Cervical vertebrae 1238189 225490715 2008-07-13T23:43:17Z Lamaybe 2353113 since caudal is ambiguous (meaning towards the back of the head or away from the head towards the tailbone, posterior is a clearer term here.) {{Infobox Bone | Name = Cervical vertebrae | Latin = vertebrae cervicales | GraySubject = 21 | GrayPage = 97 | Image = Illu vertebral column.jpg | Caption = Vertebral column | Image2 = Gray84.png | Caption2 = A cervical vertebra | Precursor = | System = | Artery = | Vein = | Nerve = | Lymph = | MeshName = Cervical+vertebrae | MeshNumber = A02.835.232.834.151 | DorlandsPre = v_07 | DorlandsSuf = 12854511 | }} In [[vertebrate]]s, '''cervical vertebrae''' (singular: ''vertebra'') are those vertebrae immediately behind (posterior to) the [[skull]]. ==Variation among species== In some species, some parts of the skull may be composed of vertebra-like elements, e.g. the [[occipital bone]] in humans is composed of four vertebra-like segments. In many vertebrate species, cervical vertebrae are variable in number; however, almost all [[mammal]]s have seven (including those with very short necks, such as [[elephant]]s or [[whale]]s, and those with very long necks, such as [[giraffe]]s). The few exceptions include the [[manatee]] and the [[two-toed sloth]], which each have only six cervical vertebrae{{Fact|date=May 2008}}, and the [[three-toed sloth]] with nine cervical vertebrae{{Fact|date=May 2008}}. [[Thoracic vertebrae]] in all species are defined as those vertebrae which also carry a pair of [[rib]]s, and lie caudal to the cervical vertebrae. In humans, '''cervical vertebrae''' are the smallest of the true [[vertebra]]e, and can be readily distinguished from those of the [[thoracic vertebrae|thoracic]] or [[lumbar vertebrae|lumbar]] regions by the presence of a [[foramen]] (hole) in each [[transverse process]], through which passes the [[vertebral artery]]. The remainder of this article focuses upon human anatomy. ==General characteristics (C3-C6)== [[Image:Gray85.png|thumb|300px|Side view of a typical cervical vertebra]] These are the general characteristics of the third through sixth cervical vertebrae. (The first, second, and seventh vertebrae are extraordinary, and detailed later.) * The [[Body of vertebra|body]] of these four vertebrae is small, and broader from side to side than from front to back. ** The ''anterior'' and ''posterior surfaces'' are flattened and of equal depth; the former is placed on a lower level than the latter, and its inferior border is prolonged downward, so as to overlap the upper and forepart of the vertebra below. ** The ''upper surface'' is concave transversely, and presents a projecting lip on either side; ** the ''lower surface'' is concave from front to back, convex from side to side, and presents laterally shallow concavities which receive the corresponding projecting lips of the underlying vertebra. * The [[pedicles]] are directed laterally and backward, and are attached to the body midway between its upper and lower borders, so that the superior vertebral notch is as deep as the inferior, but it is, at the same time, narrower. * The [[laminae]] are narrow, and thinner above than below; the [[vertebral foramen]] is large, and of a triangular form. * The [[spinous process]] is short and [[bifid]], the two divisions being often of unequal size. * The superior and inferior [[articular processes]] of neighboring vertebrae often fuse on either or both sides to form an '''articular pillar''', a column of bone which projects laterally from the junction of the pedicle and lamina. * The [[articular facet]]s are flat and of an oval form: ** the ''superior'' face backward, upward, and slightly medially. ** the ''inferior'' face forward, downward, and slightly laterally. * The [[transverse processes]] are each pierced by the [[foramen transversarium]], which, in the upper six vertebrae, gives passage to the [[vertebral artery]] and [[vertebral vein|vein]], as well as a plexus of [[sympathetic nerve]]s. Each process consists of an anterior and a posterior part. These two parts are joined, outside the foramen, by a bar of bone which exhibits a deep sulcus on its upper surface for the passage of the corresponding [[spinal nerve]]. ** The anterior portion is the homologue of the [[rib]] in the [[thorax|thoracic]] region, and is therefore named the ''costal process'' or ''costal