Didelphis
Dissections reveal the following relationships of the external adductors of the jaw in Didelphis marsupialis ([Fig. 8]).
1. Masseter
Origin: ventral surface of zygomatic arch.
Insertion: posteroventral and lateroventral surface of mandible.
2. External temporalis
Origin: sagittal crest; anteriorly with internal temporalis from frontal bone; posteriorly with internal temporalis from interparietal bone.
Insertion: lateral surface of coronoid process of mandible.
3. Internal temporalis
Origin: sagittal crest and skull roof, including posterior two-thirds of frontal bone, whole of parietal, and dorsalmost portions of squamosal and alisphenoid.
Insertion: medial surface of coronoid process; dorsal edge of coronoid process.
Fig. 8. Didelphis marsupialis. Showing masseter and temporal muscles. Skull KU 3780, 1 mi. N Lawrence, Douglas Co., Kansas. × 3/5.