Exam 2 OIAIs - Flexors and Extensors

superficial layer muscles of anterior compartment of forearm

• pronator teres

• flexor carpi radialis

• palmaris longus

• flexor carpi ulnaris

intermediate layer muscle of anterior compartment of forearm

flexor digitorum superficialis

deep layer muscles of anterior compartment of forearm

• flexor digitorum profundus

• flexor pollicus longus

• pronator quadratus

superficial layer muscles of posterior aspect of forearm

• brachioradialis

• extensor carpi radialis longus

• extensor carpi radialis brevis

• extensor digitorum

• extensor digiti minimi

• extensor carpi ulnaris

deep layer muscles of posterior aspect of forearm

• supinator

• extensor indicis

outcroppers of deep layer of posterior aspect of forearm

• abductor pollicus longus

• extensor pollicus longus

• extensor pollicus brevis

Pronator Teres PA - Ulnar Head

coronoid process

Pronator Teres PA - humeral head

medial epicondyle - common flexor tendon

Pronator teres DA

middle convexity of the lateral surface of radius (~ halfway down radius)

Pronator teres innervation

median n

Pronator teres action

• pronate forearm

• flex forearm at elbow

Flexor carpi radialis PA

medial epicondyle - common flexor tendon

Flexor carpi radialis DA

base of the 2nd metacarpal

Flexor carpi radialis innervation

median n

Flexor carpi radialis action

flex and radially deviate wrist

Palmaris longus PA

medial epicondyle - common flexor tendon

Palmaris longus DA

• distal half of the flexor retinaculum

• apex of the palmar aponeurosis

Palmaris longus innervation

median n

Palmaris longus action

• flex wrist

• tense the palmar aponeurosis

Flexor carpi ulnaris - ulnar head PA

• olecranon process

• posterior border of ulna via aponeurosis

Flexor carpi ulnaris - humeral head PA

medial epicondyle - common flexor tendon

Flexor carpi ulnaris DA

• pisiform

• hook of hamate

• 5th metacarpal

Flexor carpi ulnaris innervation

ulnar n

Flexor carpi ulnaris action

flex and ulnarly deviate wrist

Flexor digitorum superficialis - humero-ulnar head PA

• coronoid process

• common flexor tendon

Flexor digitorum superficialis - radial head PA

superior half of anterior border of radius

Flexor digitorum superficialis DA

shafts of middle phalanges of digits 2-5

Flexor digitorum superficialis innervation

median n

Flexor digitorum superficialis action

• flexes PIP joints of digits 2-5

• flexes MCP joints 2-5

• wrist flexion

Flexor digitorum profundus PA

• proximal three quarters of the medial and anterior surfaces of ulna and interosseous membrane

Flexor digitorum profundus - medial part DA

base of distal phalanges of digits 4-5

Flexor digitorum profundus - lateral part DA

base of distal phalanges of digits 2-3

Flexor digitorum profundus - medial part innervation

ulnar n

Flexor digitorum profundus - lateral part innervation

anterior interosseous n from the median n

Flexor digitorum profundus - medial part action

• flexes distal phalanges 4-5 at DIP joints

• assists with flexion of MCP and PIP joints on digits 4-5

Flexor digitorum profundus - lateral part action

• flexes distal phalanges 2-3 at DIP joints

• assists with flexion of MCP and PIP joints on digits 2-3

Flexor pollicis longus PA

anterior surface of radius and adjacent interosseous membrane

Flexor pollicis longus DA

base of distal phalanx of thumb (1st digit)

