1386 



A MANUAL OF ANATOMY 



The superior or first, middle or second, and inferior or third frontal 

 gyri are arranged in tiers, which are disposed antero-posteriorly, 

 the first and second being usually each subdivided, so as to make 

 five tiers in all. They are separated from the ascending frontal 

 or precentral gyrus by the superior and inferior parts of the pre- 

 central sulcus. 



The superior frontal gyrus is narrow, and lies between the supero- 

 mesial border of the hemisphere and the superior frontal sulcus. 

 It is continuous with the marginal gyrus on the internal surface of 



Cerebral Hemisphere 



Fig. 582. — The Encephalon (Right Lateral View) (Hirschfeld 

 AND Leveille). 



6. Ramus Horizontalis. 



7. Ramus Occipitalis. 



8. Transverse Occipital Sulcus. 



9. Lateral Occipital Sulcus. 



10. External Part of Occipito- Parietal Fissure. 



11. Superior Temporal, or Parallel, Sulcus. 



12. Inferior Temporal Sulcus. 



1 . Fissure of Rolando. 



2. Posterior Horizontal IJmb of Fissure of 



Sylvius. 



3. Anterior Ascending Limb of Fissure of 



Sylvius. 



4. Anterior Hoiizontal Limb of Fbsure of 



Sylvius. 



5. 5. Intraparietal Sulcus. 



the hemisphere, and is partially broken up into two parts, upper 

 and lower. 



The middle frontal gyrus, which is broad, lies between the superior 

 and inferior frontal sulci, and is usually connected with the ascend- 

 ing frontal or precentral gyrus by an annectant gyrus. It is broken 

 up anteriorly into two parts, upper and lower, by an antero-posterior 

 secondary sulcus ; and it is cut into behind by the upper portion of 

 the inferior part of the precentral sulcus. 



