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92-415: The basic configuration of a vertebra varies; the bone is the body, and the central part of the body is the centrum. 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

184-431: 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. 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

276-478: A proteoglycan that aggregates by binding to hyaluronan . Attached to each aggrecan molecule are glycosaminoglycan (GAG) chains of chondroitin sulfate and keratan sulfate . Increasing the amount of negatively charged aggrecan increases oncotic pressure , resulting in a shift of extracellular fluid from the outside to the inside of the nucleus pulposus. The amount of glycosaminoglycans (and hence water) decreases with age and degeneration. Anything arising from

368-421: A C shape (see image). The location of anatomical structures can also be described in relation to different anatomical landmarks . They are used in anatomy, surface anatomy, surgery, and radiology. Structures may be described as being at the level of a specific spinal vertebra , depending on the section of the vertebral column the structure is at. The position is often abbreviated. For example, structures at

460-451: 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 marsupials have thirteen, but koalas only have eleven. The usual number is twelve to fifteen in mammals , (twelve in the human ), though there are from eighteen to twenty in

552-441: 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

644-416: A large anterior middle portion called the centrum ( vertebral centrum , plural centra ) and a posterior vertebral arch , also called a neural arch . The body is composed of cancellous bone , which is the spongy type of osseous tissue , whose microanatomy has been specifically studied within the pedicle bones. This cancellous bone is in turn, covered by a thin coating of cortical bone (or compact bone),

736-423: A mucoprotein gel. The nucleus of the disc acts as a shock absorber, absorbing the impact of the body's activities and keeping the two vertebrae separated. It is the remnant of the notochord . There is one disc between each pair of vertebrae, except for the first cervical segment, the atlas . The atlas is a ring around the roughly cone-shaped extension of the axis (second cervical segment). The axis acts as

828-404: A natural lumbar lordosis (a spinal curvature that is concave posteriorly). This is due to the difference in thickness between the front and back parts of the intervertebral discs. 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

920-490: A normal part of the ageing process and do not correlate to pain. One effect of aging and disc degeneration is that the nucleus pulposus begins to dehydrate and the concentration of proteoglycans in the matrix decreases, thus limiting the ability of the disc to absorb shock. This general shrinking of disc size is partially responsible for the common decrease in height as humans age. The anulus fibrosus also becomes weaker with age and has an increased risk of tearing. In addition,

1012-458: A post around which the atlas can rotate, allowing the neck to swivel. There are 23 discs in the human spine: 6 in the neck ( cervical ) region, 12 in the middle back ( thoracic ) region, and 5 in the lower back ( lumbar ) region. Discs are named by the vertebral body above and below. For example, the disc between the fifth and sixth cervical vertebrae is designated "C5-6". During development and at birth, vertebral discs have some vascular supply to

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1104-493: A result of chronic deterioration (typically accompanied with poor posture), and has been associated with a Propionibacterium acnes infection. Both the deformed anulus and the gel-like material of the nucleus pulposus can be forced laterally or posteriorly, distorting local muscle function and putting pressure on the nearby nerve. This can give symptoms typical of nerve root entrapment, which can vary between paresthesia , numbness, chronic and/or acute pain, either locally or along

1196-478: A rudimentary rib ( costa ) which, as opposed to the thorax, is not developed in the lumbar region. There are superior and inferior articular facet joints 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 . Vertebrae take their names from the regions of the vertebral column that they occupy. There are usually thirty-three vertebrae in

1288-414: A standard set of terms to communicate clearly the position of a structure. Standard anatomical and zoological terms of location have been developed, usually based on Latin and Greek words, to enable all biological and medical scientists, veterinarians , doctors and anatomists to precisely delineate and communicate information about animal bodies and their organs, even though the meaning of some of

1380-403: A state in which a part further away is abnormally placed towards (varus) or away from (valgus) the midline. The terms proximal (from Latin proximus  'nearest') and distal (from Latin distare  'to stand away from') are used to describe parts of a feature that are close to or distant from the main mass of the body, respectively. Thus the upper arm in humans

1472-413: A thickened layer of the cancellous bone of the vertebral body, the top layer being more dense. The endplates function to contain the adjacent discs, to evenly spread the applied loads, and to provide anchorage for the collagen fibers of the disc. They also act as a semi-permeable interface for the exchange of water and solutes. The vertebral arch is formed by pedicles and laminae. Two pedicles extend from

