Pronator teres syndrome introduction Pronator teres syndrome (PTS), or pronator syndrome (PS) is caused by a compression of the median nerve (MN) by the pronator teres (PT) muscle in the forearm.
Pronator teres syndrome introduction Pronator teres syndrome (PTS), or pronator syndrome (PS) is caused by a compression of the median nerve (MN) by the pronator teres (PT) muscle in the forearm. It is a somewhat uncommon diagnosis in sports medicine and orthopedics, but should be on the differential diagnosis in certain cases describing hand numbness or forearm pain. The pronator teres muscle is a rounded muscle that pronates the forearm.
In the majority of cases (66%), it arises from unequal two heads: the larger humeral head from the upper part of the medial epicondyle and the smaller ulnar head from the coronoid process of the ulna. They pass down to the forearm, form a common flexor tendon, and insert into the radial shaft. Before the two heads unite, the median nerve passes between them in 74% to 82% of the cases, innervating both heads from C6-7 roots.
Many individuals have additional fibrous brands within the two heads of the PT muscle. The anterior interosseous nerve (AIN) then branches from the median nerve about 5 to 8 cm distal to the medial epicondyle. The median nerve can be entrapped at different anatomical locations throughout its course.
An important, and sometimes underreported, potential entrapment zone of the median nerve is between the pronator teres humeral (superficial) and ulnar (deep) heads. The compression of the median nerve at this location is called “pronator syndrome”. Pronator syndrome is associated with sensory changes on the palmar side of the first three fingers (similar to carpal tunnel syndrome) and motor deficits in the muscles innervated by the anterior interosseus and the palmar nerve branches.
In 19% of cadaveric forearms, Dellon and Mackinnon found the origin of the superficial head to be at least 2 cm proximal to the medial epicondyle. When this variant was present, the fascia, which often coalesces with the lacertus, was in a position to compress the median nerve. The presence of one constricting structure does not rule out the possibility of an additional site of compression at a separate anatomic location.
If you are experiencing symptoms that may be related to pronator teres syndrome, it is important to see a sports medicine physician. Early evaluation and treatment typically lead to better outcomes. Do not ignore pain or symptoms that are limiting your activity.
*This article is for educational purposes only and does not substitute for professional medical advice. Always consult a qualified healthcare provider.*
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