QUESTIONS AND ANSWERS 99 



Name the regions into which the abdominal cavity is divided for study. 

 Sublumbar, right and left lumbar, suprasternal, umbilical, pre- 

 pubic, right and left inguinal, hypochondriac, flank, diaphragmatic 

 and pelvic regions. 



At what point in the head would you trephine to open (a) the frontal 

 sinus, (b) the lower maxillary sinus? 



(a) At the point of intersection of a line connecting the superior 

 borders of the orbital cavities and one parallel to, but about one-half 

 inch from, the median line. 



(b) Just above the inferior extremity of the zygomatic ridge. 



Through what tissues do you cut in the operation of median neurec- 

 tomy? 



Skin, sterno-aponeuroticus muscle and antibrachial fascia. 



Histological Anatomy 



Describe (a) arteries, (b) veins, (c) nerves. 



(a) The arteries are cylindrical tubes which carry the blood from 

 the heart to the various organs of the body. All arteries carry pure 

 blood with one exception, the pulmonary artery. They originate at 

 the heart by two great trunks which divide and subdivide until their 

 size is almost imperceptible (capillaries). 



Arteries are more or less rigid and elastic and have three tunics, 

 viz., an external fibrous (tunica adventitia), a middle (tunica 

 media), and an internal (tunica intima). 



The outer coat is nourished by small blood-vessels, called vaso- 

 vasorum, which are quite voluminous in the large arteries. Nerves, 

 vasomotor, from the sympathetic system accompany these vessels. 



(b) The veins are likewise cylindrical tubes which accompany 

 the arteries and carry the impure blood from the distant parts 

 to the heart ; with one exception, the pulmonary veins which carry 

 pure blood from the lungs to the left auricle. They have two 

 distinct coats, an internal serous and an external of elastic and 

 muscular fibres. The walls of veins are thin, semitransparent and 

 elastic and collapse when empty. Nourishment is provided by vaso- 

 vasorum. 



The interior of veins is remarkable for the presence of valves 

 which favor the flow of blood. No valves are found in the pul- 

 monary and portal veins and vena cava. 



(c) The nerves are the peripheral portions of the nervous sys- 

 tem. They originate in the brain or cord and are distributed to 

 every part of the body. Their structure is made up of a collection 



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