THE VERTEBRAL COLUMN 25 



DESCRIPTIVE TERMS 



The surfaces of the bones present a great variety of eminences and depressions 

 as we 1 as perforations. The prominences and cavities may be articular, or non- 

 articular, furnishing attachment to muscles, tendons, ligaments, or fascia A 

 number of descriptive terms are used to designate these features, and the following 

 are some of those in general use : 



Process (Processus) is a general term for a prominence. 



A tuberosity (Tuber, Tuberositas) is a large, rounded projection; a tubercle 

 (Tuberculum) is a smaller one. 



The term trochanter is applied to a few prominences, e. g., the trochanters of 

 the femur. ' 



A spine (Spina) or spinous process (Processus spinosus) is a pointed projection. 



A crest (Crista) is a sharp ridge. 



A line (Linea) is a very small ridge. 



A head (Caput) is a rounded articular enlargement at the end of a bone; it 

 may be joined to the shaft by a constricted part, the neck (CoUum). 



A condyle (Condjdus) is an articular eminence which is somewhat cylindrical; 

 a non-articular projection in connection with a condyle may be termed an epi- 

 condyle (Epicondylus). 



A trochlea is a pulley-like articular mass. 



A glenoid cavity (Cavitas glenoidalis) is a shallow articular depression, and a 

 cotyloid cavity or acetabultmi is a deeper one. 



The term facet is commonly applied to articular surfaces of small extent, 

 especially when they are not strongly concave or convex. 



The terms fossa, fovea, groove or sulcus, and impression are applied to various 

 forms of depressions. 



A foramen is a perforation for the transmission of vessels, nerves, etc. 



A sinus is an air-cavity within a bone or bones; it is lined with mucous mem- 

 brane and communicates with the exterior. 



Other terms, such as canal, fissure, notch, etc., require no explanation.^ 



THE VERTEBRAL COLUMN 



The vertebral coluiim (Columna vertebralis) is the fundamental part of the 

 skeleton. It consists of a chain of median, unpaired, irregular bones which 

 extends from the skull to the end of the tail. In the adult certain vertebrae have 

 become fused to form a single bony mass with which the pelvic girdle articulates. 

 Vertebrae so fused are termed fixed (or "false") vertebrae (Vertebrse immobiles), as 

 distinguished from the movable (or "true") vertebrae (Vertebrae mobiles). 



The column is subdivided for description into five regions, which are named 

 according to the part of the body in which the vertebrae are situated. Thus the 

 vertebrae are designated as cervical, thoracic, lumbar, sacral, coccygeal (Vertebrae 

 cervicales, thoracales, lumbales, sacrales, coccygeae). The number of vertebrae in 

 a given species is fairly constant in each region except the last, so that the verte- 

 bral formula may be expressed (for the horse, for example) as follows: 



C7Tl8L6S6Cyi5.21. 



The vertebrae in a given region have characters by which they may be dis- 

 tinguished from those of other regions, and individual vertebrae have special 

 characters which are more or less clearly recognizable. All typical vertebrae have 



' As might be expected from the history of anatomy, a good many of these terms are more or 

 less interchangeable; furthermore, a given skeletal feature may differ greatly in various species. 



