Chapter 8 - The Hand

Question 1

make-up of the hand

Answer 1

19 bones
29 muscles
- takes up a large part of the motor/sensory cortex of brain

Question 2

palmar creases

Answer 2

• distal and middle digital creases
• proximal digital crease
• proximal and distal palmar creases

Question 3

concavity of the palm

Answer 3

supported by three integrated arch systems:

1) longitudinal arch(follows 3rd phalanx)
2) distal transverse arch(knuckles or MCP joints)
3) proximal transverse arch(CMC joints)

Question 4

Which metacarpals are the most mobile?

Answer 4

1st, 4th, and 5th

Question 5

Thumb CMC

Answer 5

• classic saddle joint
• Trapezium/1st metacarpal
• trapezium = concave (palmar to dorsal)
• trapezium = convex (medial to lateral)
• 2 degrees of freedom(flex/ext & abd/add)
• opposition = combination of all

Question 6

ROM of thumb CMC

Answer 6

abduction = 50 degrees
Flexion = 45-50

Question 7

abduction of the thumb

Answer 7

convex-on-concave

• caused by abductor pollicis longus
• roll anterior/slide posterior

Question 8

flexion of thumb

Answer 8

concave-on-convex

• roll medially/slide medially
• stretches medial collateral ligament

Question 9

extension of the thumb

Answer 9

concave-on-convex

• roll laterally/slide laterally
• stretches the anterior oblique ligament

Question 10

opposition

Answer 10

2 phases:

1) abduction
2) flexion with medial rotation
- posterior oblique ligament is taut
- muscle = opponens pollicis

Question 11

CMC joints of fingers

Answer 11

2nd and 3rd are more rigid for stability

• 4th and 5th are mobile
• intermetacarpal joints at bases of 2nd through 5th

Question 12

ROM CMC joints

Answer 12

• 2nd and 3rd relatively stable
• 4th flexes = 10 degrees(hamate bone)
• 5th flexes = 20-25 degrees(hamate bone)

Question 13

MCP of fingers

Answer 13

2 degrees of motion = flex/ext & abd/add

• rotation as an accessory motion
• convex head of MC’s to concave proximal phalanges
• close packed position = 70 degrees of flexion
  
  • collateral ligaments are tightest and most stable

Question 14

limiting extension of MCP

Answer 14

prevented by palmar plates

- MCP can be hyper extended(unlike IP joints)

Question 15

ROM of MCP

Answer 15

increases from 2nd digit to 5th digit

• flexion = 90 - 115
• passive hypertension = 30-45

Question 16

abduction and adduction of fingers during flexion

Answer 16

limited because radial and ulnar collateral ligaments are stretched
- dorsal capsule is also stretched

Question 17

abduction of fingers

Answer 17

concave on convex

• roll and slide in same direction
• muscles = dorsal interossei
• ulnar collateral ligament
• axis through head of MC

Question 18

flexion of MCP joint

Answer 18

head of the MC is cam-shaped

• flexion increases the distance between attachment points of the collateral ligaments
• in contrast to PIP where distance remains constant

Question 19

thumb MCP

Answer 19

1 degree of freedom(flex/ext)

• flexion = 60 degrees
• concave-on-convex(roll and slide same direction)
• limited hyperextension
• muscle = flexor pollicis brevis, some flexor pollicis longus
• dorsal capsule being stretched during flexion

Question 20

finger IP joints

Answer 20

1 degree of freedom(flexion/extension)

• tongue in groove articulation
• closed packed near full extension
• PIP flex = 100-129
• DIP flex = 70-90
• palmar plate limits extension
• collateral ligament stretched during flexion

Question 21

Thumb IP joint

Answer 21

1 degree of freedom(flex/ext)

• similar to fingers
• flex = 70 degrees
• passive hyperextension to 20 degrees

Question 22

“position of function”

Answer 22

wrist = 20-30 degrees of extension with slight ulnar deviation
fingers = 35-45 degrees of MCP flex
- 15-30 degrees of PIP and DIP flexion
thumb = 35-45 degrees of CMC joint abduction

