Anatomy of the Intrinsic Muscles of the Hand Quiz

Muscles of the Hand

• Flexor digiti minimi brevis lies laterally to the abductor digiti minimi in the hand.

Lumbricals

• There are four lumbricals in the hand, each associated with a finger.
• They link extensor tendons to flexor tendons and are crucial for finger movement.
• Denervation of these muscles causes the ulnar claw and hand of benediction.

Interossei

• Interossei muscles are located between the metacarpal bones of the hand.
• They can be divided into two groups: dorsal and palmar interossei.
• Interossei assist in flexion at the MCP joints and extension at the IP joints.

Dorsal Interossei

• There are four dorsal interossei muscles, the most superficial of all dorsal muscles.
• They can be palpated on the dorsum of the hand.

Palmar Interossei

• There are three palmar interossei muscles (although some texts describe a fourth muscle at the base of the proximal phalanx of the thumb).
• They are located anteriorly on the hand.

Other Muscles in the Palm

• Palmaris brevis is a small, thin muscle found superficially in the subcutaneous tissue of the hypothenar eminence.
• Adductor pollicis is a large triangular muscle with two heads, through which the radial artery passes anteriorly, forming the deep palmar arch.

Thenar Muscles

• Thenar muscles are three short muscles located at the base of the thumb.
• They produce a bulge, known as the thenar eminence, and are responsible for the fine movements of the thumb.
• The median nerve innervates all the thenar muscles.

Individual Thenar Muscles

• Opponens pollicis is the largest of the thenar muscles, and lies underneath the other two.
• Abductor pollicis brevis forms the anterolateral aspect of the thenar eminence, overlying the opponens pollicis.
• Flexor pollicis brevis forms the medial aspect of the thenar eminence, and has a superficial and deep part (although the deep component is variable in size).

Hypothenar Muscles

• Hypothenar muscles form the hypothenar eminence, a muscular protrusion on the medial side of the palm, at the base of the little finger.
• They are similar to the thenar muscles in both name and organisation.
• The ulnar nerve innervates the muscles of the hypothenar eminence.

Individual Hypothenar Muscles

• Opponens digiti minimi lies deep to the other hypothenar muscles.
• Abductor digiti minimi is the most superficial of the hypothenar muscle group.

Test your knowledge on the anatomy of the intrinsic muscles of the hand, including their attachments, actions, and innervation. Learn about the thenar muscles located at the base of the thumb and their role in fine movements, as well as the opponens pollicis muscle. Get ready to quiz yourself on these important hand muscles!