Page 307 - Clinical Anatomy

ECA5 7/18/06 6:50 PM Page 292

292 The head and neck

The branches of the nerve then emerge on the anterior aspect of the
parotid to lie on the masseter, thence to pass to the muscles of the face. No
branches emerge from the superficial aspect of the gland, which can there-
fore be completely exposed with impunity.

Clinical features

1◊◊A malignant tumour of the parotid gland, unlike benign lesions, may
involve VII and produce a facial palsy.
2◊◊In removing a benign mixed salivary tumour of the parotid, the facial
nerve is exposed posteriorly in the wedge-shaped space between the bony
canal of the external auditory meatus and the mastoid process. It is then
traced into the gland, its main divisions defined and the tumour excised
with a wide margin of normal gland, carefully preserving the exposed
nerves.
It is interesting that giant mixed tumours ‘extrude’ clear away from the
facial nerve and can be excised with an adequate margin without even
seeing the nerve.
3◊◊The parotid duct and its ramifications can be demonstrated radiologi-
cally by injecting radio-opaque contrast through a cannula placed in the
mouth of the duct (a parotid sialogram).

The submandibular gland
The submandibular gland is made up of a large superficial and a small deep
lobe which connect with each other around the posterior border of the
mylohyoid.
The superficial lobe of the gland lies at the angle of the jaw, wedged
between the mandible and the mylohyoid and overlapping the digastric
muscle (Fig. 200). Posteriorly it comes into contact with the parotid gland,
separated only by a condensation of its fascial sheath (the stylomandibular
ligament).
Superficially, the gland is covered by platysma and by its capsule of
deep fascia, but it is crossed by the cervical branch of the facial nerve (VII)
and by the facial vein. Its deep aspect lies against the mylohoid for the most
part, but posteriorly the gland rests against the hyoglossus muscle and here
comes into contact with the lingual (V) and the hypoglossal nerve (XII),
both of which lie on hyoglossus as they pass forward to the tongue.
The facial artery also comes into close relationship with the gland,
approaching it posteriorly, then arching over its superior aspect (which it
grooves), to attain the inferior border of the mandible and thence to ascend
on to the face in front of the masseter.
From the medial aspect of the superficial part of the gland projects its
deep prolongation along the hyoglossus.
The submandibular duct (Wharton’s duct) arises from this deep part of the
gland and runs forward, beneath the mucosa of the floor of the mouth
along the side of the tongue, to open immediately at the side of the frenu-