Forearm II- Script Diogo

Question 1

What should be assessed when you are concerned for a scaphoid fracture?

Answer 1

the anatomical snuffbox

Question 2

What are the five major nerves of the upper limb?

Answer 2

• axillary nerve
• musculocutaneous nerve
• median nerve
• ulnar nerve
• radial nerve

Question 3

The musculocutaneous nerve transmits mainly what spinal nerve fibers to the anterior arm muscles?

Answer 3

C5 and C6

Question 4

The radial nerve transmits mainly what spinal nerve fibers to the triceps brachii?

Answer 4

C7 and C8

Question 5

What are the anterior forearm muscles that are involved in pronation of the forearm? What are they innervated by?

Answer 5

• pronator teres innervated by median nerve
• pronator quadratus is the chief pronator and innervated by the anterior interosseous nerve (distal to the supinator which marks the transition of name from median nerve to the anterior interosseous nerve)

Question 6

What are the anterior forearm muscles that move the hand at the wrist and midcarpal joints?

Answer 6

• flexor carpi radialis: inserts into bases of metacarpals 2 and 3; innervated by median nerve
• flexor carpi ulnaris: inserts into base of metacarpal 5, pisiform, and hamate; innervated by the ulnar nerve
• palmaris longus: inserts into palmar aponeurosis (Deep fascia, not a bone); innervated by median nerve

all of their origins: medial epicondyle

Question 7

The radial recurrent artery supplies blood to what muscles in the upper limb?

Answer 7

brachialis (anterior)
brachioradialis (posterior superifical)
supinator (posterior deep)

Question 8

What are the anterior forearm muscles that flex the digits ?

Answer 8

• flexor pollicis longus is the sole flexor of the thumb’s distal phalanx; innervated by the anterior interosseous nerve
• flexor digitorum superficialis has the chief action of flexion of the middle phalanges of the fingers; innervated by the median nerve
• flexor digitorum profundus has the chief action of flexion of the distal phalanges of the fingers; lateral part (digits 4,5 )of the muscle is innervated by anterior interosseous nerve and the medial part (digits 2,3) is innervated by the ulnar nerve

Question 9

What is another name for the wrist joint?

Answer 9

radiocarpal joint

Question 10

What occurs with the tendon of the flexor digitorum superficialis in relation to the flexor digitorum profundus?

Answer 10

flexor digitorum superificalis: tendon splits into two slips that inserts into the base of the middle phalanx

flexor digitorum profundus: tendons travel beneath the spliting of the flexor superficialis tendons and inserts into the base of the distal phalanx

Question 11

What forms the roof of the carpal tunnel?

Answer 11

flexor retinaculum

Question 12

What major structures pass through the carpal tunnel?

Answer 12

• median nerve
• tendons of the anterior muscles that flex the digits (flexor pollicis longus, flexor digitorum superficialis, and flexor digitorum profundus)

Question 13

What is the purpose of the synovial sheaths that surrounds the flexor digitorum superificalis and flexor digitorum profundus?

Answer 13

it allows tendons to slide back and forth underneath the flexor retinaculum in an almost frictionless-fashion

Question 14

What is the function of the flexor retinaculum?

Answer 14

retains the insertion tendons of the flexor pollicis longus, flexor digitorum superficialis, and flexor digitorum profundus in close association with the underlying carpals

Question 15

What is the function of the deep fascia that lies in the palmar side of the thumb and each of the fingers called fibrous sheath?

Answer 15

keeps the flexor pollicis longus tendon, abd the flexor digitorum (superficialis and profundus) tendons close to the digit’s phalanges when the digit is flexed at its metacarpophalangeal and interphalangeal joints

Question 16

What spinal nerve provides most of the nerve fibers that control flexion of the thumb and fingers at their interphalangeal joints?

Answer 16

C8

Question 17

The anterior and posterior groups of forearm muscles are each surrounded by a compartment composed of what?

Answer 17

forearm’s deep fascia, an intermuscular septum, the shafts of the radius and ulna, and the interosseous membrane of the forearm

Question 18

Why can the compartment enclosure of the anterior and posterior groups of muscles put these muscles at risk of ischemia?

Answer 18

• it puts these muscles in a fixed volume
• should injury or disease occur, pressure within this space or compartment can increase resulting in compression of nerves, blood vessels, and muscles in the compartment

Question 19

How does a supracondylar fracture of the humerus cause Volkmann’s ischemic contracture, where the thumbs and fingers are drawn into marked flexion?

