The third occipital condyle,a constituent part of a median occipito-atlanto-odontoid joint: a case report

A compound conjunction between basiocciput, atlas (anterior arch), and dens of axis (odontoid process) was found incidentally during routine dissection of the head of an 83-year-old man. According to the patient's history, no neck disability had been recorded. A median saw-cut of the head-and-neck conjunction revealed that the basion was anteriorly reinforced by an osseous pillar 4 mm in length and 3 mm in width. Such a formation is known as a third occipital condyle (condylus tertius, CT). In our case it exhibited one surface oriented in an anterior-inferior direction and articulating with the superior border of the anterior arch of the atlas, and another surface oriented in a posterior-inferior direction and articulating with the superior portion of the dens of axis. The dens of axis itself articulated with the anterior arch of the atlas, forming the (normal) median atlanto-axial joint. Post-mortem computed tomography and post-mortem histological examination completed the investigation. The cartilage of the articular compartment between the CT and the anterior arch of the atlas and the related anterior fibrous disc exhibited severe arthrosis. The findings were discussed in the light of developmental and comparative anatomy.     

Aortic arch origin of the left vertebral artery

Complications from anterior approaches to the cervical spine are uncommon with normal anatomy. However, variant anatomy might predispose one to an increased incidence of injury during such procedures. We hypothesized that left vertebral arteries that arise from the aortic arch instead of the subclavian artery might take a more medial path in their ascent making them more susceptible to iatrogenic injury. Fifty human adult cadavers were examined for left vertebral arteries having an aortic arch origin and these were dissected along their entire cervical course. Additionally, two radiological databases of CTA and arteriography procedures were retrospectively examined for cases of aberrant left vertebral artery origin from the aortic arch over a two‐year period. Two cadaveric specimens (4%) were found to have a left vertebral artery arising from the aortic arch. The retrospective radiological database analysis identified 13 cases (0.87%) of left vertebral artery origin from the aortic arch. Of all cases, vertebral arteries that arose from the aortic arch were much more likely to not only have a more medial course (especially their preforaminal segment) over the cervical vertebral bodies but also to enter a transverse foramen that was more cranially located than the normal C6 entrance of the vertebral artery. Spine surgeons who approach the anterior cervical spine should be aware that an aortic origin of the left vertebral artery is likely to be closer to the midline and less protected above the C6 vertebral level. Clin. Anat. 30:811–816, 2017. © 2017Wiley Periodicals, Inc.     

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。     

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.     

The Okihiro syndrome of Duane anomaly, radial ray abnormalities, and deafness

We report on a child with Duane anomaly, deafness, cervical spine, and radial ray abnormalities. A sister of the proposita had hemifacial microsomia, cervical abnormalities, and hypoplasia of the thenar eminence. Four relatives had hypoplasia of the thenar eminence. A fifth had preaxial polydactyly. Duane anomaly was present in two sixth-degree relatives. This appears to be an autosomal dominant trait. Singly or in combination the abnormalities seen in this family have all been described in association with Duane anomaly. Their occurrence in the same family suggests that they are not independent entities but represent pleiotropic effects of the same gene.     

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.     

Krapina atlases suggest a high prevalence of anatomical variations in the first cervical vertebra of Neanderthals

The first cervical vertebra, atlas, and its anatomical variants have been widely studied in Homo sapiens. However, in Neanderthals, the presence of anatomical variants of the atlas has been very little studied until very recently. Only the Neanderthal group from the El Sidrón site (Spain) has been analysed with regard to the anatomical variants of the atlas. A high prevalence of anatomical variants has been described in this sample, which points to low genetic diversity in this Neanderthal group. Even so, the high prevalence of anatomical variations detected in El Sidrón Neanderthal atlases needs to be confirmed by analysing more Neanderthal remains. In this context, we analysed the possible presence of anatomical variants in the three Neanderthal atlases recovered from the Krapina site (Croatia) within the Neanderthal lineage. Two of the three Krapina atlases presented anatomical variations. One atlas (Krapina 98) had an unclosed transverse foramen and the other (Krapina 99) presented a non-fused anterior atlas arch. Moreover, an extended review of the bibliography also showed these anatomical variations in other Middle and Upper Pleistocene hominins, leading us to hypothesise that anatomical variations of the atlas had a higher prevalence in extinct hominins than in modern humans.     

