The pronator teres is the primary forearm pronator, inserting on the lateral radius to rotate it around the ulna in pronation. The median nerve passes between its two heads — the humeral and ulnar heads — making this the classic site of pronator teres syndrome (median nerve compression between the heads). Tenderness between the two heads with reproduction of forearm symptoms by resisted pronation confirms the diagnosis.
| Origin | Medial epicondyle (common flexor origin) and adjacent medial supracondylar ridge; Medial coronoid process |
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| Insertion | Middle third of the lateral radius at the pronator tuberosity |
| Nerve Supply | Median nerve — between the two heads of the pronator teres, making this muscle the primary site of median nerve compression in the forearm |
| Blood Supply | Radial and anterior interosseous arteries |
| Actions | Forearm pronation (the primary forearm pronator); Elbow flexion assistance |
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Pronator teres syndrome produces volar forearm aching with exertional provocation from repetitive gripping and forearm rotation. Distinguished from carpal tunnel syndrome by: (1) symptoms include the palmar cutaneous branch (normal in CTS since the palmar branch is above the carpal tunnel), (2) worsened by resisted pronation rather than sustained wrist flexion, (3) no nocturnal symptoms. NCS may be normal as compression is dynamic.
The pronator teres is the prominent muscle in the medial antecubital fossa, palpable as it crosses obliquely to the lateral radius during resisted pronation.
Median nerve compression between the pronator teres heads producing volar forearm aching with pronation sensitivity managed with activity modification and surgical release.
