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.     

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.     

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.     

Comments on the Serial Homology and Homologues of Vertebral Lateral Projections in Crocodylia (Eusuchia)

The literature on crocodylian anatomy presents the transverse process in an ambiguous meaning, which could represent all lateral expansions derived from the neural arch, including vertebrae from cervical to caudal series, or in a more restrictive meaning, being applied only to lumbar vertebrae. The lateral expansion of sacral and caudal vertebrae usually referred to as the transverse process has been discovered to be fused ribs, bringing more ambiguity to this term. Therefore, with the lack of a definition for transverse process and other associated terms, the present work aims to propose a nomenclatural standardization, as well as definitions and biological meaning, for vertebral rib related structures. Vertebra obtained from museum collections from a total of 87 specimens of 22 species of all extant Crocodylia genera were studied. All vertebrae, except cervical and first three dorsal, exhibit transverse processes. The transverse process is more developed in dorsal and lumbar vertebrae than in sacral and caudal vertebrae in which it is suppressed by the fused ribs. The serial homology hypotheses here proposed can also be aplied to other Crurotarsi and saurischian dinosaurs specimens. This standardization clarifies the understand of the serial homology among those homotypes, and reduces the ambiguity and misleadings in future work comparisons. Anat Rec, 301:1203–1215, 2018. © 2018 Wiley Periodicals, Inc.     

Response of the Axial Skeleton to Bipedal Loading Behaviors in an Experimental Animal Model

Many derived aspects of modern human axial skeletal morphology reflect our reliance on obligate bipedal locomotion. Insight into the adaptive significance of features, particularly in the spine, has been gained through experimental studies that induce bipedal standing or walking in quadrupedal mammals. Using an experimental animal model (Rattus norvegicus), the present study builds on earlier work by incorporating additional metrics of the cranium, employing quantitative methods established in the paleoanthropological literature, and exploring how variation in mechanical loading regimes impacts axial anatomy. Rats were assigned to one of five experimental groups, including “fully loaded bipedal walking,” “partially loaded bipedal walking,” “standing bipedally,” “quadrupedal walking,” and “no exercise control,” and engaged in the behavior over 12-weeks. From μCT data obtained at the beginning and end of the experiment, we measured foramen magnum position and orientation, lumbar vertebral body wedging, cranial surface area of the lumbar and first sacral vertebral bodies, and sacral mediolateral width. Results demonstrate that bipedal rodents generally have more anteriorly positioned foramina magna, more dorsally wedged lumbar vertebrae, greater articular surface areas of lumbar and first sacral vertebral bodies, and sacra that exhibit greater mediolateral widths, compared to quadrupedal rodents. We further document variation among bipedal loading behavior groups (e.g., bipedal standing vs. walking). Our experimental animal model reveals how loading behaviors and adaptations may be specifically linked, and implicates a potential role for developmental plasticity in the evolutionary acquisition of bipedal adaptations in the hominin lineage. Anat Rec, 2018. © 2018 American Association for Anatomy.     

Breed specific osteological features of the canine lumbosacral junction.

Inefficient facet geometry suggests the lumbosacral junction to be mechanically imperfect in a large number of dogs (especially German Shepherd Dogs) resulting in a significantly higher prevalence of osteophyte formation and increase in the longitudinal extension of the articular surface covering the caudal articular process of the seventh lumbar vertebra. Such osteological features give evidence for lumbosacral craniocaudal translation, were predominantly noticed in combination with axial rotation and are taken to be anatomic risk factors that can predispose to the development of lumbosacral stenosis. The statistically significant relationship between age and the magnitude of the caudal facet inclination angles of the seventh lumbar vertebra in juvenile specimens indicate an affection of the three-dimensional modeling of the immature caudal articular processes by formative stimuli such as body weight and locomotion. However, results additionally indicate an association between the magnitude of these inclination angles and vertebral body dimensions also suggesting a congenital influence on facet geometry.     

Participation of ventral and dorsal tail muscles in bending movements of rat tail

The rat controls the form of its tail, from straight to curved, by contraction and relaxation of its four tail muscles. The tendons of these muscles insert on any of the cranial articular, transverse, and hemal processes of each of 24 coccygeal vertebrae (Co5–Co28). In this study, we isolated for the four coccygeal muscles each muscular fascicle segment inserting on any process of the coccygeal vertebrae. We measured the length and weight of all muscular fascicles and tendons, and then divided all muscular fascicles into four groups based on their insertion: Co5–Co10, Co11–Co16, Co17–Co22, and Co23–Co28. Moreover, we used soft X-ray imaging to investigate the geometrical relationship between neighboring coccygeal vertebrae. Additionally we carried out serial sectioning at the sacral and caudal portions, and traced the course of the tendons of coccygeal muscles from their origin to the Co4 level. We discuss which muscles and tendons play important roles when coccygeal vertebrae bend along and rotate around the longitudinal axis.     

