The maxillae, pronounced /mækˈsɪliː/, are the upper fixed bones of the jaw. They are formed from the fusion of two maxillary bones.
Key Features of the Maxillae
Here's a breakdown of important aspects of the maxillae:
- Fusion: The maxillae are created by the joining of two maxillary bones.
- Fixed Nature: In most vertebrates, the maxillae are fixed, meaning they don't move. However, it's noted that they are not fixed in Neopterygii.
- Upper Jaw Formation: They are primarily responsible for forming the upper portion of the jaw.
- Hard Palate: In humans, the maxillae also include the hard palate which is the front part of the roof of the mouth.
- Intermaxillary Suture: The two maxillary bones fuse together at the intermaxillary suture.
- Anterior Nasal Spine: This fusion also forms the anterior nasal spine, a bony projection.
Maxillae in Humans
In the human skull, the maxillae play a critical role in facial structure and function. They:
- Support the upper teeth.
- Form the floor of the orbits (eye sockets).
- Contribute to the formation of the nasal cavity.
Comparison with Other Animals
While the basic function of the maxillae remains similar across many animals, some differences exist. For instance, the degree of fixation might vary, like in Neopterygii as mentioned in the reference.
Practical Considerations
The maxillae are also crucial in various medical contexts:
- Dental Procedures: Dental work often involves the maxillae, like implants and extractions.
- Facial Fractures: The maxillae are susceptible to fractures due to their prominent position on the face.
- Congenital Defects: Conditions like cleft palate involve the maxillae.
