Development and Function of the Palate

This is a course on the development and function of the palate. To maximise learning it is recommended to navigate the site and associated material chronologically. However, sections may be navigated in any order and revisited at any time for revision and consolidation.

Introduction to This Course

The following course will take you through the anatomy of the palate, its development in utero and its function. The topic is subdivided and at the end of each section you will be invited to answer questions to test your knowledge.

On completion of this course you should be able to confidently understand and describe the development of the palate as well as the clinical and functional implications of maldevelopment.

1. The Palate - An Anatomical Overview

The Palate

Figure 1. The oral cavity

The palate forms the roof of the oral cavity (Figure 1). It functions primarily to separate the oral cavity from the nasal cavities. It also plays a function in the production of speech.

Hard Palate

Figure 2. Bony components of palate.


  • Supported by the horizontal parts of the palatine bones and the palatine processes of the maxilla (Figure 2)
  • Pale pink with palatine rugae
  • Bony:  maxillae anteriorly, carry all upper teeth and palatine bones posteriorly, will have soft palate hanging from it.
  • Adult hard palate will have palatine rugae – these develop between weeks 12 and 14 (Figure 3).
  • Rugae: assist the teeth and tongue in mastication. They contain a range of intraepithelial sensory cell types, which allow them to do this, such as free nerve endings and Merkel cells. In many animals, they also assist mechanically in mastication.

  • Rugae assist the teeth and tongue in mastication. They contain a range of intraepithelial sensory cell types, which allow them to do this, such as free nerve endings and Merkel cells. In many animals, they also assist mechanically in mastication.
  • Rugae are useful clinically as dental landmarks but also have been implicated as unique to each individual thus having potential in forensic odontoloty.

Soft Palate

Figure 4. Diagram of soft palate showing musculature that aids in movement of the soft palate.


  • Forms the uvula posteriorly and attaches to the dorsal edge of the hard palate.
  • Laterally and caudally forms the palatine arches (Figure 4)
  • Support from the fibromuscular structures of the palate and the palatoglossal arch (palatoglossus, palatopharyngeus, levator veli palatini, and tensor veli palatini
  • Uvula is the most posterior part of the soft palate

Palate Vasculature and Nervous Supply

Figure 5. Nerves and arteries of the adult palate

Palatine Vasculature

  • The primary vasculature descends through the greater and lesser palatine canals, which open into the pterygomandibular fossa and into major and minor palatine foramina (Figure 5). 
  • The greater palatine nerve: supplies hard palate and inner surface of upper gingiva (stopping anteriorly at the point of the canine tooth).
  • The nasopalatine nerve: supplies the area immediately posterior to the incisors. This nerve descends through the incisive foramen, from the nasal cavity.
  • The lesser palatine nerve(s): arise from the lesser palatine foramina. They supply the soft palate. Can also carry fibres from the facial nerve to supply sensory innervation to the posterior portion of the soft palate.
  • The descending palatine artery: branch of the maxillary artery in the pterygopalatine fossa, which branches to give lesser palatine artery before continuing as the greater palatine artery.
  • Greater palatine artery runs (with the greater palatine nerve) through the greater palatine canal to emerge at the greater palatine foramen and supply the hard palate. A terminal branch of the artery ascends in the incisive foramen to supply the inferior portion of the nasal septum.
  • Lesser palatine arteries: supply the soft palate. The ascending palatine artery (branch of the facial artery) will usually anastamose with the lesser palatine aa. Supplying to muscles of the soft palate.

Drag and drop labels on Figure 6 to indicate the correct vasculature and foramina of the palate:

Figure 6. Interactive figure to test knowledge of the vessels and nerves of the adult palate

  • greater palatine arery
  • greater palatine foramen
  • lesser palatine artery
  • lesser palatine foramen
  • incisive foramen
  • nasopalatine nerve
  • greater palatine nerve
  • lesser palatine nerve

The Palate - Fill in the blanks question

The adult palate is made up of the  and palates. The hard palate is supported by the horizontal portion of  bones and the palatine processes of the 

The functional ridges on the hard palate are called . These function in  and . They can also be used in clinical and  dentistry. 

