Overview of the elbow wrist and hand/stabilizers/pathology

Question 1

What three joints make up the elbow?

Answer 1

• Humeroulnar Joint
• Humeroradial Joint
• Proximal
  Radioulnar Joint (PRUJ)

All three make up a modified hinge joint

Question 2

What degree of valgus does the elbow joint have in the frontal plane and what degree of rotation does the elbow joint have in the sagittal plane?

Answer 2

6° of valgus in the frontal plane and 30° of anterior rotation in the sagittal plane

Question 3

What bony landmark on the humerus articulates with the head of the radius and what bony landmark on the humerus articulates with the trochlear notch of the ulna?

Answer 3

Capitulum of the humerus articulates with the head of the radius

Trochlea of the humerus articulates with the trochlear notch of the ulna

Question 4

What is the normal carrying angle of the elbow for males and females?

Answer 4

11 to 14° for males and 13 to 16° for females

Angle between the axis of the humerus and the axis of the forearm

Question 5

Humeroulnar joint characteristics

Answer 5

type: hinge joint formed between concave trochlear notch of the ulna and convex trochlea of the humerus

Open chain motion roll and glide in the same direction

motions: flexion and extension

Question 6

humeroradial joint characteristics

Answer 6

type: plane/gliding by morphology; hinge/pivot by function

articulation: capitulum of the humerus and head of the radius

Roll and glide in the same direction- concave radius on convex capitulum

Motion: flexion, extension, rotation of radius

Question 7

Characteristics of the elbow capsule

Answer 7

Thin but strong, does not respond well to injury or immobilization, forms of thick scar tissue resulting in flexion contractures

Question 8

Primary ligaments of the elbow joint

Answer 8

Ulnar collateral ligament
Radial collateral ligament blends with the annular ligament
Annular ligament forming proximal radioulnar joint
Interosseous membrane of the forearm

Question 9

What bone is moving during pronation and supination and what bone is fixed?

Answer 9

The radius is moving and the ulna is fixed

Question 10

Proximal radioulnar joint characteristics

Answer 10

type: pivot/trochoid

Articulation between the radial head and the concave radial notch on the ulna

PRONATION
-radial head rolls anteriorly and glides posteriorly

SUPINATION
-radial head rolls posteriorly and glides anteriorly

Question 11

DRUJ characteristics

Answer 11

type: pivot or trochoid

articulation: between head of the ulna and the ulnar notch on the radius, AND TFCC

radius moving on the ulna: concave on convex–> roll and glide in the SAME direction

Question 12

Pronation and Supination characteristics

Answer 12

PRONATION AND SUPINATION OCCURS SIMULTANEOUSLY AT BOTHE PRUJ and the DRUJ

also requires rotation of radius at humeroradial joint in annular ligament

Question 13

On what side of the wrist joint is the TFCC?

Answer 13

MEDIAL

under the distal ulna

Question 14

Radiocarpal/ulnocarpal joint characteristics

Answer 14

type: ellipsoidal or condyloid

articulation: radius, TFCC, proximal row of carpals (minus pisiform)

ligaments of the radiocarpal joint:
-dorsal radiocarpal
-volar radiocarpal

ligaments of the ulnocarpal joint:
-dorsal ulnocarpal
-volar ulnocarpal

MOTION radiocarpal:
-gliding of proximal carpal row (convex) on radius (concave) and TFCC–> opposite
-flexion/extension: proximal row rolls & glides in the opposite direction; flex: proximal row rolls anterior and glides posterior

-RD/UD:
–RD: scaphoid/lunate flex (rocks)
–UD: proximal row extend (twists)

Question 15

midcarpal joints

Answer 15

type: plane/ gliding joints

between the proximal and distal row of carpals

**functional rather than anatomic convex on concave (tongue and groove)

MOTION:
-ulnar compartment (capitate and hamate): always convex
-radial compartment (trapezium and trapezoid):
—concave in dorsal/volar
direction (FL/EX)
—convex in radial/ulnar direction (RD/UD)
-minimal motion happens here with ligaments intact

BIOMECHANICS: favors extension over flexion, opposite of the RC joint. Also, small amounts of RD/UD
-the distal row moves as a row together in a functional manner

Question 16

Joints of the wrist

Answer 16

DRUJ
radiocarpal/ulnocarpal
midcarpal

Question 17

What prevents RD and UD in extremes of wrist flexion?

Answer 17

extrinsic ligamentous constraints

Question 18

Lichtman’s ring model

Answer 18

• Bones within each row tethered together by
  interosseous ligs.
• Ring is only complete by the addition of the
  midcarpal ligs.
• As long as the ligaments are intact, the carpal bones
  will move together as a unit.

the proximal row is concave
distal row is convex
** distal row moves on proximal row

FLEXION/EXTENSION
-both rows flex and vice versa during extension
-about 50% at the MC and 50% at the RC joints

Question 19

ROM/axis of rotation of the wrist:

Answer 19

F/E: coronal axis between lunate and capitate

RD/UD: sagittal between lunate and capitate

circumduction: polyaxial

the center of rotation is variable and dependent on wrist position and motion

Question 20

Joints of the hand complex

Answer 20

CMC
metacarpophalangeal
interphalangeal joint of the thumb
PIP and DIP

Question 21

CMC joints type/charac.

Answer 21

type thumb: sellar or saddle
-has capsule
-relatively lax capsule

articulation CMC thumb: -trapezium is concave in sagittal and convex in frontal with the opposite proximal surface of 1st MC

ligaments 1st CMC: radial collateral, ulnar collateral, dorsal, volar carpometacarpal ligaments

motion:
* CMC Radial
abduction/adduction
* CMC Palmar
abduction/adduction
* CMC Opposition

type: 2-5: plane or gliding
2 and 3: difficult to classify as interlocking articular surfaces prevent movement
4 and 5:
– the distal surface of hamate: concave
– the proximal surface of 4th and 5th metacarpals: slightly convex

-degrees of freedom: cupping of hand with slight flexion and IR of metacarpals– true roll and glide does not apply

Question 22

MCP joint type

Answer 22

2-5 types: ellipsoidal or condyloid
articulation:
–distal surface MC: biconvex
–proximal phalanges: concave

2-5 fingers:
-ligaments: transverse metacarpal ligaments, collateral ligaments
-deep: connects metacarpal heads
-superficial: connects adjacent volar plates

-motions: flexion, extension, abduction, adduction, conjuct rotation

MCP of thumb: condyloid, with capsule, volar plate, and collateral ligaments
-** less motion than finger MCP joints
-sesamoids present at thumb MCP (extracapsular)

Question 23

PIP and DIP joint types

Answer 23

type: ginglymus or hinge, synovial

proximal phalanx: convex; pulley-shaped head

distal phalanx: biconcave

roll and glide in same direction distal on proximal

MOTION:
-flexion and extension, conjunct rotation also occurs with flexion and extension

LIGAMENTS:
-collaterals, more longitudinal than MCP ; tight throughout range - max tension 15-25 deg flexion
-volar plates are similar to MCP but no transverse ligament

Question 24

Motions at CMC thumb:

Answer 24

degrees of freedom: 3

radial ab/ad : MC rolls and glides in the same direction

palmar ab/ad: MC rolls and glides in opposite direction

rotation (conjunct)- used in opposition