Summary of pronator quadratus

Summary of pronator quadratus 

Origin

From the oblique ridge on the lower one fourth of the anterior surface of the shaft of ulna and medial part of this surface

Insertion

The superficial fibres into the distal one fourth of the anterior border and anterior of the shaft of radias

The deep fibres into the triangular area above the ulnar notch of the radius

Nerve supply

Anterior interosseous nerve a branch of median nerve

Action

When pronator quadratus contracts, it pulls the lateral side of the radius towards the ulna, thus pronating the hand. Its deep fibers serve to keep the two bones in the forearm bound together. This  muscle can be absent in some humans, however, that does not affect the action of pronation very

Shape of muscle

Square shaped

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Important relation

It crosses the front of the distal parts of radius and ulna

Median nerve

The median nerve situated deep to the pronator quadrates

Direction of muscle

Muscle situated horizontally at the lower part of forearm

Variation: Absent in some individual