A handbook for nurses / by J.K. Watson.

  • Watson, J. K. (James Kenneth)
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: A handbook for nurses / by J.K. Watson. Source: Wellcome Collection.

    18/448 page 2
    Periosteum. Spinal column: its importance in com- parative anatomy, Number of vertebrae: their nameS; Sacrum, Coccyx, Curves of the spinal pplumn. latter its lightness. Inside such a bone as we are now considering is a canal, which contains the bone-marrow. Covering the bone is a membrane called the periosteum (Gk. peri^ around; osteon, bone), from which it derives its chief nourishment; for when the bone is stripped of its periosteum the affected part dies—this is known as necrosis. The ends of the long or cylindrical bones are covered with gristle (cartilage), which allows them to move freely and smoothly over each other. It is customary in describing the skeleton to commence with the spine, which is a flexible column composed of irregularly shaped bones called vertebrae (Lat. vertere, to turn). In classifying the members of the animal kingdom the presence or absence of the vertebral column is made use of, and thus arises the first broad division of animals into Vertebrata and Invertebrata. The spinal column, then, is of the greatest importance in the study of what is known as comparative anatomy—the science which deals with the study of the structure of the lower animals, as compared with that of the highest member of the animal kingdom, man himself In man the axis of the spine is vertical, which gives to him one of his most marked characteristics—namely, the erect attitude. Some of the monkeys (man-like apes), such as the gorilla or chimpanzee, approach man in this respect, having their spine semi-erect; but the spinal axis in the lower animals is more or less horizontal. The number of the vertebrae is thirty-three; they are divided into five groups, according to the region which they occupy— namely, cervical or neck vertebrge, dorsal or back, lumbar or loin, sacral, and coccygeal. The cervical region contains seven, the dorsal twelve, the lumbar five, the sacral five, and the coccygeal four. The vertebrae in the two last regions are in adult life united to form two bones, the sacrum (sacred bone) and the coccyx (so called from its resemblance to a cuckoo's beak), so that the number of vertebras is now reduced to twenty-six. The sacrum is made up of the five sacral vertebrae, and the coccyx of the four coccygeal. Between the vertebrae are discs of cartilage, to which the curves of the spinal column are largely due. These curves, when the spine is viewed laterally, are seen to be three in
    digitised image 1
    digitised image 2
    digitised image 3