurs when bone develops from a ﬁ brous membrane. The ﬂ at bones of the skull and face, the mandible, and the clavicle if present, are formed by this method.
134Anatomy and physiology of domestic animals long bones. Long bones are characterized by an elongated shaft and somewhat enlarged extremi- ties that bear articular surfaces. Examples of long bones include the humerus, radius, femur, tibia, metacarpals, and metatarsals. •Short bones.
A typical long bone shows the gross anatomical characteristics of bone. The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled with spongy bone. Red marrow fills the spaces in the spongy bone.