It has a pair of poison glands, or ducts and a pair of fangs. The poison glands are present on the upper jaw. The poison glands are the superior labial glands. Each poison gland is sac like. It gives a duct. The duct passes along the side of the upper jaw. It opens into the groove of the fang. Fangs are of two types.
1) Open type (Ex: Cobra), 2) Closed type (Ex: Viper)
In open type the poison groove is present in cased type the Poison groove forms a canal with two openings at both ends.
Digastric muscle is attached to the squamosal of the skull and articulates with the lower jaw. Sphenopterygoid is attached to the sphenoidal region and to the dorsal surface of the pterygoid. Anterior and posterior temporalis muscles are attached to the side walls of the cranium and the lower jaw.