Lower axial skeleton of the musk shrew (Suncus murinus)

Macroscopic structure as well as pre- and postnatal development of the lumbar, sacral, and caudal vertebrae of the musk shrew (Suncus murinus, Insectivora) were observed. The lumbar vertebrae possess two pairs of unusual processes, hyperapophyses and hypapophyses. The hyperapophyses are located on the dorsal surface of the caudal articular processes of all the lumbar vertebrae, whereas the hypapophyses are found on the caudal part of the ventral surface of the bodies in the first few lumbar vertebrae. The former gives attachment to the Mm. rotatores lumborum and the latter to the Mm. psoas major and minor. The articular processes of the lumbar vertebrae are oriented more horizontally compared with those in other mammals. The sacrum is very narrow transversely due to poor development of the ventrolateral wing. The auricular surface includes cranial parts of the wing and of the fused vertebral arches as well as the cranial articular process of the first sacral vertebra. In the caudal vertebrae, chevron bones are H-shaped when viewed ventrally, and give attachment to tendons of the caudal muscles. This report describes the relationships between the structural peculiarities of the lower axial skeleton and the locomotive habits of the musk shrew.     

C7 vertebra homeotic transformation in domestic dogs – are Pug dogs breaking mammalian evolutionary constraints?

The number of cervical vertebrae in mammals is almost constant at seven, regardless of their neck length, implying that there is selection against variation in this number. Homebox (Hox) genes are involved in this evolutionary mammalian conservation, and homeotic transformation of cervical into thoracic vertebrae (cervical ribs) is a common phenotypic abnormality when Hox gene expression is altered. This relatively benign phenotypic change can be associated with fatal traits in humans. Mutations in genes upstream of Hox, inbreeding and stressors during organogenesis can also cause cervical ribs. The aim of this study was to describe the prevalence of cervical ribs in a large group of domestic dogs of different breeds, and explore a possible relation with other congenital vertebral malformations (CVMs) in the breed with the highest prevalence of cervical ribs. By phenotyping we hoped to give clues as to the underlying genetic causes. Twenty computed tomography studies from at least two breeds belonging to each of the nine groups recognized by the Federation Cynologique Internationale, including all the brachycephalic ‘screw‐tailed’ breeds that are known to be overrepresented for CVMs, were reviewed. The Pug dog was more affected by cervical ribs than any other breed (46%; P < 0.001), and was selected for further analysis. No association was found between the presence of cervical ribs and vertebral body formation defect, bifid spinous process, caudal articular process hypoplasia/aplasia and an abnormal sacrum, which may infer they have a different aetiopathogenesis. However, Pug dogs with cervical ribs were more likely to have a transitional thoraco‐lumbar vertebra (P = 0.041) and a pre‐sacral vertebral count of 26 (P < 0.001). Higher C7/T1 dorsal spinous processes ratios were associated with the presence of cervical ribs (P < 0.001), supporting this is a true homeotic transformation. Relaxation of the stabilizing selection has likely occurred, and the Pug dog appears to be a good naturally occurring model to further investigate the aetiology of cervical ribs, other congenital vertebral anomalies and numerical alterations.     

An unusual foramen in the transverse process of first thoracic vertebra

The presence of foramina in the transverse processes of thoracic vertebrae is not a common feature while they are the characteristic feature of cervical vertebrae. Foramina present in the transverse process of cervical vertebrae give passage to the vertebral artery—an important artery supplying the brain and spinal cord. Thoracic vertebrae typically bear facets on the body and the transverse processes for articulation with ribs. We report the presence of a complete foramen in the left transverse process of first thoracic vertebra, which is a very rare finding. The foramen was present near the root of the transverse process in alignment with the foramina transversaria of the cervical vertebrae of the same side. This variation is explained embryologically in relation to the branches of dorsal aortae in post-branchial stage of development. Knowledge of such a variation may be of great relevance for accurate interpretation of radiological pictures and for CT and MR angiographies as well as for the management of surgical procedures.     

A quantitative study on the sacrum of the dog.

The aim of this study was to record sacral bone morphometry that may help in selection of the implant type and proper size in sacroiliac separation. For this reason, sacral lengths and width, the length of each sacral vertebrae, distances between cranial and caudal articular processes, vertical and transversal diameters of the cranial endplate, sacral tuberositas and articular surface areas were obtained from 11 dogs. Additionally, the transverse and vertical diameters of the bony structure and sacral canal were measured from six cross-sections. The data of the study were determined to be representative of the sacral values for average-sized dogs, which was confirmed statistically. The highest value was the sacral width among the linear measurements. The ventral sacral length was longer than the dorsal sacral length. The total lateral area of the sacral wing was measured as 677.46 (142.1)mm2. The transverse diameters of the first sacral vertebra important for screw implantation were 46.02 (4.33)mm and 44.18 (5.29)mm in the first and second cross-sections, respectively.     

