Accessory joints between basiocciput and atlas/axis in the median plane

To explore the many osseous irregularities that are found in the area between the basiocciput, the anterior arch of the atlas and the tip of the dens axis we studied 99 cadaver specimens using magnetic resonance tomography (MRT), computed tomography (CT), median saw-cut sections, and histological sections. Additionally, "dry" specimens of the skull (n = 110), atlas (n = 56), and axis (n = 33) were investigated. In the median plane, the dry and cadaver specimens exhibited osteoarthritis-related osseous outgrowths and osteophytes of the articular surfaces of the median atlanto-axial joint (n = 63), and the presence of congenitally developed free ossicles (n = 22) and of third occipital condyles (n = 3). The largest osteophytes (giant osteophytes) (n = 4) of the anterior arch of the atlas formed osseous contact zones with the basiocciput that were visible histologically as real joints and were designated accessory median atlanto-occipital joints. The third occipital condyles also formed osseous contact zones, visible histologically as real joints, with the anterior arch of the atlas or with the tip of the dens, and were designated accessory atlanto-occipital or occipito-odontoid joints. Frequent free ossicles, incorporated into the accessory joint, were found by histological examination to be covered with hyaline cartilage.     

The measurements of the clivus, the foramina on the external base of the skull and the superior vertebrae

Anatomical measurements are made on the clivus and the upper cervical column. These values are important for transoral, transpalatinal approaches to the clivus and to atlas and axis. The mean-values of the length of clivus in adults were 45 mm on the internal cranial base, on the external the length between the basion and the vomer was estimated with 27.9 mm, the tuberculum pharyngeum is situated on our material 11.2 mm rostral of the basion. The anterior part of clivus in the external cranial base has a width of 22.5 mm, the posterior part has one of 42.8 mm. Included are measurements of the hypoglossal canal and measurements of foramen lacerum externum. The postnasal enlargement of the most portals of the cranial base is given in Fig. 5. The occipital condyles are 22.9 mm in length, the angle between the condyles was 51.4 degrees. The thickness of clivus was 18.3 mm in a level 28 mm rostral of basion and 9.3, 11 mm rostral of basion. Given are also the thickness of substantia corticalis of clivus and the area of posterior wall of sphenoid sinus. Measured are also the distances between dens axis and anterior arch of atlas and basion. The height of anterior arch was found larger than by other researchers. Included are length and width values of the upper cervical column and the insertion areas of the longus capitis and rectus capitis anterior muscles.     

寰椎骨折前路复位内固定钢板置钉参数研究

目的　明确寰椎骨折前路复位内固定钢板寰椎侧块置钉可行性及置钉技术参数。 方法　用Mimics软件,对40例被检查者的CT数据进行三维重建,解剖测量,并模拟置入寰椎侧块螺钉,测量并获得置钉的技术参数。 结果　椎动脉孔内侧壁距离中线23.2 mm。寰椎后弓与寰椎侧块移行处内侧壁距离中线距离13.2 mm。寰椎侧块上位螺钉置钉点距离上关节面前缘6.2 mm,距离寰椎中线20.0 mm。上位螺钉长21.5 mm,于矢状面上成角范围向上1.5°～向下11.6°。寰椎侧块下位螺钉置钉点距离下关节面前缘8.9 mm,长15.2 mm,最大下倾角为20.7°,距离椎动脉孔内侧壁1.9 mm。距中线17.6~23.2 mm的侧块为JeRP钢板侧块螺钉置入的相对安全区域。 结论　寰椎侧块置入上下位螺钉具备可行性。置钉点及钉道方向必须根据患者术前的三维CT数据做最终的决定。上位螺钉置钉角度应宁下勿上,下位螺钉置钉角度应宁内勿外。     

Unusual finding of the craniocervical junction

The authors report a rare anomaly of the upper cervical spine. After an automobile accident, an 8-year-old child underwent CT of the head. Imaging showed a bony anomaly of the neck that was further imaged with thin cuts through the atlas and axis. This demonstrated an unfused anterior arch of the atlas and fusion of the odontoid process to the anterior arch of the atlas. Neurologically, the child is normal with no decreased range of motion about the cervical spine. After a review of the literature, this seems to be only the sixth reported case.     

