Elbow Complex Flashcards
Elbow Complex consists of:
-Elbow Joint; Humeroulnar + Humeroradial Joints
-Proximal radioulnar joint (PRUJ)
-Distal radioulnar joint (DRUJ)
Elbow Functions
-Mobility for the hand by shortening or lengthening entire UE
-Stability for forceful movements (Ex: tools)
-Links shoulder to hand
Elbow Joint
(HUJ, HRJ)
Compound, modified/loose Hinge Joint
1 DOF; Flexion and Extension
Small amounts of axial rotation ABD/ADD of ulna
Proximal/ Distal Radioulnar Joints
(DRUJ) (PRUJ)
Linked; Function as 1 joint
Uniaxial, diarthrodial Pivot joint
1 DOF; Rotation of forearm (Pronation/Supination)
Humeroulnar (HUJ) Articulation
Trochlea of humerus with Trochlea notch of ulna
HUJ Open-Packed Position
70 deg supination; 10 deg flexion
HUJ Close-Packed Position
Full extension and supination
During elbow flexion at the HUJ, there is an ________ roll and _______ glide.
anterior; anterior
During elbow extension at the HUJ, there is a _______ roll and ________glide.
posterior; posterior
Humeroradial (HRJ) Articulation
Capitulum with Radial Head
HRJ Open-Packed Position
Full extension and supination
HRJ Close-Packed Position
90 deg flexion; 5 deg supination
During elbow flexion at the HRJ, there is a ______roll and a ______glide.
Anterior; anterior
During elbow extension at the HRJ, there is a _______ roll and ________glide.
Posterior; posterior
HUJ and HRJ Structures
-Joint capsule
-Medial and Lateral Collateral Ligaments
HUJ and HRJ Joint Capsule
-Fairly large, loose, weak anteriorly/posteriorly
-Synovial folds expand for full ROM
Synovial Membrane
-Lines olecranon, coronoid, radial fossae
-Lines medial trochlea and lower part of annular ligament
-Folds in to divide the HUJ and HRJ
Fat Pads
-Between capsule and synovial membrane
-By the olecranon, coronoid, radial fossae
HUJ and HRJ Medial (Ulnar) Collateral Ligament
Anterior bundle
-Primary restraint to valgus at 20-120 deg elbow flexion
Posterior bundle (vertically oriented)
-Limits elbow extension; guides motion throughout flexion
Transverse fibers
-Limits longitudinal distractions
HUJ and HRJ Lateral Collateral Ligament Complex
Lateral (radial) Collateral Ligament
Lateral (ulnar)Collateral Ligament
Annular Ligament
-stabilizes radial head against ulna
What does the HUJ and HRJ Lateral Collateral Ligament Complex do combined?
Restraint to varus
Restraint to combined varus + supination
Reinforces HRJ; limits distraction
Maintains posterolateral stability
Secures ulna to humerus (prevents dislocation)
Prevents forearm from rotating off humerus in valgus and supination during flexion from a fully extended position
HUJ and HRJ Axis of Motion
Centered in middle of trochlea on a line that intersects the longitudinal axis of the humerus
Carrying angle: Acute angle formed by long axis of humerus and forearm
-Normal:8-15 deg
-Cubitus valgus: >15 deg
-Cubitus varus: <5 deg
T/F Oblique axis results in a change in the relationship of the forearm and humerus when flexed.
True
Normal carrying angle with _______, ulna guided so that it’s in line with the same plane of the humerus when fully flexed.
Flexion
T/F Ulna medially guided from extension to flexion to put in the same plane as the humerus when fully flexed.
True
When cubitus valgus, going from extension to flexion, where does the forearm rest?
Forearm rest more medially when fully flexed
When cubitus varus, going from extension to flexion, where does the forearm rest?
Forearm rests laterally to humerus
Why is the range of active flexion usually less than passive ?
