Lateral Pterygoid

ByA. Mendelson, MD
Please read the disclaimer

The lateral pterygoid is a small but important muscle in the face that plays a key role in moving the jaw. Radiologists often evaluate it on CT or MRI scans, especially when looking into jaw pain, facial trauma, or temporomandibular joint (TMJ) issues.  This article explains what the lateral pterygoid muscle is, why it’s imaged, and what abnormalities can appear on radiology reports.

What Is the Lateral Pterygoid Muscle?

The lateral pterygoid is one of the muscles involved in chewing. It sits deep inside the face near the temporomandibular joint (TMJ), which connects the jawbone to the skull. It has two parts:

  • Superior head: attaches to the sphenoid bone and the articular disc of the TMJ.
  • Inferior head: attaches to the lateral side of the pterygoid plate and the neck of the mandibular condyle.

This muscle helps open the mouth, move the jaw side to side, and stabilize the TMJ during movement.

Imaging of the Lateral Pterygoid

CT Scan of the Lateral Pterygoid

CT scans give a detailed view of the bony attachments and help assess fractures, tumors, or structural abnormalities. The lateral pterygoid appears as a soft-tissue density near the back of the cheek, just in front of the ear.

CT is often used when trauma or bone injury is suspected. In jaw fractures, for example, the lateral pterygoid may be involved in pulling fractured bone fragments apart, especially in condylar fractures.

MRI of the Lateral Pterygoid

MRI provides better soft tissue contrast than CT and is the preferred imaging method for evaluating the muscle itself and nearby TMJ structures. On MRI, the lateral pterygoid muscle should have a smooth, uniform appearance without swelling, fatty infiltration, or abnormal enhancement.

MRI is used to evaluate:

  • Muscle strain or tear
  • Inflammation or edema
  • TMJ disorders
  • Masses or tumors
  • Post-surgical changes

Why Radiologists Look at the Lateral Pterygoid

Radiologists evaluate the lateral pterygoid in several common scenarios:

1. TMJ Dysfunction (TMD)

The muscle can show changes from overuse, inflammation, or spasm in TMJ disorders. As part of TMJ MRI protocols, radiologists assess the lateral pterygoid for asymmetry, size changes, and signal intensity.

2. Facial Trauma

After facial trauma, especially involving the mandibular condyle or zygomatic arch, the lateral pterygoid may be affected. If a condylar fracture is displaced, it may be due to the pull of this muscle.

3. Masses or Tumors

Any abnormal mass, such as a sarcoma or benign lesion, may affect the lateral pterygoid. MRI is ideal for characterizing these findings, looking at the margins, enhancement, and involvement of nearby structures.

4. Trismus or Jaw Stiffness

Limited mouth opening may be due to lateral pterygoid spasm, infection, or fibrosis. Imaging helps differentiate between muscular and joint causes.

Common Findings in Radiology Reports

Asymmetry

Mild asymmetry between the right and left lateral pterygoid muscles is often normal. Significant differences may suggest prior trauma, muscle atrophy, or overuse on one side.

Muscle Enlargement

Swelling or thickening can indicate inflammation (myositis), infection (abscess), or tumor involvement. This may be accompanied by pain or dysfunction.

Fatty Infiltration

If the muscle looks bright on MRI T1 sequences, it may have fatty replacement, often due to chronic disuse or nerve injury.

Enhancement Post-Contrast

Abnormal enhancement of the muscle on post-contrast MRI could suggest infection, tumor, or inflammation.

When to Be Concerned

If your radiology report mentions:

  • “Asymmetrical enlargement of the lateral pterygoid”
  • “Abnormal enhancement of the muscle”
  • “Mass involving the masticator space”
  • “Findings consistent with myositis or abscess”

…your doctor may order further imaging or clinical evaluation. In most cases, minor asymmetry or incidental findings are not serious, especially without symptoms.

Lateral Pterygoid vs. Medial Pterygoid

The lateral and medial pterygoid muscles are often confused. Both are located in the masticator space, but they have different functions:

  • Lateral pterygoid: opens the mouth and moves the jaw forward and side to side.
  • Medial pterygoid: helps close the jaw.

Radiologists assess both muscles together when evaluating TMJ pain or suspected tumors in the masticator space.

Conclusion

The lateral pterygoid muscle is a small but essential structure that plays a big role in jaw movement and stability. When it shows up on a radiology report, it may be part of an evaluation for TMJ dysfunction, trauma, or unexplained facial pain. Many findings are benign and simply part of your anatomy, but in some cases, they can help guide further work-up or treatment.  If you have questions about your imaging report, speak with your doctor to understand the clinical significance.

References

https://radiopaedia.org/articles/lateral-pterygoid-muscle?lang=us

https://pubmed.ncbi.nlm.nih.gov/25457825/

https://insightsimaging.springeropen.com/articles/10.1007/s13244-013-0266-4

Disclaimer: The content of this website is provided for general informational purposes only and is not intended as, nor should it be considered a substitute for, professional medical advice. Do not use the information on this website for diagnosing or treating any medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.

Similar Posts