利用Unigraphics软件三维模拟寻找枢椎侧弓安全钉道的研究

目的:对枢椎标本进行薄层CT扫描,利用Unigraphics NX软件进行计算机虚拟三维实体重建和模拟,寻找安全的侧方椎弓螺钉钉道.方法:对4例干燥标本和8例新鲜枢椎标本进行薄层CT扫描(层厚、层距均为0.6 mm),利用Unigraphics的自由建模功能进行三维重建.根据需要建造出不同直径和形状的螺钉模拟体模拟侧方椎弓螺钉进钉,寻找出安全的进针点和进针方向.结果:薄层CT扫描可见枢椎侧方椎弓横突孔区域的外侧骨皮质很薄,部分标本存在滋养动脉孔,使得横突孔区域侧方椎弓外侧骨皮质先天不完整.以横突后结节为界,侧方椎弓的前部与后部的走行方向不一致,左右侧不相同.横突孔区域上部的走行方向与中下部的走向亦不一致.侧方椎弓的安全钉道方向同侧方椎弓的前部与后部的走行方向均不相同,但主要由横突孔区域的中下部分的外界所限定.对4例干燥标本按照计算机模拟的安全钉道方向进针取得了成功.结论:横突孔区域滋养动脉孔的存在使得传统的判定螺钉钉道是否正确的方法受到挑战.利用UG软件对枢椎标本进行计算机三维重建可模拟出安全的进针点和钉道,并测出螺钉直径和长度,为术中提供参考.     

新型C_2前方重建异形钛网设计的相关解剖学测量研究

目的测量并掌握一种用于C2前方重建的新型异形钛网设计相关的6组解剖学参数。方法取19具尸体的寰椎标本,男性11例,女性8例,直接测量：①寰椎前弓前后直径、②寰椎前弓高度、③寰椎前弓横径;取得37人颈椎正中矢状位层面CT影像,男性22例,女性15例,用软件测量：④C1前弓下缘到C3上终板垂直距离、⑤C3椎体高度、⑥C3椎体前后直径,分析数据,包括男女性数据间的检验以及人口学参数和测量参数之间线性相关性分析。结果 19具尸体标本平均年龄57.58±14.77岁,尸长1635.53±83.12mm,37例CT研究对象平均年龄51.32±10.89岁,身高1685.97±59.54mm,体重70.65±7.01kg;参数①~⑥的测量平均值分别为7.34±1.23、10.92±1.51、15.30±1.07、27.33±1.97、13.23±1.31、16.44±1.09mm。尸体标本测量中男女性的尸长和参数①结果具有统计差异,尸长与参数①~③均呈线性相关性;而在CT测量中男女性在身高和参数④上的差异有统计意义,身高与参数④~⑥呈线性关联,体重仅与参数④具有相关性。结论男女性在寰椎前弓前后径和C1前弓下缘到C3上终板垂直距离参数上具有差异;获得了相关解剖学数据,其测量和分析结果对C2前方重建钛网的设计、修剪、制造及专利申请奠定了理论基础。     

枢椎各结构的解剖学部位研究

目的：明确枢椎各结构的解剖部位。方法：对57例干燥成人标本进行观察与测量，对8例新鲜枢椎标本进行CT薄层扫描，寻找残存的C1-2椎体间连接痕迹。以此为依据，明确枢椎各结构的具体部位。对20例志愿者的枢椎CT三维重建以及MRI图像进行分析，验证前述结论。结果：枢椎前结构的前下方为一三角形的突起部分，皮质较厚，同典型颈椎的椎体相似；两侧的三角形突起与上关节突之间为皮质凹陷区域；CT扫描见枢椎上终板残留位于三角形突起的上厅1．2～1．8mm处，呈圆饼形跨越约1．8～2．4mm同齿突的下终板残留结合在一起。位于椎弓侧方的上下关节突间部分以横突孔后结节为界可分为前后两部分，前者内倾角、上倾角大，后者小。前者外壁菲薄，多数有滋养血管孔存在，而后者内外侧皮质厚度较一致。结论：枢椎的椎体为位于前结构下方的三角形突起部分，椎弓根位于上关节突与椎体之间，椎弓侧方为上下关节突之间的连接部分，被横突孔后结节分为横突孔内界及峡部两个部分，后者为典型Hangman骨折的部位。     

