Pronator Teres
Forearm · Upper Limb
The pronator teres is a spindle-shaped muscle that forms the medial boundary of the cubital fossa. It has two heads, a humeral head from the medial epicondyle (part of the common flexor origin) and an ulnar head from the coronoid process, that unite and cross to insert on the middle of the lateral surface of the radius. Its main action is pronation of the forearm, turning the palm downward, and it also assists in flexing the elbow. It is supplied by the median nerve (C6, C7), which passes between its two heads and can be compressed there.
Origin, Insertion, Action & Nerve
Origin
Humeral head: medial epicondyle (common flexor origin); Ulnar head: coronoid process
Insertion
Middle of lateral surface of radius
Action
Pronation of forearm; assists flexion of elbow
Nerve
Median nerve (C6, C7)
Attachments explained
The Pronator Teres is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Humeral head: medial epicondyle (common flexor origin); Ulnar head: coronoid process
Insertion
Middle of lateral surface of radius
Action & function
When the Pronator Teres contracts, it produces the following movements: Pronation of forearm; assists flexion of elbow.
As part of the Forearm group of the Upper Limb, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Pronator Teres receives its nerve supply from the Median nerve (C6, C7). This nerve carries fibres from spinal segment(s) C6, C7.
Because a muscle can only contract when its nerve is intact, injury to the Median nerve or to its spinal roots (C6, C7) can weaken or paralyse the Pronator Teres, impairing the movements it normally produces (pronation of forearm). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Pronator Teres (the OIANS method)
The name states the action: pronator teres pronates the forearm, turning the palm down. Visualise its fibres crossing obliquely from the medial epicondyle to the lateral radius, and the twisting pull that rolls the radius over the ulna becomes intuitive. Pair it with pronator quadratus, its deep partner, so the two pronators are learned as a set.
Its clinical hook is the median nerve, which dives between the muscle's two heads and can be trapped there in pronator teres syndrome. Remembering that the nerve passes through the muscle keeps both the innervation and the entrapment site linked in one image.
Frequently asked questions
Where is the Pronator Teres located?
The Pronator Teres is a muscle of the Forearm group, located in the Upper Limb.
What is the origin of the Pronator Teres?
Humeral head: medial epicondyle (common flexor origin); Ulnar head: coronoid process
What is the insertion of the Pronator Teres?
Middle of lateral surface of radius
What movements does the Pronator Teres produce?
Pronation of forearm; assists flexion of elbow
What nerve supplies the Pronator Teres?
Median nerve (C6, C7)
Is the Pronator Teres free to study in OIANS?
Yes. The Pronator Teres is free in OIANS: its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory, and because it belongs to the Upper Limb it is also covered by the free Quiz and Flashcard decks. The other regions, the "All Muscles" deck, and the Progress and Explore tools are unlocked with a one-time Lifetime purchase.
Related muscles
Study the Pronator Teres
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