Postterior Forearm And Hand

Question 1

Extensor retinaculum

Answer 1

Thickening of investing fascia of forearm to hold extensor tendons in place across back of wrist

Question 2

T/F Fibrous digital sheaths, osseofibrous tunnels, and synovial tendon sheaths are present on the Dorsum of the digits

Answer 2

F, they are absent on the dorsum

Question 3

Posterior muscle group of forearm

Answer 3

. Radiodorsal, extensor, or extensor/supination group
. All innervated by radial nerve
. Divided into superficial and deep layers

Question 4

Superficial layer of posterior forearm muscle group location

Answer 4

. Most superficial layer of extensor muscles of forearm and hand
. Originate from lat. epicondyle (common extensor origin) and lat. supracondylar ridge

Question 5

Deep posterior forearm muscle group location

Answer 5

. Deep layer of extensor muscles of forearm and hand

. Originate from post. Aspect of radius, ulna, and interosseous membrane in between

Question 6

Superficial layers of posterior muscle group from lateral to medial

Answer 6

. Brachioradialis
. Extensor carpi radialis longus
. Extensor carpi radialis brevis
. Extensor digitorum 
. Extensor digiti minimi (quinti)
. Extensor carpi ulnrius 
. Anconeus

Question 7

Brachialis OIA

Answer 7

O: Lateral supracondylar ridge of humerus
I: Distal end of the radius near the styloid process
A: Flexes the forearm, partially supinates from a fully pronated position.

Question 8

Extensor carpi radialis longus OIA

Answer 8

O: Lateral supracondylar ridge
I: Base of second metacarpal
A: Extends and abducts the hand. Weakly flexes the forearm.

Question 9

extensor carpi radialis brevis OIA

Answer 9

O: Lateral epicondyle of the humerus (common extensor origin)
I: Base of third metacarpal
A: Extends and weakly abducts the hand. Like all muscles attaching to the lat. epicondyle, it assists in extending the forearm

Question 10

Extensor digitorum OIA

Answer 10

O: Lateral epicondyle
I: Tendons go to digits II, III, IV, and often V. Each tendon inserts on the base of prox. phalanx, and splits into central band to the base of middle phalanx and two side-bands (collateral bands) to the base of the distal phalanx.
A: Extends the MCP joint, and PIP and DIP joints, assists in extending hand and forearm

Question 11

Extensor tendon assembly

Answer 11

. Tendons of interosseous and lumbrical muscles unite w/ central band and side bands
. Aponeurotic sheet unites these tendons over prox. Phalanx and MCP joint
. Sagittarius band passes on each side of MCP joint and attaches to palmer side of capsule

Question 12

Sagittal band function

Answer 12

. Hold extensor digitorum (ED) tendon in place preventing bowstringing during full extension and hyperextension of MCP joint

Question 13

Extensor expansion

Answer 13

. Triangular in nature and called “the wing”

Question 14

What occurs when MCP joint extends beyond 180 degrees?

Answer 14

. ED can’t overcome passive resistance of long digital flexors (FDS and FDP) so PIP and DIP go into flexion

Question 15

How to extend IP joints when MCP is extended over 180 degrees?

Answer 15

. Requires lumbricals and interossei

Question 16

MCP

Answer 16

Metacarpophalangeal joint

Question 17

DIP

Answer 17

Distal interphalangeal joint

Question 18

PIP

Answer 18

Proximal interphalangeal joints

Question 19

Extensor digiti minimi OIA

Answer 19

O: Lateral epicondyle
I: Joins ED tendon of little finger
A: Same actions as ED but only for digit V

Question 20

Extensor carpi ulnaris

Answer 20

O: Lateral epicondyle and posterior
border of the ulna
I: Base of fifth metacarpal
A: Extends and adducts wrist.
Assists in extending the forearm

Question 21

Anconeus OIA

Answer 21

O: Posterior side of the lateral epicondyle
I: Lateral side of the proximal part of the ulna, including the olecranon process
A: Assists triceps in extending the forearm. Stabilizes the elbow joint. Abducts
the ulna during pronation.

Question 22

Deep layer of posterior muscle group of forearm

Answer 22

. Supinator
. Abductor pollicis longus 
. Extensor pollicis brevis 
. Extensor pollicis longus 
. Extensor indicis
. Anatomical snuff box

Question 23

supinator OIA

Answer 23

O: Lateral epicondyle, radial collateral ligament of the elbow, and lateral side of
the proximal part of the ulna
I: Spirals around the proximal part of the radius to insert on its posterior, lateral,
and anterior sides
A.Supinates forearm by swiveling radius; less powerful supination than biceps
brachii unless forearm is extended.