1564-452: A wound on the upper arm, but proximal to a wound on the lower arm. The terms are also applied to internal anatomy, such as to the reproductive tract of snails . Unfortunately, different authors use the terms in opposite senses. Some consider "distal" as further from a point of origin near the centre of the body and others as further from where the organ reaches the body's surface; or other points of origin may be envisaged. This terminology

1656-674: Is bipedal or quadrupedal . Additionally, for some animals such as invertebrates , some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, Terminologia Anatomica for humans and Nomina Anatomica Veterinaria for animals. These allow parties that use anatomical terms, such as anatomists , veterinarians , and medical doctors , to have

1748-415: 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. In other animals, the vertebrae take

1840-415: 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 vein and a sympathetic nerve plexus . On the cervical vertebrae other than the atlas, the anterior and posterior tubercles are on either side of

1932-413: Is also employed in molecular biology and therefore by extension is also used in chemistry, specifically referring to the atomic loci of molecules from the overall moiety of a given compound. Central and peripheral refer to the distance towards and away from the centre of something. That might be an organ, a region in the body, or an anatomical structure. For example, the central nervous system and

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2024-447: Is concentrated toward the edge of the ring, where it provides greater strength. The stiff laminae can withstand compressive forces. The fibrous intervertebral disc contains the nucleus pulposus and this helps to distribute pressure evenly across the disc. This prevents the development of stress concentrations which could cause damage to the underlying vertebrae or to their endplates . The nucleus pulposus contains loose fibers suspended in

2116-403: 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 . 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

2208-407: Is not bifurcated, and is substantially longer than that of the other cervical spinous processes). 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

2300-409: Is often present in pregnancy and obesity. The Latin word anulus means "little ring"; it is the diminutive of anus ("ring"). However, modern English also spells the word more phonetically annulus , as with the term annular eclipse , where the moon blocks the sun except for a bright ring around it. Dorsally Standard anatomical terms of location are used to describe unambiguously

2392-418: Is often used to refer to the cervical and thoracic vertebrae together, and sometimes also their surrounding areas. The twelve thoracic vertebrae and their transverse processes have surfaces that articulate with the ribs . Some rotation can occur between the thoracic vertebrae, but their connection with the rib cage prevents much flexion or other movement. They may also be known as "dorsal vertebrae" in

2484-402: Is proximal and the hand is distal. "Proximal and distal" are frequently used when describing appendages , such as fins , tentacles , and limbs . Although the direction indicated by "proximal" and "distal" is always respectively towards or away from the point of attachment, a given structure can be either proximal or distal in relation to another point of reference. Thus the elbow is distal to

2576-402: Is rarely used in human anatomy, apart from embryology, and refers more to the front of the face than the superior aspect of the organism. Similarly, the term "caudal" is used more in embryology and only occasionally used in human anatomy. This is because the brain is situated at the superior part of the head whereas the nose is situated in the anterior part. Thus, the "rostrocaudal axis" refers to

2668-481: Is roughly symmetrical. To do this, distinct ends of an organism are chosen, and the axis is named according to those directions. An organism that is symmetrical on both sides has three main axes that intersect at right angles . An organism that is round or not symmetrical may have different axes. Example axes are: Examples of axes in specific animals are shown below. Several terms are commonly seen and used as prefixes : Other terms are used as suffixes , added to

2760-458: Is to the head or tail of an animal. To describe how close to the head of an animal something is, three distinct terms are used: For example, in horses , the eyes are caudal to the nose and rostral to the back of the head. These terms are generally preferred in veterinary medicine and not used as often in human medicine. In humans, "cranial" and "cephalic" are used to refer to the skull, with "cranial" being used more commonly. The term "rostral"

2852-434: Is to the midline, or the medial plane. Lateral (from Latin lateralis  'to the side') describes something to the sides of an animal, as in "left lateral" and "right lateral". Medial (from Latin medius  'middle') describes structures close to the midline, or closer to the midline than another structure. For example, in a human, the arms are lateral to the torso . The genitals are medial to

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2944-478: The anatomy of animals , including humans . The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position . This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes . The meaning of terms that are used can change depending on whether an organism

3036-438: The anterior superior iliac spine , the medial malleolus or the medial epicondyle . Anatomical lines are used to describe anatomical location. For example, the mid-clavicular line is used as part of the cardiac exam in medicine to feel the apex beat of the heart . Special terms are used to describe the mouth and teeth. Fields such as osteology , palaeontology and dentistry apply special terms of location to describe

3128-495: The cervical vertebrae bear ribs. In many groups, such as lizards and saurischian 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 mammals except manatees and sloths have seven cervical vertebrae, whatever

3220-651: The dermatome served by the entrapped nerve, loss of muscle tone and decreased homeostatic performance. The disc is not physically slipped; it bulges, usually in just one direction. Another kind of herniation, of the nucleus pulposus, can happen as a result of the formation of Schmorl's nodes on the intervertebral disc. This is referred to as vertical disc herniation . Before age 40, approximately 25% of people show evidence of disc degeneration at one or more levels. Beyond age 40, more than 60% of people show evidence of disc degeneration at one or more levels on magnetic resonance imaging (MRI). These degenerative changes are

3312-449: The head . Anterior (from Latin ante  'before') describes what is in front, and posterior (from Latin post  'after') describes what is to the back of something. For example, for a dog the nose is anterior to the eyes and the tail is considered the most posterior part; for many fish the gill openings are posterior to the eyes but anterior to the tail. These terms describe how close something

3404-586: 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 . There are fewer lumbar vertebrae in chimpanzees and gorillas , which have three in contrast to the five in the genus Homo . This reduction in number gives an inability of the lumbar spine to lordose 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

3496-430: 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 spinal nerves . 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

3588-648: The neuraxis is different between the two groups, and so is what is considered the standard anatomical position , such as how humans tend to be standing upright and with their arms reaching forward. Thus, the "top" of a human is the head, whereas the "top" of a dog would be the back, and the "top" of a flounder may be on either the left or right side. Unique terms are also used to describe invertebrates as well, because of their wider variety of shapes and symmetry. Because animals can change orientation with respect to their environment, and because appendages like limbs and tentacles can change position with respect to

3680-467: The pectoralis major muscle). In radiology , an X-ray image may be said to be "anteroposterior", indicating that the beam of X-rays, known as its projection, passes from their source to patient's anterior body wall first, then through the body to exit through posterior body wall and into the detector/film to produce a radiograph. The opposite is true for the term "posteroanterior," while side-to-side projections are known as either "lateromedial" (from

3772-415: The peripheral nervous systems . Central (from Latin centralis ) describes something close to the centre. For example, the great vessels run centrally through the body; many smaller vessels branch from these. Peripheral (from Latin peripheria , originally from Ancient Greek ) describes something further away from the centre of something. For example, the arm is peripheral to

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3864-416: The sacrum , with no intervertebral discs . The sacrum with the ilium forms a sacroiliac joint on each side of the pelvis , which articulates with the hips . The last three to five coccygeal vertebrae (but usually four) (Co1–Co5) make up the tailbone or coccyx . There are no intervertebral discs . Somites form in the early embryo and some of these develop into sclerotomes. The sclerotomes form

3956-404: 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

4048-463: 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 five lumbar vertebrae are the largest of the vertebrae, their robust construction being necessary for supporting greater weight than the other vertebrae. They allow significant flexion , extension and moderate lateral flexion (side-bending). The discs between these vertebrae create

4140-554: The vertebral column . Each disc forms a fibrocartilaginous joint (a symphysis ), to allow slight movement of the vertebrae, to act as a ligament to hold the vertebrae together, and to function as a shock absorber for the spine. Intervertebral discs consist of an outer fibrous ring, the anulus (or annulus) fibrosus disci intervertebralis , which surrounds an inner gel-like center, the nucleus pulposus . The anulus fibrosus consists of several layers (laminae) of fibrocartilage made up of both type I and type II collagen . Type I

4232-437: 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 costal or costiform process because it corresponds to

4324-401: 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 skull . On the under surface

4416-400: The body in a standing position with arms at the side and palms facing forward, with thumbs out and to the sides. Many anatomical terms can be combined, either to indicate a position in two axes simultaneously or to indicate the direction of a movement relative to the body. For example, "anterolateral" indicates a position that is both anterior and lateral to the body axis (such as the bulk of

