22 Anatomy of Skeleton 



morphologically different from those lower down. If the upper surfaces of the bodies 

 of the middle and lower cervical vertebra are inspected, a prominent neuro-central lip 

 is seen standing up outside the junction of the costal element and neural arch with 

 the centrum : in the recent state a small synovial cavity lies between this lip and the 

 bone above, outside and behind the intervertebral disc. 



From its position this cavity is in front of the issuing nerve : the cavities increase 

 in size in the upper part of the column, and their bases become the functional articular 

 processes on the Atlas and top of Axis, so that the issuing nerves lie behind them. These 

 small cavities are evidently in series with the costo-vertebral j oints in the dorsal region ; 

 inspection of the direction of the bony fibres in the surface texture at the junction of 

 costal element with body suggests that they are ossified representatives of the stellate 

 ligaments of the rib heads. 



The Vertebrarterial (costo-vertebral, costo-transverse) foramen transmits the artery with its 

 accompanying veins and a sympathetic plexus from the lower cervical ganglion ; it is subdivided 

 in the fifth and sixth segments, the small posterior part being for a vein, and the subdivision may 

 be present in the seventh and is occasionally suggested by bony spicules in the third and fourth. 

 The seventh foramen only transmits a vein and a filament (grey ramus) from the ganglion running 

 up to join the seventh nerve. The ganglion is situated beside the vertebral artery below the level of 

 the seventh costal process, so that its filament to the eighth nerve reaches it directly, but that to the 

 seventh must ascend through the foramen. 



At the top of the column the line of the arterial channel turns sharply outwards 

 in the Axis and is thus able to reach the foramen in the Atlas : observe that the 

 transverse process of the Atlas extends further out than any other in the series, the 

 next in range being that of the seventh. 



The laminae increase in depth from the third downwards. They tend to overlap 

 each other, so that the Ligamenta subflava, which are attached to the upper borders 

 of each lamina, pass up deep to the lower borders of the laminae above and reach their 

 anterior surface : their attachment here is marked by a transverse ridge on the neural 

 surface of the laminae. The superficial or posterior surface is roughened by marks of 

 tendinous insertions of Multifidus spinae : these are near the lower edges and the 

 spines, on to which they extend. Outside the laminae are tuberculated areas on the 

 backs of the inferior articular processes of the lower four segments : the upper fibres 

 of Multifidus arise here, and outside them is the origin of the more superficial next 

 layers, Semispinalis, Complexus, and Trachelo-mastoid. The compound nature of 

 these markings on the articular processes is sometimes apparent, particularly on the 

 fifth vertebra, where a strong fasciculus of Multifidus frequently makes the inner 

 portion of the marking into a more or less prominent tubercle (Fig. 17). 



The insertions of the still more superficial Cervicalis ascendens and Transversus 

 cervicis are on to the backs of the transverse processes, further out and further forward. 



The divergent points of the spinous processes afford insertion to Semispinalis 

 colli, and the small prominences on their inner sides, that give them an angled appear- 

 ance, mark the attachment of the bilaminar ligamentum nuchae. A median ridge on 

 the under aspect of the spine shows the attachment of the weak interspinous ligament, 

 corresponding with the median upper ridge on the bone below. 



The seventh spine is non-bifid, and this is frequently the case also in the sixth 

 and above this a condition normal in lower races ; but even when this occurs there is a 

 distinct suggestion of its double nature, which is not found in the last cervical spine. 



The three-sided spinal canal increases in size from the Axis to the fifth and then 

 decreases, so corresponding with the position of the thickest part of the cervical 

 enlargement of the cord. The front wall is the back ol the body, but this is covered 