Answer 19

• a supracondylar humeral fracture can be at risk of untreated swelling of the anterior forearm muscle compartment which will cause ischemic necrosis
• the necrotic muscle tissue is replaced by fibrous scar tissue that permanently shortens the affected forearm muscles and draws the thumb and fingers into marked flexion

Question 20

What are the posterior forearm muscles that move the forearm?

Answer 20

• aconeous assists the triceps brachii in extension of the forearm; innervated by radial nerve and supplied by deep brachial artery and recurrent interosseous artery
• brachioradialis flexes the forearm ; innervated by radial nerve and supplied by radial recurrent artery
• supinator’s only action is the supination of the forearm; innervated by deep radial nerve and supplied by radial recurrent artery

Question 21

What are the posterior forearm muscles that move the hand at the wrist and midcarpal joints?

Answer 21

extensor carpi radialis longus: extend and abduct hand; innervated by radial nerve and supplied by the radial artery

extensor carpi radialis brevis: extend and abduct the hand: innervated by radial nerve and deep radial nerve and supplied by the radial artery

extensor carpi ulnaris: extend and adduct the hand; innervated by radial nerve and supplied by ulnar artery

Question 22

Supinator is innervated by what spinal nerves?

Answer 22

C5 and C6 nerve fibers

Question 23

Marked weakness or paralysis of what muscles results in the inability to extend the hand at the wrist AKA wrist drop?

Answer 23

extensor carpi muscles

Question 24

What is another term for Saturday night palsy?

Answer 24

wrist drop

• which is the result of an inebriated person falling asleep in a chair with his/her arm draped over the back of the chair
• the resulting pressure on the radial nerve in the axilla may lead to a temporary case of wrist drop

Question 25

What are the three posterior forearm muscles that extend the thumb?

Answer 25

abductor pollicis longus: extend and abduct the thumb
extensor pollicis longus: extend the thumb
extensor pollicis brevis: extend the thumb

all are innervated by the posterior interosseous nerve and supplied by the posterior interossesous artery

Question 26

The anatomical snuffbox, which is a hollowed out triangular area consisted of what borders?

Answer 26

laterally the tendons of abductos pollicis longus and extensor pollicis brevis and medially the extensor pollicis longus

Question 27

What is the most commonly fractured carpal?

Answer 27

scaphoid

Question 28

What is the most commonly dislocated carpal?

Answer 28

lunate

Question 29

Why is the anatomical snuffbox a highly clinically relevant surface anatomy to help diagnose a fractured scaphoid?

Answer 29

the scaphoid forms part of the bony floor of the anatomical snuffbox

Question 30

What are the posterior forearm muscles that extend one or all four fingers?

Answer 30

extensor digitorum: extend all four fingers at their metacarpophalangeal and interphalangeal joints; innervated by the radial nerve and supplied by posterior interosseous artery

extensor digiti minimi: extend the little finger at its metacarpophalangeal and interphalangeal joints; innervated by radial nerve and supplied by posterior interosseous artery

extensor indicis: extend the index finger at its metacarpophalangeal and interphalangeal joints; innervated by posterior interosseous nerve and supplied by the ulnar artery

Question 31

What happens to the tendon of the extensor digitorum?

Answer 31

• the tendon broadens and thins out on each side to form a fascial hood called the extensor expansion
• the extensor expansion divides into three slips just proximal to the proximal interphalangeal joint
• the central slip extends across the proximal interphalangeal joint just before inserting onto the base of the middle phalanx
• the two side or collateral, slips merge as they extend distally and insert into the base of the distal phalanx interphalangeal joint

Question 32

Which muscles originated from the lateral epicondyle via the common extensor tendon?

Answer 32

extensor carpi ulnaris
extensor digitorum
extensor digit minimi

Question 33

What leads to lateral epicondylitis?

Answer 33

repetitive, strenuous exercise of the muscles that originate from the lateral epicondyle via the common extensor tendon

Question 34

What is the purpose of the extensor retinaculum?

Answer 34

forms a tunnel like corrideor through which the insertion tendons of the posterior forearm muscles that move the hand at the wrist or extend the thumb and finger pass

the extensor retinaculum thus retains the insertion tendons of these muscles in constant close association with the underlying bones during movements of the hands and its digits

Question 35

What arteries and nerves pass superficial and through the flexor retinaculum?

Answer 35

• median nerve pass through the carpel tunnel

- ulnar nerve and ulnar artery passes superficial to the flexor retinaculum

Question 36

What spinal nerve provides most of the sensory innervation to skin on the lateral side of the forearm?

Answer 36

C6

Question 37

What spinal nerve provides most of the sensory innervation to skin on the medial side of the forearm?

Answer 37

T1