Sem 1 - V - Posterior forearm and dorsum of hand - Posterior compartment, Radial nerve and artery, dorsum of hand (briefly)

Question 1

Just as the anterior forearm muscles have a common flexor tendon, the posterior forearm muscles have a common extensor tendon Where do both the tendons insert? What is the tendonitis of both these tendons known as?

Answer 1

The common flexor tendon inserts at the medial epicondyle of the elbow - medial epicondylitis is known as Golfer’s elbow The common extensor tendon inserts at the lateral epicondye - lateral epicondyltis is known as Tennis elbow

Question 2

Which muscles insert at the common flexor and common extensor tendon?

Answer 2

Common flexor tendon - Pronator teres, Flexor carpi ulnaris, Palmaris longus, Flexor carpi radialis, Flexor digitorum superficialis (superifical + intermediate anterior forearm muscles)

Common extensor tendon - Extensor carpi radialis brevis, Extnesor digitorum, Extensor digit minimi, Extensor carpi ulnaris

Question 3

So muscles attaching to the common extensor tendon are * Extensor carpi ulnaris * Extensor digitorum * Extensor digiti minimi * Extensor carpi radialis brevis What are the superficial and deep muscles of the posterior forearm?

Answer 3

• Superficial compartment of posterior forearm
  
  • * Aconeus
  • Brachioradialis
  • * Extensor carpi ulnaris
  • * Extensor digitorum
  • * Extensor digiti minimi
  • * Extensor radialis longus and brevis
• Deep compartment of posterior forearm
  
  • * Extensor indices
  • * Extensor pollicis longus and brevis
  • * Abductor pollicis longus
  • * Supinator

Question 4

What is the attachment of the aconeus? State its function and nerve supply (include roots)

Answer 4

The aconeus attaches from the lateral epicondyle of the humerus to the olecranon of the ulna It functions to extend the elbow Its nerve supply is the radial nerve (C7,8T1 roots)

Question 5

The aconeus is supplied by the radial nerve When does the radial nerve divide into separate branches?

Answer 5

Radial nerve divides into deep and superficial branches at the lateral epicondyle of the humerus Superficial branch of the radial nerve goes on to give cutaneous innervation Deep branch of the radial nerve pierces the supinator to travel between its two heads and is now the posterior interosseus nerve

Question 6

What arteries do the posterior interosseus nerve and the superficial branch of the radial nerve travel wih?

Answer 6

The posteiror interosseus nerve runs with the posterior interosseus artery (branch form common interosseus which is a branch of the ulnar nerve) The superficial radial nerve travels with the radial artery

Question 7

What is the attachment of the brachioradialis muscle?

Answer 7

Brachioradialis attaches at the lateral supracondylar ridge of the humerus (distal humerus) to the radius proximal to the styloid process Pic shows brachioradialis crossing anterior elbow joint

Question 8

What is the function of the brachioradialis and when is it best? What is the nerve supply? (state roots and division)

Answer 8

Function of the brachioradialis - flexion of the elbow joint (especially when the forearm is in the semi-prone position) Nerve supply - Radial nerve (C5,6,7), prior to the radial nerve division into the superficial and deep branches)

Question 9

State the attachments, function and nerve supply of the brachioradialis

Answer 9

Attachments - Attaches from the lateral supracondylar ridge to the radius proximal to the styloid process

Function - Flexes the elbow (especially when the forearm is in the semi-prone position)

Nerve supply Radial nerve (C5,6,7) - prior to the radial nerve division

Question 10

What movements of the thumb are in the plane of the palm and away from the plane of the palm? What is the most powerful supinator of the forearm?

Answer 10

Flexion and extension of thumb - in the plane of the palma Abduction - away from the plane of the palm, Adduction - towards the plane of the palm Most powerful supinator of the forearm - biceps brachii (supinator muscle also supinates the forearm)

Question 11

Superficial compartment of posterior forearm * Aconeus * Brachioradialis * Extensor carpi ulnaris * Extensor digitorum * Extensor digiti minimi * Extensor radialis longus and brevis What are the attachments of the extensor radialis longus and brevis?

Answer 11

Extensor carpi radialis longus - attaches from the lateral supraecondylar ridge of the humerus to the base of the 2nd metacarpal (index finger metacarpal)

Extensor carpi radialis brevis- attaches from the lateral epicondyle of the humerus to the base of the 3rd metacarpal

Question 12

What is the function of the extensor carpi radialis longus and brevis?

Answer 12

Both act on the wrist Extension and abduction of the wrist

Question 13

What is the nerve supply to the extensor carpi radialis longus and brevis?

Answer 13

Extensor carpi radialis longus - radial nerve (C6,7) - pre-division Extensor carpi radialis brevis - radial nerve (C7,8) - posterior interosseous division

Question 14

What is the attachment, function nerve supply of the extensor carpi radialis longus and brevis?

