出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/07/09 14:08:01」(JST)
Cervical vertebrae | |
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Position of human cervical vertebrae (shown in red). It consists of 7 bones, from top to bottom, C1, C2, C3, C4, C5, C6 and C7.
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A human cervical vertebra
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Details | |
Latin | Vertebrae cervicales |
Identifiers | |
Gray's | p.97 |
MeSH | A02.835.232.834.151 |
Dorlands /Elsevier |
v_07/12854511 |
TA | A02.2.02.001 |
FMA | 72063 |
Anatomical terms of bone |
In vertebrates, cervical vertebrae (singular: vertebra) are those vertebrae immediately below the skull.
Thoracic vertebrae in all mammalian species are defined as those vertebrae that also carry a pair of ribs, and lie caudal to the cervical vertebrae. Further caudally follow the lumbar vertebrae, which also belong to the trunk, but do not carry ribs. In reptiles, all trunk vertebrae carry ribs and are called dorsal vertebrae.
In many species, though not in mammals, the cervical vertebrae bear ribs. In many other 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 humans, cervical vertebrae are the smallest of the true vertebrae, and can be readily distinguished from those of the thoracic or 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.
By convention, the cervical vertebrae are numbered, with the first one (C1) located closest to the skull and higher numbered vertebrae (C2-C7) proceeding away from the skull and down the spine.
The general characteristics of the third through sixth cervical vertebrae are described here. The first, second, and seventh vertebrae are extraordinary, and are detailed later.
The anterior tubercle of the sixth cervical vertebra is known as the carotid tubercle or Chassaignac tubercle. This separates the carotid artery from the vertebral artery and the carotid artery can be massaged against this tubercle to relieve the symptoms of supraventricular tachycardia. The carotid tubercle is also used as a landmark for anaesthesia of the brachial plexus and cervical plexus.
The cervical spinal nerves emerge from above the cervical vertebrae. For example, the cervical spinal nerve 3 (C3) passes above C3.
The atlas (C1) and axis (C2) are the two topmost vertebrae.
The atlas, C1, is the topmost vertebra, and along with the axis; forms the joint connecting the skull and 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 axis.
The axis, C2, forms the pivot upon which the atlas rotates. The most distinctive characteristic of this bone is the strong odontoid process (dens) that 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.
The vertebra prominens, or C7, has a distinctive long and prominent spinous process, which is palpable from the skin surface. Sometimes, the seventh cervical vertebra is associated with an abnormal extra rib, known as a cervical rib, which develops from the anterior root of the transverse process. These ribs are usually small, but may occasionally compress blood vessels (such as the subclavian artery or subclavian vein) or nerves in the brachial plexus, causing pain, numbness, tingling, and weakness in the upper limb, a condition known as thoracic outlet syndrome. Very rarely this rib will occur in a pair.
The long spinous process of C7 is thick and nearly horizontal in direction. It is not bifurcated and ends in a tubercle which the ligamentum nuchae is attached to. This process is not always the most prominent of the spinous processes being found only about 70% of the time, C6 or T1 can sometimes be the most prominent.
The transverse processes are of considerable size, their posterior roots are large and prominent, while the anterior are small and faintly marked; the upper surface of each has usually a shallow sulcus for the eighth spinal nerve, and its extremity seldom presents more than a trace of bifurcation.
The transverse foramen may be as large as that in the other cervical vertebrae, but is generally smaller on one or both sides; occasionally it is double, sometimes it is absent.
On the left side it occasionally gives passage to the vertebral artery; more frequently the vertebral vein traverses it on both sides; but the usual arrangement is for both artery and vein to pass in front of the transverse process, and not through the foramen.
The movement of nodding the head takes place predominantly through flexion and extension at the atlanto-occipital joint between the atlas and the occipital bone. 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 shaking or rotating the head left and right happens almost entirely at the joint between the atlas and the axis, the atlanto-axial joint. A small amount of rotation of the vertebral column itself contributes to the movement.
Injuries to the cervical spine are common at the level of the second cervical vertebrae, but neurological injury is uncommon. C4 and C5 are the areas that see the highest amount of cervical spine trauma.[1]
If it does occur, however, it may cause death or profound disability, including paralysis of the arms, legs, and diaphragm, which leads to respiratory failure.
Common patterns of injury include the odontoid fracture and the hangman's fracture, both of which are often treated with immobilization in a cervical collar or Halo brace.
A common practice is to immobilize a patient's cervical spine to prevent further damage during transport to hospital. This practice has come under review recently as incidence rates of unstable spinal trauma can be as low as 2% in immobilized patients. Canadian studies have developed the Canadian C-Spine Rule (CCR) for physicians to decide who should receive radiological imaging.[2]
The vertebral column is often used as a marker of human anatomy. This includes:
Position of cervical vertebrae (shown in red). Animation.
Illustration of cervical vertebrae.
Shape of cervical vertebrae (shown in blue and yellow). Animation.
Cervical vertebrae, lateral view (shown in blue and yellow).
Vertebral column
Vertebral column.
X-Ray of cervical vertebrae.
X-ray of cervical spine in flexion and extension.
First cervical vertebra, or Atlas
Second cervical vertebra, or epistropheus, from above.
Second cervical vertebra, epistropheus, or axis, from the side.
Seventh cervical vertebra.
Posterior atlanto-occipital membrane and atlantoaxial ligament.
Median sagittal section through the occipital bone and first three cervical vertebræ.
Section of the neck at about the level of the sixth cervical vertebra.
This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)
Wikimedia Commons has media related to Cervical vertebrae. |
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概念 | 疫学 | 自覚症状 | 他覚症状 | ||||
頚椎症状 | 神経根症状 | 脊髄症 | 神経根症 | 脊髄症 | |||
頚椎椎間板ヘルニア | 椎間板の退行変性に基づく線維輪断裂部からの椎間板組織の脱出。後方正中ヘルニア→脊髄症。後側方のヘルニア→神経根圧迫 | 30-50歳代。男性。中下位頚椎 | 喉頭・頚部から肩甲背部の疼痛、しびれと頚椎運動制限を呈する。通常頚椎の運動時に増悪し、安静にて軽快する。 | 一側の肩甲背部の疼痛、上肢へ放散する疼痛、しびれと感覚障害、脱力、筋萎縮、筋の線維性攣縮などを呈する | 感覚以上は手指、手掌全体に及ぶしびれ感が主体で、体幹、下肢に広がる。運動系では、手指巧緻運動障害を訴える。下肢痙攣麻痺(ぎこちない歩行、階段下降時に手すりが必要、走れない)。進行すると膀胱直腸障害を自覚 | 神経障害部位に一致した上肢の筋力低下、および筋萎縮、感覚障害、腱反射減弱。Spurlingテスト陽性が多い。 | 上肢に障害髄説に一致した腱反射低下、筋力低下。それ以下は錐体路障害による腱反射亢進(Hoffmann反射、Rossolimo徴候、Mendel-Bekhterev反射、膝・足クローヌス陽性)。手指巧緻運動障害。感覚障害は初期に上肢、故知に体幹・下肢に拡大。腹壁反射、睾丸挙筋反射消失。Babinski反射陽性。排尿障害は軽微 |
変形性頚椎症 | 椎間板の退行変性により、椎間板腔の狭小化、椎体近縁の骨硬化・骨棘形成、椎間関節の狭小化などを生じる。これにより、可動域制限、疼痛、こり感などの局所症状を呈した状態 | 中下位頚椎。高齢者ではC3-4椎間。 | 椎間板および椎間関節の変形などによる頚肩部の疼痛、運動制限 | ||||
頚椎症性神経根症 | 変形性頚椎症に加え、神経根症を呈した状態 | 圧迫に伴う神経根刺激症状として、上肢のしびれ、放散痛、感覚異常(後根)がある。 | Jacksonテスト、Spurlingテスト陽性。神経脱落症状としては、感覚鈍麻、脱失および上肢の脱力、筋萎縮筋の線維束攣縮が見られる。 | ||||
頚椎症性脊髄症 | 頚椎症性神経根症に加え、脊髄症を合併した状態。 | 上肢における巧緻運動障害、myelopathy hand、下肢腱反射亢進、病的反射の亢進、痙性歩行障害などの痙性麻痺および神経因性膀胱などが見られる。 | |||||
頚椎後縦靭帯骨化症 | 椎体および椎間板の後面にあり脊柱管の前壁をなす後縦靭帯が肥硬・骨化し、脊髄を緩徐に圧迫して脊髄症状を引き起こす疾患。 | 後縦靭帯骨化:男性4%、女性2%。 | 頚椎可動性の減少、肩こり、頚部痛が見られる。重要な障害は圧迫による脊髄症の麻痺症状である。一般に脊髄症は緩徐に進行する。外傷を契機に急激に悪化する場合もある。受診時に、多くの患者は種子のしびれや巧緻運動障害、下肢の痙性麻痺による歩行障害を呈する。 |
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