寰椎椎弓和枢椎椎板的应用解剖

目的：为颈后路寰枢椎钛缆固定术和相关器械设计提供解剖学依据。方法：在100例中国成人干燥标本上,观察寰椎后弓和枢椎椎板的形态学特点并进行解剖学测量。结果：(1)寰椎后弓较纤弱,上面与椎管不平行,从后上方向内下方倾斜;(2)枢椎椎板较粗大,上窄下宽,内面基本平行椎管,内面下缘多形成一骨嵴。结论：(1)寰椎后弓和枢椎椎板穿绕钛缆时宜自上向下操作,为方便操作,可以咬除部分枢椎椎板上缘;(2)设计枢椎椎板穿绕钛缆的引导器械时需考虑到其内面的骨嵴。     

Unusual case of occipital vertebra in a medieval skeleton

The craniovertebral junction (CVJ) is a transitional region of the spine that exhibits extensive structural variability. Developmental defects include a vast array of anatomical anomalies that result, from remnants of the proatlas and are grouped under the term ‘occipital vertebra’. The purpose of the present paper is to describe the case of a medieval skeleton, which was found to display a previously unreported manifestation of occipital vertebra. It consisted of two large basilar processes that articulated with the anterior arch of the atlas. In addition, the left process exhibited a supplementary contact zone with the dens of the axis. These structural defects were associated with an accessory canal situated posterior to the right hypoglossal canal.     

The bony tentorium of the cat: Stereotaxic coordinates

The cat's tentorium cerebelli is an osseous structure which overlies much of the brain stem. None of the current brain atlases list the coordinates of this bony projection. With a stiff wire and a stereotaxic apparatus, the location of its free edge and dorsal surface was mapped in 1.0 mm steps in the skulls of 16 cats. In the midline the dorsal surface meets the calvaria at a point 7 mm posterior and 15 mm superior to the atlas zero (intra-aural plane + 10 mm horizontal). From this junction it slopes inferiorly and anteriorly between the cerebrum and cerebellum along a 50° slope to terminate along a curved line. In the midline this free edge is located 0.5 mm anterior, and 6.5 mm superior to the atlas zero. It recedes laterally along a curved line to a point 6 mm lateral, 6 mm superior and 3 mm posterior to the atlas zero. The free edge then curves forward and descends to pass through an imaginary line 3 mm anterior and 4.5 mm inferior to the atlas zero. Statistical comparisons between measurements made in male and female cats revealed no significant differences.     

两种寰椎侧块螺钉固定方法的可行性比较

背景：寰椎侧块螺钉固定技术按其入钉点的不同可分为寰椎后弓下侧块螺钉固定和经寰椎后弓侧块螺钉固定(又称寰椎椎弓根螺钉固定),这2种固定方法各有优缺点,以往缺乏关于2种寰椎侧块螺钉固定方法骨性解剖可行性的比较研究, 目的：以测量国人寰椎相关骨性解剖数据为依据,比较2种寰椎侧块螺钉固定方法的可行性。 方法：收集30例(60侧)成人颈椎病患者的寰椎螺旋CT扫描数据,利用CT工作站对数据重建,分别测量寰椎侧块螺钉固定的关键骨性解剖数据,适合行经寰椎后弓侧块螺钉固定的标准为寰椎椎动脉沟处后弓高度和宽度≥ 4 mm;适合行经寰椎后弓下侧块螺钉固定的标准为寰椎后弓下侧块高度≥ 4 mm。 结果与结论：寰椎椎动脉沟处后弓高度为(4.54±1.17) mm,椎动脉沟处后弓宽度为(8.69±1.12) mm,寰椎后弓下侧块高度为(4.98±1.07) mm。寰椎后弓椎动脉沟高度大于4 mm(适合经寰椎后弓螺钉固定组)有41侧,占68%;寰椎后弓下侧块高度大于4 mm(适合经寰椎后弓下侧块螺钉固定)有52侧,占87%,2组差异有显著性意义(P < 0.05)。提示经寰椎后弓下侧块螺钉固定较经寰椎椎弓根螺钉更具可行性。术前利用CT测量寰椎关键解剖结构数据对制定个性化手术方案具有重要意义。中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程全文链接：     