 

 of the soft palate, allow movement. This is particularly important in the production of , by temporary closure of the opening between oral and  cavities. 

2. Function of The Palate

Function of The Adult Palate

  • Mechanical barrier separating the oral cavity from the nasal cavities (n.b. the nasal cavities are separated by the vomer, which develops as the nasal septum).
  • The soft palate is moveable, controlled by the muscles described in section 1.
  • This movement of the palate allows it to function to temporarily close of the posterior connection between the nasal cavity and the oral cavity.
  • Closure of this communication aids in speech production in the adult.
  • The ability to temporarily close off the communication is called Velopharyngeal function (velopharyngeal dysfunction/insufficiency is covered in section 5).

Importance of Palatal Function in The Newborn

Sufficient velopharyngeal function in the newborn is vital to allow for suckling.


Function: Fill in the blanks

The palate serves several functions. In the newborn, the primary function is to aid in . In the adult, the palate aids in the production of . Lack of function of the palate, can be due to a congenital malformation, is termed 

3. Development of the Facial Prominences

Facial Prominences

Figure 7 A. frontal view of a 4 week embryo and B. frontal view of a 4.5 week embryo, both showing the five facial prominences. 

The frontonasal prominence (Figure 7)

  • Thickened area of ectoderm ventral to the forebrain. 
  • Develops to form the cranial boundary of the primitive mouth as well as the bridge of the nose and the nasal septum.
  • In week 5: 4 additional swellings arise from the frontonasal priminence: 
    • 2 medial nasal swellings
    • 2 lateral nasal swellings (Figure 8). 

Figure 8. Frontal view of face at 5 weeks. 

Maxillary prominences (paired)  (Figure 7)

  • Derived from the 1st pharyngeal arch
  • Form the lateral border of the primitive mouth and later the lateral border and floor of the orbit.

Mandibular prominences (paired) (Figure 7)

  • Also derived from the 1st pharyngeal arch
  • Form the inferior boundary of the primitive mouth

When does development of the face and palate occur?

  • Majority of the development of the face occurs in weeks 5-8
  • This begins with merging of the medial ends of the mandibular prominences towards the end of the 4th week.

What if something goes wrong?

  • Although the palate does not complete fusion until the 12th week, the period prior to the 5th week is critical. 
  • This is the time when the embryo is most susceptible to environmental factors, which could affect the development and lead to maldevelopment of the palate (and other facial structure) (See section 6).

Intreactive

Figure 9, interactive.  Hover over the (i) to test your knowledge on the 5 facial prominences, which make up the developing face

4. Development of The Palate

Development of The Palate

As well as superficial structures of the face, which are developing (from around the 5th week), there is also the development of deeper structures; the palate is one of these deeper structures.

The palate develops from two primordial structures: the primary palate and the secondary palate.

Primary Palate

The Primary Palate

  • Develops from the medial nasal prominences
  • Contributes to a relatively small are of the palate
  • It is located anteriorly (relative to the secondary palate)
  •  Derived from the medial nasal prominences

Intermaxillary Segment

The fusion of the medial nasal prominences gives rise to the Intermaxillary segment, which gives 3 components (Figure 10):

  • Labial component– forms the philtrum (central part) of the upper lip
  • Upper jaw component – median portion of the maxilla, carries the 4 incisors
  • Palatal component – forms the triangular shaped primary palate

Figure 10 A. Maxillary processes and intermaxillary segment. B. The intermaxillary segment giving rise to the philtrim of the upper lip, the portion of the maxilla containing the four incisors and the triangular shaped primary palate.

Secondary Palate

  •  Forms the majority of the palate
  • Derived from the maxillary prominences via downward growth as the palatine shelves (week 6)
  • (Figure 11) oral cavity is still relatively small and the tongue is positioned highly in the cavity. Shelves growing down on either side of the tongue. The nasal cavities and oral cavity are one single cavity at this time (Figure 12).

Figure 11. frontal section through the head of a 6 week- old embryo. Palatine shelved have begun to grow down lateral to the tongue. 

Figure 12. Inferior view of palatine shelves (still vertical) in embryo 6.5 weeks old. 