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：     

人体颈椎椎弓的营养孔和营养动脉

1.观察了351个成人颈椎干骨(C_237、C_(3～5)196、C_639、C_779)椎弓营养孔的数目、大小、方向和位置。椎弓外面的营养孔以单孔多见,占64.96％,平均口径为0.34mm。指向椎弓根,多位于距峡部中线后方3～6mm范围的椎板中部。椎弓内面的营养孔为单孔者占47.01％,平均口径为0.26mm。指向后,集中于距椎弓根与椎板连线0～3mm范围的椎板中部。 2.用解剖、透明法,观察了20具不同年龄新鲜尸体颈椎椎弓的营养动脉。椎弓外面营养动脉发自颈深动脉;内面营养动脉发自椎动脉脊后支的升支和脊中间支的后根支。在每一椎弓的左、右侧半内,以1支营养动脉多见。它分成短而较细的前支和长而粗的后支。前支发出分支供应上、下关节突、横突和椎弓根;后支发支供应椎板和棘突。营养动脉在骨内的形态、走行和分布与骨化过程关系密切。 3.骨膜动脉从椎弓外面进入,在儿童和成人的椎管面,未见到此种小支的存在。     

Anomalous subaortic left brachiocephalic vein in surgical cases and literature review

Anomalous subaortic left brachiocephalic vein (ASLBV) is a rare systemic venous anomaly. We review our experience with patients associated with ASLBV who underwent cardiac surgery at three institutions. From 1989 to 2009, the medical records of surgically treated patients with ASLBV were analyzed; the incidence of ASLBV, clinical characteristics, and associated anatomical findings were assessed. Fifteen patients had ASLBV. All ASLBVs coursed left lateral to the aortic arch, passed under the ascending aorta anterior to the central pulmonary artery, and joined the right brachiocephalic vein. Fourteen patients had congenital heart disease (CHD), and the remaining patient did not have cardiac anomalies. Its incidence was 0.57% (14 of 2,449) in patients with CHD and only 0.02% (1 of 4,805) in patients without CHD. In patients with CHD, 73.3% (11 of 15) of the patients had conotruncal cardiac anomalies such as tetralogy of Fallot, ventricular septal defect with pulmonary atresia, truncus arteriosus, and interruption of the aortic arch. Eight patients had aortic arch anomalies, including right aortic arch and cervical aortic arch. The deletion of chromosomal 22q11.2 was confirmed in two patients, and one patient was diagnosed with DiGeorge syndrome. ASLBV was clinically silent even without any surgical intervention. ASLBV is a very rare anomaly and is highly associated with conotruncal cardiac anomalies and aortic arch anomalies, including right aortic arch and cervical aortic arch. Preoperative diagnosis is important when any surgical interventions are intended, especially, in patients with conotruncal cardiac anomalies. Clin. Anat. 23:950–955, 2010. © 2010 Wiley‐Liss, Inc.     

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.     

寰枢关节错位与胸锁乳突肌和斜方肌疼痛的解剖关系的初步研究

目的　观察寰枢椎与副神经及第2颈神经的解剖关系,以及观察胸锁乳突肌和斜方肌的神经支配特点,为寰枢关节错位致胸锁乳突肌和斜方肌疼痛提供解剖学依据。 方法　对3具共6侧成年人颈部尸体标本进行解剖,观察寰椎横突与副神经、寰枢外侧关节与第2颈神经前支、寰枢椎椎间孔外韧带的解剖结构,以及观察胸锁乳突肌和斜方肌的神经支配特点,测量副神经与寰椎横突尖的最短距离。 结果 (1)胸锁乳突肌和斜方肌均受副神经和颈丛（第2~4）神经支配,并且副神经与颈丛神经存在交通支联系。(2)副神经走行在寰椎横突前方,二者关系密切,副神经与寰椎横突尖的距离为4.84~7.60 mm(左侧)和3.22~6.80 mm（右侧）。(3)寰枢椎存在椎间孔外韧带,该韧带与第2神经相连,并附着在寰椎横突。(4)第2颈神经前支贴着寰枢外侧小关节向前走行。 结论 寰枢关节错位可能会刺激副神经及第2颈神经或其前支,从而引起胸锁乳突和斜方肌紧张、疼痛。     

颈部三维CT血管成像在寰椎后路固定术中的应用

背景：寰枢椎后路内固定融合是治疗上颈椎病变的常用手术方式,此处解剖结构复杂多变,损伤椎动脉的案例时有报道。 目的：观察正常人上颈椎三维CT血管图像,研究寰椎后弓的解剖结构及伴行椎动脉的走形特点,为寰椎后路置钉提供解剖学依据。 方法：纳入椎动脉显影良好且寰枢椎无明显病变者400例,利用原始资料进行容积重建,同时配合分离、融合、透明和伪彩等图像处理技术,在三维图像上观察椎动脉寰枕段的走行及变异,测量寰椎与后路置钉相关的解剖数据。 结果与结论：400例头颈部三维CT血管图像清晰,满足要求。椎动脉寰枕段的行程弯曲,走形典型者385例,变异15例,共18侧。固定第一阶段动脉11侧,窗式椎动脉6侧,异常起源的小脑后下动脉1侧;椎动脉沟环48例,其中10例为双侧,共58侧。椎动脉沟底的后弓是钉道最薄弱部分,左右侧比较差异无显著性意义(P > 0.05)。说明寰椎后弓及其伴行椎动脉常存在变异,给寰椎后路置钉带来不确定因素,三维CT血管图像可以清楚地显示两者的解剖结构,置入前充分了解这些数据,可以制定准确的手术方案,提高手术的安全性。      

