DISSECTION OF THE UPPER EXTREMITY 45 



Make four additional outline sketches and insert the " re- 

 gions " of the upper extremity and thoracic wall, having first 

 marked them out accurately with the end of the probe on the 

 body. Use Figs. 1 and 2 as a guide. Ask yourself the reason 

 for the name of each region. 



EEGIONS OF THE BACK (REGION ES DORSI). 



Surface Anatomy. 



In the median region of the back (regio mediana dor si) pal- 

 pate the spinous processes (processus spinosi) of the vertebrae. 

 Are they all in one plane ? Find the spine of the seventh cervical 

 vertebra (vertebra prominens). Are any other spines especially 

 noticeable? Enumerate the spines consecutively. Is there any 

 marked kyphosis, lordosis, or scoliosis present? 1 Palpate the 

 scapula and ascertain its general outline. Move the arm in 

 various directions and note accompanying changes in position 

 of scapula. With the arm of the cadaver by the side, establish 

 the spinal level and the rib-level of the angulus medialis and 

 of the angulus inferior of the scapula. Run the finger along the 

 spina scapulae and the acromion and note that both are subcu- 

 taneous. Establish exactly the bony point corresponding to the 

 junction of the lower border of the spina scapulae with the lat- 

 eral margin of the acromion. ( Surgeons measure the arm from 

 this point, the tape being carried down to the epicondylus later- 

 alis of the humerus.) 



Superficial Structures. 



Make skin incisions (1) along the linea mediana posterior 

 from the vertebra prominens to the tip of the coccyx, (2) from 

 the tip of the coccyx to the posterior superior iliac spine, then 

 along the crista iliaca to near the anterior superior iliac spine, 

 (3) from the vertebra prominens to the medial edge of the 

 acromion, and (4) from the processus spinosus vertebrae 

 Jumbal is I. to the lateral margin of the acromion. Reflect the 

 two triangular flaps of skin, taking none of the fat of the 

 superficial fascia with it. Have your atlases open before you. 

 Having ascertained the region in which tlie medial set of cuta- 

 neous vessels and nerves is likely to be found, witli the knife 

 make a small cut through the superficial fascia down to the deep 



1 When a word is met with in this manual (or in any text-book) which is 

 new to the student, he should look up its meaning at once in a good medical 

 dictionary. 