element''. It arises from the side of the body, is directed laterally in front of the foramen, and ends in a tubercle, the [[anterior tubercle]]. ** The posterior part, the true transverse process, springs from the vertebral arch behind the foramen, and is directed forward and laterally; it ends in a flattened vertical tubercle, the [[posterior tubercle]]. ==Special cervical vertebrae (C1, C2, and C7)== * ''C1 or [[Atlas (anatomy)|atlas]]:'' The Atlas is the topmost vertebra, and &ndash; along with C2 &ndash; forms the joint connecting the [[skull]] and [[vertebral column|spine]]. Its chief peculiarity is that it has no body, and this is due to the fact that the body of the atlas has fused with that of the next vertebra. * ''C2 or [[Axis (anatomy)|axis]]:'' It forms the pivot upon which C1 rotates. The most distinctive characteristic of this [[bone]] is the strong odontoid process (dens) which rises perpendicularly from the upper surface of the body. The body is deeper in front than behind, and prolonged downward anteriorly so as to overlap the upper and front part of the third vertebra. * ''C7 or [[vertebra prominens]]:'' The most distinctive characteristic of this vertebra is the existence of a long and prominent spinous process, hence the name ''vertebra prominens''. In some subjects, the seventh cervical vertebra is associated with an abnormal pair of ribs, known as [[cervical rib]]s. These ribs are usually small, but may occasionally compress blood vessels (such as the [[subclavian artery]]) or nerves in the [[brachial plexus]], causing unpleasant symptoms. ==Movements of the cervical spine== The movements of [[Anatomical terms of motion|flexion]] and [[Anatomical terms of motion|extension]] of the head take place predominantly at the joint between the first cervical vertebra and the occipital bone, the [[atlanto-occipital joint]]. However, the cervical spine is comparatively mobile, and some component of this movement is due to flexion and extension of the vertebral column itself. The movement of rotating the head to left and right happens almost entirely at the joint between the first and second cervical vertebrae, the [[atlanto-axial joint]]. A small amount of rotation of the vertebral column itself contributes to the movement. ==Landmarks== The [[thyroid cartilage]] is from C4 to C5.<ref name="mm">{{MedicalMnemonics|3548|||}}</ref> The [[cricoid cartilage]] is from C6 to C7.<ref name="mm"> </ref> ==Clinical significance== Injuries to the cervical spine are common at the level of the second cervical vertebrae, but neurological injury is uncommon. If it does occur, however, it may cause death or profound disability, including paralysis of the arms, legs, and [[Thoracic diaphragm|diaphragm]], which leads to [[respiratory failure]]. Common patterns of injury include the [[Axis (anatomy)|odontoid]] fracture and the [[hangman's fracture]], both of which are often treated with immobilization in a [[cervical collar]] or [[Halo (medicine)|Halo brace]]. ==Additional images== <gallery> Image:Cervical coloumn.png|Cervical column Image:Gray86.png|First cervical vertebra, or Atlas Image:Gray87.png|Second cervical vertebra, or epistropheus, from above. Image:Gray88.png|Second cervical vertebra, epistropheus, or axis, from the side. Image:Gray89.png|Seventh cervical vertebra. Image:Gray_111_-_Vertebral_column-coloured.png|Vertebral column. Image:Gray305.png|Posterior atlantoöccipital membrane and atlantoaxial ligament. Image:Gray308.png|Median sagittal section through the occipital bone and first three cervical vertebræ. Image:Gray384.png|Section of the neck at about the level of the sixth cervical vertebra. </gallery> ==References== <references/> ==External links== * [http://biology.kenyon.edu/heithausp/cat-tutorial/vertebrae/cervical.htm Diagram] at kenyon.edu * [http://www.spineuniverse.com/displayarticle.php/article1021.html Cervical Spine Anatomy] * [http://www.spineuniverse.com/displayarticle.php/article201.html Degenerative Cervical Spine Disorders] {{Gray's}} {{Spine}} {{Vertebral column and spinal cord}} [[Category:Head and neck]] [[Category:Skeletal system]] [[ar:الفقرات العليا للرقبة]] [[ca:Vèrtebra cervical]] [[de:Halswirbel]] [[es:Vértebra cervical]] [[fr:Vertèbre cervicale]] [[it:Vertebra cervicale]] [[ja:頸椎]] [[lt:Kaklo slankstelis]] [[pl:Kręgi szyjne]] [[pt:Vértebra cervical]] [[sv:Halskota]]