Soft palate

Uvula without tonsils

The soft palate is a mobile flap suspended from the posterior border of the hard palate, sloping down and back between the oral and nasal parts of the pharynx. The boundary between the hard and soft palate is readily palpable and may be distinguished by a change in colour, the soft palate being a darker red with a yellowish tint. The soft palate is a thick fold of mucosa enclosing an aponeurosis, muscular tissue, vessels, nerves, lymphoid tissue and mucous glands; almost half its thickness is represented by numerous mucous glands that lie between the muscles and the oral surface of the soft palate. The latter is covered by a stratified squamous epithelium, while the nasal surface is covered with a ciliated columnar epithelium. Taste buds are found on the oral aspect of the soft palate.

Pronunciation organs diagram

In most individuals, two small pits, the fovea palatini, may be seen, one on each side of the midline; they represent the orifices of ducts from some of the minor mucous glands of the palate. In its usual relaxed and pendant position, the anterior (oral) surface of the soft palate is concave and has a median raphe. The posterior aspect is convex and continuous with the nasal floor, the anterosuperior border is attached to the posterior margin of the hard palate, and the sides blend with the pharyngeal wall. The inferior border is free and hangs between the mouth and pharynx. A median conical process, the uvula, projects downwards from its posterior border. It may be congenitally bifid and associated with submucous cleft palate, hypoplastic orifice of the pharyngotympanic tube and absence of the salpingopharyngeal folds.

Tonsils diagram

The anterior third of the soft palate contains little muscle and consists mainly of the palatine aponeurosis. This region is less mobile and more horizontal than the rest of the soft palate and is the chief area acted on by tensor veli palatini.

A small bony prominence, produced by the pterygoid hamulus, can be felt just behind and medial to each upper alveolar process, in the lateral part of the anterior region of the soft palate. The pterygomandibular raphe (a tendinous band between buccinator and the superior constrictor) passes downwards and outwards from the hamulus to the posterior end of the mylohyoid line. When the mouth is opened wide, this raphe raises a fold of mucosa that indicates the internal, posterior boundary of the cheek; it is an important landmark for an inferior alveolar nerve block.

Palatine aponeurosis

A thin, fibrous, palatine aponeurosis, composed of the expanded tendons of the tensor veli palatini muscles, strengthens the soft palate. It is attached to the posterior border and inferior surface of the hard palate behind any palatine crests, and extends medially from behind the greater palatine foramina. It is thick in the anterior two-thirds of the soft palate but very thin further back. Near the midline, it encloses the musculus uvulae. All the other palatine muscles are attached to the aponeurosis.

Palatoglossal and palatopharyngeal arches

The lateral wall of the oropharynx presents two prominent folds, the palatoglossal and palatopharyngeal folds (anterior and posterior pillars of the fauces, respectively). The palatoglossal arch, the anterior fold, runs from the soft palate to the side of the tongue and contains palatoglossus. The palatopharyngeal arch, the posterior fold, projects more medially and passes from the soft palate to merge with the lateral wall of the pharynx; it contains palatopharyngeus. A triangular tonsillar fossa (tonsillar sinus) lies on each side of the oropharynx between the diverging palatopharyngeal and palatoglossal arches, and contains the palatine tonsil.

Vascular supply

The arterial supply of the soft palate is usually derived from the ascending palatine branch of the facial artery. Sometimes, this is replaced or supplemented by a branch of the ascending pharyngeal artery, which descends forwards between the superior border of the superior constrictor and levator veli palatini, and accompanies the latter to the soft palate. The veins of the soft palate usually drain to the pterygoid venous plexus.

Innervation

General sensation from most of the soft palate is carried by branches of the lesser palatine nerve (a branch of the maxillary nerve) and from the posterior part of the palate by pharyngeal branches from the glossopharyngeal nerve and from the plexus around the tonsil (formed by tonsillar branches of the glossopharyngeal and lesser palatine nerves). The special sensation of taste from taste buds in the oral surface of the soft palate is carried in the lesser palatine nerve; the taste fibres initially travel in the greater petrosal nerve (a branch of the facial nerve) and pass through the pterygopalatine ganglion without synapsing. The lesser palatine nerve also carries the secretomotor supply to most of the mucosa of the soft palate, via postganglionic branches from the pterygopalatine ganglion. Postganglionic secretomotor parasympathetic fibres may pass to the posterior parts of the soft palate from the otic ganglion (which receives preganglionic fibres via the lesser petrosal branch of the glossopharyngeal nerve). Postganglionic sympathetic fibres run from the carotid plexus along arterial branches supplying the palate.

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