Surgical anatomy / by John A.C. Macewen.

  • Macewen, John A. C.
Date:
1910
Catalogue details

Licence: In copyright

Credit: Surgical anatomy / by John A.C. Macewen. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    The cartilage is attached to the capsule and to the condyle, with which it moves forwards and backwards on opening and shutting the mouth. It sometimes becomes displaced forwards, especially in delicate women, causing a subluxation of the jaw. The capsiile is thin, especially in front, but is strengthened externally by the external lateral ligament, which is directed downwards and backwards from the zygoma to the condyle. The accessory ligaments consist of : {a) The spheno-maxillary (internal lateral), from the spine of the sphenoid to the ligula and ascending ramus of the jaw. Be- tween it and the neck of the jaw the internal maxillary artery and vein, the inferior dental vessels and nerve, the auriculo- temporal nerve, and external pterygoid muscle, are situated. {b) The stylo-maxillary (deep parotid fascia), from styloid process to angle of the jaw. (c) The pterygo-maxillary, from hamular process of sphenoid to base of ligula. Dislocation of the jaw is nearly always forwards through the weak anterior portion of the capsule, and is said to be more frequently bilateral. Dislocation in other directions is generally asso- ciated with fracture. The forward variety occurs when the mouth is widely open, and is said to be largely due to the action of the external pterygoid muscle, which draws the condyle forward beyond the articular eminence into the zygomatic fossa (the articular cartilage remaining behind), where it is pulled up by the internal pterygoid, temporal, and masseter muscles. In reduction, therefore, it is first necessary to depress the condyle before pushing it backwards. Suppurative con- ditions may extend from the ear or parotid gland and involve the joint. Abscesses usually point at the front of the joint, and suppurative processes not infrequently lead to anchylosis. The joint is frequently affected in rheumatoid arthritis, giving rise to ' creaking' during mastication in slight cases and excessive movement or complete anchylosis in severe ones. In such cases an excision of the condyle through a curved incision along the posterior portion of the upper border of the zygoma may be necessary. Fixation of the jaw may also arise from spasms of the muscles [trismus], as in tetanus (risus sardonicus), and sometimes from reflex irritation from the lower teeth (caries or cutting a wisdom tooth), as the third division of the fifth nerve, by its motor root, supplies the muscles of mastication. Dental caries has also been known
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