4508-570: The body. These terms refer to the distance of a structure from the surface. Deep (from Old English ) describes something further away from the surface of the organism. For example, the external oblique muscle of the abdomen is deep to the skin. "Deep" is one of the few anatomical terms of location derived from Old English rather than Latin – the anglicised Latin term would have been "profound" (from Latin profundus  'due to depth'). Superficial (from Latin superficies  'surface') describes something near

4600-595: 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 primates , they are called the coccygeal vertebrae , number from three to five and are fused into the coccyx . [REDACTED] This article incorporates text in the public domain from page 96 of the 20th edition of Gray's Anatomy (1918) Intervertebral disc An intervertebral disc ( British English ), also spelled intervertebral disk ( American English ), lies between adjacent vertebrae in

4692-431: The cartilage endplates and the anulus fibrosus. These quickly deteriorate leaving almost no direct blood supply in healthy adults. The intervertebral disc space is typically defined on an X-ray photograph as the space between adjacent vertebrae . In healthy patients, this corresponds to the size of the intervertebral disc. The size of the space can be altered in pathological conditions such as discitis (infection of

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4784-528: The cartilage endplates begin thinning, fissures begin to form, and there is sclerosis of the subchondral bone . Since the fissures are formed in the anulus fibrosus due to osteo-arthritic bones or degeneration in general, the inner nucleus pulposus can seep out and put pressure on any number of vertebral nerves. A herniated disc can cause mild to severe pain such as sciatica and treatment for herniated discs range from physical therapy to surgery. (see also: Intervertebral disc arthroplasty ) Other degeneration of

4876-417: The closeness to the midline of the dental arch. Terms used to describe structures include "buccal" (from Latin bucca  'cheek') and "palatal" (from Latin palatum  'palate') referring to structures close to the cheek and hard palate respectively. Several anatomical terms are particular to the hands and feet. Additional terms may be used to avoid confusion when describing

4968-467: 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,

5060-478: The developing spinal cord , forming the vertebral arch . Other cells move distally to the costal processes of thoracic vertebrae to form the ribs. Functions of vertebrae include: There are a number of congenital vertebral anomalies , mostly involving variations in the shape or number of vertebrae, and many of which are unproblematic. Others though can cause compression of the spinal cord. Wedge-shaped vertebrae, called hemivertebrae can cause an angle to form in

5152-421: The end of words: Superior (from Latin super  'above') describes what is above something and inferior (from Latin inferus  'below') describes what is below it. For example, in the anatomical position , the most superior part of the human body is the head and the most inferior is the feet. As a second example, in humans, the neck is superior to the chest but inferior to

5244-409: The exception of C2 and C7, which have palpable spinous processes). C1 is also called the atlas , and C2 is also called the axis . The structure of these vertebrae is the reason why the neck and head have a large range of motion. The atlanto-occipital joint allows the skull to move up and down, while the atlanto-axial joint allows the upper neck to twist left and right. The axis also sits upon

5336-402: The first intervertebral disc of the spinal column. 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 bifurcated (the spinous process of C7

5428-417: The hand') is commonly used to describe the front of the hand, and dorsal is the back of the hand. For example, the top of a dog 's paw is its dorsal surface; the underside, either the palmar (on the forelimb) or the plantar (on the hindlimb) surface. The palmar fascia is palmar to the tendons of muscles which flex the fingers, and the dorsal venous arch is so named because it is on the dorsal side of

5520-409: The hard and dense type of osseous tissue. The vertebral arch and processes have thicker coverings of cortical bone. The upper and lower surfaces of the body of the vertebra are flattened and rough in order to give attachment to the intervertebral discs . These surfaces are the vertebral endplates which are in direct contact with the intervertebral discs and form the joint. The endplates are formed from

5612-568: The human context. 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

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5704-415: 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 . Excluding rare deviations, the total number of vertebrae ranges from 32 to 35. In about 10% of people, both the total number of pre-sacral vertebrae and the number of vertebrae in individual parts of

5796-399: The intervertebral disc may be termed discogenic in particular when referring to associated pain as discogenic pain . A spinal disc herniation, commonly referred to as a slipped disc, can happen when unbalanced mechanical pressures substantially deform the anulus fibrosus, allowing part of the nucleus to obtrude. These events can occur during peak physical performance, during traumas, or as

