What two muscles on your muscle list aid in mastication?

 The primary muscles which help in mastication include: Masseter. Temporalis. 

Massester : It is a rectangular muscle that covers most of the lateral aspect of the ramus. It consists of three layers that blend anteriorly: the superficial layer, intermediate layer, and deep layer. 

Function of massester: The major function of the masseter muscle is to elevate the mandible, approximate the teeth.

• The intermediate and deep muscle fibres of the masseter function to retract the mandible and the superficial fibres function to protrude the mandible. The deep fibres are important stabilisers of the TMJ. 
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• Temporalis : It is a fan-shaped muscle that fills the temporal fossa, with anterior fibres that have a vertical orientation, mid fibres have an oblique orientation, and posterior fibres have more of a horizontal orientation. 
• Function of temporalis : The function of the anterior and mid fibres of the temporalis muscle is to elevate the mandible.
• The posterior fibres of the temporalis muscle function to retract the mandible. It also contributes to side to side grinding movement.