Question 24

Outcropping muscles

Answer 24

. All originate on post. Side of interosseous membrane and adjacent parts of the radius and/or ulna
. Tendons emerge (outcrop) btw tendons of superficial muscles
. Abductor pollicis longus
. Extensor pollicis brevis
. Extensor pollicis longus
. Extensor indicis

Question 25

Abductor pollicis longus IA

Answer 25

I: Base of the first metacarpal, laterally A: Abducts and extends the first carpometacarpal (CM) joint and abducts the hand

Question 26

Extensor pollicis brevis IA

Answer 26

I: Base of the first metacarpal, laterally A: Abducts and extends the first carpometacarpal (CM) joint and abducts the hand

Question 27

Extensor pollicis longus

Answer 27

I: Base of the distal phalanx of the thumb A: Extends all joints of the thumb (CM, MCP, and IP). Also extends the hand.

Question 28

Tendon location of extensor pollicis longus

Answer 28

. Bends around dorsal tubercle of radius

Question 29

Extensor indicis IA

Answer 29

I: Joins ED tendon to index finger. A: Same actions as ED but only on digit II

Question 30

Anatomical snuff box

Answer 30

. Depression btw tendons of extensor pollicis brevis and longus . Fractured scaphoid is tender here . Radial artery passes through but pulse difficult to detect bc of tough overlying fascia

Question 31

T/F When other MCP joint are kept from extending, you can still easily extend the index and pinkie finger, but not digits III or IV

Answer 31

T

Question 32

Intertendinous connections btw ED tendons

Answer 32

. On back of hand, restrain adjacent tendons | . Exist on both sides of digits III, IV, but on 1 side of digits II and V

Question 33

T/F Index and little fingers have their own private extensor muscles

Answer 33

T, EI and EDM

Question 34

Besides ED intertendinous connections, what other connections are there to restrain separate extension of digits

Answer 34

Intertendinous connections btw tendons of flexor digitorum profundus to digits III, IV, and V . Connections proximal to wrist

Question 35

Deep transverse metacarpal ligaments

Answer 35

. Restrain adjacent digits | . On both sides of digits III and IV but only one side of II and V

Question 36

Radial Nerve

Answer 36

. Gives off post. Cutaneous nerve of forearm . Passes ant. To lat. epicondyle of humerus hidden by brachioradialis . Innervates anconeus, brachioradialis, and extensor radialis longus . THen splits into 2 terminal branches

Question 37

Terminal branches of radial nerve and what they supply

Answer 37

. Superficial radial nerve: supply skin on dorsum of hand laterally . Deep radial nerve: penetrates supinator and supplies all other dorsal forearm muscles, called post. Interosseous n. Once emerges from supinator

Question 38

What happens if posterior muscle group of forearm is denervated?

Answer 38

. Reduced strength for any movements they take part in and graduallay atrophy . other muscles can perform these actions and will hypertrophy to compensate . Contracture deformity

Question 39

What occurs if cutaneous nerve supply around post. Muscle group is affected?

Answer 39

. Reduced skin sensation in area supplied . No total anesthesia bc of overlapping distributions . If major nerve is cut there could be total anesthesia

Question 40

What occurs when radial nerve is severed in distal brachium?

Answer 40

. Inability to extend hand and MP joints . Weakened supination, ad/abduction of wrist . Eventual flexion deformity wrist and MP joints and adduction deformity of wrist . Atrophy of post. Forearm . Reduced skin sensation down post. Side of forearm, some areas total anesthesia . No loss of extension

Question 41

Posterior interosseous artery

Answer 41

. Major source of blood to dorsal forearm muscles | . Courses w/ post. Interosseous n. Distal to supinator muscle on post. Aspect of forearm

Question 42

Blood pathway to forearm

Answer 42

. Ulnar artery -> common interosseous artery -> ant. And post. Interosseous a.

Question 43

Dorsal carpal arch

Answer 43

. Formed by branches of radial and ulnar aa. On dorsum of hand . Gives off branches to dorsum of hand and digits

Question 44

Radial artery

Answer 44

. Passes through anatomical snuffbox on hand and ends as deep palmer branch (to deep palmer arterial arch) and branch to dorsal side of index finger

Question 45

Lat. epicondylitis

Answer 45

. Tennis elbow . Repetitive use injury from excessive use of superficial extensor muscles of forearm . Causes inflammation of periosteum of lat. epicondyle at origin of sup. Extensor muscles . Pain conveyed by radial n. . Radiates inf. From lat. epicondyle down post. Aspect of forearm

Question 46

Mallet/baseball finger

Answer 46

. Avulsion of insertion of extensor tendon on distal phalanx . Caused by forceful flexion of DIP while finger is being extended . Person can extend all joints except for DIP which remains flexed

Question 47

Synovial cyst of wrist

Answer 47

Cysts of mutinous fluid (ganglion) . Nontender swellings that appeal on hand (usually dorsal aspect of wrist) . Synovial sheaths can communicate w/ synovial cysts