Arm, Forearm and Hand (Week 3--Miller)

Question 1

2 compartments of the arm

Answer 1

Anterior compartment

Posterior compartment

Divided by brachial fascia (a deep fascia) and intermuscluar fascial septum

Question 2

Anterior compartment

Answer 2

Flexor compartment

Muscles are BBC: biceps brachii, brachialis, coracobrachialis

Nerve: musculocutaneous nerve

Artery: brachial artery

Question 3

Posterior compartment

Answer 3

Extensor compartment

Muscle is only triceps

Nerve: radial nerve

Artery: deep **brachial artery **

Question 4

Anterior arm cutaneous veins

Answer 4

Cephalic vein

Basilic vein

Median cubital vein

Question 5

What is so special about the basilic vein?

Answer 5

Used for central venous catheterization because is in direct line with axillary vein

And, from cubital fossa until vein reaches axillary vein, it increases in diameter

Question 6

2 layers of anterior compartment arm muscles

Answer 6

1) Superficial layer: biceps brachii
2) Deep layer: brachialis and coracobrachialis

Question 7

Course of the musculocutaneous nerve

Answer 7

Musculocutaneous nerve pierces the coracobrachialis and lies between superficial and deep layer muscles

Question 8

Medial neurovascular bundle

Answer 8

Runs down medial aspect of arm

Contains brachial artery, brachial veins, basilic vein, median nerve, ulnar nerve, medial antebrachial cutaneous nerve

Deep brachial artery originates from brachial artery in anterior compartment then travels to posterior compartment

Median and ulnar nerves pass through anterior compartment of arm without innervating anything until they reach anterior compartment of the forearm!

Question 9

3 heads of the triceps

Answer 9

Lateral head: attaches to posterior superior humerus (does not cross shoulder joint and therefore cannot act on it)

Long head: crosses shoulder joint (so can act on it) posteriorly and attaches to infraglenoid tubercle (below glenoid fossa!) of scapula

Medial head

Question 10

Course of the radial nerve

Answer 10

Originates off posterior cord of brachial plexus, travels into posterior compartment of arm and courses inferiorly along with deep brachial artery in radial groove of humerus (deep to triceps)

Question 11

Cubital fossa

Answer 11

In front of elbow (bounded by imaginary line between 2 epicondyles of the humerus (pronator teres and brachioradialis))

Superficial layers: lateral antebrachial cutaneous nerve, biceps tendon, brachial artery, median nerve

Deep layers: (between brachialis and brachioradialis) radial nerve and 2 terminal branches, superficial and deep radial nerve

Posteriorly, ulnar nerve can be palpated between olecranon process and medial epicondyle of humerus (this is what you hit when you hit your funny bone!)

Question 12

Superficial layer structures of cubital fossa

Answer 12

Lateral antebrachial cutaneous nerve: continuation of musculocutaneous nerve after it passes biceps tendon; sensory nerve to lateral forearm

Biceps tendon

Brachial artery

Median nerve

Question 13

Deep layer structures of cubital fossa

Answer 13

Radial nerve: deep, in between brachialis and brachioradialis; divides into two branches (deep and superficial radial nerve)

Deep radial nerve pierces supinator muscle and goes into posterior compartment of forearm

Superficial radial nerve travels deep to brachioradialis then becomes cutaneous on posterior side of hand

Question 14

Ulnar nerve

Answer 14

Travels from anterior compartment of arm posterior to medial epicondyle of humerus then comes back into anterior compartment of forearm

Located between medial epicondyle of humerus and olecranon process of ulna

Question 15

2 compartments of the forearm

Answer 15

Anterior compartment

Posterior compartment

Antebrachial fascia, interosseous membrane, intermuscular septa divide the compartments

Question 16

Anterior compartment of forearm

Answer 16

Flexor compartment

Wrist and digits

Nerves: median and ulnar nerves

Arteries: radial, ulnar, anterior interosseus artery

Question 17

Posterior compartment of forearm

Answer 17

Extensor compartment

Wrist and digits

Nerves: radial nerve (branches into posterior interosseus nerve)

Arteries: posterior interosseous artery

Question 18

3 muscle layers in the anterior compartment of forearm

Answer 18

Superficial layer: (wrist flexor-pronator group; all attach to medial epicondyle of humerus via common flexor tendon) pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris

Intermediate layer: flexor digitorum superficialis

Deep layer: flexor digitorum profundus, flexor pollicis longus, pronator quadratus

Question 19

Ulnar artery

Answer 19

Gives rise to common interosseus artery which terminates by forming the anterior interosseus artery and posterior interosseus artery

