

THOKACIC VEKTEBR^, 93 



The seventh cervical vertebra (vertebra prominens) receives the latter name 

 from the outstanding natureof its spinous process, which ends in a single broad tubercle. 

 This forms a well-marked surface projection at the back of the root of the neck. 

 The transverse processes are broad, being flattened from above downwards ; they 

 project considerably beyond those of the sixth. The maximum width between 

 their extremities agrees with that between the transverse processes of the atlas, 

 these two constituting the widest members of the cervical series. The anterior 

 tubercle is very small and is placed near the body. The foramen transversarium is 

 small and does not as a rule transmit the vertebral artery. Usually a small vein 

 passes through it. Not infrequently the costal element is separate from the true 

 transverse process, thus constituting a cervical rib. 



Vertebras Thoracales. 



The thoracic vertebrae, twelve in number, are distinguished by having facets 

 on the sides of their bodies for the heads of the ribs, and in most instances also 

 articular surfaces on their transverse processes for the tubercles of the ribs (Fig. 

 124, p. 111). 



The body is described as characteristically heart-shaped, though in the upper 

 and lower members of the series it undergoes transition to the typical forms of the 

 cervical and lumbar vertebrae, respectively. Its an tero- posterior and transverse 

 measurements are nearly equal ; the latter is greatest in line with the facets for 

 the heads of the ribs. The bodies are slightly thicker behind than in front, thus 

 adapting themselves to the anterior concavity which the column displays in this 

 region. The bodies of the second to the ninth thoracic vertebrae inclusive, each 

 possess four fovese costales or costal facets, a superior and larger pair placed on the 

 superior margin of the body, close to the junction of the root of the vertebral arch 

 with the body, and an inferior and smaller pair situated on the inferior edge, close 

 to and in front of the inferior intervertebral grooves. 



When contiguous vertebrae are articulated, the upper pair of facets of the lower 

 vertebra coincide with the lower facets of the higher vertebra, and, together with the 

 intervening intervertebral nbro-cartilage, form an articular cup for the reception of the 

 head of a rib. Of these facets on the body the upper pair are the primary articular 

 surfaces for the head of the rib ; the lower are only acquired secondarily. Moreover, these 

 facets, though apparently placed on the body, are in reality developed on the sides of the 

 roots of the vertebral arches behind the line of union of the roots with the body (neuro- 

 central synchondrosis), as will be explained hereafter. 



The roots of the vertebral arches (O.T. pedicles) are short and thick, and 

 directed posteriorly and slightly upwards. The superior vertebral notch is faintly 

 marked ; the inferior is deep. The laminae are broad, flat, and sloping, having sharp 

 superior and inferior margins. When the vertebrae are superposed the latter 

 overlap the former in an imbricated manner. The vertebral foramen is smaller 

 than in the cervical and lumbar regions, and nearly circular in shape. 



The spinous processes vary in length and direction, being shorter and more 

 horizontal in the upper and lower members of the series, longest and most oblique 

 in direction towards the middle of this part of the column. Nearly all have a down- 

 ward inclination, and are so arranged that they overlap one another. Triangular in 

 section where they spring from the vertebral arch, they become compressed from side 

 to side towards their extremities, which are capped by more or less distinct tubercles. 

 The transverse processes are directed backwards and laterally, and a little upwards. 

 They gradually decrease in size and length from above downwards. Each has a 

 somewhat expanded extremity, the anterior surface of which, in the case of the upper 

 ten vertebr.83, is hollowed out in the form of a circular facet for articulation with 

 the tubercle of the rib which rests in the upper facet of the vertebra to which the 

 transverse process belongs. The superior articular processes are vertical, and have 

 their surfaces directed backwards, slightly upwards, and a little laterally; the 

 inferior, correspondingly forwards, downwards, and medially. 



Certain of the thoracic vertebrae display characters by which they can readily 