Answer 14

Extensor carpi radialis longus - from the lateral supracondylar ridge - base of the 2nd metacarpal Radial nerve (C6,7) - pre-division Extensor carpi radialis brevis - from the lateral epicondyle to the base of the 3rd metacarpal Posterior interosseous branch of radial nerve (C7,8) Function of both - wrist extension and abduction

Question 15

What are the only 4 muscles supplied by the radial nerve before its division into superficial and deep radial nerve?

Answer 15

Triceps brachii (muscle of the posterior compartment of the arm) Aconeus Brachioradialis Extensor carpi radialis longus Every other muscle is supplied by the posterior interosseous nerve (all will be C7,8) (continuation of the deep interosseous nerve as it passes through the supinator muscle)

Question 16

What is the attachment of the extensor carpi ulnaris?

Answer 16

It attaches from the lateral epicondyle of the humerus (and a small slip from the ulna) to the base of the 5th metacarpal

Question 17

What is the function and nerve supply of the extensor carpi ulnaris?

Answer 17

Function: Extends and adducts the wrist Nerve supply - Posterior interosseous nerve (C7,8)

Question 18

In the midline just as we had in the flexor compartment, we have the extensor digitiorum What are the attachments of the extensor digitorum?

Answer 18

The extensor digitorum attaches from the lateral epicondyle of the humerus to the dorsal expansion of digits 2-5 (NOT THE THUMB)

Question 19

What is the dorsal expansion?

Answer 19

The dorsal expansion is the special connective tissue which allows the long extensors and short muscles of the hand to act on all three finger joints

Question 20

What is the function of the extensor digitorum? What is its nerve supply?

Answer 20

Its function is to principally extend the MCP joints but it will also extend the wrist and the PIP and DIP joints of digits 2-5 Nerve supply - radial nerve (C7,8) from the posterior interosseous nerve branch

Question 21

There is no superficialis or profundus so the extensor digitorum attaches finally to the distal phalnyx What is the attachment, function and nerve supply of the extensor digitorum?

Answer 21

Attaches from the lateral epicondyle of the humerus to the dorsal expansion of digits 2-5 (not the thumb)

Function - principal function is to extend the MCP joints Also extends the wrist, and extends the PIP and DIP joints of digits 2-5

Nerve - Posterior interosseus nerve (C7,8)

Question 22

What are the attachments of the extensor digiti minimi?

Answer 22

Attaches from the lateral epicondyle of the humerus to the dorsal expansion of the 5th digit (little finger)

Question 23

What is the function of the extensor digiti minimi? What is the nerve supply to this muscle?

Answer 23

Function - MCP joint, PIP and DIP joint extension of the little finger Also extends the wrist Nerve supply - posterior interosseous nerve (C7,8)

Question 24

What are the main extensors of the wrist?

Answer 24

The two main extensors of the wrist are the extensor carpi radialis longus and brevis and the extensor carpi ulnaris The other muscles crossing the wrist will also extend the wrist joint but it is not their main function

Question 25

This deeper layer now comes from the bones and not the lateral epicondyle What is the attachment of the extensor indices?

Answer 25

Extensor indices attaches from the posterior surface of the ulna and interosseus membrane to the dorsal expansion of the 2nd digit

Question 26

What is the function of the extensor indices? What is the nerve supply?

Answer 26

Function of the extensor indices - MCP, PIP, DIP of the 2nd digit and extends the wrist Nerve supply - Posterior interosseous nerve (C7,8)

Question 27

What word do the muscles to the thumb all have in it?

Answer 27

All have the word pollicis in it

Question 28

What is the attachment of the extensor pollicis longus?

Answer 28

Attaches from the ulna and interosseous membrane to the base of the distal phalnyx of the thumb

Question 29

What is function of the extensor pollicis longus?

Answer 29

Causes extnesion of the CMC, MCP and IP joint of the thumb It also extends the wrist joint

Question 30

What is the attachment of the extensor pollicis brevis?

Answer 30

Attaches from the radius and interosseous membrane to the base of the proximal phalynx of the thumb

Question 31

What is the function of the extensor pollicis brevis?

Answer 31

Carpometacapral and metacarpophalyngeal extension of the thumb Also extends the wrist

Question 32

State the attachments, function and nerve supply of the extensor pollicis longus

Answer 32

Extensor pollicis longus Attaches from the ulna and interosseous membrane to the base of the distal phalnyx of the thumb - Extends the CMC, MCP and IP joints of the thumb and extends the wrist Nerve supply - Posterior interosseous nerve (C7,8)

Question 33

State the attachments, function and nerve supply of the extensor pollicis brevis

Answer 33

Extensor pollicis brevis Attaches from the radius and interosseous membrane to the base of the proximal phalnyx of the thumb Function - extends the CMC and MCP joints of the thumb Also extends the wrist Nerve supply - Posterior interosseous nerve (C7,8)

Question 34

What is the most lateral muscle of the posterior forearm?

Answer 34

This is the abductor pollicis longus

Question 35

What is the attachments of the abductor pollicis longus?

Answer 35

Attaches from the radius, interosseous membrane and ulna to the base of the 1st metacarpal

Question 36

What is the function of the abductor pollicis longus?

