LUMBAR VERTEBRA. 



117 



The laminae are smooth and do not quite meet those of the next vertebra, 

 unless the head be bent backward. 



The spinous process projects backward and a little downward. It is short 

 and forked at the end, very often unevenly. 



The transverse processes are often described as double. The posterior limb, 

 which is the true transverse process, projects outward and somewhat forward from 

 the junction of the pedicle and lamina, and ends in a flattened, nearly vertical pro- 

 jection, the posterior tra7isverse tubercle. The anterior limb, a vertical plate spring- 

 ing from the side of the body and extending outward, ends in the anterior transverse 

 tubercle. This limb is the shorter of the two and its tubercle the larger. The limbs 

 are connected by a concave plate or bone, slanting slightly outward, which forms 

 the floor of a gutter ^ in which the spinal nerve lies, and which represents the costal 

 element. A round hole, the transverse foramen, for the vertebral artery and veins, 

 lies internal to this plate ; the artery usually does not pass through the foramen of 

 the seventh vertebra. Since the scalenus anticus muscle springs from the anterior 



Fig. 145. 



Spinous process 



Lamina 



Superior articular facet 

 Mammillary process. 



Transverse 



process 

 ( Costal ele- 

 ment) 



Third lumbar vertebra from above. 



tubercles and the scalenus medius from the posterior ones, on leaving the spine the 

 spinal nerves pass between these muscles. 



The articular processes are placed at the outer ends of the laminae ; the 

 upper face upward and backward, the lower forward and downward. 



Lumbar Vertebrae. — A typical lumbar vertebra is very much larger than the 

 others. 



The body is broad from side to side, the upper and lower borders projecting 

 especially at the sides. The posterior surface is slightly concave and presents two 

 large venous openings. 



The spinal foramen is three-sided, with a transverse diameter but slightly 

 exceeding the antero-posterior. 



The pedicles are short and strong, diverging only slightly. They are very 

 nearly on a level above with the top of the body, so that there is a small notch above 

 and a large one below. 



The laminae are broad at the sides, but less so near the mid-line, so that in this 



' Sulcus n. spinalis. 



