Cervical vertebrae

“ The cervical vertebrae are smaller than those in any other region of the spine, and may be readily distinguished as they lie in the neck and extend from the base of the skull to the dorsal vertebrae, or the point of attachment of the first rib to the first dorsal. ”

“ The tail of the duck, like that of all living birds, is very short, and the posterior caudal vertebrae are united together, forming the pygostyle. The vertebral column may be divided into cervical, thoracic, lumbar, sacral, and caudal regions, but the boundaries between the several regions are ill-defined.
The Cervical Vertebrae.
All the vertebrae anterior to the first one that bears a rib meeting the sternum are regarded as cervical vertebrae. There are therefore sixteen cervical vertebrae, the last two of which bear well developed ribs. All are freely movable on one another. ”

“ One of the regions of the skeleton which manifests adaptive modifications of this kind in the most remarkable degree is the cervical division of the vertebral column. In one edentate species it is lengthened out by two additional vertebræ more than in any other mammal; in another it is reduced by anchylosis to as great an extent below the regular number of moveable pieces: and these, the two most opposite conditions of the cervical vertebræ which are to be met with in the mammiferous class are related to equally diverse and opposite habits of life. ”

“ The scalenus muscles have their origin on the lower cervical vertebræ and are inserted into the first and second ribs, thus aiding in the elevation of the ribs as well as in lateral flexion of the neck. The head is held upright by the ligamentum nuchæ, which rises from the external occipital protuberance and is inserted into the spinous processes of all the cervical vertebræ except the first. ”

“ There are thirty-five vertebrae between the cervicals and the first non-rib-bearing vertebra, to which the pelvis was, evidently, attached. The distinction between the cervicals and thoracics cannot be made from any characters they possess, as the seventh vertebra does not bear a distinct hypapophysis. Neither can it be said with certainty from this specimen which is the first thoracic vertebra, as the cervical ribs had, unfortunately, been displaced in the collection and preparation of the specimen. ”

“ The transverse processes project out- ward, one from each side of the arch. The articular processes project, two upward and two downward, and are for connecting adjacent vertebrae together. The notches, situated on the upper and lower borders of the pedicles, form in the articulated spine the intervertebral foramina through which the nerves pass out of the spinal canal.
The vertebrae in each group have characters which specially distinguish them. In man and all mammals, with few exceptions, whatever be the length of the neck, the cervical vertebrae Cervical are seven in number. ”

“ The cervical vertebrae of an infant are very hard to feel, but if one of the segments is subluxated sufficiently to cause pressure on a nerve that segment will be easier to feel because it is out of the median line ”

“ In Manatus there are only six cervical vertebrae. The caudal vertebrae have well-developed chevron bones. The humerus is distinctly articulated to the [353] radius and ulna, and these two bones are about equally developed, and are often fused together. There are no clavicles, and the pelvis is vestigial, consisting of a pair of somewhat cylindrical bones suspended at some distance from the vertebral column. In living forms there is no trace of a posterior limb, but in Halitherium there is a vestigial femur connected with each half of the pelvis. ”

“ The vertebrae are generally without epiphyses to their centra. The cervical vertebrae in living forms have saddle-shaped articulating surfaces, and many of them bear ribs. The thoracic ribs in almost all birds have large uncinate processes. The sternum is very large, and the ribs are always attached to its sides, not as in many reptiles [296] to any backwardly-projecting process or processes. The sternum ossifies from two or more centres.
The skull is extremely light, and its component bones show a great tendency to fuse together completely. ”

“ The centra of the cervical vertebrae articulate by cup and ball joints. The formation of the temporal region of the skull varies considerably in the three families, some genera lacking the complete zygomatic arch, while others have a narrow parieto-squamosal arch bridging over the temporal fossa, or the latter is completely roofed over by the laterally expanded parietal, which meets the jugal and quadrato-jugal. The quadrate is always trumpet-shaped ”

“ In the young animal the odontoid process is readily seen to ossify from a centre anterior to that forming the anterior epiphysis of the axis.
The remaining five cervical vertebrae, the third to the seventh inclusive, have rather flattened wide centra, obliquely truncated at either end. The neural spine progressively increases in size as the vertebrae are followed back. The transverse processes vary considerably; those of the third are divided into a thicker backwardly-, and a more slender forwardly-projecting portion ”

“ This muscle lies laterad and ventrad to the preceding and is at times partly covered by it in its posterior half. It arises from separate heads from the spinal processes of the two anterior and six posterior cervical vertebræ; beginning caudad, thin and sharp, it gradually becomes thicker as it passes cephalad until it becomes partially tendinous and inserts itself on the hinder border of the squamosal, laterad to the occipito-cervicalis medialis muscle. ”

“ The last two cervical vertebrae bear long movable ribs which articulate by distinct capitular and tubercular processes, but do not meet the sternum. The thoracic ribs are eight in number, and each is divisible into a vertebral and a sternal portion. The first five thoracic ribs are flattened curved bars of bone, which articulate by a prominent capitulum with the centrum of the corresponding vertebra, and by a tuberculum with the transverse process. Projecting backwards from each is a large hooked uncinate process. ”

