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3D medical animation still shot of human skull. The axial skeleton is the core part of the endoskeleton made of the bones of the head and trunk of vertebrates.In the human skeleton, it consists of 80 bones and is composed of the skull (28 bones, including the cranium, mandible and the middle ear ossicles), the vertebral column (26 bones, including vertebrae, sacrum and coccyx), the rib cage ...
A typical vertebra has a body (vertebral body), also known as the centrumwhich consists of a large anterior middle portion, and a posterior vertebral arch, [2] also called a neural arch. [3] The body is composed of cancellous bone , which is the spongy type of osseous tissue , whose microanatomy has been specifically studied within the pedicle ...
It is composed of 270 bones at the time of birth, [2] but later decreases to 206: 80 bones in the axial skeleton and 126 bones in the appendicular skeleton. 172 of 206 bones are part of a pair and the remaining 34 are unpaired. [3] Many small accessory bones, such as sesamoid bones, are not included in this.
The axial skeleton (80 bones) is formed by the vertebral column (32–34 bones; the number of the vertebrae differs from human to human as the lower 2 parts, sacral and coccygeal bone may vary in length), a part of the rib cage (12 pairs of ribs and the sternum), and the skull (22 bones and 7 associated bones).
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.
In human anatomy, the five vertebrae are between the rib cage and the pelvis.They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse process (since it is only found in the cervical region) and by the absence of facets on the sides of the body (as found only in the thoracic region).
Foramen transversarium, one of a pair of openings in each cervical vertebra, in which the vertebral artery travels; Greater sciatic foramen, a major foramen of the pelvis; Interventricular foramen, channels connecting ventricles in the brain; Intervertebral foramen, foramina formed between vertebrae
An irregular bone is one that does not have an easily classified shape and defies description. These bones tend to have more complex shapes, like the vertebrae that support the spinal cord and protect it from compressive forces. Many facial bones, particularly the ones containing sinuses, are classified as irregular bones. [1]