5888-468: The intervertebral disc). The intervertebral disc functions to separate the vertebrae from each other and provides the surface for the shock-absorbing gel of the nucleus pulposus. The nucleus pulposus of the disc functions to distribute hydraulic pressure in all directions within each intervertebral disc under compressive loads. The nucleus pulposus consists of large vacuolated notochord cells, small chondrocyte-like cells, collagen fibrils, and aggrecan ,

5980-541: The larger animals since they attach to the muscles and ligaments of the body. In the elephant , the vertebrae are connected by tight joints, which limit the backbone's flexibility. Spinous processes are exaggerated in some animals, such as the extinct Dimetrodon and Spinosaurus , where they form a sailback or finback. 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

6072-512: The legs. Temporal has a similar meaning to lateral but is restricted to the head. The terms "left" and "right" are sometimes used, or their Latin alternatives ( Latin : dexter , lit.   'right'; Latin : sinister , lit.   'left'). However, it is preferred to use more precise terms where possible. Terms derived from lateral include: Varus (from Latin  'bow-legged') and valgus (from Latin  'knock-kneed' ) are terms used to describe

6164-419: The length of the neck. This includes seemingly unlikely animals such as the giraffe, the camel, and the blue whale, for example. Birds 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 ribs and their bodies differ from the other regional vertebrae due to the presence of facets. Each vertebra has

6256-416: 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. There are five sacral vertebrae (S1–S5) which are fused in maturity, into one large bone,

6348-448: The level of the fourth cervical vertebra may be abbreviated as "C4", at the level of the fourth thoracic vertebra "T4", and at the level of the third lumbar vertebra "L3". Because the sacrum and coccyx are fused, they are not often used to provide the location. References may also take origin from superficial anatomy , made to landmarks that are on the skin or visible underneath. For example, structures may be described relative to

6440-406: 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

6532-401: The main body, terms to describe position need to refer to an animal when it is in its standard anatomical position . This means descriptions as if the organism is in its standard anatomical position, even when the organism in question has appendages in another position. This helps avoid confusion in terminology when referring to the same organism in different postures. In humans, this refers to

6624-520: The morphology of intervertebral discs. For example, patients with scoliosis commonly have calcium deposits (ectopic calcification) in the cartilage endplate and sometimes in the disc itself. Herniated discs are also found to have a higher degree of cellular senescence than non-herniated discs. In addition to scoliosis, which is the lateral 'S' curvature of the spine, the fused vertebrae can also experience other abnormalities such as kyphosis (hunchback) which shows in old age, or lordosis (swayback), which

6716-456: The mouth and teeth. This is because although teeth may be aligned with their main axes within the jaw, some different relationships require special terminology as well; for example, teeth also can be rotated, and in such contexts terms like "anterior" or "lateral" become ambiguous. For example, the terms "distal" and "proximal" are also redefined to mean the distance away or close to the dental arch , and "medial" and "lateral" are used to refer to

6808-418: 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. The vertebrae fit together in a ball-and-socket articulation, in which

6900-420: The neural spine) which projects centrally. This process points dorsally and caudally from the junction of the laminae. The spinous process serves to attach muscles and ligaments . 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

6992-452: The notches align with those on adjacent vertebrae and these form the openings of the intervertebral foramina . The foramina allow the entry and exit of the spinal nerves from each vertebra, together with associated blood vessels. The articulating vertebrae provide a strong pillar of support for the body. There are seven processes projecting from the vertebra: A major part of a vertebra is a backward extending spinous process (sometimes called

7084-400: The outer surface of the organism. For example, in skin , the epidermis is superficial to the subcutis . These two terms, used in anatomy and embryology , describe something at the back ( dorsal ) or front/belly ( ventral ) of an organism. The dorsal (from Latin dorsum  'back') surface of an organism refers to the back, or upper side, of an organism. If talking about

7176-402: The outside of the left or right side of the body toward the inside) or "mediolateral"(from the inside of that side of the body toward the outside. The same logic is applied to all planes of the body and, thus top-to-bottom or bottom-to-top X-ray projections are known as "superoinferior" and "inferosuperior," respectively. However, within the diagnostic imaging industry, for this particular example,

