1114 



DIGESTIVE SYSTEM 



with the posterior border of the mandibular ramus and with the posterior aspect 

 of the internal pterygoid muscle. An irregular "pterygoid lobe" may extend 

 between the internal and the external pterygoid muscles. The posterior surface 

 is in contact with the sternomastoid muscle laterally, and with the styloid process 

 and associated muscles medially. Between the sternomastoid and styloid process 

 it touches the posterior belly of the digastric, and is in relation with the internal 

 carotid and jugular vessels. The various structures in contact with the parotid 

 gland often make more or less distinct grooves upon its posterior and anterior 

 surfaces. 



Borders. — The anterior border usually extends from below obliquely upward 

 and forward so as to give the whole superficial surface a triangular appearance. 

 Near the upper end of the anterior border, the parotid duct leaves the gland, and 

 just above this there is usually a small separate accessory lobe [gl. parotis acces- 

 soria], of variable form and size. The branches of the facial nerve also emerge 

 from the anterior border. The posterior border extends along the anterior aspect 

 of the sterno-mastoid muscle up to the mastoid process. The medial border 

 is deeply placed (at the junction of the anterior and posterior surfaces), and 

 approaches the wall of the pharynx. 



The upper extremity of the parotid sends a process into the posterior part of 

 the manibular fossa, behind the condyle of the mandible, and is related with the 



Fig. 865. — Diagram of Horizontal Section Showing the Parotid Compartment and 

 REiiATiONS. Arrow indicates opening in sheath. (Modified from Woolsey after Testut.) 



FACIAL 

 NERVE 

 PAROTID 

 APONEU- 

 ROSIS, 

 8UPERFIC 

 ' LAYER 



I 



external auditory meatus. From the upper extremity emerge the superficial tem- 

 poral vessels and the auriculo-temporal nerve. The lower extremity is separated by 

 the stylo-mandibular ligament from the posterior end of the submaxillary gland. 



Fascia. — As shown in fig. 865, the parotid gland is enclosed in a sheath (called the parotid 

 fascia or aponeurosis) derived from the deep fascia of the neighbourhood. The superficial 

 layer of the sheath covers the lateral surface of the gland, while the deep layers correspond to 

 the anterior and posterior surfaces of the gland. The sheath is very feeble or deficient at the 

 medial angle. The superficial and deep layers of the parotid sheath unite below to form a thick 

 fascial band extending from the angle of the mandible to the sterno-mastoid muscle. 



Contents. — Within the .sheath, the jKirotid gland is in intimate relation with numerous 

 important structures. Extending along the medial border, and partly embedded in the gland, 

 is the external carotid artery, dividing a})()ve into the superficial temporal and internal maxillary 

 (including the origins of the di'(!i) auricular and transverse facial); and the posterior facial 

 (temporo-maxillary) vein and branches. The auriculo-temporal nerve passes through the upper 

 part of the gland, while the facial nerve passes somewhat horizontally through it, dividing 

 into. its temporo-facial and cervico-facial divisions. Finally, there are embedded in the gland 

 two or three deep lymphatic nodes, which re(;eive lymi)liatic vessels from the external auditory 

 meatus, the soft palate and the jjostorior part of the nasal fossa; and several superficial nodes, 

 which receive lyrnj)hatic vessels from tlie t<'mple, eyebrows and eyelids, cheek and auricle. 



Structure. — The parotid is a racemose glanrl of the serous type. 



