BASE OF THE SKULL. 183 



Pre. po., Processus postorbitale. — Post orbital process of the frontal bone. 



§ 524. S. (Sinus) frontalis — Frontal sinus. — This cavity in the frontal bone is sep- 

 arated from its platetrope by a bony partition (Fig. 60). It communicates with the nasal 

 cavity through the infundibulum (I.) and is lined by an extension of the nasal mucous 

 membrane. 



§ 525. Sutura lambdoidalis, az. — Lambdoidal or occipito-parietal suture. — This is the 

 synarthrodial articulation between the parietal, the interparietal and the supraoccipital 

 bones. 



§ 526. Sutura sagittalis, az. — Sagittal suture.— The synarthrodial articulation between 

 the right and left frontal and the parietal bones. It extends from the nasal bones to 

 the lambdoidal suture. 



In Human Anatomy, the sagittal suture is confined to the articulation of the two parie- 

 tals with each other, the two frontals uniting so early that they are considered as a 

 single bone. 



§ 527. Sutura coronalis — Coronal or parieto-frontal suture. — The synarthrodial artic- 

 ulation between the frontal and parietal bones. 



§ 528. Fig. 57 — Preparation. — Tlie skull was tlioronglily 

 cleaned, and while still moist the following structures were removed 

 from the right side : — 



(A) The tympanic bulla was removed by inserting an arthro- 

 tome between it and the basioccipital and prying steadily, thus 

 exposing the Pars petrosa^ the Foramen lacerum jugular e and Fm. 

 lacerum medium^ the Fenestra ovalis and Fenestra rotunda. 



(B) The Os pterygoideum and a part of the Os palatinum were 

 removed by the nippers to expose the row of foramina. 



(C) The teeth were extracted with the nippers to expose the 

 almoli (sockets of the teeth). 



a, b. — Fractures made in removing the bulla. 



Bulla tympanica. — Tympanic or auditory bulla (Fig. 58). 



§ 529. Cd. DC, Condylus occipitalis — Occipital condyle. — The occipital condyle is 

 formed mostly by the exoccipital, but somewhat also by the basioccipital. It articulates 

 diarthrodially with the atlas. 



Cn, eu., Canalis Eustachiana. — Eustachian canal (Fig. 58). 



D. m., Dens molaris. — Molar tooth. 



DD. pm., Dentes praemolares. — Prsemolar teeth. 



D. c, Dens caninus. — Canine tooth. 



DD. i., Dentes incisores. — Incisor teeth. ^ 



Fm. m., Foramen magnum, az. 



I 530. Fm. cd., Foramen condylare — Condylar foramen. — This foramen is some- 

 times nearly hidden either by the projection of the bulla or its unusual approach to the 

 Fm. jugulare. 



§ 531. Fm. j.. Foramen jugulare — s. laccram posterius. — Jugular or posterior lacer- 

 ated foramen. 



§ 532. Fm. stm., Foramen stylo-mastoideum— Stylomastoid foramen.— This is 

 the ectal termination of the Aquanhtctus Fallopii (Fig. 53, 59, M. a. i.). 



§ 533. Fm. 1. m., Foramen lacerum medium — s. Fm. spheno-petrosum — Middle 



