PAROTID REGION.—This region (in surgical anatomy) is of a somewhat pyramidal form, the base corresponding to the surface of the skin, and the apex to the pharynx. The superficial boundaries of the region are, supe riorly, the root of the zygoma and the articu lation of the jaw; inferiorly, a line drawn from the angle of the jaw to the anterior borderof the sterno-mastoid muscle ; anteriorly, the posterior border of the masseter muscle; and posteriorly, the meatus auditorius, the mastoid process with the anterior border of the sterno-mastoid muscle.
In the present article it is intended to give the relative anatomy of the parts contained'in this irreg,ular and ill-defined region.
Commencing the dissection by removing the integument from the parotid region, we expose some delicate muscular fibres which constitute the upper part of the platysma or the risorius Santorini ; these fibres, however, are not con stantly present. After removing a fine reti cular tissue, the superficial surface of the pa rotid fascia is seen. This is a strong fibrous fascia which is continuous below with the cer vical fascia; it passes over the superficial sur faces of the parotid, being attached above to the zygoma, and behind to the cartilage of the ear, while in front it is thinner and is prolonged over die masseteric region. The fascia also dips down into the substance of the gland and divides it into lobes and lobules.
The Parotid Gland, from which the name of this region is derived, is the largest of the three salivary glands. Its form is irregular, and is determined by the surrounding parts into the interstices of which it is packed and moulded.
Relations of the parotid.—A description of the relations of the parotid gland will include the greater part of the relative anatomy of the parotid region. The external surface or base of the gland corresponds to the skin; it is of a somewhat irregular quadrilateral fortn, and its boundaries are identical with those of the pa rotid region, except that a portion of the gland, the socia parotidis, is prolonged forwards with the duct over the masseter muscle. The anterior
staliiee of the parotid is grooved to receive the posterior border of the ramus of the jaw; it also corresponds to the internal pterygoid muscle, the stylo-maxillary ligament, and the masseter muscle, upon the external surface of which it is prolonged, but separated from it by some loose cellular tissue, by branches of the portio dura nerve, and by the transverse facial artery. The posterior surface corresponds. to the cartilaginous portion of the external meatus, upon the convexity of which it is rnoulded, and to which it is connected by dense cellular tissue; this surface is also related to the mastoid process and to the sterno-mas told and digastric muscles. It is related supe riorly to the zygoma and the tempero-maxillary articulation ; inferiorly it fills up the space be tween the angle of the jaw and the anterior border of the sterno-mastoid muscle. It here comes into relation with the submaxillary gland, but is separated from it by the stylo-maxillary ligament. The internal or deep surface of the parotid is very uneven; it fills up the posterior part of the glenoid cavity and the space be tween the ear and ramus of the jaw; it sur rounds the styloid process and the muscles svhich arise from it, and passes down between the styloid process and the pterygoid muscles, so as to come in contact with the pharynx and the internal carotid artery, as well as the in ternal jugular vein, and the eighth, ninth, and syinpathetic nerves. A portion of the gland passes with the internal maxillary artery be tween the ramus of the jaw and the internal lateral ligament; it here comes into contact with the inferior maxillary nerve, and some times reaches the space between the external and internal pterygoid muscles.
In addition to the relations here pointed out to the parts by which it is surrounded and limited, the parotid has important relations to vessels and nerves which pass through its sub stance or are deeply imbedded within and beneath it.