Question 20

Anterior compartment of forearm cutaneous veins

Answer 20

1) Classic pattern: median cubital vein connects the basilic vein and the cephalic vein
2) Cephalic vein –> median cephalic vein –> median antebrachial vein, and at the same time on other side, Basilic vein –> median basilic vein –> median antebrachial vein (converge at one median antebrachial vein)

Question 21

Golfer’s Elbow

Answer 21

Painful MSK condition that may follow repetitive use of wrist flexor-pronator group

Pain on medial side of elbow

Repeated forceful movements strain common flexor tendon of these muscles and produce inflammation of medial epicondyle

Question 22

Artery and nerve relationships of anterior compartment of forearm

Answer 22

Superficial radial nerve and radial artery travel together deep to the brachioradialis muscle

Brachial artery enters proximal anterior forearm and then terminates as ulnar and radial arteries

Ulnar artery gives rise to common interosseous artery which is a short artery that terminates as anterior interosseus artery and posterior interosseus artery (posterior compartment)

Ulnar artery travels with ulnar nerve between flexor digitorum superficialis and flexor digitorum profundis

Anterior interosseous artery travels with the anterior interosseus branch of the median nerve between the flexor digitorum superficialis and flexor digitorum profundis

Question 23

Innervation of anterior compartment of forearm

Answer 23

Median nerve innervates all muscles of anterior compartment except for 1 1/2 muscles!

Median nerve branches to give off anterior interosseous nerve

Ulnar nerve innervates flexor carpi ulnaris and 1/2 flexor digitorum profundus (ulnar half)

Question 24

2 muscle layers in the posterior compartment of forearm

Answer 24

Superficial lateral: brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis

Superficial posterior: anconeus, extensor carpi ulnaris, extensor digitorum, extensory digiti minimi

Deep: extensor pollicis longus, extensor pollicis brevis, abductor pollicis longus, extensor indicis, supinator

Question 25

Posterior compartment of forearm cutaneous veins

Answer 25

Cephalic vein ascends lateral side of arm

Basilic vein ascends medial side of arm

Cephalic and basilic veins originate from dorsal venous arch on dorsum of hand

Question 26

Tennis Elbow

Answer 26

Inflamation of lateral epicondyle of the humerus through repeated use

Many superficial layer muscles have attachment to lateral epicondyle of humerus via common extensor tendon

Question 27

Nerves and arteries of posterior compartment of forearm

Answer 27

Neurovascular plane between superficial layer and deep layer muscles contains posterior interosseus nerve and posterior interosseus artery

Posterior interosseus nerve is continuation of deep radial nerve (changes names once it enters posterior compartment)

Question 28

Anatomical “snuff box”

Answer 28

Triangular space between extensor pollicis brevis (along with abductor pollicis longus, APL), extensor pollicis longus and extensor retinaculum

Radial artery crosses floor (so pulse can be taken here)

Scaphoid bone lies in floor of snuff box and may be palpated in assessing scaphoid fracture

Question 29

Course of radial artery

Answer 29

Radial artery crosses floor of anatomical “snuff box” then through two heads of 1st dorsal interosseus muscle and gives off princeps pollicis and radial index arteries

Question 30

Extensor retinaculum

Answer 30

Band of deep fascia that helps keep extensor tendons in place when extensor muscles contract

Question 31

Synovial tendon sheaths

Answer 31

Protect extensor tendons by reducing friction when tendons slide under retinaculum

(are between extensor tendons and extensor retinaculum)

Question 32

Extensor expansions

Answer 32

Extensor tendons become flattened to form extensor expansions distally

Question 33

Dorsal interossei muscles vs. palmar interossei muscles

Answer 33

Dorsal: seen deep to extensor tendons; only interossei muscles that can be seen on dorsum of hand; “DAB” = dorsal abducts fingers (4)

Palmar: “PAD” = palmar adducts fingers (3)

Question 34

Movements of joints of the hands

Answer 34

Interphalangeal (IP) joints: flexion and extension

Metacarpophalangeal (MCP) joints: flexion, extension, abduction, adduction, circumduction

Carpometacarpal joints: gliding

Intercarpal (IC) joints: gliding and sliding

Carpometacarpal joint of thumb: flexion, extension, abduction, adduction, opposition

Note: movement away from 3rd digit is abduction, movement toward 3rd digit is adduction

Question 35

Carpal bones proximal row from lateral to medial (palmar view)

Answer 35

Scaphoid

Lunate

Triquetrum (w/ Pisiform)

“So Long To Pinky…”

Question 36

Carpal bones distal row from lateral to medial (palmar view)

