1324 THE SKIN, MAMMARY GLANDS AND DUCTLESS GLANDS 



whose principal function seems to be to aid in keeping up the tone and activity of 

 the muscle and other tissues innervated by the sympathetic system. 



Situation. — The glands are deeply placed in the epigastric region (fig. 1080) 

 hdng in the dorsal and cephalic part of the abdominal cavity, one on either side of 

 the vertebral column in variable relation with the upper extremity of the kidney 

 of the corresponding side. 



Rarely they retain the foetal relation, capping the superior extremity of the kidney and 

 extending a little upon both medial and lateral borders. More frequently (especially on the 

 left) they are placed more upon the medial borders of the kidneys, extending (on the left) as 

 far caudal as the hilus, sometimes coming in contact with the renal vessels. An intermediate 

 position is often found, especially on the right. In the high positions the suprarenals may be 

 on a level with the tenth intercostal space or eleventh rib. In the low positions they may 

 extend as far caudally as the first lumbar vertebra. The left is usually, but not always, a 

 little higher than the right, corresponding to the position of the kidneys. 



Fixation. — The suprarenals, enclosed in the renal adipose capsules, are attached 

 to the renal fascia by connective-tissue strands and are loosely bound by connect- 

 ive tissue to the kidneys. The attachment to the kidneys is, however, so loose 

 that the suprarenals are not dislocated when the kidneys are displaced. In 

 addition to the attachments common to them and to the kidneys, they are joined 

 by connective-tissue bands to the diaphragm, vena cava, and liver on the right 

 side and to the diaphragm, aorta, pancreas and spleen on the left. They have also 

 additional means of fixation through the arteries, veins, and nerve fibres which 

 enter and leave them, and through the parietal peritoneum which in places 

 covers their ventral surfaces. 



Fig. 1079. — Diagrammatic Section of the Suprarenal Gland. 



Size and weight. — The size of the suprarenals is subject to considerable 

 variation within physiological limits, in some cases being relatively twice as large 

 as in others. The two glands are rarely of the same size, the right being more 

 often the smaller. 



Proportionately they are much larger in the foetus and embryo than in the adult, but they 

 do not decrease in size in old age. Thej' appear to be slightly lighter in women than in men. 

 The average weight in the adult is from 4 to 5^ grams. As a rule, they measure about 30 mm. 

 in height; 7 or 8 mm. in thickness; and have a breadth at the base of about 45 mm. They 

 augment in volume during digestion and also increase in size during the acute infectious 

 diseases and in intoxications such as uremia. 



Colour and consistency. — The suprarenal glands as seen from the surface 

 have a yellowish or brownish-yellow colour. Upon section the colour of the 

 surface layer appears a little darker while the central part of the gland appears 

 greyish or, if it contains much blood, of a reddish colour. If some little time has 

 elapsed since death, the central part of the suprarenal may be almost black in 

 colour. 



The glands arc very fragile and softer in consistency than the thyroid or thymus. As a 

 rule, they are harder and more resistant than the fat of the adipose capsule and may be thus 

 readily detected in it. 



Form. — The suprarenal glands are markedly flattened dorso-ventrally. Their 

 surfaces are roughened by irregular tubercles and furrows. They vary consider- 

 ably in shape (figs. 1077, 1078). TIk; right gland is usually somewhat triangular 

 in outline while the left is, as a rule, semilunar. Each gland has an anterior and a 

 posterior surface, a base and an apex, a medial and a superior margin. 



The anterior surface [facias anterior] may be either convex or concave, and 