A contribution by the ascending pharyngeal artery to the arterial supply of the odontoid process of the axis vertebra

The origin of transverse arterial branches that contribute to the arterial supply of the odontoid process (dens axis) is not clear. Dissections were performed on 20 injected fetal and adult human cranio-cervical junctions to demonstrate the origin of the arteries that contribute feeding branches to the arteries supplying the neck of the odontoid process. At its termination near the anterior arch of the atlas, the ascending pharyngeal artery gave off transverse branches that anastomosed with the anterior ascending arteries to the odontoid process. It also gave off a branch that traversed the hypoglossal canal and anastomosed with the posterior ascending artery. A small branch linked the posterior ascending artery to the first transverse branch. This investigation complements previous work on the arterial supply to the odontoid process. Clin. Anat. 10:14–18, 1997 © 1997 Wiley-Liss, Inc.     

Development and growth of the craniocervical junction with special reference to topographical relationship between the occipital basion,the anterior arch of atlas,and the odontoid process of axis: A study using human fetuses

The embryonic occipital bone and odontoid process of the axis are attached and connected by the notochord, but become separated in later development and growth. With special attention to the process of separation, we examined sagittal sections of the craniocervical junction in 18 human fetuses at 8–16 weeks and 22 fetuses at 31–37 weeks. At 8–9 weeks, the anterior arch of atlas was always seen overriding the occipital basal part. The odontoid process was close to the occipital with or without a transient joint cavity until 16 weeks. Near term, the top of the odontoid process was usually higher than the anterior arch, but the former was sometimes (7 of 22) at a level almost equal to or lower than the latter. The apical ligament was evident in a few specimens (5 of 22). A distance between the occipital basion and odontoid process was sometimes less than 1.5 mm (8 of 22) or less than half the thickness of the arch (10 of 22). A transient joint cavity between the basion and odontoid process was often (10 of 22). In three fetuses near term, the atlanto-occipital joint cavity was continuous with the median atlanto-axial joint cavity, and the anterior arch was overriding the occipital basal part. Therefore, rather than stage or age, individual differences were evident in the topographical relationship between the three bony elements at the craniocervical junction. An understanding of the embryology and normal development will aid in the correct interpretation of radiologic images of the pediatric cervical spine.     

枢椎软骨基质融合程度对齿突骨折类型影响的生物力学评估

目的:探讨枢椎软骨基质融合程度对齿突骨折类型的影响。方法:基于正常成人颈椎CT图像建立枢椎精细三维有限元模型。在齿突寰齿关节面上施加前后方向载荷,通过分别降低枢椎松质骨软骨基质融合部位的弹性模量以模拟该部位松质骨不同融合程度,分析枢椎齿突在两种不同约束条件下的应力、应变分布情况,以及枢椎发生骨折的可能类型。结果:两种约束条件下,枢椎有限元计算预测结果发现枢椎软骨基质的融合程度对枢椎高应力集中带分布无明显影响,最大von Mises等效应力值改变亦不明显。结论:枢椎体内软骨基质融合程度对齿突骨折类型无明显影响。     