Mechanism of change in the orientation of the articular process of the zygapophyseal joint at the thoracolumbar junction

The orientation of the superior articular processes in thoracic and lumbar vertebrae differs. The present study was undertaken to investigate the possible mechanism for the change from a posterolaterally facing superior articular surface in the thoracic region to a posteromedially facing curved articular surface in the lumbar region. The material of the study consisted of dry macerated bones of 44 adult human vertebral columns. The orientation of the superior articular process and its relation to the mamillary tubercle (process) was examined between T9 and L5 vertebrae in each column. An abrupt change from the thoracic to lumbar type of articular process was observed in 3 columns (7%). Forty-one (93%) columns showed a gradual change extending over either 2 or 3 successive vertebrae. The present study suggests that the change in the orientation of the superior articular process, from the coronal to the sagittal plane (sagittalisation), occurs due to the change in the direction of weight transmission through zygapophyseal joints at the thoracolumbar junction. It was observed that the gradual sagittalisation of the superior articular process in the transitional zone brought it close to the mamillary tubercle which eventually fused with it. Thus the study suggests that the characteristic posteromedially facing concave superior articular process of lumbar vertebrae may have formed because of the fusion of the articular process and the mamillary tubercle.     

Prenatal diagnosis and fetopathological investigation of dorsolumbosacral agenesis

Sacral and lumbosacral spine agenesis, as characteristic signs of a rare congenital malformation – caudal regression syndrome – has been well described. However, dorsolumbosacral agenesis involving the lower thoracic, lumbar, and sacral vertebrae has rarely been reported, and prenatal diagnosis of this severe form has not been published yet.     

Changes in the surface of the superior articular joint from the lower thoracic to the upper lumbar vertebrae

Thirty-two human vertebral columns were selected from the Kanazawa Collection at the University of Kanazawa, Japan. The superior articular joint surface was categorised into the thoracic type and the lumbar type, and the pattern of the change from one type to the other in the lower thoracic and upper lumbar region was examined. In 21 of 32 cases (66%), the change from the thoracic to the lumbar type occurred over 2 vertebral segments, either between the 12th thoracic and 1st lumbar vertebrae (44%) or between the 11th and 12th thoracic vertebrae (22%). In the remaining 11 cases (34%), the change occurred over 3 vertebral segments, with a transitional type of articular surface. The change from the thoracic to lumbar type of articular surface has been believed to occur over 2 vertebral segments, but occurs over 3 segments in as many as 34% of the articular surfaces.     

The influence of lumbosacral transitional vertebrae on lumbar lordosis and the angle of pelvic incidence

Pelvic incidence and lumbar lordosis have only normative values for spines comprising five lumbar and five sacral vertebrae. However, it is unclear how pelvic incidence and lumbar lordosis are affected by the common segmentation anomalies at the lumbo-sacral border leading to lumbosacral transitional vertebrae, including lumbarisations and sacralisations. In lumbosacral transitional vertebrae it is not trivial to identify the correct vertebral endplates to measure pelvic incidence and lumbar lordosis because ontogenetically the first sacral vertebra represents the first non-mobile sacral segment in lumbarisations, but the second segment in sacralisations. We therefore assessed pelvic incidence and lumbar lordosis with respect to both of these vertebral endplates. The type of segmentation anomaly was differentiated using spinal counts, spatial relationship with the iliac crest and morphological features. We found significant differences in pelvic incidence and lumbar lordosis between lumbarisations, sacralisations and the control group. The pelvic incidence in the sacralised group was mostly below the range of the lubarisation group and the control group when measured the traditional way at the first non-mobile segment (30.2°). However, the ranges of the sacralisation and lubarisation groups were completely encompassed by the control group when measured at the ontogenetically true first sacral vertebra. The mean pelvic incidence of the sacraliation group thus increased from 30.2° to 58.6°, and the mean pelvic incidence of the total sample increased from 45.6° to 51.2°, making it statistically indistinguishable from the control sample, whose pelvic incidence was 50.2°. Our results demonstrate that it is crucial to differentiate sacralisations from lumbarisation in order to assess the reference vertebra for pelvic incidence measurement. Due to their significant impact on spino-pelvic parameters, lumbosacral transitional vertebrae should be evaluated separately when examining pelvic incidence and lumbar lordosis.     

