Muscles of the Posterior (Extensor-Supinator) Compartment of the Forearm

Question 1

The most superficial muscles of the posterior compartment of the forearm arise from where?

Answer 1

lateral epicondyle of the humerus via common extensor tendon

Question 2

The deep muscles of the posterior compartment of the forearm mainly arise from where

Answer 2

posterior ulna, radius, and interosseous membrane

Question 3

Are all muscles in the posterior compartment of the forearm innervated by the same nerve? Which nerve(s)?

Answer 3

all innervated by radial nerve

Question 4

What holds the extensor tendons in place?

Answer 4

extensor retinaculum

prevents bowstrigning of tendons when hand is hyperextended @ wrist joint

Question 5

What is synovial sheath

Answer 5

encompasses tendons that pass over dorsum of wrist to reduce friction between extensor tendons and bones`

Question 6

What muscles are included in the wad of three?

Answer 6

Brachioradialis, Extensor carpi radialis longus, extensor carpi radialis brevis

Question 7

What is considered the ‘beer drinking muscle’?

Answer 7

brachioradialis

Question 8

What is the origin of the brachioradialis

Answer 8

proximal 2/3 of lateral supracondylar ridge

Question 9

What is the insertion of the brachioradialis

Answer 9

superior to styloid process of radius

Question 10

What muscle of the posterior compartment passes anterior to the axis of flexion/extension
?

Answer 10

brachioradialis

Question 11

What nerve innervates the brachioradialis

Answer 11

radial nerve

Question 12

What is the origin of the extensor carpi radialis longus

Answer 12

distal 1/2 of lateral supracondylar ridge

Question 13

What is the insertion of the extensor carpi radialis longus

Answer 13

base of 2nd metacarpal bone

Question 14

What are the functions of the extensor carpi radialis longus

Answer 14

ext of hand @ wrist joint

abduction of hand @ wrist joint

Question 15

What is the innervation of the extensor carpi radialis longus

Answer 15

radial nerve

Question 16

What is the origin of the extensor carpi radialis brevis

Answer 16

lateral epicondyle vis common extensor tendon

Question 17

What is the insertion of the extensor carpi radialis brevis

Answer 17

base of 3rd metacarpal bone

Question 18

What are the functions of the extensor carpi radialis brevis

Answer 18

ext of hand @ wrist joint

abduction of hand @ wrist joint

Question 19

What nerve innervates the extensor carpi radialis brevis

Answer 19

radial nerve

Question 20

What is the origin of the extensor digitorum

Answer 20

lateral epicondyle via common extensor tendon

Question 21

What is the insertion of the extensor digitorum

Answer 21

distal and middle phalanges of digits 2-5 via dorsal digital expansion

Question 22

What are the functions of the extensor digitorum

Answer 22

ext of digits 2-5 @ MCP, PIP, DIP
weak ex of forearm @ elbow joint
ex of hand @ wrist joint

Question 23

What nerve innervates the extensor digitorum

Answer 23

radial nerve

Question 24

What is the origin of the extensor digit minimi

Answer 24

lateral epicondyle via common extensor tendon

Question 25

What is the insertion of the extensor digiti minimi

Answer 25

middle and distal phalanges of pinkie via its dorsal digital expansion

Question 26

What are the functions of the extensor digiti minimi

Answer 26

ext of pinkie @ MCP, PIP, DIP ext of hand @ wrist joint weak ext of forearm @ elbow joint

Question 27

What nerve innervates the extensor digiti minimi

Answer 27

radial nerve

Question 28

What is the dorsal digital expansion also known as

Answer 28

extensor hoods

Question 29

What is a dorsal digital expansion

Answer 29

triangular tendinous aponeurosis that wraps the metacarpalphalageal joints and extent along proximal and middle phalanges across two interphalangeal joints to attach to the distal phalanx on the dorsal aspect of digits 2-5

Question 30

what muscles attach to the sides of the dorsal digital expansion

Answer 30

interossei and lumbrical muscles

Question 31

What causes the ‘Ta-Ta’ movement. What is the ‘Ta-Ta’ movement

Answer 31

muscles come from the palm to the sides of the digits and insert to the corners of the base of the dorsal digital expansion does flex of MCP and passive ext of PIP+DIP

Question 32

What is the origin of the extensor carpi ulnaris

Answer 32

lateral epicondyle via common extensor tendon middle posterior border of ulna

Question 33

What is the insertion of the extensor carpi ulnaris

Answer 33

base of 5th metacarpal

Question 34

What are the functions of the extensor carpi ulnaris

Answer 34

``` ext of hand @ wrist joint ulnar deviation (ADD) of hand @ wrist joint ext of forearm @ elbow joint ```

Question 35

What nerve innervates the extensor carpi ulnaris

Answer 35

radial nerve

Question 36

What is the origin of the anconeus?

Answer 36

lateral epicondyle of humerus *note NOT via common extensor tendon

Question 37

What is the insertion of the anconeus

Answer 37

lateral side of olecranon proximal 1/4 of posterior surface of shaft of ulna

Question 38

What are the functions of the anconeus

Answer 38

extension of forearm @ elbow joint

Question 39

What nerve innervates anconeus

Answer 39

radial nerve

Question 40

What is the origin of the supinator

Answer 40

supinator crest of ulna, lateral epicondyle of humerus

Question 41

What is the insertion of the supinator

Answer 41

proximal lateral surface of radius

Question 42

What is the innervation of supinator

Answer 42

radial nerve

Question 43

What is medial epicondylitis also known as

Answer 43

golf elbow

Question 44

What causes medial epicondylitis

Answer 44

forceful and repeated flexion/pronation of wrist and digits causes ruptures of common flexor tendon, small tears in muscle begin to heal but when re-injured becomes painful

Question 45

What are the symptoms of medial epicondylitis

Answer 45

tenderness/pain @ med. epicondyle made worse by flexing wrist

Question 46

What is lateral epicondylitis also known as

Answer 46

tennis elbow

Question 47

What causes lateral epicondylitis

Answer 47

repeated extension and supination of common extensor tendon usually result of specific strain, overuse and direct impact (sometimes no cause)

Question 48

What are the symptoms of lateral epicondylitis

Answer 48

tenderness/pain @ lat epicondyle

Question 49

What is drop wrist

Answer 49

patient cannot extend hand due to damage and/or paralysis of radial nerve

Question 50

What is transient nerve palsy also known as

Answer 50

Saturday night palsy

Question 51

What causes transient nerve palsy? What happens?

Answer 51

leaning over surface (ie chair) causes compression of radial nerve in axilla or upper arm in patient sleeping causing drop wrist