DISSECTION OF THE HEAD AND NECK 337 



(h) Parieto-occipital fissure (ftssura parietooccipitalis) . 



(i) Cuneus (cuneus) ("wedge"). This belongs to the occipital lobe. 



(j) Calcarine fissure (ftssura calcarina). 



Island (Insula) (O. T. Island of Reil, or Central Lobe). 



Pull the lips of the Sylvian fissure apart and examine the 

 island. If possible, study the island on a fresh brain or on one 

 prepared especially to show the island. How is it bounded! 

 Examine carefully the overhanging operculum, and note that it 

 is subdivisible into a frontal part (pars frontalis), a parietal 

 part (pars parietalis), and a temporal part (pars temporalis). 

 In the island study 



(a) Sulci of island (sulci insulae). 



(b) Gyri of island (gyri insulae). 



(ba) Long gyrus of island (gyrus longus insulae). 



(bb) Short gyri of island (gyri breves insulae). 



Olfactory Brain (Rhinencephalon). (Vide Fig. 151.) 

 Examine 



(a) Anterior parolfactory sulcus (sulcus parolfactorius anterior). 



(b) Anterior part of rhinencephalon (pars anterior [rhinencephali]). 



(ba) Olfactory lobe (lobus olfactorius) . 



(baa) Olfactory bulb (bulbus olfactorius). 



(bab) Olfactory tract (tractus olfactorius) (incorrectly 



sometimes designated "olfactory nerve"). 



(bac) Olfactory trigone (trigonum olfactorium) . 



(bad) Medial stria (stria medialis). 



(bae) Intermediate stria (stria intermedia). 



(bb) Parolfactory area of Broca (area parolfactoria [Brocae]). 



(c) Posterior parolfactory sulcus (sulcus parolfactorius posterior). 



(d) Posterior part of rhinencephalon (pars posterior [rhinencephali]). 



(da) Subcallosal gyrus (gyrus subcallosus [pedunculus corporis 



callosi] ) . 



(daa) Anterior perforated substance (substantia perforata 

 anterior). 



(db) Lateral olfactory stria (stria olfactoria lateralis). 



(dc) Threshold of island (limen insulae). 



Note that, in the broader sense, the gyrus fornicatus, fimbria 

 and fascia dentata hippocampi, fornix, and corpora mammilla- 

 ria are often classed as belonging to the rhinencephalon. In the 

 fissura hippocampi note the fimbria hippocampi and the fascia 

 dentata hippocampi (O. T. gyrus dentatus), lying side by side. 

 The handle of the scalpel shoved deeply into the brain just above 

 the fimbria would enter the inferior cornu of the lateral ventricle. 



22 



