Overview of the elbow wrist and hand/stabilizers/pathology Flashcards
What three joints make up the elbow?
- Humeroulnar Joint
- Humeroradial Joint
- Proximal
Radioulnar Joint (PRUJ)
All three make up a modified hinge joint
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?
6° of valgus in the frontal plane and 30° of anterior rotation in the sagittal plane
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?
Capitulum of the humerus articulates with the head of the radius
Trochlea of the humerus articulates with the trochlear notch of the ulna
What is the normal carrying angle of the elbow for males and females?
11 to 14° for males and 13 to 16° for females
Angle between the axis of the humerus and the axis of the forearm
Humeroulnar joint characteristics
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
humeroradial joint characteristics
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
Characteristics of the elbow capsule
Thin but strong, does not respond well to injury or immobilization, forms of thick scar tissue resulting in flexion contractures
Primary ligaments of the elbow joint
Ulnar collateral ligament
Radial collateral ligament blends with the annular ligament
Annular ligament forming proximal radioulnar joint
Interosseous membrane of the forearm
What bone is moving during pronation and supination and what bone is fixed?
The radius is moving and the ulna is fixed
Proximal radioulnar joint characteristics
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
DRUJ characteristics
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
Pronation and Supination characteristics
PRONATION AND SUPINATION OCCURS SIMULTANEOUSLY AT BOTHE PRUJ and the DRUJ
also requires rotation of radius at humeroradial joint in annular ligament
On what side of the wrist joint is the TFCC?
MEDIAL
under the distal ulna
Radiocarpal/ulnocarpal joint characteristics
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)
midcarpal joints
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
Joints of the wrist
DRUJ
radiocarpal/ulnocarpal
midcarpal
What prevents RD and UD in extremes of wrist flexion?
extrinsic ligamentous constraints
Lichtman’s ring model
- 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
ROM/axis of rotation of the wrist:
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
Joints of the hand complex
CMC
metacarpophalangeal
interphalangeal joint of the thumb
PIP and DIP
CMC joints type/charac.
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
MCP joint type
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)
PIP and DIP joint types
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
Motions at CMC thumb:
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
