Human Anatomy: Head & Neck Skull Views and Muscles of Mastication

Skull Views

• Norma frontalis: anterior view of the skull
• Norma verticalis: superior view of the skull
• Norma occipitalis: posterior view of the skull
• Norma basalis: inferior view of the skull

Mandible and Fossae

• Temporal fossa: location of the temporalis muscle
• Infratemporal fossa: location of the lateral and medial pterygoid muscles

Muscles of Mastication

• 4 muscles: temporalis, masseter, lateral pterygoid, and medial pterygoid
• All muscles originate from the skull and insert into the mandible
• All muscles receive nerve supply from the mandibular nerve

Temporalis Muscle

• Origin: floor of temporal fossa and deep surface of temporal fascia
• Insertion: coronoid process and anterior border of ramus mandible
• Nerve supply: anterior division of mandibular nerve
• Action: elevation of mandible by anterior fibers and retraction by posterior fibers

Masseter Muscle

• Origin: lower border and inner surface of the zygomatic arch
• Insertion: lateral surface of the ramus of the mandible
• Nerve supply: anterior division of the mandibular nerve
• Action: elevation and protraction of the mandible

Lateral Pterygoid Muscle

• Origin: upper head from infratemporal surface of the greater wing of sphenoid bone, lower head from lateral surface of the lateral pterygoid plate
• Action: depression of the mandible (opening the mouth), protraction of the mandible, and movement of the mandible side to side (chewing)

Important Notes

• All muscles of mastication elevate the mandible (close the mouth) except the lateral pterygoid
• All muscles of mastication protract the mandible except the temporalis
• Medial and lateral pterygoid muscles move the mandible side to side (chewing)