Temporalis Muscle

Also written as Temporalis, Temporal muscle.

The temporalis is a broad, fan‑shaped muscle of mastication covering the temporal fossa. It elevates and retracts the mandible and its wasting signals chronic malnutrition.

Overview

The temporalis is a superficial muscle of the side of the head that works with the masseter and pterygoids to close the jaw. Its size reflects nutritional status and can be examined at the bedside.

• Broad, fan‑shaped, originates on temporal fossa, inserts on coronoid process
• Primary actions: elevation and retraction of mandible

Location and structure

It fills the temporal fossa, a shallow depression on the lateral skull between the superior and inferior temporal lines. Fibres run downward and forward to the coronoid process of the mandible.

• Origin: temporal fossa, deep to temporal fascia
• Insertion: anterior border of coronoid process

Relations

Deep to the temporalis lies the deep temporal fascia and the middle meningeal artery. Laterally it is covered by the skin and subcutaneous tissue; medially it contacts the lateral pterygoid.

• Superficial: skin, subcutaneous tissue, temporal fascia
• Deep: deep temporal fascia, middle meningeal vessels

Blood supply

Supplied mainly by the deep temporal arteries, branches of the maxillary artery, and by the middle temporal artery from the superficial temporal artery.

• Deep temporal arteries (maxillary branch)
• Middle temporal artery (superficial temporal branch)

Nerve supply

Innervated by the deep temporal nerves, branches of the anterior division of the mandibular division (V3) of the trigeminal nerve.

• Deep temporal nerves (V3)
• Motor function only

Function

Elevates the mandible (closing the mouth) and retracts it (pulls the jaw backward). Works synergistically with masseter for powerful bite; important for chewing tough foods.

• Mandibular elevation
• Mandibular retraction

Clinical relevance and injuries

Temporalis wasting is a bedside marker of chronic protein‑energy malnutrition, especially in children and HIV‑positive adults. Trauma can cause temporalis hematoma or myositis, and overuse may lead to temporomandibular joint pain.

• Physical examination of temporalis bulk: Is the muscle visibly thin or atrophic? Thin muscle suggests chronic malnutrition; normal bulk supports adequate nutrition.
• Ultrasound of temporal region (if available): Is there a fluid collection? Detects hematoma or abscess when imaging is limited.
• Serum albumin (if available): Is albumin low (<30 g/L)? Confirms protein deficiency contributing to muscle wasting.

• Wasting → severe malnutrition, kwashiorkor, chronic HIV
• Hematoma after temporal region blow → swelling, pain
• Myositis in TB or bacterial infection → tenderness, fever

Exam pearls

Ask the patient to clench teeth while you palpate the temporalis from the side; a firm contraction indicates intact motor supply. Compare bulk bilaterally; asymmetry may signal focal pathology.

• Palpate during clench – feel fan‑shaped contraction
• Check for tenderness, swelling, or skin changes

Questions an examiner may ask

• A 7‑year‑old with kwashiorkor shows marked temporal hollowing – what does this sign indicate and how does it affect management? — Indicates severe protein‑energy malnutrition; prioritize nutritional rehabilitation and monitor for complications such as infections.
• A patient with HIV presents with jaw pain and a tender, swollen temporalis – what is your next diagnostic step? — Perform bedside ultrasound to look for myositis or abscess; if unavailable, treat empirically for infection while arranging referral.
• During a trauma assessment you note a bulging temporalis region after a fall – which structure is most likely injured and why? — Likely a hematoma of the temporalis muscle or deep temporal fascia; the area is superficial and prone to bleeding from the deep temporal arteries.
• How would you differentiate temporalis wasting from normal variation in a malnourished adult? — Compare bilateral bulk, assess for overall signs of malnutrition (hair loss, skin changes), and correlate with serum albumin if possible.
• A patient cannot close their mouth fully; you suspect temporalis dysfunction – what bedside test confirms motor involvement? — Ask the patient to clench teeth while you palpate the temporalis; lack of firm contraction suggests motor nerve or muscle pathology.
• Why is the temporalis muscle less likely to be affected by dental infections compared with the masseter? — Its attachment is to the coronoid process, not directly to teeth; infection spreads more readily to muscles attached to the mandible near the teeth.
• In a low‑resource clinic you cannot obtain MRI; how would you evaluate a suspected temporalis abscess? — Use clinical signs (pain, swelling, fever) and bedside ultrasound; start broad‑spectrum antibiotics covering Staphylococcus and anaerobes.
• What are the key features that distinguish temporalis myositis from temporomandibular joint arthritis? — Myositis presents with diffuse temporal tenderness and swelling, worsens with jaw retraction; TMJ arthritis shows pain on opening/closing, joint crepitus, and limited mouth opening.

When to seek help

• Rapidly expanding temporal swelling with fever (possible abscess)
• Severe facial trauma with loss of bite force (possible nerve injury)
• Unexplained severe jaw pain limiting oral intake

Quick questions

Why is temporalis wasting important in low‑resource settings?

It is a quick visual cue for severe protein‑energy malnutrition when laboratory tests are unavailable.

Can temporalis atrophy be reversed?

Improving overall nutrition and treating underlying disease (e.g., HIV) can restore muscle bulk over weeks to months.

How does temporalis injury differ from masseter injury?

Temporalis injury presents with pain on jaw retraction and swelling over the temple, while masseter injury causes pain on jaw opening and swelling over the cheek.