Answer 36

Hamate

Capitate

Trapezoid

Trapezium

“…Here Comes The Thumb”

Question 37

Wrist joint (radiocarpal joint)

Answer 37

Articulation between distal radius, articular disc, proximal row of carpal bones

Synovial joint that permits adduction, abduction, flexion, extension, circumduction

Question 38

Distal radioulnar joint

Answer 38

Articulation between distal radius and ulna

NOT part of the wrist joint, but is synovial joint that acts with proximal radioulnar articulation of the elbow joint to permit abduction and supination

Question 39

Structures crossing wrist anteriorly

Answer 39

From lateral to medial:

Radial artery

Flexor carpi radialis

Median nerve

Flexor digitorum superficialis (palmaris longus)

Ulnar artery

Ulnar nerve

Flexor carpi ulnaris

Question 40

Carpal tunnel

Answer 40

Space between flexor retinaculum and carpal bones

Roof is flexor retinaculum; floor is carpal bones

Contains 10 structures:

4 FDS tendons (flexor digitorum superficialis)

4 FDP tendons (flexor digitorum profundis)

FPL tendon (flexor pollicis longus)

Median nerve

Question 41

Tunnel of Guyon

Answer 41

Fascial tunnel that carries ulnar nerve and artery

(aka ulnar nerve tunnel)

Question 42

Carpal Tunnel Syndrome

Answer 42

Inflammation within carpal tunnel compresses median nerve

Sensory effects: pain and sensory deficits (paresthesia, hypothesia, anesthesia) along distribution of its cutaneous branches which innervate 3 1/2 lateral digits of the hand

Motor effects: motor deficits to thenar compartment muscles and lateral 2 lumbrical muscles which it innervates; muscle weakness, loss of coordination, inability to oppose thumb; motor effects come AFTER sensory effects bc sensory fibers fatter

Carpal Tunnel Release: surgical division of flexor retinaculum (partially or completely) to relieve symptoms of carpal tunnel syndrome

Question 43

4 compartments of the hand

Answer 43

1) Thenar compartment
2) Hypothenar compartment
3) Central (or midpalmar) compartment
4) Deep (adductor/interossei) compartment

Question 44

Thenar compartment

Answer 44

3 muscles relating to the thumb:

Abductor pollicis brevis (outside)

Flexor pollicis brevis (inside)

Opponens pollicis (deep)

Question 45

Hypothenar compartment

Answer 45

3 muscles relating to the 5th digit (pinky)

Abductor digiti minimi (outside)

Flexor digiti minimi (inside)

Opponens digiti minimi (deep and a bit lateral)

Question 46

Central compartment

Answer 46

Flexor tendons (of FDS and FDP)

4 lumbricals attach to tendons of flexor digitorum profundis: lateral 2 lumbricals (1 and 2) innervated by median nerve; medial 2 lumbricals (3 and 4) innervated by ulnar nerve

Lumbricals flex at MCP joints and extend at IP joints

Extensor expansions: aponeurosis-like extensor tendons which form a “hood” that crosses IP joints posteriorly

Question 47

Deep compartment

Answer 47

Adductor pollicis

Interossei muscles (palmar and dorsal):

4 Dorsal interossei abduct (“DAB”)

3 Palmar interossei adduct (“PAD”)

Question 48

Palmar aponeurosis

Answer 48

Attaches to palmaris longus tendon

Which comes from flexor digitorum superficialis?

Question 49

Motor innervation of the hand

Answer 49

Most muscles innervated by ulnar nerve, except for 1 1/2 compartments!

Thenar compartment and lateral 2 lumbricals innervated by median nerve

Question 50

Overview of blood supply to upper limb

Answer 50

Brachial artery gives rise to radial and ulnar artery in forearm

These pass into the hand to form superficial (mostly from ulnar artery) and deep palmar (mostly from radial artery) arches

The arches give rise to common palmar digital arteries (related to metacarpals) which then give rise to proper palmar arteries (related to digits)

Question 51

Cutaneous nerve pattern

Answer 51

Supraclavicular nerves

Axillary nerve

Radial nerve

Musculocutaneous nerve

Superficial radial nerve

Median nerve

Ulnar nerve

Medial antebrachial cutaneous nerve

Intercostobrachial nerve and Medial brachial cutaneous nerve

Question 52

Dermatomal pattern of upper limb

Answer 52

From side of head/neck all the way down to fingers

C2-T1

Question 53

Why is the cutaneous nerve innervation pattern different from the dermatomal pattern of innervation?

Answer 53

A dermatome is a strip of skin innervated by fibers from a single spinal cord level but a cutaneous nerve contains fibers from several spinal cord levels!