猫骶髓“内脏面”传出神经元和二级传入神经元的分布

应用HRP和荧光金标记技术,在荧光显微镜下观察了猫骶體“內脏面”的传出神经元和二级传入神经元的分布?咀偌磷⑷肱枭窬?标记的骶髓副交感节前神经元主要分布于同侧中间带外侧核,由它组成的骶髓副交感核在以S2为中心的两个骶髓节段内(有时为三个),形成长约6-10mm的细胞柱。在横切面上,核的中段以上分为位于Ⅶ层外侧缘的外侧带和位于Ⅴ层的背侧带,但在核的尾侧段则二者融合为一。中介核和中间带内侧核也存在少量逆标神经元。示踪剂注于臂旁外侧核或Barrington核(一侧或双侧)后,逆标的盆内脏二级传入神经元主要存在于骶髓中间带外侧核和骶髓后连合核,在中间带外侧核位于两团传出神经元之间的中间带,但在核的尾侧段则位于骶髓副交感核的背外侧部,个别细胞混杂于副交感节前神经元之间,中介核和中间带內侧核也有少量二级传入神经元分布?送?相当数量的盆内脏二级传入神经元位于后角Ⅰ层。本文结果证明猫骶髓中间带外侧核至少由两种不同性质的神经元即骶髓副交感节前神经元和盆内脏二级传入神经元组成,两者在中间带外侧核区有明确的定位分布,因此,可将骶髓中间带外侧核划分为传出亚核和传入亚核,传统上笼统地将骶髓副交感核等同于中间带外侧核是不恰当的。     

Further observations on the cutaneous branches of the dorsal primary rami of the spinal nerves

Recent investigators suggest that dermatomes extend as consecutive bands from the dorsal median line and question the existence of dorsal axial lines. Our observations were made on serial sections of human embryos and fetuses prepared with neurofibrillar stains. Cervical nerves 1, 6, 7 and 8 failed to have cutaneous branches in most cases, the remainder usually had cutaneous branches. With a few exceptions in T 1, all thoracic dorsal rami had cutaneous branches. Usually T 1, 2 and 3 became cutaneous through medial branches, while T 9 through 12 did so through lateral branches. However T 4 through 8 constitute a transition zone where many of these nerves became cutaneous through both medial and lateral branches. Thoracic 4, 5 and 6 tended to have cutaneous distribution through medial branches, but T 7 and 8 through lateral branches. All lumbar dorsal rami having cutaneous distribution did so through lateral branches, but independent branches became progressively less frequent below L 1. Lumbar 4 lacked direct cutaneous branches in most cases and succeeding nerves in all cases. These nerves form the dorsal sacral plexus. The deficit in cutaneous distribution of lower lumbar rami was not as pronounced as in the lower cervical region. A deficit is significant in relation to dorsal axial lines.     

New dysostosis showing multilevel absence of vertebral pedicles: unique developmental anomaly of vertebral arches?

We report on an apparently normal child who shows hypopaplasia of the vertebral pedicles and posterior arches of several cervical, thoracic, and lumbar vertebrae with normally fused spinous apophyses, hypoplastic sacrum, lumbar epidural lipomatosis, synostoses of some cervical vertebral disks, and sacral spina bifida. The most likely mechanism is an abnormal differentiation of the spinal processes, due most probably to an absence of differentiation in cartilage of the dense mesenchyme forming their most anterior part. Because the anomalies affect multiple levels, we highly suspect a genetic basis to this unusual dysostosis affecting the development of the posterior sclerotomes.     

