426 PRACTICAL ANATOMY. 



4. H<nv many synovial cavities has the tcmporo-mandibular articulation and 

 /low are they produced ? 



It has two ; they are produced by interposition of the interarticular fibro- 

 cartilage. The periphery of this disc is attached to the capsule. (Fig. 294.) 



5. Explain the use of this interarticular cartilage. 



When the mouth is opened, the condyle of the mandible slides forward onto 

 the eminentia articularis, in the concave cup of the articular cartilage ; when the 

 mouth is shut, the condyle and cartilage recede into the glenoid. (Fig. 59.) 



6. By what are the condyle and cartilage drawn forward f 



By the external pterygoid muscle, a portion of the muscle being inserted into 

 the cartilage as well as into the condyle. (Fig. 58.) 



DISSECTION. 



It is to be hoped that the foregoing has prepared the student to begin an 

 intelligent dissection of the articulations. 



TEMPORO-MANDIBULAR ARTICULATION. 



1 . Class. Diarthrosis, because there is free motion. 



2. Subdivision. Condylarthrosis, because axial rotation is absent. 



3. Osteological Units. Mandible and temporal bone. 



4. Subdivisional Parts. Condylar process and glenoid cavity. 



5. Articular Surfaces. Condylar of temporal ; temporal of condyle. 



6. Basis. A complete capsule lined by synovial membrane. 



7. Subdivisions. Anterior, posterior, internal, and external portions. 



8. Accessories. Spheno-mandibular, stylo-mandibular, fibro-cartilage. 



9. Incorporation of Tendons. None. 



10. Limitations. Articular eminence, post-glenoid tubercle. 



1 1. Ligamcntous Muscles. Internal and external pterygoids,masseter. 



12. Nerve-supply. Masseteric and auriculo-temporal of the fifth. 



13. Blood-supply. Temporal, middle meningeal, ascending pharyngeal. 



1. Name the osteological parts concerned in t/iis articulation. 



(i) The zygomatic arch ; (2) the spine of the sphenoid ; (3) the styloid pro- 

 cess of the temporal bone ; (4) the lingula of the mandible ; (5) the eminentia 

 articularis of the temporal bone ; (6) the post-glenoid tubercle and tympanic plate 

 of the temporal bone ; (7) the Glaserian fissure of the temporal bone. 



2. Give attachments of the spheno-mandibular ligament as you find them, and 

 tell by what nerve this ligament is pierced. 



The ligament extends from the spine of the greater wing of the sphenoid bone 

 to the lingula or mandibular spine, and is perforated by the mylo-hyoid nerve. 



3. Locate and give attachments of tJic stylo-mandibular ligament. 



It is between the masseter and internal pterygoid muscles ; it is attached to 

 the styloid process and to the angle of the mandible. (Fig. 296.) 



SHOULDER-JOINT. 



1. Class. Diarthrosis, because of free motion. 



2. Subdivision. Knarthrodia an^nl.ir movements and axial rotation. 



3. I'eclinienl \,ime. I lutnero-scapular ; common name, shoulder-joint. 



4. Osteological ('nits. Humerus and scapula. 



