World Library  
Flag as Inappropriate
Email this Article

Maxilla

Article Id: WHEBN0000242299
Reproduction Date:

Title: Maxilla  
Author: World Heritage Encyclopedia
Language: English
Subject: Dentofacial osteotomy, Osteonecrosis of the jaw, Inferior nasal concha, Lacrimal bone, Palatine bone
Collection: Bones of the Head and Neck, Dental Anatomy, Human Mouth Anatomy, Irregular Bones
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Maxilla

Maxillae
Side view. Maxilla visible at bottom left, in green.
Front view. Maxilla visible at center, in yellow.
Details
Precursor 1st branchial arch[1]
Identifiers
MeSH A02.835.232.781.324.502.645
Dorlands
/Elsevier
Maxilla
FMA 9711
Anatomical terms of bone

The maxillae (plural: maxillae )[2] are the two maxilla bones forming the upper jaw and palate of the mouth.[3][4] The two halves are fused at the intermaxillary suture to form the upper jaw. This is similar to the mandible (lower jaw), which is also a fusion of two halves at the mandibular symphysis.

Sometimes (e.g. in bony fish), the maxilla is called "upper maxilla," with the mandible being the "lower maxilla." Conversely, in birds the upper jaw is often called "upper mandible."

Contents

  • Structure 1
    • Articulations 1.1
    • Development 1.2
      • Changes by age 1.2.1
  • Function 2
  • In other animals 3
  • Additional images 4
  • See also 5
  • References 6
  • External links 7

Structure

Each half of the fused maxillae consists of:

Articulations

Each maxilla articulates with nine bones:

Maxilla

Sometimes it articulates with the orbital surface, and sometimes with the lateral pterygoid plate of the sphenoid.

Development

Figure 5: Anterior surface of maxilla at birth.
Figure 6: Inferior surface of maxilla at birth.

The maxilla is ossified in membrane. Mall[5] and Fawcett[6] maintain that it is ossified from two centers only, one for the maxilla proper and one for the premaxilla.

These centers appear during the sixth week of prenatal development and unite in the beginning of the third month, but the suture between the two portions persists on the palate until nearly middle life. Mall states that the frontal process is developed from both centers.

The maxillary sinus appears as a shallow groove on the nasal surface of the bone about the fourth month of development, but does not reach its full size until after the second dentition.

The maxilla was formerly described as ossifying from six centers, viz.,

  • one, the orbitonasal, forms that portion of the body of the bone which lies medial to the infraorbital canal, including the medial part of the floor of the orbit and the lateral wall of the nasal cavity;
  • a second, the zygomatic, gives origin to the portion which lies lateral to the infraorbital canal, including the zygomatic process;
  • from a third, the palatine, is developed the palatine process posterior to the incisive canal together with the adjoining part of the nasal wall;
  • a fourth, the premaxillary, forms the incisive bone which carries the incisor teeth and corresponds to the premaxilla of the lower vertebrates;
  • a fifth, the nasal, gives rise to the frontal process and the portion above the canine tooth;
  • and a sixth, the infravomerine, lies between the palatine and premaxillary centers and beneath the vomer; this center, together with the corresponding center of the opposite bone, separates the incisive canals from each other.

Changes by age

At birth the transverse and antero-posterior diameters of the bone are each greater than the vertical.

The frontal process is well-marked and the body of the bone consists of little more than the alveolar process, the teeth sockets reaching almost to the floor of the orbit.

The maxillary sinus presents the appearance of a furrow on the lateral wall of the nose. In the adult the vertical diameter is the greatest, owing to the development of the alveolar process and the increase in size of the sinus.

Function

The alveolar process of the maxillae holds the upper teeth, and is referred to as the maxillary arch. Each maxilla attaches laterally to the zygomatic bones (cheek bones).

Each maxilla assists in forming the boundaries of three cavities:

Each maxilla also enters into the formation of two fossae: the infratemporal and pterygopalatine, and two fissures, the inferior orbital and pterygomaxillary.

In other animals

Sometimes (e.g. in bony fish), the maxilla is called "upper maxilla," with the mandible being the "lower maxilla." Conversely, in birds the upper jaw is often called "upper mandible."

In most vertebrates, the foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae. These fuse with the maxilla proper to form the bone found in humans, and some other mammals. In bony fish, amphibians, and reptiles, both maxilla and premaxilla are relatively plate-like bones, forming only the sides of the upper jaw, and part of the face, with the premaxilla also forming the lower boundary of the nostrils. However, in mammals, the bones have curved inward, creating the palatine process and thereby also forming part of the roof of the mouth.[7]

Birds do not have a maxilla in the strict sense; the corresponding part of their beaks (mainly consisting of the premaxilla) is called "upper mandible."

Cartilaginous fish, such as sharks, also lack a true maxilla. Their upper jaw is instead formed from a cartilagenous bar that is not homologous with the bone found in other vertebrates.[7]

Additional images

See also

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

  1. ^ hednk-023—Embryo Images at University of North Carolina
  2. ^ OED 2nd edition, 1989.
  3. ^ Merriam-Webster Online Dictionary.
  4. ^ Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, page 55
  5. ^ American Journal of Anatomy, 1906, vol. v.
  6. ^ Journal of Anatomy and Physiology, 1911, vol. xlv.
  7. ^ a b
  • Harry Sicher and E. Lloyd Du Brul, Oral Anatomy
  • Peter Warthington, Controversies in Oral and Maxillofacial Surgery

External links

  • Anatomy photo:22:os-1901 at the SUNY Downstate Medical Center
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.