寰枢椎的解剖学测量及其临床意义

目的 :为寰枢椎区病损机制和手术治疗提供解剖学依据。方法 :在 15 0例中国成年人干燥寰枢椎标本上 ,对具有临床意义的数据进行解剖学测量。结果 :寰椎上关节面内倾角、下关节面外倾角及侧块内倾角两侧不对称分别占 19.3 %、10 .7%和 7.3 % ;椎动脉沟处形成沟环者占 16 .0 % ;所有横突孔的前后径和横径均大于 4mm ;后弓内侧半距仅为外侧半距的 1/2。枢椎椎弓根内倾角变异较大 (-3 .5°～2 1.5°) ;齿突腰部宽度小于 9mm者占 71.2 % ,齿突后倾角的变异较大 (0°～ 2 2°) ;2 7.5 %的椎动脉在经过枢椎侧块下方时会形成一动脉压迹沟 ,致使侧块外端和椎弓根变薄。结论 :①寰枢椎的解剖学形态与其生物力学性质及损伤机制密切相关 ;②手术时寰椎前弓向外显露不宜超过 2 0mm ,后弓切除向外不宜超过 10mm ,经寰枢外侧关节融合或内固定术应选择在关节的内侧 2 /3 ;③大部分中国人不适宜于两枚齿突螺钉内固定术 ;④ 2 7.5 %的中国人不适宜于经椎弓根螺钉固定术 ,枢椎椎弓根变异较大 ,手术前应作CT检测。     

成人寰椎后弓部分结构测量及意义

目的　获得成人寰椎后弓部分解剖参数,为后弓内固定钉板系统的设计提供依据。 方法　对60名成人（男30,女30）寰椎三维CT及40具干燥寰椎标本进行测量,测量指标有后结节中央及距中央5、10、15 mm处高度（矢状面垂直距离）及厚度（轴位垂直距离）、后弓水平面夹角、内侧面椎动脉沟半距、外侧面椎动脉沟半距,比较CT测量数据与标本测量数据有无差异。 结果　CT测量：后结节中央高度为（9.48±0.95）mm,厚度为（7.80±1.60）mm,后弓夹角为（130.70±12.31)°,内侧面椎动脉沟半距为（11.08±1.28）mm,外侧面椎动脉沟半距为（20.13±1.53）mm;标本测量：后结节中央高度为（9.97±2.18）mm,厚度为（7.44±1.32）mm,后弓夹角为（135.07±9.59）°,内侧面椎动脉沟半距为（11.33±0.52）mm,外侧面椎动脉沟半距为（20.86±0.84）mm。CT测得内、外侧面椎动脉沟半距均小于标本测得数据,且差异有统计学意义。 结论　CT资料可较好反映实体的解剖特征,解剖学测量可为临床实践提供有力参考。     

3D morphometry of the transverse and alar ligaments in the occipito-atlanto-axial complex: an in vitro analysis

This study verifies the three-dimensional anatomical features of the transverse and alar ligaments with reference to the axis using a direct in vitro approach. In 20 fresh spine specimens, metal markers were inserted on the cranium, atlas, and axis. After registration of the intact specimen, the bony segments were separated, and markers and anatomical landmarks were digitized. The length and the orientation of the ligaments with reference to the axis were derived from the relative position data. The transverse ligaments of the atlas have a mean estimated length of 21 mm and an absolute angle (i.e., independent of any reference frame) of 119 degrees +/- 17 degrees . The alar ligaments have a mean length of 9 +/- 2.5 mm, and the mean absolute angle between the ligaments is 117 degrees +/- 31 degrees . The plane of the alar ligaments shows a mean backward inclination of -10 degrees +/- 52 degrees . This plane has a mean inclination of 6 degrees +/- 4 degrees with reference to the sagittal plane indicating left-right symmetries. The transverse ligament arches around the dens and demonstrating its function as a stabilizer for the dens as well as guidance for axial rotation movements. A posterior inclination of the alar ligaments may induce a coupled extension in combination with a lateral bending during axial rotation. These detailed aspects of motion steering may be important to consider when attempting to reduce or restore movement.     

