Logan Steele
The supinator muscle is a spiral muscle that rotates the radius laterally to accomplish forearm supination. It is innervated by the posterior interosseous nerve, a branch of the radial nerve. The nerve passes between the muscle's superficial and deep heads, supplying the muscle with two to nine branches. The supinator muscle is located in the posterior compartment of the forearm, along with the brachioradialis and forearm extensors. Its function is to rotate the radius, producing the movement of forearm supination.
| Characteristics | Values |
|---|---|
| Location | Posterior compartment of the forearm |
| Shape | Spiral |
| Function | Supinates the forearm |
| Layers | Superficial and deep |
| Innervation | Posterior interosseous nerve (C6, C7, C8) |
| Blood supply | Radial artery |
| Attachments | Radius, ulna, lateral epicondyle of humerus, radial collateral ligament of humeroulnar joint, annular ligament of the superior radioulnar joint, supinator crest of ulna, ulnar fossa |
| Antagonist | Pronator quadratus muscle |
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What You'll Learn
The supinator muscle is innervated by the posterior interosseous nerve
The supinator muscle is a spiral muscle located deep in the forearm, in the posterior compartment. It is responsible for rotating the radius laterally, resulting in forearm supination. Its unique anatomy allows it to wrap around the proximal part of the radius, connecting it with the ulna.
The innervation of the supinator muscle can vary, with studies finding between two and nine branches of the posterior interosseous nerve supplying it. This variability has important clinical implications, particularly during surgical procedures such as distal biceps tendon repair, where there is a risk of nerve branch injury.
The radial nerve itself has deep and superficial sensory branches, and the supinator muscle receives blood from the radial artery through its radial recurrent branch. The deep branch of the radial nerve also innervates several other muscles in the forearm, including the extensor carpi radialis brevis, extensor carpi ulnaris, and various extensor muscles.
In summary, the supinator muscle, with its ability to supinate the forearm, plays a crucial role in human anatomy. Its innervation by the posterior interosseous nerve, a branch of the radial nerve, highlights the intricate network of nerves supplying the muscles of the forearm. Understanding the innervation of the supinator muscle is essential for surgical procedures and for comprehending its function in the context of the human body's complex neuromuscular system.
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This nerve is a branch of the radial nerve
The supinator muscle is innervated by the posterior interosseous nerve, a nerve that arises from the deep branch of the radial nerve. This nerve is a branch of the radial nerve, which courses distally in the posterior aspect of the upper arm. The radial nerve innervates the triceps and the anconeus muscles, and then enters the spiral groove, winding around the humerus from the medial to the lateral side.
At the level of the lateral epicondyle, the radial nerve is located in the anterolateral aspect of the lower arm between the brachioradialis and the brachialis muscles. Here, it divides into superficial and deep branches. The deep branch, also known as the posterior interosseous nerve, continues under the extensor carpi radialis and supinator muscles. As it passes between the superficial and deep heads of the supinator muscle, it becomes the posterior interosseous nerve.
The posterior interosseous nerve innervates the supinator muscle and several other muscles in the forearm, including all the extensor muscles and the abductor pollicis longus. The nerve roots supplying the supinator muscle are primarily from C6, with some C5 involvement and possible additional C7 innervation.
The supinator muscle is a broad muscle located in the posterior compartment of the forearm, curling around the upper third of the radius. Its function is to supinate the forearm, rotating the radius laterally. The muscle consists of two layers of fibres, or superficial and deep layers, which differ in their mode of attachment. The deep branch of the radial nerve passes through the supinator muscle, contributing to its innervation and enabling its important role in forearm movement.
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The nerve passes between the muscle's superficial and deep heads
The supinator muscle is a spiral muscle located in the posterior compartment of the forearm. It wraps around the proximal third of the radius, connecting it with the ulna. This muscle is responsible for rotating the radius laterally, resulting in a movement known as forearm supination. Its antagonist is the pronator quadratus muscle, which produces the opposite movement of pronation.
The supinator muscle consists of two layers: the superficial layer and the deep layer. These layers differ in their mode of attachment, with the superficial layer arising from tendinous fibres and the deep layer originating from already formed muscular slips. Despite this difference, both layers originate from common landmarks, including osteofibrous structures of the elbow.
The nerve that innervates the supinator muscle is the posterior interosseous nerve, which is a branch of the radial nerve. Specifically, it is the deep branch of the radial nerve that passes between the muscle's superficial and deep heads. This nerve arises proximal to the supinator muscle and then enters the extensor compartment of the forearm.
