24 APPLIED ANATOMY. 



noid in the subarachnoid space. If, however, the blood has escaped with consider- 

 able force, it tears its way through the arachnoid and spreads in the subdural, as well 

 as through the subarachnoid space. The origin of this form of hemorrhage is the 

 vessels of the pia mater. The arachnoid does not give rise to hemorrhages, neither 

 does the inner surface of the dura, unless it has previously been the seat of pachy- 

 meningitis interna. 



The hemorrhage is the result either of injury or disease. In children it is 

 usually due to injury; in adults to either injury or disease. These hemorrhages are 

 most common in infancy and occur in childbirth. They are due apparently to 

 hard, protracted labor or injury done to the child in effecting delivery by forceps, 

 etc. , especially in infants born before full term. They are a cause of idiocy and the 

 cerebral palsies of childhood. These hemorrhages in the new-born have been 



Olfactory tract 

 Optic nerve 

 Optic chiasm 

 Optic tract 



3rd motor 



oculi 



4th trochlear 

 (pathetic) 



5th trigenii- 

 nal (trifacial) 



6th abducent 



7th facial 

 8th auditory 



9th glosso- 

 pharyngeal 

 loth vagus 

 (pneumogas- 

 tric) 



nth spinal 

 accessory 



I2th hypoglossal 



FIG. 28. Base of brain, showing exit of cranial nerves. 



recognized by the convulsions they produce, and successful operations have been 

 performed for their relief (see Harvey Gushing "Surgical Intervention for the 

 Intracranial Hemorrhages of the New-born " Am. Jour. Med. .SVz., October, 1905). 

 Injuries received later in life from blows on the head often produce subdural or pial 

 hemorrhages, without breaking the overlying bone. They are found either at the site 

 of impact or on the side opposite that on which the blow was received, the latter being 

 produced by contre-coup. When pial hemorrhage occurs from disease, it is usually 

 from rupture of an aneurism of one of the vessels of the pia mater. If it does not break 

 through the arachnoid into the subdural space, it may spread over a considerable 

 portion of the cerebral cortex, especially filling the sulci. Unless the quantity is quite 

 large, so that it interferes with the motor area, hemiplegia will not occur. Convulsions 

 may occasionally occur from irritation of the cortex. Blood in the subdural space 

 may travel along the base of the brain and into the sheath of the optic nerve. 