计算机3D建模在个体化寰枢椎椎弓根钉最佳进钉方式的研究

目的 利用3D建模技术设计寰、枢椎椎弓根钉手术模拟系统, 为迅速模拟置钉安全区、置钉方案及统一术前设计操作标准。 方法 从本院PACS系统14例健康成人（男7例,女7例;年龄30～68岁,平均45岁）的寰枢椎CT连续断层扫描数据导入Mimics 10.01软件,三维重建后利用.dwg文件导入3dmax2009。确定三维参照坐标和原点,导入标尺确定进钉点,导入原创设计阵列模型,寰椎以3.5 mm直径,长度为22 mm螺钉,枢椎以3.5 mm直径,长度为24 mm螺钉为研究对象,模拟安全区置钉区间内最佳置钉方案,记录最佳置钉数据,最后输入最佳置钉数据指导计算机模拟置钉,并在透视图中观察置钉效果。 结果 185个元素符合寰椎进钉要求,枢椎395个元素符合进钉要求。通过透视图检查,其中寰椎27枚,枢椎25枚共53枚最佳角度模拟螺钉均准确位于椎弓根内。对双侧椎体左、右侧直径3.5 mm椎弓根螺钉最远距离进行比较,差异不具有显著差异（P>0.05）。 结论 利用数字3D建模技术能建立标准、简化、精确地术前设计。     

寰椎的测量及临床应用意义

目的测量国人寰椎骨,为寰椎螺钉设计和内固定提供解剖学依据。方法用游标卡尺和量角器测量55例干燥的成人寰椎标本的相关参数,包括寰椎侧块的长度、侧块中间宽度、侧块中间厚度、侧块外侧缘中点高度、侧块内侧缘中点高度、寰椎侧块的内倾角、寰椎侧块的上倾角、侧块后下缘的宽度和高度、寰椎前弓与侧块交接处高度和厚度;横突孔的前后径和左右径;椎动脉沟宽度和高度;椎动脉沟底骨质最薄处宽度和高度等等,并进行统计学分析。结果寰椎侧块长（23．29±1．47）mm,侧块中间宽（11．13±1．17）mm,侧块中间厚（13．33±1．40）mm,侧块外侧缘中点高（19．18±1．61）mm,侧块内侧缘中点高（10．45士1．46）mm;寰椎侧块的内倾角（19．95±3．32）。寰椎侧块的上倾角（24．53±2．31）。;侧块后下缘宽（9．64±0．94）mm,侧块后下缘高（4．275=0．63）mm;前弓与侧块交接处高（11．05±1．12）mm,前弓与侧块交接处厚（4．82±0．65）mm;横突孔的前后径（7．30±0．89）mm,横突孔的左右径（5．90±0．78）mm椎动脉沟宽（8．40±0．58）mm,椎动脉沟高（6．38±0．79）mm椎动脉沟底骨质最薄处宽（7．25±1．27）mm,椎动脉沟底骨质最薄处高（4．16±0．83）mm。以上数据左、右侧比较差异无显著性（P〉0．05）。结论测得55例寰椎骨数据,寰椎侧块和寰椎椎弓根具备实行内固定的条件。     

寰椎骨折的生物力学分析

目的采用有限元方法,预测寰椎在不同位置条件下寰椎应力的分布,并以此推断可能出现的寰椎骨折类型。方法构建寰椎三维骨性结构,分析寰椎在中立、屈曲、后伸三种位置下应力分布状况。结果寰椎高应力在中立位时,出现在寰椎前部和双侧椎弓根;屈曲位时,分布在寰椎前部;后伸位时,存在寰椎前弓和双侧椎弓根。结论寰椎前弓和前结节交界处、前弓和侧块交界处、后弓和侧块交界处、后弓和后结节交界处是应力较为集中的部位,也是寰椎骨折容易发生的部位。骨折部位和骨折类型与寰椎损伤时所处的位置、寰椎几何形状、外力的方向以及寰椎的力学特征密切相关。