Flexor pollicis longus innervation

anterior interosseous n from the median n

Flexor pollicis longus action

flexes phalanges of 1st digit at IP, MCP, and CMC joints

Pronator quadratus PA

distal quarter of the anterior surface of the ulna

Pronator quadratus DA

distal quarter of the anterior surface of the radius

Pronator quadratus innervation

anterior interosseous n from the median n

Pronator quadratus action

• pronate the forearm

• stabilize the distal radial-ulnar joint

Brachioradialis PA

proximal 2/3 of lateral supracondylar ridge of humerus

Brachioradialis DA

lateral surface of distal end of radius proximal to styloid process

Brachioradialis innervation

radial n

Brachioradialis action

maximal flexion when forearm is in neutral position

Extensor carpi radialis longus PA

lateral supracondylar ridge of humerus

Extensor carpi radialis longus DA

dorsal aspect of base of 2nd metacarpal

Extensor carpi radialis longus innervation

radial n

Extensor carpi radialis longus action

extend and radially deviate wrist

Extensor carpi radialis brevis PA

lateral epicondyle of humerus - common extensor tendon

Extensor carpi radialis brevis DA

dorsal aspect of base of 3rd metacarpal

Extensor carpi radialis brevis innervation

deep branch of radial n

Externsor carpi radialis brevis action

extend and radially deviate wrist

Extensor digitorum PA

lateral epicondyle of humerus - common extensor tendon

Extensor digitorum DA

extensor expansions of digits 2-5

Extensor digitorum innervation

deep branch of radial n

Extensor digitorum action

extends digits 2-5 at MCP, PIP, and DIP joints

Extensor digiti minimi PA

lateral epicondyle of humerus - common extensor tendon

Extensor digiti minimi DA

extensor expansion of 5th digit

Extensor digiti minimi innervation

deep branch of radial n

Extensor digiti minimi action

extends 5th digit at MCP, DIP, and PIP joints

Extensor carpi ulnaris PA

• lateral epicondyle of humerus

• posterior border of ulna via a shared aponeurosis

Extensor carpi ulnaris DA

dorsal aspect of base of 5th metacarpal

Extensor carpi ulnaris innervation

deep branch of radial n

Extensor carpi ulnaris action

extends and ulnarly deviates wrist

Supinator PA

• lateral epicondyle of humerus

• radial collateral ligament

• annular ligament

• supinator fossa

• crest of ulna

Supinator DA

lateral, posterior, and anterior surfaces of proximal third of radius

Supinator innervation

deep branch of radial n

Supinator action

• supinates forearm

• rotates radius to turn palm anteriorly or superiorly

Extensor indicis PA

posterior surface of distal third of ulna and interosseous membrane

Extensor indicis DA

extensor expansion of 2nd digit

Extensor indicis innervation

posterior interosseous n

Extensor indicis action

• extends 2nd digit

• helps extend hand at wrist

Outcropper muscles

• abductor pollicis longus

• extensor pollicis longus

• extensor pollicis brevis

Abductor pollicis longus PA

posterior surface of proximal halves of ulna, radius, and interosseous membrane

Abductor pollicis longus DA

base of 1st metacarpal

Abductor pollicis longus innervation

posterior interosseous n of deep branch of radial n

Abductor pollicis longus action

abucts thumb and extends it at CMC joint

Extensor pollicis longus PA

posterior surface of middle third of ulna and interosseous membrane

Extensor pollicis longus DA

dorsal aspect of base of distal phalanx of thumb

Extensor pollicis longus innervation

posterior interosseous n from deep branch of radial n

Extensor pollicis longus action

• extends distal phalanx of thumb at IP joint

• extends MCP and CMC joints

Extensor pollicis brevis PA

posterior surface of distal third of radius and interosseous membrane

Extensor pollicis brevis DA

dorsal aspect of proximal phalanx of thumb

Extensor pollicis brevis innervation

posterior interosseous n from deep branch of radial n

Extensor pollicis brevis action

• extends proximal phalanx of thumb at MCP joint

• extends CMC joint

Thenar muscles

• opponens pollicis

• abductor pollicis brevis

• flexor pollicis brevis — superficial and deep heads

Opponens pollicis PA

flexor retinaculum and tubercles of scaphoid and trapezium

Opponens pollicis DA

lateral side of 1st metacarpal

Opponens pollicis innervation

recurrent branch of median n

Opponens pollicis action

to oppose thumb, draws 1st metacarpal medially to center of palm and rotates it medially

Abductor pollicis brevis PA

flexor retinaculum and tubercles of scaphoid and trapezium

Abductor pollicis brevis DA

lateral side of base of proximal phalanx of thumb

Abductor pollicis brevis innervation

recurrent branch of median n

Abductor pollicis brevis action

• abducts thumb

• helps oppose thumb

Flexor pollicis brevis — both heads PA

flexor retinaculum and tubercles of scaphoid and trapezium

Flexor pollicis brevis — both heads DA

lateral side of base of proximal phalanx of thumb