In this region we may include the parts limited above by the zygoma, in front by the eye, nose, and mouth, below by the lower edge of the lower jaw, and behind by the ear. The soft parts of the cheek are supported by the malar and superior and inferior maxillary bones. Between the skin and the buccinator muscle, the hollow beneath and in front of the malar bone and masseter muscle is filled with fat, sometimes called the sucking pad or cushion. In disease this fat disappears, hence the hollow cheek of invalids. The muscles of expression are superficial to this fat and have their insertion in the skin. Swelling occurs readily from contusions and inflammations because the tissues of the cheek are lax. Inflammations may either start in the skin, which is quite prone to disease, or may be the result of inflammation of some surrounding structure, as the parotid gland, the roots of the teeth, the lachrymal sac, eyelids, etc.

The skin of the cheek contains numerous sebaceous and sweat glands. It is a favorite site for the pustular eruptions of infancy and childhood, the acne of youth, and the non-malignant as well as the cancerous ulcers of the aged. It is also the seat of noma or cancrum oris. This starts on the mouth surface as a gangrenous stomatitis and implicates the cheek, causing death or great disfigurement owing to the loss of cheek substance. Facial carbuncle or malignant pustule occurs on the cheek, or sometimes on the lips. It is very often fatal.

Fig. 58.   The facial artery and its branches.

Fig. 58. - The facial artery and its branches.

Wounds and contusions of the cheeks are common, and, as the blood supply is abundant, bleeding is free and healing prompt. On account of the insertion of the muscles into the skin, gaping is quite marked.

The malar bone is the most prominent bone of the cheek. It is such a strong bone and so strongly supported that fracture of it, as well as that of the zygoma, is rare. It may be broken by direct violence, as being hit with a stone, etc. It is extremely difficult and often impossible to restore the fractured parts to their original level, therefore deformity following fracture is of frequent occurrence. The fracture may involve the margin of the orbit and cause an effusion of blood into the orbit, pushing the eye forward. A fracture of the zygoma, if very much depressed, may interfere with the use of the temporal muscle below, necessitating operation. This occurrence is, however, rare.

The facial artery runs upward and inward, from a couple of centimetres in front of the angle of the jaw, along the anterior border of the masseter muscle to the angle of the mouth, and thence to the inner canthus of the eye. The anterior edge of the masseter muscle can usually be distinctly felt beneath the skin. At this point the vessel can be ligated or temporarily compressed by passing a pin beneath it and winding a silk ligature above it, around the ends of the pin. This procedure is desirable in some operations on the cheek, as angiomas frequently affect this region. If the facial artery is ligated, the blood supply comes from the superior and inferior coronary arteries of the opposite side; the nasal branch of the ophthalmic, anastomosing with the angular; the transverse facial below the zygoma, from the temporal; the infra-orbital, a branch of the internal maxillary; and to a slight extent from the inferior labial and others still less important (Fig. 58).

The internal maxillary artery, one of the terminal branches of the external carotid, arises in the parotid gland opposite the neck of the lower jaw. This is just below and behind the articulation, which can be readily felt through the skin. It

Fig. 59.   The internal maxillary artery, passes between the bone and the sphenomandibular (long internal lateral) ligament, then between the two pterygoid muscles or between the two heads of the external pterygoid muscle to the posterior surface of the superior maxillary bone in the sphenomaxillary fossa. The branches of its first part, where it is behind the neck of the jaw, are the deep auricular, tympanic, middle and small meningeal, and inferior alveolar {dental). The branches of its second part, as it passes between the pterygoid muscles, are all muscular: they are the masseteric, pterygoid, anterior and posterior deep temporal, and the buccal. The branches of the third portion of the artery, in the sphenomaxillary fossa, are the posterior dental, infra orbital, descending palatine, Vidian, pterygopalatine, and spheno  or nasopalatine.

Fig. 59. - The internal maxillary artery, passes between the bone and the sphenomandibular (long internal lateral) ligament, then between the two pterygoid muscles or between the two heads of the external pterygoid muscle to the posterior surface of the superior maxillary bone in the sphenomaxillary fossa. The branches of its first part, where it is behind the neck of the jaw, are the deep auricular, tympanic, middle and small meningeal, and inferior alveolar {dental). The branches of its second part, as it passes between the pterygoid muscles, are all muscular: they are the masseteric, pterygoid, anterior and posterior deep temporal, and the buccal. The branches of the third portion of the artery, in the sphenomaxillary fossa, are the posterior dental, infra-orbital, descending palatine, Vidian, pterygopalatine, and spheno- or nasopalatine.

The main trunk of the internal maxillary artery is not often involved either by injury or operations. The various branches are, however, of considerable importance, as they supply parts which are often the site of operative measures. The importance of the middle meningeal artery in reference to fractures of the skull has already been pointed out. The inferior alveolar gives rise to troublesome hemorrhage when the lower jaw is operated on. The deep temporal branches bleed freely when the temporal muscle is incised in operating on the Gasserian ganglion. The infraorbital is involved in operating on the infra-orbital nerve. The posterior or descending palatine branch descends in the posterior palatine canal, in company with a branch from Meckel's ganglion, to emerge on the roof of the mouth at the posterior palatine foramen. It causes free hemorrhage in operating on cleft palate.

The Vidian and pterygopalatine branches supply mostly the roof of the pharynx; they bleed when adenoids are removed. The descending and sphenopalatine supply the upper part of the tonsil with blood and may give rise to serious hemorrhage in the removal of the tonsils. In operating on Meckel's ganglion, bleeding from these vessels is free. The nasopalatine runs forward in the nose in the groove on the vomer. It is often the cause of serious nasal hemorrhages in operations on the septum. In removal of the upper jaw, bleeding occurs from many of the branches of the internal maxillary, but it is hardly so free as might be expected, especially if the external carotid has been previously ligated.