“ Post-sacral vertebræ, of which seven were embedded in stone matrix, show plano-plano surfaces. Transverse processes united to centra. Nature of cervical vertebræ not determined. Ribs large, not greatly curved in dorsal region, tapering gradually to those of cervical region. ”

“ The cervical vertebrae of the infant are very small and extreme care must be exercised in adjusting. Sufficient force must be used to move the vertebra.
The importance of proper attention to adjusting the segments of the sacrum of the infant and small child can not be overestimated. During childhood the child is subject to many falls and jars which are likely to be centered upon the sacrum. ”

“ Owing to the great development of the spinous processes of the cervical vertebrae, and of the muscles attached to them, and to the occipital bones of the skull, the neck is very powerful, almost like that of a bull. The shoulders are remarkable for their breadth, and the pectoral muscles for their large size. ”

“ Numerical anomalies of the vertebrae are quite common, generally in the lumbar and dorsal regions, being quite rare in the cervical, although there have been instances of six or eight cervical vertebrae. In the lower animals the vertebrae are prolonged into a tail, which, however, is sometimes absent, particularly when hereditary influence exists. It has been noticed in the class of dogs whose tails are habitually amputated to improve their appearance that the tail gradually decreases in length. ”

“ The cord is rarely subjected to pressure as a result of curving of the spine alone, but occasionally, especially in the cervical region, a sequestrum becomes displaced backward and exerts pressure on it, and it sometimes happens, also in the cervical region, that the cord is nipped by sudden displacement of diseased vertebræ—a condition comparable to a fracture-dislocation of the spine. ”

“ Hair-clad Vertebrates, with cutaneous glands in the female, secreting milk for the nourishment of the young. Skull without prefrontal, postfrontal, quadrato-jugal, and some other bones, and with two occipital condyles formed entirely by the exoccipitals. Lower jaw composed of dentary bone only, articulating only with the squamosal. Ear bones a chain of three or four separate bonelets. Cervical vertebrae sharply distinguished from the dorsals, and if with free ribs, showing no transition between these and the thoracic ribs. Brain with four optic lobes. ”

“ The cervical vertebrae are of normal form, the orbit (as in the second family) is encircled by bone, the last molar has a third lobe, the single pair of upper incisors are somewhat elongated, and have a gap between and behind them, while the outer lower incisors are larger than the inner pair, the canines being small. ”

“ The next twelve vertebræ, in order below the cervical, are known as the thoracic vertebræ. They form the back part of the framework of the thorax and have little freedom of motion. The five vertebræ below the thoracic are known as the lumbar vertebræ. These bones are large and strong and admit of considerable motion. Below the last lumbar vertebra is a wedge-shaped bone which has the appearance of five vertebræ fused together. This bone, known as the sacrum, connects with the large bones which form the pelvic girdle. ”

“ Once formed, a palpation habit, right or wrong, is very hard to break. Many a teacher has expended himself uselessly in the effort to undo some technical fault acquired by the student in a blundering undirected trial.
Facts Concerning the Spine
The spinal column is composed of twenty-six segments called vertebrae, twenty-four movable and two fixed. The movable vertebrae are divided for convenience in study into three sections. There are seven Cervical vertebrae, twelve Dorsal, and five Lumbar in the normal individual. ”

“ Among these modifications were a lengthening of the tail, a lengthening of the hind legs, the development of a calcaneal-navicular-ectocuneiform contact instead of a calcaneal-navicular contact for additional strength in leaping, a shortening of the forelimb, an increase in size and inflation of the mastoid and tympanic portions of the skull with a consequent reduction in size of the interparietal region and the fusion of certain of the cervical vertebrae. ”

“ The dorsal or thoracic vertebrae are the next in rotation down the spine and are intermediate in size between those in the cervical and those in the lumbar region, and increase in size from above downward. ”

“ The plastron is roughly indicated by a section through the middle line. Fe, Femur, foreshortened; Fi, fibula; H, humerus; Il, ilium; Is, ischium; P.P., pubis; R, radius; Scap, scapula; Tb, tibia; u, ulna; 3, third cervical vertebra; 1, 3, 5, first, third, and fifth fingers; XIII, thirteenth (fifth thoracic) vertebra.
The pelvis is strong. Ilium, pubis, and ischium meet at the acetabulum. The dorsal end of the ilium is generally broadened, and is attached to one or both sacral vertebrae, but it is also in contact with the superimposed last costal plate. ”

“ Hence the sacrum and coccyx of the adult are the false, whilst the lumbar, dorsal and cervical are the true vertebrae.
The vertebrae are irregularly-shaped bones, but as a rule have certain characters in common. Each possesses a body and an arch, which enclose a ring, with certain processes and notches. The body, or centrum, is a short cylinder, which by its upper and lower surfaces is connected by means of fibro- cartilage with the bodies of the verte- brae immediately above and below. The collective series of vertebral bodies forms the great column of the spine. ”