Development of the epaxial muscles in the human embryo

Although the intrinsic muscles of the back are defined by their embryological origin and innervation pattern, no detailed study on their development is available. Human embryos (5–10 weeks development) were studied, using Amira3D® reconstruction and Cinema4D® remodeling software for visualization. At Carnegie Stage (CS)15, the epaxial portions of the myotomes became identifiable laterally to the developing vertebrae. At CS16, these portions fused starting cranially to form a longitudinal muscle column, which became innervated by the dorsal branches of the spinal nerves. At CS17, the longitudinal muscle mass segregated into medial and lateral columns (completed at CS18). At CS18, the medial column segregated again into intermediate and medial columns (completed at CS20). The lateral and intermediate columns did not separate in the lower lumbar and sacral regions. Between CS20 and CS23, the cervical portions of the three columns segregated again from lateral to medial resulting ventrolaterally in rod‐like continuations of the caudal portions of the columns and dorsomedially in spade‐like portions. The observed topography identifies the iliocostalis and splenius as belonging to the lateral column, the longissimus to the intermediate column, and the (semi‐)spinalis to the medial column. The medial (multifidus) group acquired its transversospinal course during closure of the vertebral arches in the early fetal period. Hence, the anatomical ontology of the epaxial muscles is determined by craniocaudal and lateromedial gradients in development. Three longitudinal muscle columns, commonly referred to as the erector spinae, form the basic architectural design of the intrinsic muscles of the back. Clin. Anat. 29:1031–1045, 2016. © 2016 Wiley Periodicals, Inc.     

Radiographic and Magnetic Resonance Imaging Identification of Thoracolumbar Spine Variants with Implications for the Positioning of the Conus Medullaris in Rhesus Macaques

The anatomy of the vertebral column in mammals may differ between species and between subjects of the same species, especially with regards to the composition of the thoracolumbar spine. We investigated, using several noninvasive imaging techniques, the thoracolumbar spine of a total of 44 adult rhesus macaques of both genders. Radiographic examination of the vertebral column showed a predominant spine phenotype with 12 rib‐bearing thoracic vertebrae and 7 lumbar vertebrae without ribs in 82% of subjects, whereas a subset of subjects demonstrated 13 rib‐bearing thoracic vertebrae and 6 lumbar vertebrae without ribs. Computer tomography studies of the thoraco‐lumbar spine in two cases with a pair of supernumerary ribs showed facet joints between the most caudal pair of ribs and the associated vertebra, supporting a thoracic phenotype. Magnetic resonance imaging (MRI) studies were used to determine the relationship between the lumbosacral spinal cord and the vertebral column. The length of the conus medullaris portion of the spinal cord was 1.5 ± 0.3 vertebral units, and its rostral and caudal positions in the spinal canal were at 2.0 ± 0.3 and 3.6 ± 0.4 vertebral units below the thoracolumbar junction, respectively (n = 44). The presence of a set of supernumerary ribs did not affect the length or craniocaudal position of the conus medullaris, and subjects with13 rib‐bearing vertebrae may from a functional or spine surgical perspective be considered as exhibiting12 thoracic vertebrae and an L1 vertebra with ribs. Anat Rec, 300:300–308, 2017. © 2016 Wiley Periodicals, Inc.     

Anatomy of the human thoracolumbar Rami dorsales nervi spinalis

Medial, lateral, and intermedial ramifications have been described for the dorsal branch of the human spinal nerve (R. dorsalis n. spinalis, (RDNS)). Further branching has not been described. We report a ventral approach for dissecting the nerves around the thoracolumbar vertebral column to visualise the spreading of the nerves within the dorsal muscles and towards the skin. We defined three compartments of the deep back muscles in the thoracolumbar region: (A) the origin from the (1) transverse, (2) accessory, and (3) mammillary processes in the lumbar segments, (B) from the (1) ribs, (2)transverse and, (3) articular processes in the thoracolumbar segments. Each compartment was supplied by a ramification of the RDNS. The medial muscle compartment was reached by the descending medial branch of the RDNS. The lateral iliocostal compartment was innervated by an ascending lateral branch of the RDNS, and also by the descending distal branches of an intermedial branch of RDNS. This is a long nerve of the intermedial branch of the RDNS extended to the dorsal–caudal area, where the lateral and the intermedial nerve connected. This nerve, termed as the dorsal intermedial branch of the RDNS, innervated the skin in a more caudal region. Such nerve divided the lateral and the intermediate compartments. A short intermedial branch entered the intermediate segmental compartment from the ventral side. This is a ventral intermedial branch of the RDNS. The dorsal branches were often connected by a connecting branch of the RDNS. The lateral compartment represented the Iliocostalis. The medial and intermediate compartments comprised the Longissimus, part of the Iliocostalis, and additional dorsal muscles.     