Week 7

  • (week 7)(Figures 13 & 14) The tongue lowers in the oral cavity
  • Rotation of palatine shelves to lie in more horizontal position

Figure 13. Frontal section through the head of a 7.5 week old embryo. 

Figure 14. Inferior view of palatine shelved in 7.5 week old embryo. Clefts still present between primary and secondary palate components. However, the shelves are now horizontal. 

Fusion of The Palatine Shelves

Once horizontal, the palatine shelves then approach one another in the midline and fuse together to form secondary palate (Figure 15). This also fuses anteriorly with primary palate (Figure 16).

Figure 15. Frontal section through the head of a 10 week old embryo. Shows palatal shelves having fused in the midline to form the secondary palate. Fusion has also occurred between the secondary palate and the nasal septum. 

Figure 16. Inferior view of the palate in the 10th week once the palatine shelves have fused to give the secondary palate. 

Incisive Foramen 

Site of union where the primary palate and the two palatine shelves (of the secondary palate) all come together. Remains in adult skull and allows the passage of vessels and nerves to supply the palate (Section 1).

Recap

Video 1. Time lapse video of development of the palate from a frontal view, beginning at week six and ending at week 10 with fusion of the palatine shelves in the midline. 

Video 1 can be paused at any time to view the development between 6 and 10 weeks. 

  • Want to test yourself? Pause the video and see if you can identify the time-point and the state of the structures at that time. Use Figure 18 below for comparison. Hover over the information tabs (i) to remind yourself of the process covered in this section.

Figure 19 can also be used to review the process of palatal fusion from an inferior view - it is important to remember that this process is occurring in 3D. Try to use a combination of both Figure 18 & Figure 19 to conceptualise this. Hover over the information tabs (i) to reveal details. 

Figure 18.(Interactive figure). Frontal view of palatine shelves from the 6th to 10th week as they grow and rotate to fuse in the midline.

Figure 19 (Interactive figure). Inferior view of palatine shelves from the 6th to 10th week as they grow and rotate to fuse in the midline.

5. Abnormal Development of The Palate

Cleft Palate

Cleft palate and associated cleft lip is them most common facial defect in babies born in the UK.

Cleft will occur along the line(s) of fusion in the oral cavity. Cleft palate can occur alone or simultaneously with cleft lip (cleft lip can also occur in the absence of cleft palate).

Figure 20 A. Cleft of only the soft palate, not affecting the hard palate. B. Cleft extending the full length of the palate. 

Cleft palate can affect the palate to varying degree (Figure 20). Broadly this can be categorised as to whether it is affecting the soft or had palate.

Diagnosis and Classification of Cleft Palate

Diagnosis

Diagnosing cleft palate in the newborn can be difficult but it has been shown that a combination of visual examination in combination with palpitation of the roof of the mouth is necessary for timely and accurate diagnosis.

Classification

In the last century ‘Y’ classification of cleft palate have been modified and adapted by several authors; increasing in detail and specificity of the sub regions affected by the cleft.

The ‘Y’ shape of the embryological lines of fusion are divided to denote different extent of cleft

  • The Kernahn ‘Y’ classification is a highly cited method, which highly sub divides the oral cavity to thoroughly describe variation of cleft palate (Figure 21).

Figure 21. Kernhan 'Y' classification for cleft lip and palate. Shading of the 'Y' represents degree of clefting. For example, for a complete cleft palate to the level of the incisive foramen, 9-11 would be shaded. 

Functional Impact of Cleft Palate

Possible functional complications of clef palate include:

  • Velopharyngeal insufficiency is the major functional complication in cleft palate patients: the inability to properly close off the nasal cavity from the oral cavity, can lead to:

    • Hypernasality: results in abnormal resonance as a result of increased air flow in the nasal cavity.
    • Difficulty in newborns when feeding:  unable to form a good seal with their mouth when suckling.
  • Hearing problems: studies have shown that babies with cleft palate are more susceptible to otitis media with effusion (glue ear), which can lead to hearing problems both long and short term
  •  Dental problems:  cleft palate can disrupt normal development of the teeth. This can cause arrangement problems, where teeth are forced to grow in an abnormal direction. It can also affect the development of tooth components

Repair of Cleft Palate

  • Cleft palate can often be surgically repaired, in an attempt to restore function. There are various methods, but commonly it onvolved a skin flap graft from another part of the body (e.g. forearm) to repair the cleft.  
  • It has been shown in epidemiological studies that cleft palate is often silent until it becomes syndromic (for example, by one of the functional complications above). 
  • It has also been shown that best return of velopharyngeal function is achieved the earlier surgical repair is carried out. 

