Product Code Database
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of . The proportions of the vertebrae differ according to their spinal segment and the particular species.
The basic configuration of a vertebra varies; the vertebral body (also centrum) is of bone and bears the load of the vertebral column. The upper and lower surfaces of the vertebra body give attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch, in eleven parts, consisting of two pedicles (pedicle of vertebral arch), two laminae, and seven processes. The laminae give attachment to the ligamenta flava (ligaments of the spine). There are vertebral notches formed from the shape of the pedicles, which form the intervertebral foramina when the vertebrae articulate. These foramina are the entry and exit conduits for the . The body of the vertebra and the vertebral arch form the vertebral foramen; the larger, central opening that accommodates the spinal canal, which encloses and protects the spinal cord.
Vertebrae articulate with each other to give strength and flexibility to the spinal column and the shape at their back and front aspects determines the range of movement. Structurally, vertebrae are essentially alike across the vertebrate species, with the greatest difference seen between an aquatic animal and other vertebrate animals. As such, vertebrates take their name from the vertebrae that compose the vertebral column.
A major part of a vertebra is a backward extending spinous process (sometimes called the neural spine) which projects centrally. (2025). 9780323079549 ISBN 9780323079549 This process points dorsally and caudally from the junction of the laminae. The spinous process serves to attach and .
The two transverse processes, one on each side of the vertebral body, project laterally from either side at the point where the lamina joins the pedicle, between the superior and inferior articular processes. They also serve for the attachment of muscles and ligaments, in particular the intertransverse ligaments. There is a facet on each of the transverse processes of thoracic vertebrae which articulates with the tubercle of the rib. A facet on each side of the thoracic vertebral body articulates with the head of the rib. The transverse process of a lumbar vertebra is also sometimes called the costalPlatzer (2004), pp 42–43Latin costa refers to either a "rib" or "side" of the body. (Diab (1999), p 76) or costiform processTweedie, A. The library of medicine p. 31 because it corresponds to a rudimentary rib ( costa) which, as opposed to the thorax, is not developed in the lumbar region.Heinz Feneis, Wolfgang Dauber (2000) Pocket Atlas of Human Anatomy: Based on the International Nomenclature p. 2
There are superior and inferior articular on each side of the vertebra, which serve to restrict the range of movement possible. These facets are joined by a thin portion of the vertebral arch called the pars interarticularis.
The regional vertebrae increase in size as they progress downward but become smaller in the coccyx.
Cervical vertebrae possess transverse foramina to allow for the vertebral arteries to pass through on their way to the foramen magnum to end in the circle of Willis. These are the smallest, lightest vertebrae and the vertebral foramina are triangular in shape. The spinous processes are short and often (the spinous process of C7 is not bifurcated, and is substantially longer than that of the other cervical spinous processes). (2025). 9780323079549 ISBN 9780323079549
The atlas differs from the other vertebrae in that it has no body and no spinous process. It has instead a ring-like form, having an anterior and a posterior arch and two lateral masses. At the outside centre points of both arches there is a tubercle, an anterior tubercle and a posterior tubercle, for the attachment of muscles. The front surface of the anterior arch is convex and its anterior tubercle gives attachment to the longus colli muscle. The posterior tubercle is a rudimentary spinous process and gives attachment to the rectus capitis posterior minor muscle. The spinous process is small so as not to interfere with the movement between the atlas and the human skull. On the under surface is a facet for articulation with the dens of the axis.
Specific to the cervical vertebra is the transverse foramen (also known as foramen transversarium). This is an opening on each of the transverse processes which gives passage to the vertebral artery and vertebral vein and a sympathetic nerve plexus. On the cervical vertebrae other than the atlas, the anterior and posterior tubercles are on either side of the transverse foramen on each transverse process. The anterior tubercle on the sixth cervical vertebra is called the carotid tubercle because it separates the carotid artery from the vertebral artery.
There is a hook-shaped uncinate process on the side edges of the top surface of the bodies of the third to the seventh cervical vertebrae and of the first thoracic vertebra. Together with the vertebral disc, this uncinate process prevents a vertebra from sliding backward off the vertebra below it and limits lateral flexion (side-bending). Luschka's joints involve the vertebral uncinate processes.
The spinous process on C7 is distinctively long and gives the name vertebra prominens to this vertebra. Also a cervical rib can develop from C7 as an anatomical variation.
The term cervicothoracic is often used to refer to the cervical and thoracic vertebrae together, and sometimes also their surrounding areas.
The vertebral bodies are roughly heart-shaped and are about as wide anterio-posteriorly as they are in the transverse dimension. Vertebral foramina are roughly circular in shape.
The top surface of the first thoracic vertebra has a hook-shaped uncinate process, just like the cervical vertebrae.
The thoracolumbar spine or thoracolumbar division refers to the thoracic and lumbar vertebrae together, and sometimes also their surrounding areas.
The thoracic vertebrae attach to ribs and so have articular facets specific to them; these are the superior, transverse and inferior costal facets. As the vertebrae progress down the spine they increase in size to match up with the adjoining lumbar section.
