O-I-A-N Posterior Forearm Muscles

PT605 Anatomy, Oregon Tech

Origin of Brachioradialis

Proximal 2/3 of the lateral supracondylar ridge, lateral intermuscular septum.

Insertion of Brachioradialis

Radial styloid process.

Actions of Brachioradialis

Elbow flexion, forearm pronation, forearm supination.

Nerve Supply of Brachioradialis

Radial nerve C5, C6.

Origin of Extensor Carpi Radialis Longus

Distal 1/3 of the lateral supracondylar ridge, lateral intermuscular septum.

Insertion of Extensor Carpi Radialis Longus

Base of MC #2.

Actions of Extensor Carpi Radialis Longus

Elbow flexion, wrist extension, wrist RD.

Nerve Supply of Extensor Carpi Radialis Longus

Radial nerve C6, C7.

Origin of Extensor Carpi Radialis Brevis

Lateral epicondyle via the CET.

Insertion of Extensor Carpi Radialis Brevis

Base of MC #3.

Actions of Extensor Carpi Radialis Brevis

Wrist extension, wrist RD.

Nerve Supply of Extensor Carpi Radialis Brevis

Deep Radial nerve C6, C7.

Origin of Extensor Digitorum

Lateral epicondyle via the CET.

Insertion of Extensor Digitorum

Base of the middle and distal phalanges 2-5 via DDE.

Actions of Extensor Digitorum

Wrist extension, finger extension 2-5 of MCP, PIP, DIP joints.

Nerve Supply of Extensor Digitorum

Radial nerve (PIN) C7, C8.

Origin of Extensor Digiti Minimi

Lateral epicondyle via the CET.

Insertion of Extensor Digiti Minimi

Base of distal phalanx #5 via DDE, runs on ulnar side of ED.

Actions of Extensor Digiti Minimi

Wrist extension, wrist UD, little finger extension at MCP, PIP, DIP joints.

Nerve Supply of Extensor Digiti Minimi

Radial nerve (PIN) C7, C8.

Dorsal Digital Expansion

Allows MCP flexion while maintaining PIP and DIP extension.

Origin of Extensor Carpi Ulnaris

Humeral head: Lateral epicondyle via the CET.

Ulnar head: Posterior border of ulna.

Insertion of Extensor Carpi Ulnaris

Base of MC #5.

Actions of Extensor Carpi Ulnaris

Wrist extension, wrist UD.

Nerve Supply of Extensor Carpi Ulnaris

Radial nerve (PIN) C7, C8.

Origin of Supinator

Humeral head: Lateral epicondyle via CET.

Ulnar head: Supinator fossa.

Insertion of Supinator

Proximal 1/3 posterior surface of the radius.

Actions of Supinator

Forearm supination.

Nerve Supply of Supinator

Deep Radial nerve C5, C6.

Origin of Abductor Pollicis Longus

Middle 1/3 posterior surface of the radius and ulna, interosseous membrane.

Insertion of Abductor Pollicis Longus

Radial side of the base of MC #1.

Actions of Abductor Pollicis Longus

Wrist RD, thumb abduction at CMC joint.

Nerve Supply of Abductor Pollicis Longus

Radial nerve (PIN) C7, C8.

Origin of Extensor Pollicis Brevis

Middle 1/3 posterior surface of radius just distal to APL, interosseous membrane.

Insertion of Extensor Pollicis Brevis

Base of proximal phalanx #1.

Actions of Extensor Pollicis Brevis

Wrist RD, thumb extension at the CMC and MCP joints.

Nerve Supply of Extensor Pollicis Brevis

Radial nerve (PIN) C7, C8.

Origin of Extensor Pollicis Longus

Middle 1/3 posterior surface of the ulna just distal to APL, interosseous membrane.

Insertion of Extensor Pollicis Longus

Base of distal phalanx #1, EPL tendon travels around ulnar side of “Lister’s tubercle” like a pulley.

Actions of Extensor Pollicis Longus

Wrist extension, thumb extension at the CMC, MCP, IP joints.

Nerve Supply of Extensor Pollicis Longus

Radial nerve (PIN) C7, C8.

Origin of Extensor Indicis

Distal 1/3 posterior surface of the ulna, interosseous membrane.

Insertion of Extensor Indicis

Base of distal phalanx #2 via the DDE, runs on ulnar side of ED.

Actions of Extensor Indicis

Wrist extension, index finger extension at the MCP, PIP, DIP joints.

Nerve Supply of Extensor Indicis

Radial nerve (PIN) C7, C8.

Deep Posterior Forearm Muscles

Supinator*, Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB), Extensor Pollicis Longus (EPL), Extensor Indicis (EI).

On Cross Section: Abductor Pollicis Longus (APL), Extensor Pollicis Brevis (EPB), Extensor Pollicis Longus (EPL)

Anatomical Snuff Box

1. EPL,

2. EPB,

3. APL.