TBL 6 - Forearm and Hand

Question 1

What does the musculocutaneous nerve become and what does it innervate?

Answer 1

Lateral cutaneous nerve of the forearm, skin of the anterolateral forearm to wrist

Question 2

Where do the medial cutaneous nerve of the forearm and the the median cutaneous nerve of the arm come from and what do they innervate?

Answer 2

The medial cord of the brachial plexus and the forearm nerve innervates the anteromedial aspect to wrist and the arm nerve innervates the medial aspect of the distal arm

Question 3

What does the superior lateral cutaneous nerve do?

Answer 3

skin over lower part of deltoid and lateral of midarm

Question 4

What does the posterior cutaneous nerve of the forearm innervate?

Answer 4

Posterior forearm to wrist

Question 5

Cephalic vein receives blood from where and what part of the arm does it run up and where does it empty

Answer 5

The lateral aspect of the dorsal venous network and the vein runs laterally up the arm to the axillary vein

Question 6

The median vein of the forearm receives blood from where, what does it empty into?

Answer 6

Medial aspect of dorsal venous network. Runs medially along arm and turns into the basilic vein which joins the axillary vein

Question 7

What is the medial cubital vein

Answer 7

It is in the cubital fossa and connects the cephalic vein to the basilic vein

Question 8

How are the median nerve and brachial artery somewhat protected when the median cubital vein is used for venipuncture?

Answer 8

The bicipital aponeurosis sits in the cubital fossa above the median nerve and brachial artery and below the median cubital vein protecting whats underneath

Question 9

What is the most common cause of Colles fracture and what causes the resulting dinner fork deformity?

Answer 9

Transverse fracture of the distal 2 cm of the radius. It results from forced extension of the hand when trying to break a fall by outstretching the upper limb. Results in the dinner fork deformity where the radius is shortened relative to the ulna causing posterior angulation in the forearm

Question 10

Role of interosseous membrane

Answer 10

Distribute forces received by the radius and hand to the ulna and humerus

Question 11

Which carpal bones articulate with the radius

Answer 11

Scaphoid and lunate

Question 12

Which artery is at risk when the scaphoid bone is fractured and what are clinical consequences when arterial injury occurs?

Answer 12

Radial artery at risk. Results in poor blood supply to scaphoid leading to necrosis of the bone and degenerative wrist joint disease.

Question 13

Why is fracture-separation of the distal radius common in children and what is the prognosis for normal bone growth?

Answer 13

They fall a lot on their hands causing dorsal displacement of the distal radial epiphysis. If the epiphysis is positioned normally during reduction, normal bone growth is likely to occur

Question 14

How are brachydactyly and polydactyly distinguished and what causes syndactyly?

Answer 14

Brachydactyly - Shortening of the digits
Polydactyly - extra digits are present
Syndactyly - two or more fused digits. Occurs because cell death does not occur properly in the hand/foot plates

Question 15

Name the muscles of the superficial layer of the anterior forearm from lateral to medial

Answer 15

Brachioradialis, Pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris

Question 16

Name the muscle of the second layer of the anterior forearm

Answer 16

Flexor digitorum superficialis

Question 17

Name the muscles deep in the anterior forearm

Answer 17

Flexor digitorum profundus, Flexor pollicis longus, pronator quadratus

Question 18

Describe relationship of pronator quadratus and teres

Answer 18

Quadratus initiates pronation. Teres is only necessary for more speed and power

Question 19

Which activities cause pronator syndrome and where does pain occur?

Answer 19

Repeated pronation. Pain occurs in the proximal part of the anterior forearm and there is hypesthesia of the palmar aspects of radial three and a half digits. It is a problem with the median nerve compression at the elbow

Question 20

What is the anatomical basis for avulsion of the medial epicondyle in children and which nerve is often injured?

Answer 20

The epiphysis of the medial epicondyle may not fuse to the distal end of humerus until age 20 making it easier for kids to injure. The ulnar is often hurt because it passes posterior to the medial epicondyle

Question 21

What does the ulnar nerve innervate

Answer 21

The flexor carpi ulnaris and the flexor digitorum profundus on the 4th and 5th digits

Question 22

What does the median nerve innervate

Answer 22

Superficial and intermediate muscles of the anteromedial forearm except the flexor carpi ulnaris

Question 23

What nerve acts on the flexor digitorum profundus for the 2nd and 3rd digits, the pronator quadratus, and the flexor palmaris longus and where does it come from

Answer 23

The anterior interosseous nerve that comes from the median nerve

Question 24

What nine tendons go through the carpal tunnel, what nerve, and what courses alongside and just superior to the carpal tunnel

Answer 24

Flexor digitorum superficialis and profundus along with the flexor pollicis longus. Just next to it is the tendon of the flexor carpi radialis

Question 25

How does dislocation of the lunate typically occur and what are the resulting symptoms?

Answer 25

Fall on the dorsiflexed wrist. It can compress the median nerve and lead to carpal tunnel syndrome. Necrosis of the lunate can occur if blood is lacking

Question 26

How are the 4th and 5th digits affected by Dupuytren contracture and how is it treated?

Answer 26

Dupuytren contracture is a disease of the palmar fascia that causes progressive shortening, thickening, and fibrosis of the fascia and aponeurosis on the medial side of the hand. This causes the 4th and 5th digits to be partially flexed. Treated with surgery to remove the fibrotic parts of the fascia

Question 27

How do the common flexor sheath and the digital synovial sheathes determine the spread of infection from tenosynovitis?

Answer 27

Because only the 5th digit is continuous between the digital synovial sheath and common flexor sheath, only tenosynovitis in that finger is likely to spread to the common flexor sheath. Tenosynovitis in the other fingers is likely to be contained.

Question 28

When does the supinator muscle supinate the forearm and when does the biceps contribute to the supination?

Answer 28

Supinator in all situations (slow, unopposed). Biceps to help when there is resistance or need for speed

Question 29

What mainly enables extension at the MCP joints and secondarily at the IP joints

Answer 29

Extensor digitorum

Question 30

What causes elbow tendinitis, what are its symptoms, and when does it lead to lateral epicondylitis?

Answer 30

Repetitive use of the superficial extensor muscles. Pain is over the lateral epicondyle and radiates to the posterior surface of the forearm. Repeated forceful flexion and extension of the wrist causes inflammatino in the periosteum of the lateral epicondyle

Question 31

How is a long extensor tendon commonly avulsed from its distal attachment and what is the resultant deformity?

Answer 31

Sudden severe tension can cause avulsion at the phalanx attachment. Results in the mallet or baseball finger

Question 32

Name the superficial posterior forearm muscles from lateral to medial

Answer 32

6 muscles - Brachioradialis, Extensor Carpi Radialis Longus, Extensor Carpi Radialis Brevis, Extensor Digitorum, Extensor Digiti minimi, Extensor Carpi Ulnaris

Question 33

Deep layer of posterior forearm muscle

Answer 33

Supinator and extensor indicis

Question 34

What the outcropping muscles from the posterior forearm and their attachments. What artery goes along the floor of the snuff box?

Answer 34

Abductor pollicis longus, Extensor pollicis longus, and extensor pollicis brevis and they attach to the ulna. They form the anatomical snuff box on the lateral side of wrist . The radial artery goes through the floor of the snuff box.

Question 35

Describe the course of the radial nerve

Answer 35

Continues from posterior cord to innervate triceps. It courses along the radial groove and passes anterior to the lateral epicondyle of the humerus of the cubital fossa and innervates the brachioradialis. It bifurcates into the superficial (sensory) and deep branches

Question 36

What does the deep branch of the radial nerve innervate?

Answer 36

Superficial extensor muscles and the supinator. Becomes the posterior interosseous nerve that innervates the other muscles of the deep extensor layer

Question 37

What is the characteristic clinical sign after radial nerve injury in the radial groove of the humerus?

