14 SURGICAL APPLIED ANATOMY. [Chap. 11. 



some of the pus, escaping through the mastoid vein, 

 led to an abscess in the neck. 



Certain venous tumours are met with on the skull. 

 They consist of collections of venous blood under the 

 pericranium that communicate, through holes in the 

 skull, with the superior longitudinal sinus. They are 

 median, are reducible on pressure, and receive a faint 

 pulsation from the brain. The holes are sometimes the 

 result of accident, others depend upon bone disease or 

 atrophy about a Pacchionian body, and a few are due 

 to a varicose emissary vein, or to a congenital defect 

 in the cranium. 



The scalp nerves, especially such as are branches 

 of the fifth pair, are often the seat of neuralgia. To 

 relieve one form of this affection, the supraorbital 

 nerve has been divided (iieurotomy) at its point of 

 exit from the orbit, and a portion of the nerve has 

 been resected (neurectomy) in the same situation. 



Some forms of frontal headache depend upon neu- 

 ralgia of this nerve. The inner branch of the nerve 

 reaches the middle of the parietal bone ; the outer 

 branch, the lambdoid suture. 



The lymphatics from the occipital and posterior 

 parietal regions of the scalp enter the suboccipital and 

 mastoid glands ; those from the frontal and anterior 

 parietal regions go to the parotid glands, while some of 

 the vessels from the frontal region join the lymphatics 

 of the face, and end in the submaxillary glands. 



CHAPTER II. 



THE BONY VAULT OF THE CRANIUM. 



Position of the sutures. The bregma, or 

 point of junction of the coronal and sagittal sutures, 

 is in a line drawn vertically upwards from a point just 

 in front of the external auditory meatus, the head 



