UL2 - Osteology, joints & ligaments of the forearm, wrist and hands

Question 1

articulations that form the proximal radioulnar joint?

Answer 1

radial notch of ulna articulates with radial head proximally

Question 2

articulation that forms the distal radioulnar joint?

Answer 2

ulnar notch of radius articulates with ulnar head distally

Question 3

what type of joint is the radioulnar joint (proximal and distal)? what movement does this joint allow for?

Answer 3

synovial pivot joint

allows for rotation around a single axis - ulna remains stationary as radius rotates on top of it

Question 4

describe position of the anterior borders of the radius and ulna?

Answer 4

radial anterior border - on the lateral ridge
ulnar anterior border - on the medial ridge

Question 5

what are the styloid processes of the radius & ulna?

Answer 5

styloid process of radius - where the radial collateral ligament attaches

styloid process of ulna - where the ulnar collateral ligament attaches

Question 6

interosseus membrane - what is it? position?

Answer 6

dense connective tissue that connects the radius and ulna, and separates the forearm into its anterior & posterior compartments

placed between the interosseus borders of the ulna and radius

Question 7

interosseus membrane - functions (3)?

Answer 7

provides stability to radius and ulna, prevents separation

site of muscle attachment

transfers forces from radius to ulna

Question 8

list the proximal carpal bones (lateral to medial)

Answer 8

scaphoid
lunate
triquetral
pisiform

Question 9

list the distal carpal bones (lateral to medial)

Answer 9

hamate
capitate
trapezoid
trapezium

Question 10

which one of the proximal carpal bones is a sesamoid bone? what does this mean?

Answer 10

pisiform

a bone that develops within tendons - pisiform bone is embedded in the flexor carpi ulnaris tendon

Question 11

articulation of bones that forms the radiocarpal/ wrist joint?

Answer 11

(concave) distal end of the radius with the scaphoid & lunate bones directly & indirectly with the triquetral bone via an articular disc

Question 12

what type of joint is the wrist joint?

Answer 12

synovial condyloid joint

Question 13

articulation of bones that forms the midcarpal joint?

Answer 13

proximal row of carpal bones articulate with distal row of carpal bones

Question 14

what type of joint is the midcarpal joint?

Answer 14

synovial plane joint

Question 15

articulation of bones that form the intercarpal joints?

Answer 15

articulations between individual carpal bones - e.g. scaphoid and lunate, lunate and triquetral

Question 16

what type of joint is the intercarpal joint?

Answer 16

synovial plane joint

Question 17

difference between the potential movements of intercarpal vs midcarpal joints?

Answer 17

both are synovial plane joints - midcarpal joint allows for more significant gliding movements

Question 18

what is the most common carpal injury?

Answer 18

scaphoid fracture - occurs at the waist of the scaphoid bone

Question 19

what is the most common cause of a scaphoid fracture, and why is the scaphoid bone particularly vulnerable?

Answer 19

often caused by falling on an outstretched hand

as the distal end of the radius articulates with the scaphoid bone, the radius transfers all the weight to the scaphoid bone - causes a fracture

Question 20

why is there a risk of avascular necrosis in scaphoid fractures?

Answer 20

in 10% of cases, the scaphoid receives blood supply from distal to proximal part of the wrist

a fracture can disrupt blood flow to the proximal portion - leads to avascular necrosis

Question 21

why might a scaphoid fracture be missed? what can happen if it goes untreated?

Answer 21

scaphoid fractures (and avascular necrosis) are often missed on x-rays as they require an MRI for diagnosis

if untreated, it can lead to future complications such as advanced osteoarthritis and impaired wrist mobility

Question 22

how many bones of the hand? - describe

Answer 22

5 metacarpals
12 phalanges - thumb has 2 (proximal and distal), other 4 fingers have 3 (proximal, middle, distal)

19 bones

Question 23

articulation of bones that form the carpometacarpal joint?

Answer 23

between carpal and metacarpal bones

Question 24

what type of joints are the carpometacarpal joints? which one is different & what movement does it allow for?

Answer 24

most CMC joints are synovial plane-type joints

only the thumb (the first CMC joint) is a synovial saddle joint - allows for flexion, extension, adduction, abduction, circumduction

Question 25

articulation of bones that form the metacarpophalangeal joints?

Answer 25

between distal ends of metacarpals & proximal phalanges

Question 26

what type of joint is the metacarpophalangeal joint? what movement does it allow for?

Answer 26

synovial condyloid joint

allows for flexion, extension, adduction, abduction, circumduction

Question 27

list the four ligaments associated with the radiocarpal joint - what do they each do?

Answer 27

ulnar collateral - prevents excessive radial deviation of the hand

radial collateral - prevents excessive ulnar deviation

palmar and dorsal radiocarpal ligaments - prevents excessive flexion & extension, stabilises wrist joint

Question 28

ulnar collateral ligament - location? function?

Answer 28

location - from the ulnar styloid process to the triquetral & pisiform bones

function - prevents excessive radial deviation of the hand

Question 29

what ligament runs from the radial styloid process to the scaphoid & lunate bones? what is its function?

Answer 29

radial collateral ligament

prevents excessive ulnar deviation of the hand

Question 30

list the three types of ligaments of the hand

Answer 30

palmar ligaments (or palmar/ volar plates)
deep transverse metacarpal ligaments
collateral ligaments

Question 31

palmar ligaments - location? structure? function?

Answer 31

location - at the anterior aspect of MCP, DIP & PIP joints

structure - thickening of the joint capsules that extends from the head of one bone to the base of the adjacent bone

function - stabilises joints, prevents hyperextension

Question 32

deep transverse metacarpal ligaments - location? function?

Answer 32

location - extends between the heads of the 2nd to 5th metacarpals at the base of the knuckles

function - resists separation of metacarpal bones from each other & gives hand stability

Question 33

collateral ligaments - location? function?

Answer 33

location - medial & lateral thickenings of joint capsules at MCP, DIP & PIP joints

function - provide lateral stability to joints
- makes separating fingers harder during flexion, easier during extension as the ligament is relatively relaxed

Question 34

what movements is the wrist capable of?

Answer 34

flexion/ extension
ulnar deviation (adduction)/ radial deviation (abduction)
circumduction

Question 35

what movements are the medial 4 digits capable of?

Answer 35

flexion/ extension
adduction/ abduction - relative to the 3rd metacarpal as a midline

Question 36

what movements is the thumb capable of?

Answer 36

flexion (thumb across palm)/ extension
adduction/ abduction
opposition (tip of thumb & tip of finger)

movements occur across a sagittal plane as thumb is at a right angle

Question 37

medial & lateral borders of the anatomical snuff box?

Answer 37

medial - extensor pollicis longus
lateral - extensor pollicis brevis & abductor pollicis brevis

Question 38

what bones form the floor of the anatomical snuff box?

Answer 38

scaphoid & triquetrium

Question 39

contents of the anatomical snuff box?

Answer 39

radial artery
superficial branch of the radial nerve