The lumbar vertebrae are located between the ribcage and the pelvis and are the largest of the vertebrae. The pedicles are strong, as are the laminae, and the spinous process is thick and broad. The vertebral foramen is large and triangular. The transverse processes are long and narrow and three tubercles can be seen on them. These are a lateral costiform process, a mammillary process and an accessory process.Postacchini, Franco (1999) Lumbar Disc Herniation p. 19 The superior, or upper tubercle is the mammillary process which connects with the superior articular process. The multifidus muscle attaches to the mammillary process and this muscle extends through the length of the vertebral column, giving support. The inferior, or lower tubercle is the accessory process and this is found at the back part of the base of the transverse process. The term lumbosacral is often used to refer to the lumbar and sacral vertebrae together, and sometimes includes their surrounding areas.
Spondylolysis is a defect in the pars interarticularis of the vertebral arch. In most cases this occurs in the lowest of the lumbar vertebrae (L5), but may also occur in the other lumbar vertebrae, as well as in the thoracic vertebrae.
Spinal disc herniation, more commonly called a slipped disc, is the result of a tear in the outer ring (anulus fibrosus) of the intervertebral disc, which lets some of the soft gel-like material, the nucleus pulposus, bulge out in a hernia. This may be treated by a minimally-invasive endoscopic procedure called Tessys method.
A laminectomy is a surgical operation to remove the laminae in order to access the spinal canal. (2025). 9781416062578, Elsevier Saunders. ISBN 9781416062578 The removal of just part of a lamina is called a laminotomy.
A pinched nerve caused by pressure from a disc, vertebra or scar tissue might be remedied by a foraminotomy to broaden the intervertebral foramina and relieve pressure. It can also be caused by a foramina stenosis, a narrowing of the nerve opening, as a result of arthritis.
Another condition is spondylolisthesis when one vertebra slips forward onto another. The reverse of this condition is retrolisthesis where one vertebra slips backward onto another.
The vertebral pedicle is often used as a radiographic marker and entry point in vertebroplasty, kyphoplasty, and spinal fusion procedures.
The arcuate foramen is a common anatomical variation more frequently seen in females. It is a bony bridge found on the first cervical vertebra, the atlas where it covers the groove for the vertebral artery.
Degenerative disc disease is a condition usually associated with ageing in which one or more discs degenerate. This can often be a painfree condition but can also be very painful.
Vertebrae with saddle-shaped articular surfaces on their bodies, called "heterocoelous", allow vertebrae to flex both vertically and horizontally while preventing twisting motions. Such vertebrae are found in the necks of birds and some turtles.
"Procoelous" vertebrae feature a spherical protrusion extending from the caudal end of the centrum of one vertebra that fits into a concave socket on the cranial end of the centrum of an adjacent vertebra. These vertebrae are most often found in reptiles, but are found in some amphibians such as frogs. (2025). 9780078023026, McGraw-Hill Education. ISBN 9780078023026 The vertebrae fit together in a ball-and-socket articulation, in which the convex articular feature of an anterior vertebra acts as the ball to the socket of a caudal vertebra. This type of connection permits a wide range of motion in most directions, while still protecting the underlying nerve cord. The central point of rotation is located at the midline of each centrum, and therefore flexion of the muscle surrounding the vertebral column does not lead to an opening between vertebrae.
In many species, though not in mammals, the cervical vertebrae bear ribs. In many groups, such as and dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The transverse processes of mammals are homologous to the cervical ribs of other amniotes. In the whale, the cervical vertebrae are typically fused, an adaptation trading flexibility for stability during swimming. All except and have seven cervical vertebrae, whatever the length of the neck. This includes seemingly unlikely animals such as the giraffe, the camel, and the blue whale, for example. Bird anatomy usually have more cervical vertebrae with most having a highly flexible neck consisting of 13–25 vertebrae.
In all mammals, the thoracic vertebrae are connected to and their bodies differ from the other regional vertebrae due to the presence of facets. Each vertebra has a facet on each side of the vertebral body, which articulates with the head of a rib. There is also a facet on each of the transverse processes which articulates with the tubercle of a rib. The number of thoracic vertebrae varies considerably across the species. Most have thirteen, but only have eleven. The usual number is twelve to fifteen in , (twelve in the human), though there are from eighteen to twenty in the horse, tapir, rhinoceros and elephant. In certain sloths, there is an extreme number of twenty-five and at the other end only nine in the cetacean.Hyman (1922), p. 124
There are fewer lumbar vertebrae in and , which have three in contrast to the five in the genus Homo. This reduction in number gives an inability of the lumbar spine to lordosis but gives an anatomy that favours vertical climbing, and hanging ability more suited to feeding locations in high-canopied regions. The bonobo differs by having four lumbar vertebrae.
Caudal vertebrae are the bones that make up the tails of vertebrates. They range in number from a few to fifty, depending on the length of the animal's tail. In humans and other tailless , they are called the coccygeal vertebrae, number from three to five and are fused into the coccyx.
|
|