Question 23

intrinsic hand muscles

Answer 23

interossei, lumbricals, adductor pollicis, opponens pollicis

Question 24

extrinsic hand muscles

Answer 24

muscles that cross wrist joint

Question 25

flexor digitorum superficialis

Answer 25

medial epicondyle to middle phalanx | - median nerve

Question 26

flexor digitorum profundus

Answer 26

to distal phalanx | - median and ulnar nerve

Question 27

lumbricals

Answer 27

attach on the tendon of flexor digitorum profundus - flexion of MCP and extension of IP's - insert on the dorsal hood - 1&2 = median nerve - 3&4 = ulnar nerve

Question 28

through the carpal tunnel

Answer 28

``` through the tunnel: - flexor digitorum superficialis and profundus - flexor pollicis longus - flexor carpi radialis - median nerve - ulnar(flexor digitorums) and radial(flexor pollicis longus) synovial sheath outside of tunnel: - ulnar nerve ```

Question 29

make up of carpal tunnel

Answer 29

``` top = transverse carpal ligament bottom = pisiform, triquetrum, lunate, scaphoid ```

Question 30

during PIP flexion

Answer 30

flexor digitorum superficialis flexes | - extensor digitorum and extensor carpi radialis brevis isometrically contract to prevent wrist flexion and MCP flexion

Question 31

tendodesis action

Answer 31

as the wrist is extended, thumb and fingers automatically flex because of stretch placed on the extrinsic digital flexors(passively)

Question 32

finger abduction

Answer 32

dorsal interossei and abductor digiti minimi

Question 33

finger adduction

Answer 33

palmar interossei | - also thumb flexion

Question 34

intrinsic-plus position

Answer 34

MCP's flexed DIP's and PIP's extended - lumbricals and interossei

Question 35

extrinsic-plus position

Answer 35

MCP's extended | DIP's and PIP's flexed

Question 36

"claw" position

Answer 36

ulnar nerve lesion(3&4 lumbricals paralyzed) - 4&5 MCP's hyperextended - DIP's and PIP's partially flexed - manually holding MCP's in flexion, extensor digitorum extends DIP and PIP joints

Question 37

active finger extension progression

Answer 37

1) intrinsic muscles activate(lumbricals and interossei) 2) PIP joints extend 3) oblique retinacular ligament is stretched 4) DIP joint extends

Question 38

Finger flexion progression

Answer 38

Early Phase: - flexor digitorum profundus and superficialis, and interosseus muscles flex joints of finger Late Phase: - flexing continues, extensor carpi radialis brevis extends wrist slightly, extensor digitorum decelerates flexion of MCP joint

Question 39

finger extension progression

Answer 39

Early phase: - extensor digitorum extends MCP joint Middle phase: - intrinsic muscles(lumbricals and interossei) assist in extension of PIP and DIP - also they produce flexion at MCP to prevent hyperextension Late phase: - muscle activation continues - flexor carpi radialis slightly flexes wrist

Question 40

zigzag deformity of the thumb

Answer 40

radially directed dislocation of CMC joint - hyperextension of MCP joint(from extensor pollicis longus) - IP joints remain partially flexed(flexor pollicis longus) - caused by rheumatoid arthritis

Question 41

palmar dislocation of the MCP joint

Answer 41

palmar directed bowstring force of flexor tendons(FDP & FDS) against the palmar plate - rupture of the weakened collateral ligaments - caused by rheumatoid arthritis

Question 42

ulnar drift MCP joint

Answer 42

ruptured radial collateral ligament | - extensor digitorum pulls in ulnar direction at MCP joint

Question 43

Swan-neck deformity

Answer 43

1) hyperextension of PIP - palmar plate damaged(over stretch) 2) flexion of DIP - flexor digitorum profundus

Question 44

Boutonniere deformity

Answer 44

1) flexion of PIP - ruptured central band - slipped lateral band 2) hyperextension of DIP