6. Cleft Palate Scenario

Scenario

Dr. Smith is a neonatal surgeon who has been asked to advise on a case of suspected cleft palate in a newborn that has not yet left hospital. Have a look at Figure 22 and on the following pages you will be asked questions about the diagnosis and course of action for this patient based on the functional implication to the patient. 

A

B

Figure 22 A. Inferior view of palate when Dr. Smith visually examines the patients oral cavity. B. Dr Smith's classification using the Krtnahn 'Y' classification. 

Based on Figure 22, what is the diagnosis of this newborn's palatal condition?

  • Cleft hard palate
  • Cleft soft palate
  • Cleft lip and palate
  • Complete cleft palate (soft and hard)

What went wrong embryologically to cause this malformation?

  • The primary and secondary palates failed to fuse
  • The secondary palate failed to fuse with the nasal septum
  • The palatine shelves failed to completely fuse in the midline
  • The intermaxillary segment failed to fuse in the midline

Foreseeing clinical and functional complications in a newborn with the malformation, what advise could Dr. Smith give to the parents of the patient?

  • The palate may finish fusion throughout childhood
  • Surgical repair would not have an positive impact in reducing functional complications
  • Surgery may be recommended, but not until the child is 2 years old, as the later the the repair is completed, the higher than chance of improved velopharyngeal function
  • Surgery may be recommended, and the sooner the repair is completed the higher the chance of improved velopharyngeal function

List some of the potential functional implications if the cleft is left un-repaired

Congratulations!

Congratulations! You have come to the end of the course and completed an applied clinical scenario when faced with a newborn with a cleft palate. 

You should now have a sound understanding of the anatomy and development of the palate and an insight into malformation that can occur as a result of improper embryological development. 

Any section of the course can be repeated from the home menu if you would like to revisit any of the topics and try and quizzes again now you have covered the full course. 

References

References

Gray, H., Carter, H. and Davidson, G. (2016.). Gray's Anatomy - The Anatomical Basis of Clinical Practice, Expert Consult. 40th ed. Philadelphia: Elsevier Limited.

Kernahn, D. (1971). New classification for cleft lip and palate. Plastic Reconstruction Surgery, 47(1), pp.469-470.

Lv, M., Shen, Y., Li, J., Zhang, C., Zhu, H. and Sun, J. (2014). Immediate reconstruction of soft palate defects after ablative surgery and evaluation of postoperative function: ananalysis of 45 consecutive patients. Journal of Oral and Maxillofacial Surgery, 72(7), pp.1397-1406.

Ma, L., Shi, B., Li, Y. and Zheng, Q. (2013). Velopharyngeal function assessment in patients with cleft palate. Journal of Craniofacial Surgery, 24(4), pp.1229-1231.

Magreni, A. and May, J. (2015). Embryology of the oral structures. Operative Techniques in Otolaryngology-Head and Neck Surgery, 26(3), pp.110-114.

Matsuo, K. and Palmer, J. (2008). Anatomy and physiology of feeding and swallowing: normal and abnormal. Physical Medicine and Rehabilitation Clinics of North America, 19(4), pp.691-707.

McCombe, D., Lyons, B., Winkler, R. and Morrison, W. (2005). Speech and swallowing following radial forearm flap reconstruction of major soft palate defects. British Journal of Plastic Surgery, 58(3), pp.306-311.

Moore, K., Agur, A. and Dalley, A. (2015). Essential Clinical Anatomy. 12th ed. Philadelphia: Wolters Kluwer Health.

Patil, M., Patil, S. and Acharya, A. (2008). Palatine rugae and their significance in clinical dentistry. The Journal of the American Dental Association, 139(11), pp.1471-1478.

Sadler, T. (2015). Langman's Medical Embryology. 4th ed. Philadelphia: Wolters Kluwer.