Anatomy Upper Limb (extensor compartment)

Question 1

Extensor Carpi radialis Longus

Answer 1

Origin: lateral supracondylar ridge, forms a flat tendon in the posterior side of the radius runs deep to abductor pollicis Longus and extensor pollicis brevis it then passes beneath the dorsal carpal ligament

Insertion: base of the second metacarpal

Innervation: radial

Action: extension and abduction

Question 2

Extensor Carpi radialis brevis

Answer 2

Origin: lateral epicondyle of humerus

Insertion: runs deeper to extensor pollicis brevis and abductor pollicis Longus

Insertion: base of third metacarpal some to the second
Action: extension adduction

Innervation: deep branch of radial nerve

Question 3

Extensor Carpi ulnaris

Answer 3

Origin: lateral epicondyle of humerus

Insertion: base of the fifth Metacarpal

Action: extends wrist

Innervation: posterior interosseous nerve continuation of the deep branch of the radius

Action: extends the wrist

Question 4

Brachioradialis

Answer 4

Origin: lateral supracondylar ridge of the humerus

Insertion: distally on the radius close to the styloid
process forms the lateral border of cubital fossa

Innervation: radial nerve

Function: flexes forearm, supinates arm in pronation stabilise elbow during rapid flexion

Question 5

Aconeus

Answer 5

Origin: lateral epicondyle humerus

Insertion: superior proximal part of the posterior ulna

Innervation: radial nerve

Function: trivial extension forearm

Question 6

Extensor digitorim

Answer 6

Origin: lateral epicondyle splits into four tendons past the mpj it spread into a large aponeurosis

Insertion: once past the first ipj the aponeurosis divides into three slips an intermediate and two collateral the former inserts into the middle phalanx and the later are inserted into the distal phalanx

Innervation: PIN

Action: extension of wrist, phalanges and the elbow
Innervation: posterior interosseous nerve

Question 7

Extensor digiti minimi

Answer 7

Origin; later epicondyle

Insertion: proximal phalanx of 5

Function: extension at wrist and 5th

Innervation: pin

Question 8

Abductor pollicis Longus

Answer 8

Origin: lateral part dorsal surface of the ulna, interosseous membrane and middle third of the radius

Insertion: superficial: radial side of the first metacarpal, proximal deep: trapezium and into the belly of abductor pollicis brevis

Innervation: pin

Action: abduct thumb at the cmj, extends and rotates the thumb

Question 9

Extensor pollicis longus

Answer 9

Origin: dorsal surface of the middle third ulna and interosseous membrane

Insertion: base 1st distal phalanx

Innervation: pin

Action: extends the terminal phalanx of the thumb

Question 10

Extensor pollicis brevis

Answer 10

Origin: radius distal to abductor pollicis Longus and interosseous membrane

Insertion base of first phalanx of thumb

Action extends and abducts the thumb

Innervation: pin

Question 11

Extensor indices

Answer 11

Origin: distal third dorsal portion of the ulna and interosseous membrane

Insertion: opposite the head of the second metacarpal bone ulnar side tendon of extensor digitorim

Action: extends index

Innervation: pin

Question 12

Supinator

Answer 12

Origin: supinator crest of ulnar, lateral epicondyle radial collateral ligament and the annular ligament

Insertion: lateral edge of radial tuberosity

Innervation: deep branch of radial nerve

Function: supination

Question 13

Describe the extensor tendon compartments

Answer 13

1: most radial occupied by extensor pollicis brevis and abductor pollicis Longus
2: extensor Carpi radialis brevis and Longus
3: extensor pollicis Longus hooks around listers tubercle
4: largest extensor digitorum, extensor indicis
5: extensor digiti minimi
6: extensor Carpi ulnaris