The termination of spinomesencephalic fibers in cat

Summary The projections to the midbrain from the spinal cord have been investigated in the cat with the degeneration technique and by using horseradish peroxidase (HRP) as an anterograde tracer. Two types of spinal cord lesions were performed: 1) Cordotomies at cervical or thoracic levels transecting the ventral and lateral funiculi. 2) Transections of the ventral, ventrolateral, dorsolateral or dorsal funiculus, respectively, at cervical levels. In the anterograde tracing experiments HRP was injected into the spinal cord at cervical, lumbar or sacral levels.The results show large projections to the lateral and ventrolateral parts of the periaqueductal gray (PAG1), the posterior pretectal nucleus (PP) and the nucleus of Darkschewitsch (D). More moderate projections go to the medial division of the periaqueductal gray (PAGm), the cuneiform nucleus (CF), the mesencephalic reticular formation (MRF), lateral part of the deep layer of the superio colliculus (SP) and magnocellular medial geniculate nucleus (GMmc), while scattered spinal fibers are present in the dorsal part of the periaqueductal gray (PAGd), the external inferior collicular nucleus (IX), the intermediate layer of the superior colliculus (SI), the lateral part of the red nucleus (NR) and in the Edinger-Westphal portion of the oculomotor nucleus (3). In addition a few fibers are present in the interstitial nucleus of Cajal (CA) and anterior pretectal nucleus (PAc).The results indicate that at midcervical levels most of the spinomesencephalic fibers ascend in the ventral funiculus, with only a moderate fraction ascending in the ventral half of the lateral funiculus. Almost no fibers ascend in the dorso-lateral funiculus and none appear to pass in the dorsal funiculus.No distinct somatotopic pattern was found in the spinomesencephalic projections, but more fibers from cervicobrachial segments terminate in the rostral than in the caudal parts of the terminal fields in PAG, CF, SP and IX, while the lumbar fibers were more numberous in the caudal parts. PP seems to receive spinal fibers mainly from the caudal half of the cord.     

侧隐窝横、矢径测量在腰椎管狭窄症的诊断意义

目的探讨侧隐窝狭窄的原因及其横、矢径测量在腰椎管狭窄症的诊断意义。方法利用30例横断面、8例矢状面标本,观测侧隐窝、黄韧带、椎间盘等结构。结果 (1)L3-5骨性侧隐窝矢径为(6.97±0.95)、(6.46±0.86)、(6.37±0.54)mm,盘黄间隙矢径为(7.21±0.82)、(7.20±0.79)、(7.01±0.59)mm;(2)椎间盘横径、矢径均存在性差,各椎体间的椎间盘也存在差异;黄韧带厚度、侧隐窝横径及矢径均无侧差,但黄韧带厚度存在性差,侧隐窝横径、矢径均无性差;(3)椎间盘前缘高度大于后缘,L4～5前、后缘高度之比较L5～S1小。结论⑴不同性别、不同腰椎间的形态数据存在显著差异;⑵椎间盘、黄韧带数据均可作为诊断侧隐窝狭窄的参考指标;⑶侧隐窝狭窄是导致腰椎管狭窄的一个重要因素。     

经横突侧腹入路显露兔腰椎的实验研究

目的探讨一种改进的兔腰椎侧腹入路-经横突入路及其技术路线。方法实验家兔麻醉后，侧卧位，在横突前作纵行切口，分离腹外斜肌，经腹膜外即可显露兔第2腰椎至第6腰椎的椎体及横突部。结果共完成67例手术，切口愈合好，均无腹膜破裂及切口感染等并发症，所有动物均顺利存活。结论经横突侧腹入路显露兔腰椎的方法具有解剖位置恒定、操作简单、并发症少等优点，可用于兔腰椎椎体及横突等部位的手术显露。     

Vertebral pattern variation in the North Sea harbor porpoise (Phocoena phocoena) by computed tomography

Vertebral series in the harbor porpoise (Phocoena phocoena) include cervical, thoracic, lumbar, and caudal. In contrast to studying skeletons from museums, in which small bones can be missed, evaluation of full body computed tomography (CT) scans provides an overview of the vertebral column, while maintaining interrelationship of all structures. The aim of this study was to document variations in vertebral patterning of the harbor porpoise via evaluation of CT images of intact stranded harbor porpoises. The harbor porpoises were divided into age classes, based on developmental stage of reproductive organs on postmortem examination and closure of proximal humeral physis on CT. Numbers of vertebrae per series, fusion state of the syncervical, type of first hemal arch, number of double articulating ribs, and floating ribs were recorded based on CT images. Included in the study were 48 harbor porpoises (27 males and 21 females), which were divided in two age classes (27 immatures and 21 adults). Total vertebral count varied from 63 to 68 with vertebral formula range C7T12-14L12-16Cd29-33. Twenty-five different vertebral formulas were found, of which C7T13L14Ca30 was the most common (n = 8, 17%). Thoracic vertebrae with six, seven, or eight double articulating ribs and zero, one, or two vertebrae with floating ribs were seen. Four different fusion states of the syncervical and four types of hemal arches were recognized. This study showed a great variation in vertebral patterning in the harbor porpoise, with homeotic and meristic variation in the thoracic, lumbar, and caudal vertebral series.     

