The secondary palate is an anatomical structure that divides the nasal cavity

Nasal cavity

The nasal cavity is a large air filled space above and behind the nose in the middle of the face.- Function :The nasal cavity conditions the air to be received by the other areas of the respiratory tract...

 from the oral cavity

Mouth

The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....

 in many vertebrate

Vertebrate

Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

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In human embryology

Embryology

Embryology is a science which is about the development of an embryo from the fertilization of the ovum to the fetus stage...

, it refers to that portion of the hard palate

Hard palate

The hard palate is a thin horizontal bony plate of the skull, located in the roof of the mouth. It spans the arch formed by the upper teeth.It is formed by the palatine process of the maxilla and horizontal plate of palatine bone....

 that is formed by the growth of the two palatine shelves medially and their mutual fusion in the midline. It forms the majority of the adult palate and meets the primary palate at the incisive foramen

Incisive foramen

The fossa incisiva is an opening in the bone of the oral hard palate where blood vessels and nerves may pass. There are four of these openings in the incisive fossa.-Formation:...

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Clinical significance

Secondary palate development

Secondary palate development

The development of the secondary palate commences in the sixth week of human embryological development. It is characterised by the formation of two palatal shelves on the maxillary prominences, the elevation of these shelves to a horizontal position, and then a process of palatal fusion between the...

 begins in the sixth week of pregnancy

Pregnancy

Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...

 and can lead to cleft palate when development goes awry.

There are three major mechanisms known to cause this failure:

1. Growth retardation - Palatal shelves do not grow enough to meet each other.
2. Mechanical obstruction - Improper mouth size, or abnormal anatomical structures in the embryonic mouth prevent fully grown shelves from meeting each other.
3. Midline epithelial dysfunction (MED) - The surface mucosa of embryonic shelves is impaired, which causes a failure of palatal fusion.

Evolution

The secondary palate is thought to have a significant role in the development of warm-blooded

Warm-blooded

The term warm-blooded is a colloquial term to describe animal species which have a relatively higher blood temperature, and maintain thermal homeostasis primarily through internal metabolic processes...

 animals. The first creatures with secondary palates are known from the fossil record starting from the mid-Permian

Permian

The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...

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