Anatomy study note · Upper limb

Lumbricals of the hand

Four small worm-like muscles arising from the tendons of flexor digitorum profundus. They flex the knuckle joints while straightening the finger joints.

Key points

• Arise from FDP tendons → extensor expansions.
• Lateral two: median. Medial two: ulnar.
• Flex MCP + extend IP.
• Paralysis → claw hand.
• Limb muscles: in situ from limb-bud mesenchyme.
• Upper limb bud C4–T2; lower limb bud L2–S2.
• Skeletal muscle: multinucleated, peripheral nuclei, striated.
• Epimysium → perimysium → endomysium.

The full note in the atlas also covers

Origin · Insertion · Action · Nerve supply · Histology · Development · Clinical notes

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Written from

• Snell’s Clinical Anatomy by Regions, 10th ed., ch. 3, PDF pp. 315–316, 322
• Inderbir Singh’s Human Embryology, ch. 7, PDF p. 109; ch. 10, PDF pp. 142–145
• BRS Cell Biology & Histology, 7th ed., ch. 8, PDF pp. 135–144

More from the upper limb

• Medial cutaneous nerves of arm and forearm
• Median cubital vein
• Median nerve
• Metacarpal bones
• Metacarpophalangeal and interphalangeal joints of the hand
• Musculocutaneous nerve
• Nerve to subclavius
• Palmar aponeurosis
• Palmaris longus
• Pectoral nerves
• Pectoralis major
• Pectoralis minor

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