Jugal bone

Gegenbaur 1870 skull homology color

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Gymnogyps californianus (Shaw, 1798)

Jugal bone is a term used in zoology to refer to a bone found in the skulls of many types of vertebrate animals, including some species of mammals, reptiles, and birds. It is not commonly referred to in human anatomy; in humans, the equivalent structure is considered part of the zygomatic bone, which contributes to the cheekbone and the orbit of the eye. The jugal bone plays a significant role in the structure of the skull, providing support for various facial features and contributing to the formation of the orbit.

Structure and Function

The jugal bone is typically located on the sides of the skull, extending from the lower part of the orbit, where it contributes to the eye socket, towards the rear part of the skull. It serves as an anchor point for various muscles and supports the structure of the face. In many animals, the size and shape of the jugal bone can significantly influence the overall appearance of the head, affecting factors such as the width of the face and the size of the eye sockets.

In reptiles and birds, the jugal bone is a crucial component of the skull, contributing to the strength and stability of the jaw. It often connects with other bones in the skull, including the maxilla (upper jaw bone) and the quadratojugal, further supporting the jaw and facial structure.

Evolutionary Significance

The jugal bone has been a subject of interest in the study of evolution due to its variations across different species. Its presence and form can provide valuable insights into the evolutionary relationships between species, as well as adaptations to different environments and feeding habits. For example, in some extinct reptiles, such as certain dinosaurs, the jugal bone was part of a more complex jaw mechanism that allowed for powerful bites.

Comparative Anatomy

In comparative anatomy, the study of the jugal bone across different species helps scientists understand the functional and evolutionary adaptations of vertebrates. For instance, in some carnivorous mammals, the jugal bone is robust and well-developed, reflecting the need for a strong jaw to capture and process prey. In contrast, in some herbivorous animals, the jugal bone may be adapted to support a wider jaw, facilitating the consumption of plant material.

Human Anatomy

In human anatomy, the term "jugal bone" is not commonly used. The human equivalent is the zygomatic bone, which is a key component of the facial skeleton. The zygomatic bone forms the prominence of the cheek, part of the lateral wall, and floor of the orbit. It articulates with the maxilla, temporal bone, sphenoid bone, and the frontal bone, playing a critical role in the aesthetics and function of the human face.

See Also

• Skull
• Zygomatic bone
• Maxilla
• Temporal bone
• Sphenoid bone
• Frontal bone