Masseter muscle

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Reading list
  • Trigger point
    • Masseter Muscle
    • Masseter
  • Anatomy
    • Gilroy

Origin

SF layer: zygomatic arch (ant 2/3); Deep layer: Zygomatic arch (post. 1/3)

Insertion

Mandibular angle (Masseteric tuberosity)

Innervation

Trigeminal CN V: Mandibular (V3)

Action

The primary function of the masseter is to develop potentially large forces between the molars for effective crushing of food. This is possible since the force vector of the muscle is nearly perpendicular to the biting surface of the molars. The masseter’s ability to combine ipsilateral excursion (unilateral function) with a strong biting force (Bilateral function) makes it very suitable for grinding food

SF Fibers: Protrude mandible

  • Bilateral contraction: Elevation and slight protrusion
    • Elevates the mandible to bring the teeth into contact during mastication
    • Bilateral action of the masseters also protrudes the mandible slightly.
  • Unilateral contraction: Slight I/L excursion
    • This muscle action is most effective when the mandible is positioned in C/L excursion
    • This position not only stretches the muscle (presumably augmenting its activation), but also increases its force potential within the horizontal plane.
    • Therefore, this muscle at moving the jaw OUT of C/L excursion and into neutral

Clinical Significance

Strain-Counterstrain

“Location of Tender Point: In the superficial and deep fibers of the masseter muscle. Anatomical Correlation: Masseter muscles. Direction to Press on Tender Point: Place palpating fingers on cheek anterior to muscle. Press posteriorly toward the anterior border of the ascending ramus of mandible. Treatment Position(s): With patient supine, push slightly open jaw toward the Tender Point side to produce lateral glide. Apply counterforce to frontal bone on Tender Point side to stabilize head. Masseter muscle Frequency of Occurrence: Very common. Clinical Correlation(s): 1) Pain with yawning 2) Unable to fully open mouth 3) Lateral shift to same side with mouth open 4) Jaw muscle tension 5) Bruxism 6) Cervical tension Alternate Names/Nomenclatures: Sphenomandibularis muscle. Explanatory Notes: Successful treatment of this Tender Point often reduces tone in the upper trapezius and sternocleidomastoid muscles.”

References

1.
Donnelly JM, Simons DG, eds. Travell, Simons & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual. Third edition. Wolters Kluwer Health; 2019.
2.
Finando D, Finando SJ, Finando D. Trigger Point Therapy for Myofascial Pain: The Practice of Informed Touch. Healing Arts Press; 2005.
3.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
4.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
5.
Myers HL, Devine WH, Fossum C, et al. Compendium Edition: Clinical Application of Counterstrain. Compendium ed. Osteopathic Press; 2012.

Citation

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