Corpus: Lumbrical muscles of the hand

The Musculi lumbricales manus are four short, fleshy muscles that belong to the palm muscles of the hand.

Origin[Bearbeiten]

The lumbricales manus muscles originate from the tendons of the flexor digitorum profundus muscle. The 1st and 2nd muscles originate on the radial and volar sides of the tendon of the index and middle finger respectively. The 3rd muscle originates from the tendons of the middle and ring finger, the 4th from the tendons of the ring and little finger.

Attachment[Bearbeiten]

The short tendons of the muscles each extend to the radial side of the corresponding finger and attach to the dorsal aponeurosis of the 2nd-5th finger at the level of the metacarpophalangeal joint.

The two radial lumbrical muscles (2nd and 3rd fingers) are innervated by the median nerve from the brachial plexus (segments: C8 and Th1). The two ulnar lumbrical muscles (4th and 5th fingers) are innervated by the ramus profundus of the ulnar nerve (segments: C8 and Th1).

Variety[Bearbeiten]

The innervation of the muscles can vary. In approx. 20% of cases there is a different innervation pattern:

• Musculus lumbricalis I from the median nerve, Musculus lumbricalis II - IV from the ulnar nerve or.
• Musculus lumbricalis I - III from the median nerve, Musculus lumbricalis IV from the ulnar nerve

The following vessels are responsible for the blood supply to the muscles:

• Branches of the superficial palmar artery and the profund palmar artery
• Arteriae digitales palmares communes
• Arteriae digitales dorsales manus

The lumbrical manus muscles cause flexion (bending) in the base joints of the fingers and extension (stretching) in the middle and end joints.