258 ANATOMY IN A NUTSHELL. 



In Front. — (1) .Superior vena cava. (2) upper portion of right auricle of 

 heart. (3) anterior pulmonary plexus, (4) right phrenic nerve. 



Behind. — (1) Posterior pulmonary plexus, (2) pneumogastric nerve, (3) 

 vena azygos major. 



Above. — (1) Vena azygos major. 



Below. — Broad ligament (ligamentum latum pulmonis.) 



Relations of the left root. (Plate CXXVIL) 



In Front. — (1) The anterior pulmonary plexus. (2) the left phrenic nerve. 



Behind. — The descending aorta, (2) pneumogastric nerve, (3) posterior 

 pulmonary plexus. 



Above. — The arch of the aorta. 



Below. — The broad ligament (ligamentum latum pulmonis.) 



About one hundred cubic inches of air remains in the lungs which cannot 

 be expelled. (Plate CXXIY.) This is called residual air. After an ordinary 

 expiration one hundred cubic inches of air can be expelled by forced expira- 

 tion, this is called reserve air. About twenty or thirty cubic inches of air which 

 passes in and out during the ordinary breathing is called tidal air. After an 

 ordinary inspiration one can inhale one hundred and twenty cubic inches of air, 

 which is called eomplemental air. After the complemental air has been taken 

 into the lungs then one may expell all the air, except the residual air, and this 

 is called vital capacity. 



LESSON LXXI. 



A vertebra (Plate XC1X) consists of a body and an arch, the latter being 

 formed by two pedicles ami two laminae which support the seven processes. 

 The body is thick and spongy, convex in front from side to side and concave 

 vertically on the upper and lower surfaces which are surrounded by bony rims. 

 Anteriorly are small foramina for nutrient vessels, posteriorly a large foramen 

 for the exit of the venae basis vertebrarum. The pedicles project backward from 

 the body, inclining outward; they are noticed above and below, thus forming, 

 with the adjacent notches, the intervertebral foramina for the entrance of ves- 

 sels and the exit of spinal nerves. The laminae are two broad plates meeting 

 in the spinous process belaud and rough on the upper and lower borders for the 

 attachment of the ligamenta subfiava. The transverse processes, one on each 

 vide, project outward. The articular processes, two on each side, superior and 

 inferior, project from the junction of the lamina? and the pedicles, articulating 

 above and below with the articular processes of the adjacent vertebrae. Their 

 superior facets look upward in the cervical region, outward in the dorsal region, 

 and inward in the lumbar. The spinous process projects backward from the 

 junction of the lamina?, sometimes very obliquely. The spinal foramen is the 

 -pace enclosed by the body, pedicles, and lamina?, and each foramen when the 

 vertebrae are articulated, form part of the spinal canal. 



There are thirty-three vertebra? in number, exclusive of those which form 

 the skull, having received the names of cervical, dorsal, lumbar, sacral, and 

 coccygeal, according to the position which they occupy, seven being found in 



