_1.R._, First thoracic vertebra; _1.L._, first lumbar vertebra; _2.
K._, second sacral spine; _S_, scapula; _A_, humerus; _B_, ilium;
_O._, femur; _Sch._, pubis; _Si._, ischium; _St._, sternum; _L._,
right lobe of liver; _r.N._, right kidney; _C._, body, _C′._, base,
_C″._, apex of cæcum; _r.v.C._, right ventral colon; _v.Q._, sternal
flexure of colon; _d.Q._, diaphragmatic flexure of colon; _r.d.C._,
right dorsal colon; _F._, pelvic flexure of colon; _D._, small
intestine; _H._, urinary bladder; _M._, rectum; _a_, left ventricle;
_a′_, right ventricle; _b_, _b′_, right coronary artery; _c_, left
atrium; _c′_, right atrium; _d_, small (left) coronary vein; _e_,
vena azygos; _f_, anterior vena cava; _g_, posterior vena cava; _h_,
sinus venosus; _i_, right phrenic nerve; _k_, right vagus, with its
dorsal (_k′_) and ventral (_k″_) divisions; _l_, aorta; _m_,
œsophagus; _n_, trachea; _o_, diaphragm (median section); _p_, right
lateral ligament of liver; _q_, duodenum; _r_, dotted line
indicating position in median section of diaphragm in inspiratory
phase; _s_, recto-coccygeus; _t_, suspensory ligament of rectum;
_u_, sphincter ani; _v_, vesicula seminalis; _w_, prostate; _x_,
bulbo-urethral (Cowper’s) gland; _y_, urethra; _z_, abdominal wall;
_z′_, xiphoid cartilage. (After Ellenberger, in Leisering’s Atlas,
reduced.)
]
The first part of the great colon is attached to the lesser curvature of
the cæcum by two layers of peritoneum which form the =cæco-colic fold=.
The ventral parts of the colon are similarly connected to the dorsal
parts of the same side by the mesocolon. The right portions are united
also by areolar tissue and muscular fibers, the surface of contact being
about four or five inches (ca. 10 to 12 cm.) wide; the left portions are
attached to each other by a peritoneal fold wide enough to allow them to
be drawn apart five or six inches (ca. 12 to 15 cm.) near the pelvic
flexure. The terminal part of the colon is attached by peritoneum and
areolar tissue to the ventral surface of the pancreas dorsally and to
the base of the cæcum externally. It is connected indirectly with the
diaphragm and liver by means of a fold derived from the right lateral
ligament of the liver.
The =relations= are complex, but the more important facts are as
follows: The ventral portions (first and second) have extensive contact
with the abdominal wall ventrally and laterally. On the right side the
colon is almost entirely excluded from contact with the flank by the
cæcum; on the left side it has no contact with the upper part of the
flank, being excluded here by coils of the small colon and small
intestine. Dorsally the chief relations are to the stomach, duodenum,
liver, pancreas, small colon, small intestine, aorta, vena cava, and
portal vein. Since there are no transverse attachments of the right and
left portions, and the latter have no attachment to the wall, they are
subject to considerable displacement.[94] The pelvic flexure is variable
in position, but usually it is directed to the right across the pelvic
inlet.
[Illustration: