Sievert: Forearm and Posterior Hand

Question 1

What are the three joints of the fingers?

Answer 1

MP: metacarpo-phalangeal between metacarpals and proximal phalanx
PIP: proximal interphalangeal between between proximal and middle phalanx
DIP: distal interphalangeal between middle and distal phalanx

Question 2

Are there muscles associated with the posterior hand?

Answer 2

No muscles, just tendons of muscles of the forearm that are crossing the wrist.

Question 3

How many phalanges are associated with each finger? How many are associated with each thumb?

Answer 3

3 for each finger: distal, middle, and proximal

2 for each thumb: distal and proximal

Question 4

How many metacarpals are associated with each hand?

Answer 4

5

Question 5

This is an apparatus that runs across the phalanges, giving off a central band and two lateral bands that come together and attach to the distal phalanx

Answer 5

extensor hood

Question 6

When you pull on the extensor hood, what happens to tension in the central and lateral bands? What happens when you attach an extensor tendon to the hood?

Answer 6

When you pull on the hood, you cause increased tension in both of these bands. Attaching an extensor tendon to the hood causes extension at the PIP and DIP joints.

Question 7

On which side of the extensor hood is the extensor tendon attached?

Answer 7

dorsal side

Question 8

What do extensor tendons do?

Answer 8

Cause extension of all of the joints

Question 9

The MP, PIP, and DIP joints can be acted on individually in the anterior hand digits. However, what happens to these joints when the extensor digitorum contracts?

Answer 9

Because of the arrangement of the extensor hood, all of these joints are extended at the same time in any single digit when the extensor digitorum contracts

Question 10

The long extensor tendon gives off a central band. Where does this go? It also gives off a lateral band. Where does this go?

Answer 10

central band goes to the base of the middle phalanx; lateral band to distal phalanx

Question 11

What do the lumbricals and interossei do?

Answer 11

extend interphalangeal joints

flex metacarpophalangeal joints

Question 12

What does the flexor digitorum profundus do?

Answer 12

flexes the distal interphalangeal joint (DIP)

Question 13

What does the flexor digitorum superficialis do?

Answer 13

flexes the PIP

Question 14

Can you make a tight fist without the extendor tendons at the wrist?

Answer 14

No

Question 15

T/F: Tendons passing through the compartments must be protected from wear by a synovial tendon sheath.

Answer 15

True

Question 16

In the anterior and posterior forearm, when long muscles and their tendons cross into the wrist into the base of the metacarpals, what must they pass under?

Answer 16

the retinaculum

Question 17

What is the purpose of the retinaculum?

Answer 17

It is a dense CT sheath that holds the tendons in place. It keeps the tendons nice and tight and prevents bow-stringing.

Question 18

There is a retinaculum on the posterior side called the (blank) retinaculum, which corresponds to the (blank) retinaculum on the anterior side.

Answer 18

extensor; flexor

Question 19

What allows tendons to slide smoothly beneath the retinaculum without causing damage to the tendons?

Answer 19

tubes filled with synovial fluid

Question 20

Not a part of any muscle, it is a band around tendons that holds them in place. Its function is mostly to stabilize a tendon.

Answer 20

retinaculum

Question 21

In which portion of the hand, dorsum or anterior side, are there more tendon sheaths? Can these sheaths become infected?

Answer 21

On the dorsum of the hand, tendon sheaths are more numerous. They can become infected.

Question 22

Where do most posterior forearm muscles arise from?

Answer 22

from the common extensor tendon off of the lateral epicondyle or the supracondylar ridge of humerus

Question 23

Which posterior forearm muscles DO NOT arise from the lateral epicondyle or supracondylar ridge?

Answer 23

3 thumb muscles (arise from radius, ulna, interosseus membrane)
extensor indices
supinator

Question 24

All posterior forearm muscles are innervated by this nerve.

Answer 24

radial nerve (mostly deep branch)

Question 25

How many muscles are there to the thumb? The fingers? The wrist? Muscles that don't cross at the wrist?

Answer 25

THREE!

Question 26

What does the snuffbox form between?

Answer 26

two extensor tendons: most posterior is the extensor pollicis longus, anterior: extensor pollicis brevis and abductor pollicis longus** most lateral (these two tendons run together)

Question 27

What is it important to consider when thinking about the actions of the thumb?

Answer 27

The thumb is not in the same place as the fingers - it is 90 degrees from the plane of the fingers.

Question 28

Describe abduction and adduction of the fingers. What is unique about the middle finger?

Answer 28

Abduction is moving away from the middle finger, while adduction is moving toward the middle finger. Middle finger can ONLY abduct in both directions.

Question 29

In what plane do you flex and extend the fingers? On what axis is this motion occurring?

Answer 29

sagittal plane; transverse axis

Question 30

On what plane do you flex and extend the thumb? On what axis is this motion occurring?

Answer 30

coronal plane; AP axis

Question 31

What is adduction of the thumb? What's abduction?

Answer 31

thumb moving close to the midline (palm); thumb moving away from midline

Question 32

What's extension of the thumb?

Answer 32

Hitchhiker thumb!

Question 33

What are three posterior forearm thumb muscles, that do not arise from the lateral epicondyl and supracondylar ridge?

Answer 33

abductor pollicis longus extensor pollicis brevis extensor pollicis longus

Question 34

Which muscle to the thumb is more toward the anterior surface and most lateral? This muscle goes to the base of the metacarpal and crosses 1 joint.

Answer 34

abductor pollicis longus

Question 35

Which muscle to the thumb runs along the same line as the abductor pollicis longus, goes to the proximal phalanx, and crosses 2 joints?

Answer 35

extensor pollicis brevis

Question 36

Which muscle to the thumb goes to the distal phalanx and crosses 3 joints?

Answer 36

extensor pollicis longus

Question 37

again, list the three tendons that make up the anatomical snuffbox.

Answer 37

abductor pollicis longus extensor pollicis brevis extensor pollicis longus

Question 38

What are the contents of the anatomical snuffbox. List them.

Answer 38

radial artery base of 1st metacarpal styloid process of the radius crossing of dorsal digit branches of the radial nerve

Question 39

What happens to the radial artery at the anatomical snuffbox?

Answer 39

It is the place where this artery turns to gain access to the dorsum of the hand - where the artery courses from the anterior to the posterior side (you can feel a pulse here)

Question 40

What are the three forearm muscles that go to the digits?

Answer 40

extensor digitorum extensor digiti minimi extensor indicis

Question 41

Which of the muscles to the digits comes from the lateral epicondyl and divides into four tendons (to index, middle, ring, and little finger)

Answer 41

extensor digitorum

Question 42

Which of the muscles to the digits is a tendon just for the little finger - might aid in sipping a cup of tea like a snob.

Answer 42

extensor digiti minimi

Question 43

Which muscle to the digits is a tendon for the index finger that arises similarly to the muscles of the thumb?

Answer 43

extensor indices

Question 44

Besides providing the digits with movement, what else do the muscles of the digits do?

Answer 44

assist in wrist extension

Question 45

List the three muscles to the wrist

Answer 45

extensor carpi radialis longus extensor carpi radialis brevis extensor carpi ulnaris

Question 46

How many muscles that act on the wrist joint are on the radial side? Which arises the highest on the supracondylar ridge? Where do both of the radial muscles attach to? Where does the muscle on the ulnar side attach?

Answer 46

2 muscles on the radial side (longus and brevis); extensor carpi radialis longus arises from highest point; radial side muscles attach to base of first and second metacarpals; extensor carpi ulnaris attaches to base of metacarpal on ulnar side

Question 47

What do the muscles to the wrist do?

Answer 47

These muscles assist in abduction/adduction and are extensors of the wrist (work in conjunction with flexors on the anterior side)

Question 48

3 posterior forearm muscles that don't cross the wrist joint.

Answer 48

anconeus brachioradialis supinator

Question 49

What is unique about the brachioradialis muscles?

Answer 49

It is a posterior compartment muscle innervated by a posterior compartment nerve that performs an anterior compartment function (flexion of elbow)

Question 50

This muscle is a powerful flexor of the elbow, and is considered the friendly muscle, because it is used in handshakes to maintain a semi-prone-semi-supinated position.

Answer 50

brachioradialis

Question 51

What does the supinator muscle wrap around? What does it "point to" on the anterior side? What does it do to the radius? What is another muscle that supinates?

Answer 51

The supinator wraps around the radius, and points to the pronator on the anterior side. It rolls the radius. The two heads of the biceps are also supinators.

Question 52

This nerve provides innervation to all muscles in the posterior compartment and plays a big role in cutaneous innervation of the dorsum of the hand.

Answer 52

Radial nerve

Question 53

Two branches of the radial nerve are superficial and deep. What does the deep nerve innervate? Is it sensory or motor? What does the superficial nerve innervate?

Answer 53

deep innervates most of the muscles in the forearm, and is only motor. The superficial is sensory and ends in the hand as cutaneous branches to the fingers.

Question 54

What happens if there is damage to the deep radial nerve?

Answer 54

Just a motor loss, but no sensory loss

Question 55

If the radial nerve is damaged high up before coursing over the elbow joint, what muscle can lose innervation?

Answer 55

triceps

Question 56

There is a thin strip of skin supplied by the radial nerve on the posterior forearm. What are the medial and lateral sides supplied by?

Answer 56

medial is supplied by medial antebrachial cutaneous (from medial cord) and the lateral is supplied by the lateral antebrachial cutaneous

Question 57

What is the medial antebrachial cutaneous nerve a branch of? What is the lateral antebrachial cutaneous a CONTINUATION of?

Answer 57

the medial cord; the musculocutaneous nerve

Question 58

Which fingers does the median nerve supply? What fingers does the ulnar nerve supply?

Answer 58

3.5 fingers: the thumb, index, middle, and half of ring finger. 1.5 fingers: little and half of ring finger.

Question 59

what happens if there is damage to the radial nerve? What does damage high in the arm cause? What does damage to the nerve in the forearm mostly affect?

