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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.
Modern human hip joints are larger than in quadrupedal ancestral species to better support the greater amount of body weight passing through them. [7] They also have a shorter, broader shape. This alteration in shape brought the vertebral column closer to the hip joint, providing a stable base for support of the trunk while walking upright. [15]
Vertebrae take their names from the regions of the vertebral column that they occupy. There are usually thirty-three vertebrae in the human vertebral column — seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, five fused sacral vertebrae forming the sacrum and four coccygeal vertebrae, forming the coccyx.
Migrations to Eurasia happened in waves, and now the discovery of a 1.5-million-year-old fossil vertebra from an ancient hominid species is revealing more about where they went.
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 spinal nerves arise from the spinal column. The top section of the spine is the cervical section, which contains nerves that innervate muscles of the head, neck and thoracic cavity, as well as transmit sensory information to the CNS. The cervical spine section contains seven vertebrae, C-1 through C-7, and eight nerve pairs, C-1 through C-8.
Median sagittal section through the occipital bone and first three cervical vertebrae, showing ligamentous attachments The posterior arch forms about two-fifths of the circumference of the ring: it ends behind in the posterior tubercle, which is the rudiment of a spinous process and gives origin to the recti capitis posteriores minores and the ...
The four main divisions of the spinal column, from top to bottom: cervical, thoracic, lumbar, and sacral. The lateral grey column (lateral column, lateral cornu, lateral horn of spinal cord, intermediolateral column) is one of the three grey columns of the spinal cord (which give the shape of a butterfly); the others being the anterior and posterior grey columns.