Answer 36

It abducts the thumb and extends it at the carpometacarpal joint Also extends the wrist joint

Question 37

What is the attachment and function of the abductor pollicis longus? What is its nerve supply?

Answer 37

Abductor pollicis brevis Attachment - attaches from the radius, interosseous membrane and ulna to the base of the 1st metacarpal It abducts the thumb and extends the carpometacarpal joint It also extends the wrist Posterior interosseous nerve (C7,8)

Question 38

What are the boundaries of the anatomical snuffbox? Medial (ulnar) border Lateral (radial border) Roof Floor

Answer 38

• Medial border - Tendon of the extensor pollicis longus
• Lateral border - Tendon of the extensor pollicis brevis and the abductor pollicis longus
• Roof - skin
• Floor - Carpal bones - scaphoid and trapezium

Question 39

What are the muscles for pronation? What are the muscles for supination? State the main muscle

Answer 39

Muscles for pronation - pronator teres and pronator quadratus Supination - Biceps brachii (main muscle of supination) and supinator muscle

Question 40

The supinator lies in the floor of the cubital fossa. It has two heads, which the deep branch of the radial nerve passes between. What is the attachment of the supinator muscle?

Answer 40

Attaches from the lateral epicondyle of the humerus (humeral head), crest of the ulna (ulnar head) , radial collateral and annnular ligaments to the lateral surface of the proximal 1/3rd of the radius

Question 41

What is the fucntion of the supinator muscle?

Answer 41

Supination of the forearm - rotates the radius so that the radius and ulna are parallel

Question 42

State the attachments of the supinator, its function and nerve supply?

Answer 42

Attachments - lateral epicondyle of humerus and crest of ulna, radial collateral and annular ligaments to the lateral surface of the proximal (1/3rd) of the radius Function - Supination of the forearm Nerve supply - Posterior interosseous nerve (C7,8)

Question 43

Brachial artery goes down the anterior compartment where it divides in the cubital fossa, Radial artery runs in the anterior compartment of the forearm When does it go to the posterior compartment of the forearm? What is the course of the radial nerve?

Answer 43

Radial artery passes over the floor of the anatomical snuffbox into the anterior aspect of the hand

Radial nerve - Passes through triangular hiatus to wrap around humerus before piercing the lateral intermuscular septum. It will divide at the laeral epicondyle of the humerus into superficial & deep radial nerve branches

Question 44

State what these nerves and arteries are branches of Anterior interosseous artery? Anterior interosseous nerve? Posterior interossoeus artery? Posterior interosseous nerve?

Answer 44

• Anterior interosseous artery - Branch of the common interosseous artery from the ulnar artery
• Anterior interosseous nerve runs with the anterior interosseous artery - branch of the median nerve as it passes through the pronator teres
• Posterior interosseous artery - branch of the common interosseous artery from the ulnar artery
• Posterior interosseous nerve - continuation of the deep branch of the radial nerve after it pierces the supinator

Question 45

This shows the tendons coming through with their synovial sheaths Can see them joining at the dorsal expansions of the digits What side of the extensor digitorum do the extensor indicis and extensor digiti minimi lie on?

Answer 45

Extensor indicis and extensor digiti minimi both lie on the medial side of the extensor digitorum

Question 46

Dorsal venous arch of the back of the hand What vein will it form on the thumb side? What vein will it form on the little finger side?

Answer 46

Dorsal venous arch of the back of the hand forms the cephalic vein on the thumb side Dorsal venous arch of the back of the hand forms the basilic vein on the little finger side

Question 47

What nerve does the cephalic vein run with? State the boundaries of the anatomical snuffbox again?

Answer 47

Cephalic vein runs with lateral cutaneous nerve of the forearm in the cubital fossa and the superficial branch of the radial nerve distally Medial boundary - extensor pollicis longus Lateral boundary - extensor pollicis brevis and abductor pollicis brevis Roof - skin Floor - scaphoid and trapezium

Question 48

Apart form the extensor digitorum, extensor digiti minimi and extensor indices attaching to the dorsal expansion, what are the small muscles attaching to this? What does the dorsal expansion allow?

Answer 48

This would be the lumbricals and interossei - will talk more about these in next set of cards Dorsal expansion - allows the long extensors and short muscles of the hand to act on all three finger joints

Question 49

What is the order in which the extensor tendons pass through the extensor retinaculum from lateral to medial? Only 9 of the 12 posterior compartment of the forearm pass through this

Answer 49

Lateral - Abductor pollicis longus and extensor pollicis brevis - Extensor carpi radialis longus and extensor carpi radialis brevis - Extensor pollicis longus - Extensor indicis and extensor digitorum - Extensor digiti minimi - Extensor carpi ulnaris Medial

Question 50

State again the order of which the tendons pass through the extensor retinaculum and which pass through together?

Answer 50

Lateral -

• Abductor pollicis longus and extensor pollicis brevis
• • Extensor carpi radialis longus and extensor carpi radialis brevis
• • Extensor pollicis longus
• • Extensor indices and extensor digitorum
• • Extensor digiti minimi
• • Extensor carpi ulnaris

Medial