Median (third) occipital condyle

Abnormalities of the craniovertebral junction, most of which are associated with the occipital bone, are of interest not only to anatomists but also to clinicians because many of these deformities produce clinical symptoms. The occipital bone in humans is formed by the fusion of the sclerotomes corresponding to the roots of the hypoglossal nerve. In lower vertebrates, the cranial half of the first cervical sclerotome forms a separate bone between the atlas and occipital bone, the proatlas; in man it may contribute to anomalous structures around the foramen magnum. One such structure, a median occipital condyle, which exhibited an articular facet for the odontoid process, was observed in an adult male skull at the anterior margin of the foramen magnum. This anomaly is discussed in light of available literature.     

介绍一种颈椎前路手术定位器

目的介绍一种新的颈椎前路前路手术定位器。方法定位器用6.5㎜松质骨空心镙钉和1.5㎜克氏针两部分组织成,克氏针插入空心镙钉后将尖部打入椎体进行定位。结果没有发生定位失败和与定位器有关的并发症。结论这种定位方法使用相对简单、安全,适用于颈椎前路手术定位。     

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。     

“工”型纯钛自锁颈椎钢板的生物力学研究

目的　探讨“工”型纯钛自锁颈椎钢板的生物力学特性 ,为手术方法的选择、改进提供可靠的依据 ,减少术后颈椎不稳的发生率 ,提高手术疗效。方法　采用 7具新鲜人颈椎标本 [C1 ～T1 ],制作成前路植骨融合术加“工”型纯钛自锁颈椎钢板固定的标本 ,从生物力学角度对颈椎不稳三种情况下 (前屈、后伸、侧弯 )进行了 7具新鲜尸体标本实验研究 ,采用前路手术减压、椎间盘切除术 ,颈椎造成创伤后采用植骨融合加钢板固定 ;用生物力学实验手段比较创伤前后颈椎强度、侧度的变化以及颈椎的稳定性 ,加以定量研究和评价 ,对颈椎稳定性影响进行生物力学研究。结果　颈椎创伤与固定前后其应力相差1 8% ,应变平均增加 1 5 % ,两者呈显著性差异 (P <0 0 1 )。颈椎植骨加“工”型纯钛自锁颈椎钢板固定后 ,颈椎总体稳定性增加 ,移位减小 ,轴向刚度、弯曲刚度和扭转刚度增加 4 0 %以上 (P <0 0 1 )。结论　“工”型纯钛自锁颈椎钢板设计、选材科学性和先进性 ,很值得临床应用和推广。     

颈椎椎体次全切除，钛网植骨钢板固定三维有限元模型的建立

目的 探讨利用螺旋 CT建立颈椎椎体次全切除减压植骨固定的三维有限元模型的高度数字化方法,为研究颈椎减压手术的生物力学实验提供标准模型。方法 对健康成年男性志愿者进行CT 扫描,获得C4～C7节段的断层图片,将数据保存为Dicom格式,导入Mimics 9.1 软件进行三维几何模型重建,形成三维图像,利用Freeform 软件进行模型修改和表面划分,以IGES格式转入有限元软件Ansys 9.0完成颈椎骨性模型的建立。利用有限元软件Ansys 9.0,在颈椎骨性模型的基础上,补建终板、补充建立终板、 椎间盘、 髓核、 前纵韧带、 后纵韧带、 黄韧带、 棘间韧带、 棘上韧带等结构。然后模拟颈椎椎体次全切除,将C5椎体、前纵韧带、上下椎间盘切除,将建立的钛网、钢板实体模型添加到减压区。采用合适的材料性质和实体单元类型对模型进行有限元网格划分。结果 颈椎脊柱三维模型有限元网格划分结果：利用三维重建软件Mimics 和有限元软件Ansys 9.0 , 成功进行椎体次全切除减压钛网植骨钢板固定三维模型有限元网格划分。整个模型共有138995个节点和94039个单元,建成后的三维有限元模型与实体组织具有良好的几何相似性。结论 建立的椎体次全切除植骨固定手术三维有限元模型接近真实的生物力学标本,可以进行临床和实验研究。