Spread of the dorsal root potentials in lower lumbar,sacral and upper caudal spinal cord

Spread of the dorsal root potentials (DRPs) along lower lumbar, sacral, and upper caudal segments of the cord has been studied in spinal cats. Ipsilateral DRPs produced by stimulation of L5 dorsal root with single volleys and recorded in consecutively more and more caudal segments gradually decrease and after passing 6 segments attain 47% of amplitude observed in L6 dorsal root. DRPs spreading cranially from Ca2 dorsal root along 6 segments decrease virtually to zero. Depolarizations spreading caudally show greater conduction velocity, are maintained during repetitive stimulation in larger number of segments and display larger occlusion than DRPs spreading cranially. These findings show the preponderance of depolarization spreading from lower lumbar cord to sacral and caudal segments over that produced in caudal parts of the cord and spreading cranially. The extent of cranial spread of DRPs, appearance of sudden increases in latency of DRPs and changes in effectiveness of stimulation in maintaining prolonged depolarization show correlations with neuronal arrangement of the substantia gelatinosa. This suggests that substantia gelatinosa subserves the spread of DRPs along the spinal cord.     

Sexual dimorphism of the posterior cervical spine muscle attachments

Cervical spinal injury and neck pain are common disorders with wide physical implications. Neck pain and disability are reported to occur in females more often than in males, and chronic or persistent neck pain after whiplash is twice as common in females. Female athletes also sustain a higher percentage of concussions compared to male athletes. Still, while sexual differences in clinical presentation and outcome are well-established, the underlying etiology for the disparity remains less clear. It is well-established that the origin and insertion landmarks of posterior neck muscles are highly variable, but we do not know if these interindividual differences are associated with sex. Expanding our knowledge on sexual dimorphism in the anatomy of the cervical muscles is essential to our understanding of the possible biomechanical differences between the sexes and hence improves our understanding as to why females suffer from cervical pain more than males. It is also of paramount importance for accurate planning of posterior cervical spine surgery, which cuts through the posterior cervical musculature. Therefore, our main objective is to characterize the anatomy of posterior neck musculature and to explore possible sexual differences in the location of their attachment points. Meticulous posterior neck dissection was performed on 35 cadavers, 19 females, and 16 males. In each specimen, 8 muscle groups were examined bilaterally at 45 osseous anatomical landmarks. Muscles and their attachment sites were evaluated manually then photographed and recorded using Microscribe Digitizer technology built into 3D models. A comparison of attachment landmarks between males and females for each muscle was conducted. Out of the eight muscles that were measured, only two muscles demonstrated significant sex-related anatomical differences—Spinotranversales (splenius capitis and cervicis) and Multifidus. Male Spinotransversales muscle has more attachment points than female. It showed more cranial insertion points in the upper cervical attachments (superior nuchal line, C₁ posterior tubercle, and mastoid process) and more caudal insertion points in the spinous processes and transverse processes of the lower cervical and upper thoracic vertebrae. Thus, the male subjects in this study exhibited a greater coverage of the posterior neck both cranially and caudally. Female Multifidus has more attachment points on the spinous processes and articular processes at middle and lower cervical vertebrae and at the transverse processes of the upper thoracic vertebrae. All remaining muscles exhibited no sexual differences. Our findings highlight, for the first time, a sexual dimorphism in attachment points of posterior cervical musculature. It reinforces the notion that the female neck is not a scaled version of the male neck. These differences in muscle attachment could partially explain differences in muscle torque production and range of motion and thus biomechanical differences in cervical spine stabilization between sexes. It sheds a much-needed light on the reason for higher whiplash rates, concussion, and chronic cervical pain among females. Surgeons should take these sexual morphological differences into consideration when deliberating the best surgical approach for posterior cervical surgery.     

Which portion in a facet is specifically affected by articular cartilage degeneration with aging in the human lumbar zygapophysial joint?

Using 10 osteoligamentous vertebral columns obtained from elderly donated cadavers, we describe in detail degenerative changes of the articular cartilage in lumbar zygapophysial joints to show which portion in a facet is specifically affected. Degenerative changes, including extended cartilage defects, occurred in multiple facets of every specimen. The results demonstrated 5 basic morphologies of degeneration, i.e., 1) marginal dominace in the articular surface, 2) lower segment dominance except for the lowest (L5/S) facet, 3) advancement in the inferior articular process, 4) cranial and caudal dominance rather than the dorsal dominance in the articular surface and 5) progress in a mirror-image manner. These rules seemed to be consistent with differences in size, shape and kinesiological aspects of the facet between segments and between portions in a facet.     

