Forearm, radius, and ulna

Question 1

How do you orientate the radius if it’s given to you?

Answer 1

Remember that the circular head is proximal and the radial tuberosity always points medially.

Question 2

Which surface of the humerus articulates with the ulna? Which surface articulates with the radius?

Answer 2

Remember T and U are together in the alphabet, so trochlea and ulna must articulate.

That leaves the Capitulum and the radius… no fancy way to remember that

Question 3

What are the three ligaments of the elbow?

Answer 3

ulnar collateral

radial collateral

anular (allows for pronation and supination of the radius)

Question 4

Describe the radioulnar joints

Answer 4

They are synovial pivot joints

There is a proximal and distal joint

they allow for pronation and supination

there is an interosseous membrane between the two bones

Question 5

What are the two functional groupings of the forearm muscles?

Answer 5

Those that cause wrist movement and those that cause finger/thumb movement

Question 6

What forearm muscle is a synergist with the biceps brachii in supination of the forearm?

Answer 6

The supinator muscle

Question 7

What are the two pronators of the forearm? What is their innervatino?

Answer 7

pronator teres

pronator quadratus

*median nerve*

Question 8

What are the two supinator muscles in the arm? What are their innervations?

Answer 8

Biceps Brachii (musculocutaneous nerve)

supinator (radial nerve)

Question 9

What is the common extensor origin?

What is the common flexor origin?

Answer 9

common extensor origin= lateral humeral condyle

Common flexor origin= medial humeral condyle

Question 10

Name the superficial flexor muscles of the forearm

Answer 10

pronator teres (median nerve)

flexor carpi radialis (median nerve)

palmaris longus (median nerve)

flexor carpi ulnaris (ulnar nerve)

“PFPF”

Question 11

Name the muscles in the middle layer of the anterior forearm

Answer 11

Flexor Digitorum Superficialis

(median nerve)

pass through carpal tunnel and inserts onto middle phalanges of the medial 4 digits.

Question 12

Name the muscles that make up the deep flexors of the forearm

Answer 12

flexor digitorum profundus (mixed innervation)

flexor pollicis longus (median nerve)

pronator quadratus (median nerve)

Question 13

Describe the nerve supply of the forearm

Answer 13

all muscles except 1 1/2 supplied by the median nerve

the extra 1 1/2 supplied by the ulnar nerve = flexor digitorum profundus (1/2) and the entire flexor carpi ulnaris

Question 14

What muscles of the forearm are responsible for abduction and adduction of the wrist?

Answer 14

Flexor carpi radialis and ulnaris respectively

Question 15

Describe the path of the median nerve

Answer 15

forms the medial relation in the cubital fossa, passes between the two heads of pronator teres, near the wrist it becomes superficial, gives off muscular branches to the thumb and pointer finger (below the carpal tunnel) gives off palmar cutaneous branch - sensory to skin of palm- which passes over the flexor retinaculum

Question 16

Describe the path of the ulnar nerve

Answer 16

Descends under flexor carpi ulnaris

it is accompanied by ulnar artery

gives off dorsal cutaneous branch to supply the dorsal fingers

crosses over the flexor retinaculum and gives muscular branches to everything but LOAF

Question 17

Use your favorite sentence to describe the carpal bones

Answer 17

“some lovers try positions that they can’t handle”

scaphoid, lunate, triquitrum, pisiform, trapezium, trapezoid, capitate, hamate

Question 18

Which bones contribute to the wrist joint?

Answer 18

the radius, the scaphoid, the lunate

Question 19

What four carpal bones are attached to the flexor retinaculum?

Answer 19

scapoind, trapezium, hamate, and pisiform

Question 20

Describe the arterial supply of the forearm

Answer 20

brachial artery descends and passes through the cubital fossa bifurcating to become the radial and ulnar arteries.

The radial artery: lies deep to brachoradialis - lies lateral to the flexor carpi radialis tendon at the risk - runs posteriorly to the anatomical snuffbox - supplies the posterior aspect of the forearm

The ulnar artery: runs beneath pronator teres and flexor digitorum superficialis - passes beneath and lateral to Flexor carpi ulnaris- supplies the anterior aspect of the forearm

They both anastimose in the hand by forming two arches deep/superficial

*common interosseous artery is a branch of the ulnar artery*

Question 21

What is an Allen’s Test?

Answer 21

Allens test demonstrates the blood supply in the hand - press down on radial and ulnar arteries, then release the radial artery - if there is a true anastomosis then the hand will profuse with blood.

Question 22

What are the cutaneous nerves of the forearm?

Answer 22

Lateral cutaneous nerve of forearm- branch of musculocutaneous

medial cutaneous nerve of forearm - branch of medial cord

Question 23

What muscles are part of the superficial compartment of the posterior forearm?

Answer 23

Anconeous

Extensor Carpi radialis longus

Extensor carpi radialis brevis

Extensor digitorum

Extensor carpi ulnaris

Extensor digiti minimi

Question 24

What nerve supplies the posterior compartment of the forearm?

Answer 24

Radial Nerve for both the deep and superficial compartment

Question 25

What structure extends the extensor digitorum tendons on the phalanges?

Answer 25

The ‘Extensor Expansion’ which passes over the entire posterior finger

Question 26

What muscles are a part of the posterior compartment of the forearm (deep compartment?)

Answer 26

Supinator

Abductor Policis longus

Extensor Pollicis longus

Extensor pollicis brevis

Extensor indicis

Question 27

If you fracture your scaphoid bone, where will you experience tenderness?

Answer 27

in your anatomical snuffbox

Question 28

What is the real concern with a scaphoid fracture?

Answer 28

The scaphoid may fracture at a point that leaves it vulnerable for necrosis of the medial half of bone.

Question 29

What would damage to the radial nerve result in?

Answer 29

results in the inability to extend fingers and wrist drop

Question 30

Why might a mid shaft humerus fracture lead to difficulty flexing elbow mid-pronation?

Answer 30

Because of damage to the radial nerve, brachioradialis may not be functional. In the pronated position, the brachioradialis is responsible for flexion of the elbow.

Question 31

What may result in ‘saturday night palsy?’

Answer 31

Damage to the radial nerve causes ‘wrist drop’ characteristic of saturday night palsy

Question 32

What is a colles’ fracture?

Answer 32

‘dinner fork deformity ‘

fall on an extended hand causes dorsal angulation of radius

Question 33

what is a Smith’s fracture?

Answer 33

Fall on a flexed wrist causes anterior angulation of the radius