The radial nerve plays a crucial role in innervating several muscles in the forearm. In addition to the supinator muscle, it innervates the triceps, the anconeus, the brachioradialis, and the extensor carpi radialis longus. The radial nerve divides into superficial and deep branches, with the deep branch being a motor branch known as the posterior interosseous nerve. This nerve innervates not only the supinator muscle but also a variety of extensor muscles in the forearm and the abductor pollicis longus.
The deep branch of the radial nerve, or the posterior interosseous nerve, passes through the supinator muscle, contributing to the complexity of its innervation. The innervation of the supinator muscle can vary significantly, with studies finding between two and nine branches of the posterior interosseous nerve supplying the muscle. This variation is important to consider during surgical procedures, as certain patterns of innervation may be at higher risk for nerve branch injuries.
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The supinator muscle is located deep in the forearm
The supinator muscle consists of two layers: the superficial layer and the deep layer. These layers differ in their mode of attachment. The superficial layer arises from tendinous fibres, while the deep layer originates from already formed muscular slips. Despite their different attachments, both layers originate from the same landmarks, including several osteofibrous structures of the elbow. These structures include the lateral epicondyle of the humerus, the radial collateral ligament of the humeroulnar joint, the annular ligament of the superior radioulnar joint, the supinator crest of the ulna, and the adjacent part of the ulnar fossa.
The deep branch of the radial nerve passes through the supinator muscle and is known as the posterior interosseous nerve (C7, C8). This nerve innervates the supinator muscle and travels between its two heads. The nerve enters the extensor compartment of the forearm, supplying the muscle with motor function. The superficial and deep layers of the supinator muscle receive blood supply from different sources. The superficial layer receives blood from the radial artery, specifically through its radial recurrent branch.
The supinator muscle plays a crucial role in forearm supination, and its function is closely related to the biceps muscle. During unresisted supination, the supinator is the most active muscle, while the biceps become increasingly active with heavier loads. If the supinator is disabled or injured, forearm supination strength decreases significantly. The supinator muscle also contributes to the formation of the floor of the cubital fossa, a crucial anatomical landmark in the forearm.
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It rotates the radius laterally to produce forearm supination
The supinator muscle is a spiral muscle contained in the posterior compartment of the forearm. It wraps around the proximal third of the radius, connecting it with the ulna. This unique anatomy allows the supinator muscle to rotate the radius laterally, resulting in a movement known as forearm supination.
Forearm supination is a crucial movement that involves the rotation of the radius, causing the palm to face anteriorly or forward. This rotation occurs primarily at the proximal radioulnar joint, where the radial head rotates against the radial notch of the proximal ulna, held in place by the annular ligament.
The supinator muscle plays a central role in this movement by facilitating the lateral rotation of the radius. It works in conjunction with the biceps muscle, except when the elbow joint is extended. The supinator is the most active muscle during forearm supination in unresisted supination, while the biceps become more active with heavier loads.
The deep branch of the radial nerve supplies the supinator muscle with innervation. Specifically, the nerve gives off the posterior interosseous nerve just proximal to the supinator muscle, which then passes between its superficial and deep heads. The nerve roots are primarily from C6, with some contributions from C5 and possible additional innervation from C7.
The supinator muscle consists of two layers: the superficial layer and the deep layer. These layers differ in their mode of attachment, with the superficial layer arising from tendinous fibres and the deep layer originating from muscular slips. Despite their distinct attachments, both layers originate from common landmarks, including osteofibrous structures of the elbow.
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Frequently asked questions
The supinator muscle is innervated by the posterior interosseous nerve (C7, C8), a branch of the radial nerve.
The supinator is a broad muscle in the posterior compartment of the forearm, curved around the upper third of the radius. Its function is to supinate the forearm.
The supinator muscle supinates the forearm at the radioulnar joints. It rotates the radius laterally, producing a movement known as forearm supination.
The radial nerve courses distally in the posterior aspect of the upper arm and innervates the supinator muscle. The deep branch of the radial nerve runs through the supinator muscle and is then known as the posterior interosseous nerve.
Supinator entrapment syndrome is a nerve syndrome that occurs when there is entrapment and compression of the deep part of the radial nerve, potentially resulting in selective paralysis of the muscles served by this nerve.
