Anterior & posterior forearm

The forearm has loads of things to remember and so many muscles, which helps with the super-mobile hand movements!

Let’s start by looking at the bones of the forearm.

Screenshot 2018-12-15 at 20.53.19.png
Figure 1. Bones of the forearm.

Anterior forearm

Superficial muscles

Figure 2. Superficial muscles of the forearm
Screenshot 2019-01-17 at 13.54.24.png
Figure 1. Superficial muscles of the forearm

Intermediate muscles

  • Flexor digitorum superficialis is the only muscle in this compartment
  • Important because the median nerve and ulnar artery passed between two heads & travel posteriorly
  • Origin – one head from medial epicondyle of humerus, other from radius
  • Insertion – splits into four tendons near the wrist that pass through the carpal tunnel and attach to the bodies of middle phalanges of medial 4 digits on the palmar aspect
  • Innervation – median nerve (C8-T1)
  • Action – flexes middle phalanges of medial 4 digits, weak flexor of the wrist & forearm

Deep muscles

Screenshot 2019-01-17 at 13.28.16.png
Figure 3. Deep muscles of the anterior forearm
Screenshot 2019-01-17 at 13.47.54.png
Table 2. Deep muscles of the anterior forearm

Arteries & veins the forearm

Brachial artery bifurcates in the cubital fossa and gives rise to:

  • Radial artery (supplies posterolateral aspect of the forearm)
  • Ulnar artery (supplies anteromedial aspect of the forearm – gives rise to interosseous arteries, which supply deep structures)

The veins accompany the arteries and have pretty much the same names.

Screenshot 2019-02-02 at 08.54.02.png
Figure 4. Arteries of the flexor compartment

Radio-ulnar joints

Radius & ulna articulate in two different parts of the forearm:

  • Proximal joint (pivot type)
    • head of the radius & radial notch of the ulna
    • movement mainly produced by the head of radius rotating within the annular radial ligament
    • pronation & supination
  • Distal joint (pivot type)
    • ulnar notch & ulnar head
    • pronation & supination

Posterior compartment

Superficial muscles

Screenshot 2019-02-02 at 09.04.11.png
Figure 5. Superficial muscles of posterior forearm
Screenshot 2019-02-02 at 09.15.35.png
Table 3. Superficial muscles of posterior forearm

Deep muscles

Screenshot 2019-02-02 at 09.17.47.png
Figure 6. Deep muscles of posterior forearm
Screenshot 2019-02-02 at 09.26.21.png
Table 4. Deep muscles of posterior forearm

Anatomical snuffbox

  • Important to have high suspicion of scaphoid fractures if localised pain in the anatomical snuffbox
  •  Borders
    • Medial border – tendon of EPL
    • Lateral border – tendon of APL & EPB
    • Proximal border – styloid process of radius
    • Floor – carpal bones, scaphoid & trapezium
    • Roof – skin

References

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s