Hi there! It’s Matt from Kenhub, and in
this tutorial, we will discuss the lumbrical muscles of the hand. The lumbrical muscles
are four short muscles of the hand located in the metacarpus deep to the palmar fascia.
Fun fact: Lumbricidae is Latin for earthworm. One feature of these muscles is that they
originate from tendons instead of bony structures making their origin surfaces quite moveable.
Usually, they arise from the radial side of the tendons of the flexor digitorum profundus.
In addition, the third and fourth lumbrical muscles have a second head attached to the
ulnar side of the adjacent tendon. Distally, their insertion tendons attach to
the dorsal aponeurosis of the respective finger. The first and second lumbricals are innervated
by the median nerve whereas the ulnar nerve is responsible for the innervation of the
third and fourth lumbricals. The lumbricals fulfill movements of the second
to fifth finger. Their contraction leads to flexion in the metacarpophalangeal joints
and extension in both the proximal and distal interphalangeal joints. The reason for the
opposite actions is that the tendons cross the metacarpophalangeal joints on the palmar
side but distally insert at the dorsal side of the finger. These combined movements support
a strong hand grip use, for example, to hold a pen. This video is more fun than reading a textbook,
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