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The trilobite body is divided into three major sections: a cephalon (head section) with eyes, mouthparts and sensory organs such as antennae; a thorax of multiple segments which are similar to each other; and a pygidium, or tail section. In many species, the cephalon had sutures running from back to front round the outside edges of the eyes.
Sutures: The skull bones are connected by fibrous joints called sutures. [1] In fetal skulls, the sutures are wide to allow slight movement during birth. They later become rigid (synarthrodial). Syndesmosis: Some of the long bones in the body such as the radius and ulna in the forearm are joined by a syndesmosis (along the interosseous membrane).
If certain bones of the skull grow too fast then premature fusion of the sutures, craniosynostosis, may occur. [1] This can result in skull deformities. [1] These deformities include: [3] Brachycephaly (both sides) Plagiocephaly (one side only) Oxycephaly (both sides)
Bones are commonly described with the terms head, neck, shaft, body and base. The head of a bone usually refers to the distal end of the bone. The shaft refers to the elongated sections of long bone, and the neck the segment between the head and shaft (or body). The end of the long bone opposite to the head is known as the base.
Increased cranial pressure in infants may cause the fontanelles to bulge or the head to begin to enlarge abnormally. [7] It can occur due to: [4] Craniosynostosis – premature fusion of the cranial sutures [8] Encephalitis – swelling (inflammation) of the brain, most often due to infections; Hydrocephalus – a buildup of fluid inside the skull
The sutures are an essential part of growth and development, allowing the skull to expand as the brain increases in size. Different sutures between the frontal and parietal bones of the skull expand in specific directions, causing a symmetrically shaped human head. [3] The frontal bone and the parietal bones are joined at the frontal suture ...
Wormian bones, also known as intrasutural bones or sutural bones, [1] are extra bone pieces that can occur within a suture (joint) in the skull. These are irregular isolated bones that can appear in addition to the usual centres of ossification of the skull and, although unusual, are not rare. [2] They occur most frequently in the course of the ...
The head rests on the top part of the vertebral column, with the skull joining at C1 (the first cervical vertebra known as the atlas). The skeletal section of the head and neck forms the top part of the axial skeleton and is made up of the skull, hyoid bone, auditory ossicles, and cervical spine. The skull can be further subdivided into: