Soft Palate

The soft palate is a movable muscular flap, which hangs downwards from the posterior margin of the hard palate into the pharyngeal cavity. It divides the nasopharynx from the oropharynx. The soft palate can be easily distinguished from the hard palate at the front of the mouth since it does not contain bone.

External Features

The soft palate presents the following external features:

• Anterior (oral) surface is concave as well as indicated by a median raphe.
• Posterior surface is convex and continuous with the floor of the nasal cavity.
• Superior border is connected to the posterior border of the hard palate.
• Inferior border is free and creates the anterior boundary of the pharyngeal isthmus.
• A conical, small, tongue like projection hanging down from its middle is referred to as uvula.

On every side from the base of the uvula, 2 curved folds of mucous membrane stretch laterally and downwards:

• The anterior fold unites inferiorly with the side of the tongue (at the junction of oral and pharyngeal parts) and is called palatoglossal fold. The palatoglossal fold includes the palatoglossus muscle and creates the lateral boundary of the oropharyngeal isthmus.
• The posterior fold unites inferiorly with the lateral wall of the pharynx and is called palatopharyngeal fold. The palatopharyngeal fold includes palatopharyngeus muscle and creates the posterior boundary of the tonsillar fossa.

Structure

The soft palate is created from a fold of mucous membrane enclosing 5 pairs of muscles. The nasal surface of the soft palate is covered by pseudostratified ciliated columnar epithelium with the exception of posteriorly (the part that abuts on the Passavant’s ridge of posterior pharyngeal wall) that is lined by non-keratinized stratified squamous epithelium. The oral surface of the soft palate is thicker and lined by non-keratinized stratified squamous epithelium.

Soft Palate

In the submucosa on both the surfaces are mucous glands, which are in loads around the uvula and on the oral aspect of the soft palate. The mucosa on the oral surface of the soft palate also includes some taste buds (particularly in children) and lymphoid follicles.

Muscles

The soft palate is composed of the 5 pair of muscles, viz

• Tensor palati (tensor veli palatini).
• Levator palati (levator veli palatini).
• Palatoglossus.
• Palatopharyngeus.
• Musculus uvulae.

All the muscles of soft palate are extrinsic with the exception of musculus uvulae that are intrinsic.

Origin, Insertion and Activities of Muscle of The Soft Palate

Functions of Soft Palate

• Separates the oropharynx from nasopharynx during swallowing so that food will not go into the nose.
• Sequester the oral cavity from oropharynx during mastication so that breathing isn’t changed.
• Helps to change the attribute of voice, by altering the level of blockage of the pharyngeal isthmus.
• Shields the damage of nasal mucosa during sneezing, by suitably breaking up and directing the gust of air via both nasal and oral cavities.
• Prevents the entrance of sputum into nose during coughing by directing it in the oral cavity.

Arterial Supply

The soft palate is supplied by the following arteries:

• Lesser palatine branches of the maxillary artery.
• Ascending palatine branch of the facial artery.
• Palatine branches of the ascending pharyngeal artery.

Venous Drainage

The venous blood from palate is drained into pharyngeal venous plexus and pterygoid venous plexus.

Lymphatic Drainage

The lymphatics from soft palate drain into retropharyngeal and upper deep cervical lymph nodes.

Nerve Supply

Motor Supply:

All the muscles of soft palate are supplied by the cranial root of accessory nerve via pharyngeal plexus with the exception of tensor palati, which is supplied by the nerve to medial pterygoid, a branch of the mandibular nerve.

Sensory Supply:

• General sensations from palate are carried by:
• Lesser palatine nerves to the maxillary division of trigeminal nerve via pterygopalatine ganglion.
• Glossopharyngeal nerve.

Clinical Significance

Gag reflex

It’s a protective reflex demarcated by the elevation of the palate and contraction of the pharyngeal muscles with related retching and gagging in response to stimulant of the mucous membrane of the oropharynx. It takes place when the palate, tonsil, posterior part of the tongue, or posterior pharyngeal wall are contacted by unknown things like swab, spatula, etc. The afferent limb of the reflex is supplied by the glossopharyngeal nerve and efferent limb by the vagus nerve.

Paralysis of soft palate

The paralysis of the muscles of soft palate due to lesion of vagus nerve creates:

• Nasal regurgitation of liquids.
• Nasal twang in voice.
• Flattening of the palatal arch on the side of the lesion.
• Deviation of uvula, opposite to the side of the lesion.

Oropharyngeal Cancer

The inferior aspect of the soft palate creates the upper part of the oropharynx and is the location of the where most of the soft palate cancers occur.

The superior surface of the soft palate i.e. portion of the nasopharynx, is rarely a primary site of neoplasm formation.

• The soft palate has a substantial amount of minor salivary glands.
• These glands act as the location of origin for non-squamous neoplasms of the soft palate.
• A soft palate tumor can extend anteriorly as well as also encompass the hard palate.
• Perineural extend also appear superiorly inside the pterygopalatine fossa alongside the greater as well as lesser palatine divisions of the maxillary nerve.

Further perineural extension from the pterygopalatine fossa can cause extension:

• Via the inferior orbital fissure along divisions of the maxillary division of the trigeminal nerve inside the orbit.
• Via the foramen rotundum inside the central skull base.
• Via the nerve of the pterygoid canal inside the facial nerve and temporal bone.

Both the trigeminal and facial nerves palsies can appear due to this perineural spread.

1. Gray’s Anatomy for Students Topic Soft Palate P. 267
2. The Journal of family practice  vol 5 P. 55
3. The Cleft palate journal p. 134–61. 4524356