Answer 59

varying effects depending on location; wrist drop, weak or absent wrist/digit extension, no extension at elbow, decreased grip strength; in forearm will affect wrist and digit extensors

Question 60

T/F: Trauma in the forearm can cause swelling which may be restricted by fascial compartments. This can cause elevated pressure in the compartment and subsequent damage to all structures due to blood flow impairment.

Answer 60

True

Question 61

Anterior and posterior compartments of the forearm are surrounded by an investing fascia. If you have injury to this tissue, edema can result and lead to pressure build up. This can compress the artery and vein and restrict blood flow and venous return, leading to ischemia. What is the treatment for compartment syndrome?

Answer 61

make large slits in the investing fascia to relieve the pressure

Question 62

This is a large branch off of the brachial artery that mimics the course of the radial nerves by wrapping around the spiral groove of the humerus

Answer 62

profunda brachii

Question 63

After passing anterior to the elbow joint, the brachial artery divides into what two branches? These two arteries continue all the way down to the anterior forearm.

Answer 63

radial and ulnar arteries

Question 64

This is a branch off of the ulnar artery, which divides into an anterior and posterior branch and runs inside the interosseus membrane

Answer 64

interosseus artery

Question 65

T/F: There are significant anastomoses around the elbow joint providing great collateral flow.

Answer 65

True

Question 66

Down beyond the wrist, there are many anastomotic connections between the radial and ulnar arteries. What can the radial artery be used for? What test is important to do before removing the radial artery?

Answer 66

radial artery can be used for bypass surgery, and you need to know if there is good collateral flow because it varies. If you have a dominant radial artery supplying the hand, you will not want to take this and leave hand with poor blood flow. Allen test can be performed to tell (looks at capillary bed reperfusion)

Question 67

Two palmar arches of the arteries of the hand? There is collateral flow between the arches, but which provides most blood to the digits? What are exceptions to this?

Answer 67

superficial and deep palmar arches; superficial arch provides most blood to digits, except the index finger and thumb

Question 68

What does the musculocutaneous nerves supply?

Answer 68

anterior arm muscles (motor branches) | forearm (lateral cutaneous nerve)

Question 69

The median nerve supplies muscular branches to all forearm anterior compartment muscles except for which two?

Answer 69

flexor carpi ulnaris | medial two heads of flexor digitorum profundus (middle and ring finger)

Question 70

What does the ulnar nerve supply?

Answer 70

muscular branches to forearm (1.5 muscles: flexor carpi ulnaris medial two heads of FDP) and hand, cutaneous branches to hand

Question 71

Cutaneous innervation of median nerve?

Answer 71

3.5 digits

Question 72

What does the radial nerve supply?

Answer 72

posterior arm muscles | posterior cutaneous nerve of forearm

Question 73

What does the radial nerve supply in the arm and forearm? In regards to cutaneous innervation?

Answer 73

innervates all muscles in posterior compartment; inntervates 3.5 digits on posterior surface of hand

Question 74

* Nice place to attach muscles * Maintains integrity of radius and ulna – allows them to rotate around each other * Referred to as middle radial ulnar joint * Has a particular orientation of fibers – designed to get tighter when you fall on your hand

Answer 74

interosseus membrane

Question 75

3 tendons of the wrist; which is most prominent and is absent in some people?

Answer 75

flexor carpi ulnaris flexor carpi radialis palmaris longus ** most prominent

Question 76

List 5 superficial forearm muscles that arise from the medial epicondyl and are attached by a common flexor tendon

Answer 76

1. pronator teres 2. flexor carpi radialis 3. palmaris longus 4. flexor digitorum superficialis 5. flexor carpi ulnaris

Question 77

From an anatomical position, is the radius lateral or medial?

Answer 77

lateral

Question 78

How many anterior compartment muscles are there? How many are superficial vs deep?

Answer 78

8; 5 superficial, 3 deep

Question 79

Where do the deep anterior compartment muscles arise from? What are they?

Answer 79

interosseus membrane or radius and ulna; flexor pollicis longus, flexor digitorum profundus, and pronator quadratus

Question 80

What is the order of tendon, artery, and nerve that is significant in regards to the biceps tendon?

Answer 80

biceps tendon: brachial artery: radial nerve (lateral to medial)

Question 81

This deep anterior compartment muscle courses into the thumb

Answer 81

flexor pollicis longus

Question 82

This deep anterior compartment muscle gives off four tendons, one to each finger

Answer 82

flexor digitorum profundus

Question 83

This deep anterior compartment muscle is a pronator

Answer 83

pronator quadratus

Question 84

List two pronators

Answer 84

pronator terres | pronator quadratus

Question 85

What are the 3 wrist flexors?

Answer 85

palmaris longus flexor carpi ulnaris flexor carpi radialis

Question 86

What are 3 finger flexors? Which is most deep?

Answer 86

flexor digitorum superficialis flexor pollicis longus flexor digitorum profundus** deep

Question 87

T/F: Long tendons to the fingers split to attach to the base of the proximal phalanx and then the base of the distal phalanx. These tendons have to be held down to prevent bow-stringing.

Answer 87

True

Question 88

What does the interosseus artery arise from?

Answer 88

the ulnar artery