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Meckel's cartilage is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first branchial arch in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. [1]
In contrast to the Meckel's cartilage of the first pharyngeal arch it does not constitute a continuous element, and instead is composed of two distinct cartilaginous segments joined by a faint layer of mesenchyme. [15]
The Meckel's cartilage consists of a pair of thin, flattened cartilage plates which support the rostrum and which attach to the palatoquadrates. [7] [8] Restored skull of the distantly related Helicoprion davidsii, displaying well-developed palatoquadrates and a lack of a mandibular rostrum
The mesenchymal cells within the mandibular prominence condense to form Meckel's cartilage. [2] It is innervated by the mandibular nerve. [3] References.
Meckel's cartilage is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first gill arch (nearest the front) in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. [76]
In some fishes, the palatoquadrate is the dorsal component of the mandibular arch, the ventral one being Meckel's cartilage. The palatoquadrate forms from splanchnocranium in various chordates including placoderms and acanthodians .
The function of the sphenomandibular ligament is to limit distension of the mandible in an inferior direction. It is slack when the temporomandibular joint (TMJ) is in closed position; it is taut when the condyle of the mandible is situated anterior to the temporomandibular ligament. [2]
Meckel's cartilage has an additional projection right before the joint with the palatoquadrate. This extra process, unique to Helicoprion , likely served to limit jaw closure to prevent the whorl from puncturing the chondrocranium.