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A primary ossification center is the first area of a bone to start ossifying. It usually appears during prenatal development in the central part of each developing bone. In long bones the primary centers occur in the diaphysis/shaft and in irregular bones the primary centers occur usually in the body of the bone. Most bones have only one ...
The dens, also called the odontoid process, or the peg, is the most pronounced projecting feature of the axis. The dens exhibits a slight constriction where it joins the main body of the vertebra. The condition where the dens is separated from the body of the axis is called os odontoideum and may cause nerve and circulation compression syndrome ...
Dogs have ear mobility that allows them to rapidly pinpoint the exact location of a sound. Eighteen or more muscles can tilt, rotate, raise, or lower a dog's ear. A dog can identify a sound's location much faster than a human can, as well as hear sounds at four times the distance. [41] Dogs can lose their hearing from age or an ear infection. [42]
Diagram showing stages of endochondral ossification. Endochondral ossification is the formation of long bones and other bones. This requires a hyaline cartilage precursor. There are two centers of ossification for endochondral ossification. The primary center. In long bones, bone tissue first appears in the diaphysis (middle of shaft).
A schematic for long bone endochondral ossification. In developing bones, ossification commences within the primary ossification center located in the center of the diaphysis (bone shaft), [5] where the following changes occur: The perichondrium surrounding the cartilage model transforms into the periosteum. During this transformation, special ...
The anterior arch forms about one-fifth of the ring: its anterior surface is convex, and presents at its center the anterior tubercle for the attachment of the longus colli muscles and the anterior longitudinal ligament; posteriorly it is concave, and marked by a smooth, oval or circular facet (fovea dentis), for articulation with the odontoid process (dens) of the axis.
Hypertrophic Osteodystrophy (HOD) is a bone disease that occurs most often in fast-growing large and giant breed dogs; however, it also affects medium breed animals like the Australian Shepherd. The disorder is sometimes referred to as metaphyseal osteopathy , and typically first presents between the ages of 2 and 7 months. [ 1 ]
However, the secondary center of ossification may have evolved multiple times, having been found in the Jurassic sphenodont Sapheosaurus as well as in the therapsid Niassodon mfumukasi. [ 8 ] [ 9 ] The epiphysis is filled with red bone marrow , which produces erythrocytes (red blood cells).