7268-476: The same regional names except for the coccygeal – in animals with tails, the separate vertebrae are usually called the caudal vertebrae . Because of the different types of locomotion and support needed between the aquatic and other vertebrates, the vertebrae between them show the most variation, though basic features are shared. The spinous processes which are backward extending are directed upward in animals without an erect stance. These processes can be very large in

7360-425: The sides of the vertebral body to join the body to the arch. The pedicles are short thick processes that extend, one from each side, posteriorly, from the junctions of the posteriolateral surfaces of the centrum, on its upper surface. From each pedicle a broad plate, a lamina , projects backward and medially to join and complete the vertebral arch and form the posterior border of the vertebral foramen, which completes

7452-442: The skull, the dorsal side is the top. The ventral (from Latin venter  'belly') surface refers to the front, or lower side, of an organism. For example, in a fish, the pectoral fins are dorsal to the anal fin , but ventral to the dorsal fin . The terms are used in other contexts; for example dorsal and ventral gun turrets on a bomber aircraft. Specific terms exist to describe how close or far something

7544-480: The spine can vary. The most frequent deviations are eleven (rarely thirteen) thoracic vertebrae, four or six lumbar vertebrae and three or five coccygeal vertebrae (rarely up to seven). The regional vertebrae increase in size as they progress downward but become smaller in the coccyx. There are seven cervical vertebrae (but eight cervical spinal nerves ), designated C1 through C7. These bones are, in general, small and delicate. Their spinous processes are short (with

7636-419: The spine which can result in the spinal curvature diseases of kyphosis , scoliosis and lordosis . Severe cases can cause spinal cord compression. Block vertebrae where some vertebrae have become fused can cause problems. Spina bifida can result from the incomplete formation of the vertebral arch. Spondylolysis is a defect in the pars interarticularis of the vertebral arch. In most cases this occurs in

7728-460: The surfaces of the hand and what is the "anterior" or "posterior" surface. The term "anterior", while anatomically correct, can be confusing when describing the palm of the hand; Similarly is "posterior", used to describe the back of the hand and arm. This confusion can arise because the forearm can pronate and supinate and flip the location of the hand. For improved clarity, the directional term palmar (from Latin palma  'palm of

7820-429: The terms "cranial" (towards the head) and "caudal" (towards the tail, or, downwards, away from the head) are known interchangeable alternatives to the previous two projection terms. Combined terms were once generally hyphenated, but the modern tendency is to omit the hyphen. Anatomical terms describe structures with relation to four main anatomical planes : The axes of the body are lines drawn about which an organism

7912-404: The terms often is context-sensitive. Much of this information has been standardised in internationally agreed vocabularies for humans ( Terminologia Anatomica ) and animals ( Nomina Anatomica Veterinaria ). Different terms are used for groups of creatures with different body layouts, such as bipeds (creatures that stand on two feet, such as humans) and quadrupeds . The reasoning is that

8004-399: 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

8096-404: The triangle of the vertebral foramen. The upper surfaces of the laminae are rough to give attachment to the ligamenta flava . These ligaments connect the laminae of adjacent vertebra along the length of the spine from the level of the second cervical vertebra . Above and below the pedicles are shallow depressions called vertebral notches ( superior and inferior ). When the vertebrae articulate

8188-449: The vertebrae as well as the rib cartilage and part of the occipital bone . From their initial location within the somite, the sclerotome cells migrate medially toward the notochord . These cells meet the sclerotome cells from the other side of the paraxial mesoderm . The lower half of one sclerotome fuses with the upper half of the adjacent one to form each vertebral body. From this vertebral body, sclerotome cells move dorsally and surround

8280-428: The vertebrae that compose the vertebral column. In the human vertebral column , the size of the vertebrae varies according to placement in the vertebral column, spinal loading, posture and pathology. Along the length of the spine , the vertebrae change to accommodate different needs related to stress and mobility. Each vertebra is an irregular bone. A typical vertebra has a body ( vertebral body ), which consists of

8372-526: The vertebral column includes diffuse idiopathic skeletal hyperostosis (DISH) which is the calcification or ossification of the ligaments surrounding the vertebrae. This degeneration causes stiffness and sometimes even curvature in the lumbar and thoraco-lumbar spinal region. Burgeoning evidence suggests that long-term running may mitigate age-related degeneration within lumbar intervertebral discs While this may not cause pain in some people, in others it may cause chronic pain. Other spinal disorders can affect

8464-422: 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

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