Final answer:
The cartilaginous neurocranium is part of the skull that encloses and protects the brain. In humans, it consists of eight bones fused by connective tissue. It provides protection to the brain and attachment points for head and neck muscles.
Step-by-step explanation:
Cartilaginous Neurocranium
The cartilaginous neurocranium is part of the skull that forms the protective vault surrounding the brain. In vertebrates, it comprises either bony or cartilaginous elements, depending on the developmental stage and the species. For instance, in human fetal development, the neurocranium initially starts as a cartilaginous structure and later ossifies to form the bony neurocranium.
The human neurocranium consists of eight bones at maturity: one frontal bone, two parietal bones, two temporal bones, one occipital bone, one sphenoid bone, and one ethmoid bone. These bones are developed separately but are tightly fused in the adult with fibrous connective tissue known as sutures. The ethmoid bone is of particular interest as it forms part of the anterior base of the neurocranium and separates the nasal cavity from the brain, featuring two parts, the crista galli and cribriform plates.
The neurocranium protects the brain and provides anchoring sites for the structures of the face and the muscles of the head and neck. Within the broader context of the Craniata clade, which also includes non-vertebrate members like hagfishes, the neurocranium can be cartilaginous, bony, or fibrous.