This aponeurosis becomes a tense framework as bilaterally the portion of the muscle ascending from the hamulus contracts, pulling the opposing fan-shaped portions apart. The firm, horizontal plate thus formed closes the oral cavity from the nasal pharynx. Because the aponeurosis serves as an origin for the palatoglossus and palatopharyngeal muscles, it is a substitute skeletal frame-work. The tensor palati muscle also helps open the auditory tube, which is how swallowing tends to equalize pressure on the middle ear.

Clinically, that portion of the soft palate primarily concerning the implantologist is the area near the hamulus. When a pterygoid extension implant is contemplated, the incision must extend to the bulge formed by the hamulus. The tissues here separate very easily with slight pressure from the scalpel. A deep incision is not only unnecessary, it is inadvisable. The tendinous strap over the hamulus may be severed.

The tissues over the incised area may be so delicate that the sutures will not hold. In that case, it may be necessary to include the tougher, tendinous aponeurosis in the grip.

Arteries

The maxilla receives its blood supply from branches of the maxillary artery (1), which arises from the external carotid (2) and enters deep behind the neck of the condyle within the sub-stance of the parotid gland. The maxillary artery supplies both dental arches, as well as the deep structures of the face, masticatory muscles, palate, and part of the nasal cavity. One branch also passes into the cranial cavity as the main supply of the dura mater of the brain. The branches of the maxillary artery are numerous, and the majority of them supply nondental structures. These branches are well out of range of most implant surgical procedures.

Of specific interest in the maxilla are the arterial supply to the residual dental ridge and its overlying mucoperiosteal tissues and to the palate, the hamular notch area, and the sinus. These shall be approached clinically, on the assumption that the reader is already familiar with the road map approach to the vascular anatomy of the head and neck.

The residual ridge and its mucoperiosteal tissue are supplied anteriorly by the anterior superior alveolar artery (3) , which

39