Levator Palati.
Azygos Uvulae.
Tensor Palati.
Palato-glossus.
Palato-pharyngeus.

Lay open the pharynx from behind, by a vertical incision extending from its upper to its lower part, and the posterior surface of the soft palate is exposed. Having fixed the uvula so as to make it tense, the mucous membrane and glands should be carefully removed from the posterior surface of the soft palate and the muscles of this part are at once exposed.

The Levator Palati is a long, thin muscle, placed on the outer side of the posterior aperture of each nasal fossa. It arise." from the apex of the basilar surface of the petrous portion of the temporal bone and from the adjoining cartilaginous portion of the Eustachian tube; after passing into the interior of the pharynx, above the upper concave margin of the Superior constrictor, it descends obliquely downwards and inwards, its fibres spreading out in the posterior surface of the soft palate as far as the middle line, where they blend with those of the opposite side.

Relations. Externally, with the Tensor palati and Superior constrictor. Internally, it is lined by the mucous membrane of the pharynx. Posteriorly, with the mucous lining of the soft palate. This muscle must be removed and the pterygoid attachment of the Superior constrictor dissected away, in order to expose the next muscle.

The Circumflexus or Tensor Palati is a broad, thin, flat muscle, placed on the outer side of the preceding, mid consisting of two distinct portion*, a vertical and horizontal. The vertical portion arises by a broad, thin, and flat lamella from the scaphoid fossa at the base of the internal pterygoid plate, its fibres of origin extending as far back as the spine of the sphenoid; it also arises from the anterior aspect of the cartilaginous portion of the Eustachian tube, descending vertically downwards between the internal pterygoid plate and the inner surface of the Internal pterygoid muscle; it terminates in a tendon which winds around the hamular process, being retained in this situation by a tendon of origin of the Internal pterygoid muscle, and lubricated by a synovial membrane. The tendon or horizontal portion then passes horizonally inwards, and expands into a broad aponeurosis on the anterior surface of the soft palate, which unites in the median line with the aponeurosis of the opposite muscle, the fibres of which are attached anteriorly to the transverse ridge on the posterior border of the horizontal portion of the palate bone.

Relations. Externally, with the Internal pterygoid. Internally, with the Levator palati, from which it is separated by the Superior constrictor, i\nd the internal pterygoid plate. In the soft palate its aponeurotic expansion is anterior to that of the Levator palati, being covered by mucous membrane.

The Azygos Uvulae is not a single muscle as implied by its name, but a pair of small cylindrical fleshy fasciculi, placed side by side in the median line of the soft palate. Each muscle arises from the posterior nasal spine of the palate bone, and from the contiguous tendinous aponeurosis of the soft palate, and descending vertically downwards, is inserted into the uvula.

Relations. Anteriorly, with the tendinous expansion of the Levatores palati; behind, with the mucous membrane.

The two next muscles are exposed by removing the mucous membrane which covers the pillars of the soft palate on each side throughout their whole extent.

The Palato-Glossus (or, Constrictor Isthmi Faucium) is a small fleshy fasciculus, narrower in the middle than at either extremity, forming, with the mucous membrane covering its surface, the anterior pillar of the soft palate. It arises from the soft palate on each side of the uvula, and passing forwards and outwards in front of the tonsil, is inserted into the side and upper surface of the tongue, where it blends with the fibres of the Stylo-glossus muscle. In the soft palate, the fibres of origin of this muscle are continuous with those of the opposite side, and with the Palato-pharyngeus.

The Palato-Pharyngeus is a long fleshy fasciculus, narrower in the middle than at either extremity, forming, with the mucous membrane covering its surface, the posterior pillar of the soft palate. It is separated from the preceding by an angular interval, in which the tonsil is lodged. It arises from the soft palate by an expanded fasciculus, its fibres being divided into two unequal parts by the Levator palnti, and being continuous partly with the muscle of the opposite side, and partly with the fibrous aponeurosis of the palate. Passing outwards and downwards behind the tonsil, it joins the Stylo-pharyngeus, and is inserted with it into the posterior border of the thyroid cartilage, some of its fibres being lost on the side of the pharynx.

Relations. In the soft palate, its anterior and posterior surfaces are covered by mucous membrane, from which it is separated by a layer of palatine glands. By its superior border, it is in relation with the Levator palati. Where it forms the posterior pillar of the fauces, it is covered by mucous membrane, excepting on its outer surface. In the pharynx, it lies between the mucous membrane and the constrictor muscles.

Nerves. The Tensor palati is supplied by a branch from the otic ganglion; the other muscles by the palatine branches of Meckel's ganglion.

Actions. When the morsel of food has been driven backwards into the fauces by the pressure of the tongue against the hard palate, the Palato-glossi muscles, the constrictors of the fauces, contract behind it, the soft palate is slightly raised (by the Levator palati), and made tense (by the Tensor palati), and the Palato-pharyngsei contract, and come nearly together, the Uvula filling up the slight interval between them. By these means, the food is prevented passing into the upper part of the pharynx or the posterior nares; at the same time the latter muscles form an inclined plane, directed obliquely downwards and backwards, along which the morsel descends into the pharynx.

Surgical Anatomy. The muscles of the soft palate should be carefully dissected, the relations they bear to the surrounding parts especially examined, and their action attentively studied upon the dead subject, as the surgeon is required to divide one or more of these muscles in the operation of staphyloraphy. Mr. Ferguson has shewn, that in the congenital deficiency, called cleft palate, the edges of the fissure are forcibly separated by the action of the Levatores palati and Palato-pharyngsei muscles, producing very considerable impediment to the healing process after the performance of the operation for uniting their margins by adhesion ; he has, consequently, recommended the division of these muscles as one of the most important steps in the operation: by these means, the flaps are relaxed, lie perfectly looso and pendulous, and are easily brought and retained in apposition. The Palato-pharyngsoi may be divided by cutting across the posterior pillar of the soft palate, just below the tonsil, with a pair of blunt-pointed curved scissors, and the anterior pillar may be divided also. To divide the Levator palati, the plan recommended by Mr. Pollock is to be greatly preferred. The flap being put upon 'the stretch, a double-edged knife is passed through the soft palate just on the inner bide of the hamular process, and above the line of the Levator palati. The handle being now alternately raised and depressed, a sweeping cut is made along the posterior surface of the soft palate, and the knife withdrawn, leaving but a small opening in the mucous membrane on the anterior surface. If this operation is performed on the dead body, and the parts afterwards dissected, the Levator palati will be found completely divided.