When the wing is folded the long glenoid surface of the head of the humerus is bordered above by the tuberculum externum or superius, in the middle and below by the tuberculum medium or inferius for the insertion of the coraco-brachialis posterior muscle.
The post-glenoid, post-tympanic and paroccipital processes of the skull are large, and there is an alisphenoid canal.
As in the last family, the post-glenoid process of the skull is broad; the whole skull be i ng depressed with a shortened facial portion.
The post-glenoid process is small, and the facial and cranial portions of the skull are approximately of equal length.
- The rodent skull is characterized by the great size of the premaxillae, which completely separate the nasals from the maxillae; by the presence of zygomatic arches; and by the wide unoccupied space existing between the incisors and the cheek-teeth; and (except in the Duplicidentata) by the antero-posteriorly elongated glenoid cavity for the articulation of the lower jaw.
The glenoid surface for the articulation of the mandible is greatly extended transversely, concave from side to side, convex from before backwards in front, and hollow behind, and is bounded posteriorly at its inner part by a prominent post-glenoid process.