Joints And Ligaments of the Thumb

Question 1

CMC joint of the thumb

Answer 1

articulation of the trapezium and base of the 1st metacarpal

Question 2

the trapezium is ______ and the 1st metacarpal is ______ (CMC joint)

Answer 2

trapezium is concave in the sagittal plane and convex in the frontal plane

1st metacarpal has a congruent shape

Question 3

what kind of joint is the CMC joint

Answer 3

saddle joint

2 degrees of freedom

Question 4

what does the CMC joint allow

Answer 4

flexion/extension

ABD/ADD

Rotation

Question 5

flexion/extension in CMC joint

Answer 5

in the frontal plane around an oblique A/P axis

Question 6

flexion/extension CMC join ROM

Answer 6

flexion –> 0-15 degrees

extension –> 0-20 degrees

a lot of variability

Question 7

ABD/ADD in the CMC joint

Answer 7

sagittal plane around an oblique frontal axis

Question 8

ABD/ADD ROM CMC joint

Answer 8

0-70 degrees

Question 9

rotation CMC joint

Answer 9

a combination motion

termed opposition and reposition

important for hand function

normal ROM is top of thumb to tip of other fingers

Question 10

ligaments of CMC joint

Answer 10

radial, ulnar, volar and dorsal ligaments that reinforce the capsule

intermetacarpal ligament

Question 11

intermetacarpal ligament CMC joint

Answer 11

tethers the bases of the 1st and 2nd metacarpals which limits extreme motions of base of 1st metacarpal

Question 12

joint capsule CMC joint

Answer 12

relatively lax and reinforced by ligaments

Question 13

MCP joint of the thumb

Answer 13

articulation is between the concave base of proximal phalange articulating w/ the convex head of the first metacarpal

moves concave on convex (BM, roll and glide in the same direction)

Question 14

what type of joint is the MCP joint

Answer 14

condyloid joint with 2 degrees of freedom

Question 15

MCP joint allows for

Answer 15

flexion/extension

ABD/ADD

Rotation

Question 16

flexion/extension MCP joint

Answer 16

frontal plane around an AP axis

Normal ROM: 0-75 or 80 degrees

Question 17

ABD/ADD MCP joint

Answer 17

sagittal plane around frontal axis

we don’t need this joint to move alone b/c of CMC joint ABD/ADD

Normal ROM is next to nothing

Question 18

rotation at MCP joint

Answer 18

is passive movement allowed by the lax capsule

Question 19

ligaments of MCP joint

Answer 19

radial and ulnar collateral ligaments

accessory collateral ligament

Question 20

radial and ulnar collateral ligaments

Answer 20

run obliquely from dorsal aspect of metacarpal to ventral aspect of the base of proximal phalanx

are taut in flexion and lax in extension

Question 21

accessory collateral ligaments

Answer 21

run from dorsal aspect of metacarpal to palmar plate

are slack in flexion

Question 22

joint capsule MCP joint

Answer 22

moderately loose and lined by synovial membrane

Question 23

volar plate MCP joint

Answer 23

is fibrocartilage and firmly attached to the phalange

similar in form and function to volar plates of MCP’s of fingers

Question 24

sesamoid bone MCP joint

Answer 24

presence of 2 sesamoid bones provides reinforcement extra capsularly on the volar surface

appear at approximately 12 years of age

the inter-sesamoid ligaments secure the bones the joint

Question 25

CMC joint arthrokinematics flexion/extension

Answer 25

concave on convex

everything in the same direction w/in the frontal plane

Question 26

ABD/ADD arthrokinematics

Answer 26

convex on concave

BM, roll –> same direction

glide –> opposite direction

w/in the sagittal plane***