Anatomical variation between the muscles of mastication in black-tip shark (Carcharhinus limbatus) and shovelnose ray Fish (Glaucostegus typus)

The current study aims to differentiate, morphologically, between the masticatory muscles in black-tip sharks and shovelnose ray fish, which control the opening and closure of jaws. This work was applied to four specimens of each species, obtained from the Red Sea in Suez. Anatomical dissection was conducted on the cephalic region is order to expose the musculature. The obtained results illustrate each muscle's position, origin, and insertion. The common muscles involved in the feeding of both species were the muscles of mandibular arch: adductor mandibulae, levator palatoquadrati, while the muscles of hyoid arch were levator hyomandibulae, also the hypobranchial arch contained coracomandibularis, coracohyoideus, and coracoarcualis. All muscles of the jaws are responsible for the abduction of mouth except Adductor mandibulae M, Intermandibularis M. involved in closing the mouth, in addition, Preorbitalis M. assists in protruding of upper jaw.