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| iiss SALIVARY GLANDS. 961 
fossa. Infer vorly it usually reaches a little distance below a line prolonged hori- 
zontally backwards from the angle of the jaw, but its limit in this direction is 
variable. 
Occasionally the parotid gland passes down a considerable distance below the angle of the 
mandible, lying here superficial to the posterior part of the submaxillary gland, from which it 
is separated by” a thickened band of the deep cervical fascia, passing from the angle of the jaw to 
the fascia of the sterno-mastoid. At other times it does not quite reach the angle. 
The facial process of the gland—often of considerable size—is a flat and some- 
what triangular portion which runs forwards from the upper part of the gland, 
covering the masseter muscle to a varying extent; from its most anterior part 
the parotid duct emerges, and a separated portion of this process, often found lying 
immediately above the duct, is known as the socia parotidis (glandula parotis 
acGessoria ). 
Traversing the substance of the gland (Fig. 646) are found :—(1) the temporo- 
maxillary vein; (2) on a deeper plane, the branches of the facial nerve passing 
forwards ; and ( 5) more deeply still, the external carotid artery which hes beneath 
the lower part of the gland, but is embedded in its deep surface above: just 
before it emerges, the artery divides into its two terminal branches in the gland 
substance. 
The parotid or Stenson’s duct (ductus parotideus) leaves the anterior border 
of the gland at its most prominent part (Fig. 647). It first runs forwards across 
the masseter, usually accompanied by the socia parotidis which lies above it, 
and also by branches of the facial nerve; whilst the transverse facial artery 
is commonly some distance above, though its relation is variable. Having crossed 
the masseter, it arches round the anterior border of this muscle and runs inwards 
through the fat of the cheek, practically at right angles to the first part of its 
course, to reach the buecinator, which it pierces. Then passing for some distance 
(5 to 10 mm.) between the buccinator and mucous membrane, 1t opens into the 
vestibule of the mouth by a very small orifice, on a variably-developed papilla, 
opposite the crown of the second upper molar. 
The course of the duct, which is fairly constant, can be marked on the side of 
the face by drawing a line from the lower edge of the auditory meatus to a point 
midway between the ala of the nose and the red of the lip; the middle third 
of this line corresponds fairly accurately on the surface, to the course pursued 
by the duct. 
The gland varies in weight from half an ounce to an ounce or more. Several small lobes or 
processes are found in connexion with it—viz. one running backwards between the sterno-mastoid 
and the digastric ; a glenoid lobe of very small size, which lies in the posterior part of the 
glenoid cavity ; a pharyngeal process (Fig. 646), which runs forwards and inwards between the 
styloid process and the external carotid artery towards the pharynx. A pterygoid extension 
running forwards between the two pterygoid muscles, although described, cannot properly be said 
to exist. 
Stenson’s duct measures from 1} to 24 inches (88 to 62 mm.) in length, and } inch (3 to 4 mm.) 
in diameter. The calibre of the duct is very much greater than that of its orifice, which only 
admits a fine bristle, and for this reason the duct may, to some extent, be looked upon as a 
reservoir for the saliva, as well as a duct for its conveyance. In the child it pierces the “sucking 
pad” on its way to the mouth. 
Vessels and Nerves.—The arteries which supply the gland arise from the external carotid, 
and from the branches of this artery in relation to the gland. 
The veins join the temporo-maxillary and its tributaries. The lymphatics pass to both the 
superficial and the deep cervical glands ; there are also a few small parotid lymphatic glands, 
which lie on the surface of the upper and lower part of the parotid beneath the capsule. Some 
are said to be embedded in the substance of the parotid itself. 
The nerves are derived (a) from the auriculo-temporal, and (b) from the sympathetic on the 
external carotid. The fibres of the sympathetic are mainly vaso-constrictor. Those of the 
auriculo-temporal convey to the gland secretory fibres from the glosso-pharyngeal. 
Submaxillary Gland.—The submaxillary gland is next in size to the parotid, 
and resembles it in its lobulation and colour. It is placed partly in the sub- 
maxillary triangle and partly under cover of the posterior part of the mandible 
near its angle (Fig. 647). 
In size and shape it may be compared to a small walnut with three flattened 
61 
