Distal attachment: Base of second and third metacarpal bones, palmar surface.

Action: Flexes and abducts the wrist. May assist in flexion of the elbow.

Nerve: Median.

Proximal attachment of the humeral head: Common flexor tendon from medial epicondyle of humerus.

Proximal attachment of ulnar head: Medial margin of olecranon process and the proximal two-thirds of posterior border of ulna.

Distal attachment: Base of the fifth metacarpal, the hamate and the pisiform bones on the palmar surface of the hand.

Action: Flexes and adducts the wrist. May assist in flexion of the elbow.

Nerve: Ulnar.

Proximal attachment: Common flexor tendon from medial epicondyle of humerus.

Distal attachment: Metacarpals 2-5 via the flexor retinaculum and palmar aponeurosis.

Action: Tenses the palmar fascia and flexes the wrist. May assist in flexion of the elbow.

Nerve: Median.

FINGER II-V FLEXORS

Proximal attachment of humeral head: Common flexor tendon from medial epicondyle of humerus.

Proximal attachment of ulnar head: Medial side of coronoid process of the ulna.

Proximal attachment of radial head: Oblique line on the anterior, proximal 2/3 of radius.

Distal attachment: By four tendons into sides of middle phalanges of second through fifth digits (a bifurcated insertion or distal attachment).

Action: Flexes the proximal interphalangeal (PIP) joints of second through fifth digits. Assists in flexion of the metacarpophalangeal (MCP) joints and in flexion of the wrist.

Nerve: Median.

Proximal attachment: Anterior and medial surfaces of proximal three-fourths of ulna.

Distal attachment: By four tendons into bases of distal phalanges of the fingers, anterior surface.

Action: Flexes distal interphalangeal (DIP) joints of index (II), middle (III), ring (IV), and little fingers (V), and assists in flexion of proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints. May assist in flexion of the wrist.

Nerve to profundus II and III: Median.

Nerve to profundus IV and V: Ulnar.

WRIST - EXTENSORS

Proximal attachment: Distal one-third of lateral supracondylar ridge of humerus.

Distal attachment: Posterior surface of base of second metacarpal bone, radial side and dorsal surface.

Action: Extends and abducts the wrist. Assists in extension of the elbow.

Nerve: Radial.

Proximal attachment: Common extensor tendon from lateral epicondyle of humerus.

Distal attachment: Posterior surface of base of third metacarpal bone, dorsal surface.

Action: Extends and abducts the wrist.

Nerve: Radial.

Proximal attachment: Common extensor tendon from lateral epicondyle of humerus.

Distal attachment: Base of fifth metacarpal bone, ulnar side and dorsal surface.

Action: Extends and adducts the wrist.

Nerve: Radial.

FINGER II-V EXTENSORS

Proximal attachment: Common extensor tendon from lateral epicondyle of humerus.

Distal attachment: By four tendons, each penetrating a membranous expansion on the dorsum of the second (index finger) to fifth (little finger) digits and dividing over the proximal phalanx into a middle and two lateral bands.

The middle band inserts into the base of the middle phalanx. The lateral bands reunite over the middle phalanx and insert into the base of the distal phalanx.

Action: Extends the metacarpophalangeal (MCP) joints and extends the interphalangeal (both PIP and DIP) joints of the second through fifth digits. Assists in extension of the wrist.

Nerve: Radial.

Proximal attachment: Posterior surface, distal 1/3 of body of ulna.

Distal attachment: Into extensor expansion of index finger with Extensor Digitorum tendon.

Action: Extends the metacarpophalangeal (MCP) joint and interphalangeal (both PIP and DIP) joints of the index finger. Assist in extension of the wrist.

Nerve: Radial.

Proximal attachment: Common extensor tendon from lateral epicondyle of humerus.

Distal attachment: Into extensor expansion of little finger with Extensor Digitorum tendon.

Action: Extends the metacarpophalangeal (MCP) joint and interphalangeal (both PIP and DIP) joints of the little finger. Assists in extension of the wrist.

Nerve: Radial.

Proximal attachment: Posterior surface, mid-shaft on the body of ulna, and the posterior surface of middle one-third of body of radius, and the adjacent interosseous membrane.

Distal attachment: Base of first metacarpal bone, radial and dorsal aspect.

Action: Abducts the carpometacarpal (CMC) joint of the thumb; abducts (radial deviation) the wrist.

Nerve: Radial.

Proximal attachment: Flexor retinaculum, trapezium and scaphoid bones.

Distal attachment: Base of proximal phalanx of thumb, radial and anterior aspect.

Action: Abducts the carpometacarpal (CMC) joint of the thumb.

Nerve: Median.

Proximal attachment: Middle to distal one-third of posterior surface of ulna.

Distal attachment: Base of distal phalanx of thumb, dorsal surface.

Action: Extends the interphalangeal (IP) joint and assists in extension of the metacarpophalangeal (MCP) and carpometacarpal (CMC) joints of the thumb.

Nerve: Radial.

Proximal attachment: Posterior, distal surface of the body of radius.

Distal attachment: Base of the proximal phalanx of the thumb, dorsal surface.

Action: Extends the metatcarpophalangeal (MCP) joint of the thumb, and extends the carpometacarpal (CMC) joint.

Nerve: Radial.

Proximal attachment: Anterior surface of body of radius below tuberosity, and the medial border of coronoid process of ulna.

Distal attachment: Base of distal phalanx of thumb, palmar surface.

Action: Flexes the interphalangeal (IP) joint of the thumb, and assists in flexion of the metacarpophalangeal (MCP) and carpometacarpal (CMC) joints.

Nerve: Median..

Proximal attachment of superficial head: Flexor retinaculum and trapezium bone.

Proximal attachment of deep head: Trapezoid and capitate bones.

Distal attachment: Base of proximal phalanx of thumb on the radial side.

Action: Flexes the metacarpophalangeal (MCP) and carpometacarpal (CMC) joints of the thumb.

Nerve to superficial head: Median.

Nerve to deep head: Ulnar.

Proximal attachment of oblique fibers: Capitate and trapezoid bones, and bases of second and third metacarpal bones.

Proximal attachment of transverse fibers: Palmar surface of third metacarpal bone.

Distal attachment: Base of proximal phalanx of thumb.

Action: Adducts the carpometacarpal (CMC) joint.

Nerve: Ulnar.

Proximal attachment: Flexor retinaculum and trapezium bone.

Distal attachment: Entire length of first metacarpal bone, radial side.

Action: Opposes (i.e., flexes and abducts with slight medial rotation) the carpometacarpal (CMC) joint of the thumb, placing the thumb in a position so that, by flexion of the metacarpophalangeal (MCP) joint, it can oppose the fingers.

Nerve: Median.