Musculoskeletal pain is one of the conditions the clinician will need to address, and proper evaluation of masticatory muscles include a careful examination of function and tenderness.
See https://ostrowon.usc.edu/2020/08/27/orofacial-pain-muscle-tenderness-exam/
- Flat Palpation: Using the padded aspect of the fingers or thumb and proceeding at a right angle across the muscle fibers while pressing them against the underlying tissue or bone. When trigger points exist taut bands, exquisite, focal tenderness (Trigger Points), and a twitch response will be detected.
- Pincer Palpation: The muscle or muscles are rolled between the tips of the digits to detect taut bands of fibers, to detect exquisite, focal tenderness (Trigger Points), and to elicit local twitch responses.
- Snapping Palpation: Locate a taut band of muscle and place fingertip at right angles. Begin moving your fingers back and forth to roll the underlying fibers under the finger. This is just as plucking a guitar string except contact with the surface is maintained. The purpose of this method is to elicit a local twitch response and is most effective when done near or on the trigger point with the muscle at a neutral length or slightly lengthened.
- Relative tenderness assessment: with all muscles in that you palpate there are two methods.
- First is the relative tenderness assessment, which is done using a standard anatomic location and a standard pressure level. The locations are described below for each muscle but the pressure to be used is 2 kg of pressure with one finger for 2 seconds. While palpating you ask the patient to rate the pressure as none, mild, moderate or severe.
- Trigger point assessment: The second aspect of a muscle palpation assessment is to palpate across the muscle with your fingers to identify any taut bands. This involves sliding the overlying skin back and forth across the muscle. Taut bands will be evident if it is present and once you find the band, you move up and down the band applying firm pressure while asking the patient to report the tender point in the band. Once found this point needs to be compressed for 5 seconds (with 2 kg pressure) to see if the pain radiates or refers.
- Deep masseter muscle palpation: point out the insertion and origin on a dry skull of the deep masseter. This site is anterior and inferior to the lateral condyle pole, posterior to the posterior edge of the superficial masseter, and beneath the zygomatic arch.
- Superficial masseter muscle palpation: point out the insertion and origin on a dry skull of the superficial masseter. This site is beneath the zygomatic arch and the muscle is angled back towards the angle of the mandible.
- Anterior temporalis muscle palpation: point out the insertion and origin on a dry skull of the anterior temporalis. The anterior temporalis muscle best palpated at the hairline and opposite the eyebrow.
- Posterior temporalis muscle palpation: point out the insertion and origin on a dry skull of the posterior temporalis. This site is just above the pinna or the ear and its direction is posterior from the coronoid process.
- SCM (Sternocleidomastoid) muscle palpation: point out the insertion and origin on a human skeletal diagram of the SCM. This site is from the manubrium of the sternum (sterno-) and the clavicle (cleido-), and has an insertion at the mastoid process of the temporal bone of the skull.
- Temporalis muscle tendon palpation: point out the insertion and origin on a dry skull of the temporalis muscle tendon (at the coronoid process just beneath the zygomatic process and is accessed by having the mouth open).
- Lateral pterygoid muscle functional exam: point out the insertion and origin on a dry skull of the lateral pterygoid muscle anatomically. Explain that it cannot be palpated but you can assess the function of this muscle by asking the patient to protrude the jaw.
- Medial pterygoid palpation: point out the insertion and origin on a dry skull of the medial pterygoid muscle: (insertion) angle of the mandible and (origin) the inner surface of the pterygoid plate behind the maxilla. Describe which portion of the muscle is palpated intraorally and the most common complication: inferior portion and anterior band (laterally to the point where inferior alveolar nerve block is performed) can be palpated intraorally. Intraoral palpation can trigger a gag response. To palpate the muscle in a patient, look for the angle of the jaw, and use the index and thumb to feel both masseter (outside) and medial pterygoid (inside) muscle’s insertions.
Some of the possible findings or conditions this test might identify are:
- Myofascial taut band.
- Trigger point.
- Hypertrophy.
- Spasm.
- Injection induced myositis.