Answer 37

Medial head of triceps is weakened. The posterior forearm muscles are paralyzed resulting in wrist drop

Question 38

What do the ulnar and anterior interosseous arteries and also the radial artery supply

Answer 38

Anteromedial forearm

Question 39

What does the posterior interosseous artery and radial artery supply

Answer 39

Posterolateral forearm

Question 40

What are the thenar muscles? Where is the adductor pollicis

Answer 40

Abductor pollicis brevis, flexor pollicis brevis and underneath the APB, is the opponens pollicis. The adductor pollicis is just medial of the flexor pollicis brevis

Question 41

What are the hypothenar muscles?

Answer 41

The abductor digiti minimi

Question 42

Describe the innervation of the thenar muscles and the adductor pollicis

Answer 42

Opponens pollicis, abductor pollicis brevis, and superficial head of flexor pollicis brevis are innervated by the recurrent branch of median nerve. The adductor pollicis and deep head of the flexor pollicis brevis are innervated by the deep branch of the ulnar nerve

Question 43

Describe the innervation of the lumbricals

Answer 43

Ulnar for 3rd and 4th, Median for 1st and 2nd

Question 44

What innervates the dorsal interosseous and palmar interosseous and what they do

Answer 44

Deep branch of ulnar nerve. Dorsal abduct 2nd-4th digits

Palmar adduct 2nd, 4th, and 5th

Question 45

Describe the ulnar, median, and radial sensory innervation of the hand

Answer 45

The ulnar does the medial half on both sides. The median does the lateral 3 and a half on the palm and the tips of the digits. The radial does the lateral 3 and a half on dorsum

Question 46

How does median nerve injury near the elbow affect the ability to make a fist? How does injury of the anterior interosseous nerve alter the ability to make the “okay” sign?`

Answer 46

The 2nd and 3rd digits remained partially extended and thenar muscles are affect. The anterior interosseous muscle affects the flexor digitorum proudness and the flexor pollicis longus causing a pinched posture rather than the round “ok” sign

Question 47

Where is the ulnar nerve most commonly injured and how is the ability to flex the wrist or make a fist altered? Where does paresthesia occur after the injury?

Answer 47

Where the nerve passes posterior to the medial epicondyle of the humerus. The MCP joints become hyperextended and the FCU does not work preventing flexion of the wrist. Paresthesia at the medial part of the palm

Question 48

What are the sensory and motor deficits after injury of the superficial or deep branches of the radial nerve?

Answer 48

Deep branch - Extensors of wrist affected leading to wrist drop. Can’t extend thumb or MCP joints.
Superficial branch - sensory loss of coin shaped area distal to the bases of the 1st and 2nd metacarpals

Question 49

How do cubital tunnel syndrome and Klumpke paralysis alter the ability to flex the wrist or make a fist? Where do the lesions produce paresthesia?

Answer 49

Ulnar nerve could be compressed by cubital tunnel syndrome.
Klumpke paralysis is where the inferior part of the brachial plexus is torn causing problems in the short extensors resulting in claw hand

Question 50

What are typical causes of carpal tunnel syndrome? Where do paresthesias, hypothesia, or anesthesia occur and which motor functions of the thumb are lost or weakened?

Answer 50

anything that reduces the size of the carpal tunnel or increases size of something in the tunnel. Median nerve affected so lateral 3 and a half digits affected. The 3 thenar muscles are affected. No opposing of thumb.

Question 51

What does the ulnar artery continue as

Answer 51

the superficial palmar arch which supplies the deep palmar arch along with the radial artery

Question 52

What branch of the radial artery generates the digital arteries of the thumb

Answer 52

The princeps pollicis

Question 53

Where is the best place to stop bleeding after laceration of the palmar arches?

Answer 53

compress brachial artery proximal to the elbow

Question 54

What causes Raynaud syndrome and if it becomes a chronic condition, how is it treated?

Answer 54

Idiopathic ischemia of the digits. It is treated via a cervicodorsal presynaptic sympathectomy that dilates the digital arteries