How many caudal vertebrae

Toggle navigation. Institutional subscriptions support Language. Keep me signed in. Forgot your password? Sign in with Facebook. Sign in with Apple. Caudal vertebrae [Coccygeal] - Vertebrae caudales [coccygeae]. Description The caudal or coccygeal vertebrae reduce in size gradually, with a graduate simplification of their form losing arches and processes, and with a simple cylindrical shape at the end.

Subscribe now Discover our subscription plans Subscribe. Manage cookies Accept. Cookie settings. Essential technical cookies Description. Analytics cookies Description. Google Analytics. Save and continue. There were no sex-related differences observed in this study. There were 7 cervical vertebrae; the atlas and the axis were the largest while the rests were shorter and wider.

The greatest diameter of the vertebral canal was observed at the atlas bone C 1 0. The transverse processes were positioned caudolaterally and penetrated by the transverse canal Figures 1 b , 1 c , and 1 f. Homologue of the cervical ribs was observed as caudoventrally directed bony plates from the base of C 6 Figure 1 h. Transverse foramen and alar foramen were present in the atlas.

In the axis, the caudodorsally directed spinous process of axis was thicker and higher than the spinous processes of the other cervical vertebrae, and there was a deep groove on the caudal face of the spinous process. There were ventral tubercles on the ventral surfaces of the bodies of the cervical vertebrae Figure 1 b.

The spinous processes of the axis C 2 and the 3rd and 4th cervical vertebrae were slightly caudodorsally directed; the 6th and 7th were slightly craniodorsally directed, while the 5th cervical vertebra was dorsally directed. The small transverse processes of the 2nd—5th cervical vertebrae were caudolaterally directed, and the 6th and 7th cervical vertebrae were laterally directed.

The caudal end of the costal process of the transverse process of the 6th cervical vertebra was pointed. Fovea costalis caudalis was present on the 7th cervical vertebra.

There were 13 thoracic vertebrae with a total thoracic column length of 7. The spinous process of T 1 was comparable to the rest of the cervical bones but, from T 2 , it arose to an average of 1. Many of the caudal thoracic bones T 10—13 distinctly bore mammillary processes arising laterally to the cranial articular process.

The caudal ends of the transverse processes were craniolaterally directed. Fovea costalis caudalis was more distinct than fovea costalis cranialis. Spinous processes of the thoracic vertebrae were caudodorsally inclined, and the dorsal processes of the last two thoracic vertebrae were wide and dorsally projected. There were 6 well-developed lumbar vertebrae with a total average length of 6. Their spinous process and transverse processes increased in size caudally as the spinous process became more erect.

There was observed presence of the mammillary processes on all lumbar vertebrae Figure 2 c. The diameter of the vertebral canal had an average range of 0. The level of the spinous processes was the same on all lumbar vertebrae, but their lengths varied between 0.

The ventral crest was present on all of the lumbar vertebrae. The transverse processes of the 3rd—5th lumbar vertebrae were larger than the other lumbar vertebrae.

The transverse process of the last lumbar vertebra was craniolaterally directed. The lumbar vertebrae were slightly larger than the thoracic vertebrae from the dorsal view. Os sacrum was composed of 4 sacral vertebrae, appeared fused but the outlines of the transverse and articular processes were visible in most specimens studied Figure 3 a.

The total length of the sacrum varied from 3. The fused transverse processes of S 1 and S 2 pars lateralis articulated with the ilium while the remaining two were never involved. There were 31—36 caudal or coccygeal vertebrae forming the bone of the tail with a total length ranging between 0. Cranial articular processes of the Ca 1 to Ca 7 caudal vertebrae were present Figures 3 b and 3 c.

There were rudimentary cranial articular processes from the Ca 8 caudal vertebrae. Hemal arch was observed at Ca 6 and hemal processes from Ca 7 Figure 3 d. Caudal parts of the coccygeal bones formed an hourglass shape, and their processes gradually became shorter; the vertebral bones also became shorter and thinner progressively towards the tip of the tail.

There were 13 pairs of ribs; the first seven pairs were sternal costae verae and the remaining six pairs were asternal costae spuriae of which the last pairs were floating ribs costae fluctuantes having no distinct attachment to the costal arch.

There was a distinct costal groove on the external faces of the shafts of the 3rd, 4th, and 5th ribs. The second rib had a faint groove and there were no costal grooves on the shafts of other ribs. The shafts of the first five ribs were flat, while the bodies of the other ribs were cylindrical Figure 4 a. The sternum was composed of deltoid-shaped manubrium sterni, four sternebrae, and slender processus xiphoideus.

The sternebrae bodies were slender and laterally compressed. The longest sternebrae were the manubrium and xiphoid processes with average length of 1. The second and third sternebrae were approximately 0.

Most of the features found in this study are largely typical for rodents. In the rat, the major axes of vertebral column and skull are roughly in the same horizontal line [ 20 ]. This is in consonance with results observed in mole-rats [ 8 ] as well as in this study. The vertebral column gives support to the muscles and ligaments of the back which appear firm and tough yet flexible.

This probably gives the AGR great strength as it utilizes the vertebral column in motion. The homologue of cervical ribs in the Wistar rat occurs at C 6 [ 15 ] same as in the African giant rat. All other features appeared typical for rodents. Mammalian sacrals are generally three to five in number [ 21 ].

In Insectivora, sacral conditions vary widely and, in moles, the vertebrae are firmly fused [ 22 , 23 ]. In our study, Os sacrum was composed of 4 sacral vertebrae. The spinous processes of both sacral vertebrae and transverse processes were fused to form pars lateralis in mole-rats; as in moles [ 8 ].

In the African giant rat, the spinous processes were not fused and though the transverse processes of some had fused probably by ossification due to ageing, most were still separable only by thin connective tissue and ligaments.

In the Wistar rat, the articular processes of the coccygeal bones made no articulations caudal to Ca 3 where the hemal arch was formed. In preparation of the bones, tough ligamentous attachments were observed holding the various muscles of the back and tail.

The authors speculate that the strong articulations on the back and tail of the AGR form part of the explanations for the flexibility and ease with which this rodent coils up despite its sheer size and the use of the tail in the African giant rat which is reported to dig, fight, and sometimes prop itself on the tail personal observation. The body of the sternum consists of five sternebrae in the mink [ 3 ], eight sternebrae in the badger [ 4 ], six sternebrae in the porcupine [ 6 ], and five sternebrae in mole-rats [ 8 ].

In this current study, four sternebrae were found in African giant rats apart from a manubrium proximally and a xiphoid process capped with a xiphoid cartilage. In conclusion, this study demonstrates the African giant rat as a rodent with a highly flexible vertebral column as it readily coils up in defense or motion.

This report presents features of the vertebral column that may be responsible for this and adds to the body of knowledge on this rodent. The authors declare that there is no conflict of interests regarding the publication of this paper.

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