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Flexor Carpi Radialis Muscle Anatomy

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Origin
  • Medial epicondyle of the humerus
Insertion
  • Bases of the second and third metacarpal bones
Action
  • Flexion of the wrist joint
  • Abduction of the wrist joint
Innervation
  • Median nerve (C6-C7)
Blood Supply
  • Radial artery
  • Posterior branch of the ulnar recurrent artery
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Location & Overview

The flexor carpi radialis is a superficial muscle located in the forearm. It is a long and relatively thin muscle running just lateral to flexor digitorum superficialis. It connects the humerus to the metacarpals in the hand. Its visibility from the skin’s surface is more pronounced during wrist flexion. It is one of four muscles in the superficial layer of the anterior compartment of the forearm. The other three are the palmaris longus, flexor carpi ulnaris, and the pronator teres.[1]

flexor carpi radialis anterior view
Here we can see the flexor carpi radialis from an anterior view.
flexor carpi radialis medial view
Here we can see the flexor carpi radialis from a medial view.
flexor carpi radialis highlighted in red anterior view
Here we can see an anterior view of the flexor carpi radialis, highlighted in red, among the other muscles of the arm. The tissue overlaying the flexor carpi radialis at the proximal forearm is the bicipital aponeurosis.
flexor carpi radialis medial view highlighted in red
Here we can see a medial view of the flexor carpi radialis, highlighted in red, among the other muscles of the arm. The tissue overlaying the flexor carpi radialis at the proximal forearm is the bicipital aponeurosis.

Origin & Insertion

The flexor carpi radialis originates on the medial epicondyle of the humerus. It then travels down toward the lateral side of the forearm. Once it reaches the wrist, its tendon then continues downward to insert at the bases of the second and third metacarpal bones.[2,1,3,4]

origin of the flexor carpi radialis
Highlighted in red is the origin of the flexor carpi radialis on the medial epicondyle of the humerus.
insertion of the flexor carpi radialis
Highlighted in blue is the insertion of the flexor carpi radialis on the bases of the second and third metacarpal bones.

Action & Function

The main function of the flexor carpi radialis is to perform flexion at the wrist joint. It also plays an assistive role in performing abduction of the hand and wrist.[1,4]

Image shows an arm demonstrating the movement of wrist flexion.
This image shows wrist flexion, a motion that involves bending the wrist toward the anterior surface, or the underside, of the forearm. Conversely, wrist extension refers to the movement of extending the wrist toward the posterior surface, or the top side, of the forearm. Wrist flexion is the main action of the flexor carpi radialis.
Image of a person demonstrating the movement of wrist abduction.
This image shows wrist abduction, a movement in which the wrist bends sideways toward the thumb. In the anatomical position, wrist abduction occurs away from the body. The opposite motion of wrist abduction is wrist adduction. The flexor carpi radialis plays an assistive role in performing wrist abduction. Wrist abduction is not the flexor carpi radialis’ primary action.

Innervation

Innervation of the flexor carpi radialis is provided by the median nerve (C6-C7). The median nerve is part of the brachial plexus.[1]

median nerve
Pictured here, we can see the median nerve, which innervates the flexor carpi radialis. The specific nerve roots which innervate it are C6 and C7.
brachial plexus
Pictured here, we can see the brachial plexus. As you can see from the image, the median nerve is a branch of the brachial plexus.

Blood Supply

Blood is supplied to the flexor carpi radialis via the radial artery and the posterior branch of the ulnar recurrent artery.[5,1]

References

  1. [1] Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincott Williams & Wilkins; 2017.
  2. [2] Schmidt HM. Clinical anatomy of the m. flexor carpi radialis tendon sheath. Acta Morphol Neerl Scand. 1987;25(1):17-28. PMID: 2449801.
  3. [3] Irie, T., Motomiya, M. & Iwasaki, N. Absence of flexor carpi radialis identified during volar approach for fixation of distal radius fracture: a case report. BMC Res Notes 11, 240 (2018). https://doi.org/10.1186/s13104-018-3348-z
  4. [4] Kanevsky J, Zammit D, Brutus JP. Rupture of the flexor carpi radialis tendon secondary to trauma: case report and literature review. Plast Aesthet Res 2015;2:138-9. http://dx.doi.org/10.4103/2347-9264.157108
  5. [5] Standring S, editor. Gray’s anatomy: the anatomical basis of clinical practice. 42nd ed. Amsterdam: Elsevier; 2021.

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