Ultrastructural study of postnatal development of the tonsillar crypt epithelium of the musk shrew, Suncus murinus

Summary An ultrastructural study was made of the postnatal development of the tonsillar crypt epithelium in the musk shrew, Suncus murinus. On day 3 after birth, a particular kind of large lymphoid cell was first seen to move through the basement membrane into the epithelium. The next migration was that of lymphocytes, which passed through holes in the basement membrane. On days 5 to 7, the lymphocytes formed clusters, and pale epithelial cells of low electron density appeared. The cell clusters and pale epithelial cells fused on day 10. By day 14, these epithelial cells extended cytoplasmic projections to the surface of the epithelium, which had many heterophagic vacuoles and some microvilli-like structures. These findings suggest that the lymphoepithelial relationship is important for the organization of the immunological microenvironment in tonsillar crypt epithelium of the neonatal musk shrew.     

Distribution of gonadotrophins within the anterior pituitary cells of the musk shrew (Suncus murinus L.)

Gonadotrophs in the anterior pituitary gland of the musk shrew were first identified by means of electron microscopic immunocytochemistry. The gonadotrophs of the musk shrew revealed quite unusual ultrastructural features that have never been seen before in other species. These cells contained two types of secretory granules, i.e., small dense, roundshape granules and large lucent, irregular-shape granules. FSHβ and LHβ were mostly observed together on both small and large secretory granules. The distribution pattern of the subunits of gonadotrophs was slightly altered following gonadectomy in the musk shrew. © 1992 Wiley-Liss, Inc.     

Distribution of gonadotrophins within the anterior pituitary cells of the musk shrew (Suncus murinus L.).

Gonadotrophs in the anterior pituitary gland of the musk shrew were first identified by means of electron microscopic immunocytochemistry. The gonadotrophs of the musk shrew revealed quite unusual ultrastructural features that have never been seen before in other species. These cells contained two types of secretory granules, i.e., small dense, round-shape granules and large lucent, irregular-shape granules. FSH beta and LH beta were mostly observed together on both small and large secretory granules. The distribution pattern of the subunits of gonadotrophs was slightly altered following gonadectomy in the musk shrew.     

Scanning electron microscopy of the ovary in the house musk shrew, Suncus murinus

The structure of the house musk shrew (Suncus murinus) ovary, prepared by the Osmium-DMSO-Osmium method, was examined with a scanning electron microscope. Many ovarian follicles in various stages of development can be seen in the musk shrew ovary, but fully matured follicles (Graafian follicles) are never observed. In the inner layer of zona granulosa of the preantral follicles, the follicular cells containing a large amount of glycogen deposition in the cytoplasm are observed. Folded and collapsed zona pellucida surrounding the remnant of the degenerated oocyte, which is thought to be a residual form of atretic follicle, is observed in a small, crypt-like depression on the surface of the ovary where it has been split by cracking.     

Development of the embryonic chick wing bud from stage 24 to stage 32

If a graft is placed in an early chick wing bud, the location of the graft after several days of further development cannot be predicted solely from the rate of proximal-distal outgrowth. The movement of the graft depends on the rate of outgrowth of the wing but also on morphogenetic tissue movements intrinsic to the wing and on accommodation to the growth and morphogenetic movements of the body of the embryo. Numerous experiments have been reported in which tissue grafted into ectopic sites in the wing causes abnormal wing development. These experiments have been discussed in terms of pattern formation of positional information. However, until the movement of wing tissue during normal development is understood, it cannot be known in what way the development of grafts placed in ectopic sites is abnormal. Previous experiments have demonstrated that carbon particles placed in the wing move in the same manner as grafts of wing mesenchyme, but the carbon particles do not affect normal wing development. Carbon particles were placed in the wing, dorsal to the base of the wing, and cranial and caudal to the wing, to plot the expected movement of a graft and to discover how this movement can be predicted from the tissue movements at the base of the wing. It is concluded that three tissue movements are responsible for the movement of a graft. These are outgrowth at a rate determined by the rate of cell division, formation of the shoulder through caudal movement of the tissues cranial to the wing, and ventral movement of prospective flank ventral to somite 19. These three tissue movements and their influence on normal wing development are discussed.     

胎儿脊髓脊柱发育的观察

用１９３例正常胎儿尸体观察测量了脊髓的全长、重量，体积，颈膨大，腰骶膨大及终丝等方面出生前的逐月发育值及的变化。在４个月时脊髓已脱离了骶管；出生时脊髓下端位于腰２￣腰３椎体间高度；硬脊膜囊下界位于骶１￣骶２椎体间高度；外终丝止点基本在尾１￣尾２椎体间；脊髓长与身长之比逐月下降，至出生前约为１／３；脊髓重与体重之比始终保持在０．１％左右，脊髓发的性别差异不明显。上述结果可为教学及临床提供基本的参考数