Functional adaptations of facet geometry in the canine thoracolumbar and lumbar spine (Th10-L6).

The shape, size and transverse distance between contralateral caudal articular processes of caudal thoracic and lumbar vertebrae were evaluated in a sample of 140 macerated canine spines to contribute to the understanding of the development of vertebral misalignment. Dogs were grouped as large, chondrodystrophic, and small breeds. In large dogs, caudal articular surfaces were adapted to higher body-weight by the presence of larger articular surfaces. Additionally, caudal articular surfaces not only covered the lateral, but also the ventral (i.e. ventral facet) and/or caudal aspects (i.e. caudal facet) of the caudal articular processes. Ventral facets, which increase loading capacity of the zygapophyseal joints in normally aligned vertebrae, were more frequently observed in large breeds (p < 0.001) than in small and chondrodystrophic breeds. With some exceptions, caudal facets primarily were present in large dogs, especially at the vertebral levels L3-L5. Their formation is induced by extension of the normal lykphotic thoracic and lumbar spine causing lumbar lordosis and denotes loss in elasticity of the bow-and-string-construction of the trunk. Because ventral and caudal facets are consistent with convexity of the caudal articular surfaces, which to a great degree was noted to result in formation of ball-and-socket joints, spinal stability is supposed to be decreased under such conditions.     

Distribution of sensory neurons of ventral and dorsal cervical cutaneous nerves in dorsal root ganglia of adult rat--a double-label study using DiO and DiI

To examine distribution of sensory neurons of ventral and dorsal cervical cutaneous nerves in dorsal root ganglia (DRGs), DiO and DiI tracers were applied at the proximal section of nerves (transverse superficial cervical and anterior supraclavicular nerves were selected as ventral cervical cutaneous nerves; dorsal cutaneous branches of second, third and fourth cervical nerves were selected as dorsal cervical cutaneous nerves). Located distributions were observed in DRGs of C2, C3, and C4 (25/46 DRGs). Sensory neurons of the ventral cervical cutaneous nerves were distributed in dorso-lateral or dorso-medial portions; neurons of dorsal cervical cutaneous nerves were distributed in ventro-medial or ventro-lateral portions of DRGs. Moreover, sensory neurons of transverse superficial cervical and anterior supraclavicular nerves were mainly distributed from the caudal half of C2 to whole part of C4 DRGs. Results show that there is a tendency for located distribution in two group sensory neurons; also, sensory neurons of ventral cervical cutaneous nerves have a segmental distribution, which has been verified in the brachial and lumbar plexus.     

Anatomical studies on the ovine spinal cord

The root attachment lengths were consistently greater in the cranial cervical (C3), midthoracic (T7), caudal lumbar (L5) and cranial sacral (S1) cord segment levels than the corresponding caudal cervical, caudal thoracic, cranial lumbar and caudal sacral levels respectively. As to the root emergence length the greatest values were obtained bilaterally at C3, T1, L4 and S1 cord segment levels respectively. The interroot intervals were maximum at C3, T13, L1 and S1 cord levels in the respective regions. The longest cord segments were located at C2, T13, L3 and S1 levels; the shortest were at C8, T1, L6, and S4 cord levels. The greatest diameter and cross-sectional area were confined to the last cervical, first 2 thoracic, last lumbar and first sacral cord segment levels. The spinal cord segments C2, T13, L4 and S1 were most voluminous in the respective regions. The topography of cord segments and the level of termination of the spinal cord have been studied and recorded.     

New dysostosis showing multilevel absence of vertebral pedicles: Unique developmental anomaly of vertebral arches?

We report on an apparently normal child who shows hypopaplasia of the vertebral pedicles and posterior arches of several cervical, thoracic, and lumbar vertebrae with normally fused spinous apophyses, hypoplastic sacrum, lumbar epidural lipomatosis, synostoses of some cervical vertebral disks, and sacral spina bifida. The most likely mechanism is an abnormal differentiation of the spinal processes, due most probably to an absence of differentiation in cartilage of the dense mesenchyme forming their most anterior part. Because the anomalies affect multiple levels, we highly suspect a genetic basis to this unusual dysostosis affecting the development of the posterior sclerotomes. Am. J. Med. Genet. 95:473–476, 2000. © 2000 Wiley‐Liss, Inc.