The palate (also known as the ‘roof of the mouth’), forms a division between the nasal and oral cavities. It is separated into two distinct parts:
- Hard palate – comprised of bone.
- It is immobile.
- Soft palate – comprised of muscle fibres covered by a mucous membrane.
- It can be elevated to close the pharyngeal isthmus during swallowing – this prevents the food bolus from entering the nasopharynx.
In this article, we will look at the anatomy of the palate; its structure, function and neurovascular supply.
The palate divides the nasal cavity and the oral cavity, with the hard palate positioned anteriorly and the soft palate posteriorly.
It forms both the roof of the mouth and the floor of the nasal cavity. Reflecting this, the superior and inferior palatal surfaces have different mucosae:
- Superior aspect of palate (nasal cavity) – respiratory epithelium.
- Inferiorly aspect of palate (oral cavity) – oral mucosa, populated by secretory salivary glands.
The hard palate forms the anterior aspect of the palate.
The underlying bony structure is composed of (i) palatine processes of the maxilla; and (ii) horizontal plates of the palatine bones.
There are three main foramina/canals in the hard palate:
- Incisive canal – located in the anterior midline, transmits the nasopalatine nerve.
- Greater palatine foramen – located medial to the third molar tooth, transmits the greater palatine nerve and vessels
- Lesser palatine foramina – located in the pyramidal process of the palatine bone, transmits the lesser palatine nerve.
The soft palate is located posteriorly. It is mobile, and comprised of muscle fibres covered by a mucous membrane.
Anteriorly, it is continuous with the hard palate and with the palatine aponeurosis. The posterior border of the soft palate is free (i.e. not connected to any structure), and has a central process that hangs from the midline – the uvula.
The soft palate also forms the roof of the fauces; an area connecting the oral cavity and the pharynx. Two arches bind the palate to the tongue and pharynx; the palatoglossal arches anteriorly and the palatopharyngeal arches posteriorly. Between these two arches lie the palatine tonsils, which reside in the tonsillar fossae of the oropharynx.
Muscles of the Soft Palate
There are five muscles which give the actions of the soft palate.
They are all innervated by the pharyngeal branch of the vagus nerve (CN X) – apart from Tensor veli palatini – which is innervated by the medial pterygoid nerve (a branch of CN V3).
Tensor Veli Palatini
- Attachments: Originates from the medial pterygoid plate of the sphenoid and inserts into the palatine aponeurosis.
- Function: Tenses the soft palate.
Levator Veli Palatini
- Attachments: Arises from the petrous temporal bone and the eustachian tube, before inserting into the palatine aponeurosis.
- Function: Elevation of the soft palate.
- Attachments: Originates from the palatine aponeurosis, and travels anteriorly, laterally and inferiorly to insert into the side of the tongue.
- Function: Pulls the soft palate towards the tongue.
- Attachments: Arises from the palatine aponeurosis and the hard palate, and inserts into the upper border of the thyroid cartilage.
- Function: Tenses soft palate and draws the pharynx anteriorly on swallowing.
- Attachments: Arises from the posterior nasal spine and the palatine aponeurosis, and inserts into the mucous membrane of the uvula.
- Function: Shortens the uvula.
The palate receives arterial supply primarily from the greater palatine arteries, which run anteriorly from the greater palatine foramen.
In addition, the anastomosis between the lesser palatine artery and ascending palatine artery provide collateral supply to the palate.
Venous drainage is into the pterygoid venous plexus.
Sensory innervation of the palate is derived from the maxillary branch of the trigeminal nerve (CN V). The greater palatine nerve innervates most of the glandular structures of the hard palate.
The nasopalatine nerve innervates the mucous membrane of the anterior hard palate and the lesser palatine nerves innervate the soft palate.
Clinical Relevance: Cleft Lip and Cleft Palate
A cleft refers to a gap/split in the upper lip or palate. It results from a defect during development of face and palate:
- Cleft lip – occurs when the medial nasal prominence and maxillary prominence fail to fuse.
- Cleft palate – can occur in isolation when the palatal shelves fail to fuse in the midline, or in combination with cleft lip.
Cleft lip and cleft palate are relatively common, occurring in approximately 1/1000 births. In Native Americans, the rate is around 4 times that.
In addition to the cosmetic and psychosocial implications, severe cleft lip/palate can be a cause of death if a baby is unable to feed. Other complications include recurrent ear infections and speech impediment.