Muscle bulk with contraction; decrease in approximation of joint surfaces
When is there more elbow flexion AROM?
when forearm is supinated
When is there less elbow flexion AROM?
when arm in neutral or pronated
Brachialis
(Flexor)
Mobility
Large CSA and work capacity volume
MA greatest at 100 deg elbow flexion
Not affected by shoulder position
Activated with & without added resistance; slow & fast speeds
Biceps Brachii
(Flexor)
Mobility
Smaller CSA but largest work capacity volume
MA greatest between 80-100 deg elbow flexion
-Small as it approaches full elbow extension
Activated without resistance IF elbow is supinated or in neutral (NOT in pronation)
-when resistance increases beyond weight of limb, biceps is active in ALL positions
Affected by shoulder position
Brachioradialis
(flexor)
Stability
Smallest CSA, larger peak MA 100-120 deg elbow flexion
Not affected by shoulder position
Not active during:
-eccentric elbow flexion with supination
-slow, unresisted, concentric elbow flexion
Active during:
-Increased speed
-load is applied in forearm neutral OR full pronation
Triceps Brachii
(extensor)
Mobility and Stability
Prime Mover for elbow extension
-Synergist to prevent elbow flexion when the biceps is acting as a supinator
Max torque at 90 deg elbow flexion
Long Head:
-Affected by shoulder position
-Active with heavy resistance to extension, with quick extension
Medial Head:
-Not affected by shoulder position
-Active in unresisted elbow extension, with heavy resistance to extension, with quick
extension
Lateral Head:
-Not affected by shoulder position
-Active with heavy resistance to extension, with quick extension
Anconeus
(extensor)
Stability
15% contribution to elbow extension torque
Co-contracts with triceps to stabilize during functional tasks, dependent on load and speed
Proximal Radioulnar Joint (PRUJ) Articulation
Radial notch of ulna
-annular ligament
Rim of radial head
HRJ
PRUJ Open-Packed Position
70 deg elbow flexion, 35 deg supination
PRUJ Close-Packed Position
5 deg supination, full extension
Distal Radioulnar Joint (DRUJ) Articulation
Ulnar notch of radius
Articular disc
-Triangular fibrocartilage complex (TFCC)
Head of ulna
DRUJ Open-Packed Position
10 deg supination
DRUJ Close-Packed Position
5 deg supination
PRUJ and DRUJ are _____________ linked
mechanically
PRUJ Structure
Annular ligament
Quadrate Ligament
-Keeps radial head close to radial notch
-Checks pronation/supination
Oblique Cord
-Assists with preventing separation of radius and ulna
DRUJ Structure
TFCC: divides DRUJ from the radiocarpal joint
-Proximal surface: articulates with ulnar head at DRUJ
-Distal surface: articulates with carpals
-Both surfaces are concave
Dorsal & Palmar Radioulnar ligaments
DRUJ and PRUJ Interosseous Membrane
Stabilizes both
-Central band: prevents splaying
-Membranous portion
-Dorsal Oblique Cord
Help transmit loads Radius to Ulna
DRUJ and PRUJ Axis of motion
Radius pivots around ulna during pronation and supination
With pronation at the PRUJ, there is _______ roll and ______glide.
anterior; posterior
convex-concave
With pronation at the DRUJ, there is _______ roll and ______glide.
anterior; anterior
concave-convex
With supination at the PRUJ, there is _______ roll and ______glide.
posterior; anterior
Convex-concave
With supination at the DRUJ, there is _______ roll and ______glide.
posterior; posterior
concave-convex
Range of pronation is at its maximal when elbow is ….
extended
Range of supination is at its maximal when elbow is ….
flexed
Pronator Teres
(pronator)
Most efficient at 90 deg elbow flexion, between 40 deg supination & 40 deg pronation
Long head crosses elbow
MOBILITY for forearm pronation
STABILITY for elbow flexion
Pronator Quadratus
(pronator)
Mobility
Most efficient at 90 deg elbow flexion, between 40 deg supination & 40 deg pronation
Active in:
-Unresisted & resisted pronation
-Slow and fast speed
Supinator
(supinator)
Mobility
Peak torque achieved 40-50 deg of pronation
Single-joint muscle
Active in:
-Unresisted slow supination in all positions
-Unresisted fast supination when elbow is extended
Biceps
(supinator)
Mobility
Peak torque achieved 40-50 deg of pronation
Activity:
-always evident when supination is performed against resistance
-during fast supination when elbow is flexed at 90 deg
Integrated Stability - Pronator quadratus
Deep head active throughout pronation & supination to support DRUJ
Integrated Stability - Extensor Carpi Ulnaris
Stabilizes head of ulnar during pronation and supination at DRUJ
Integrated Stability - Extensor Carpi Radialis Brevis
-Active to stabilize DRUJ during pronation & supination
-Supports forearm for griping during forceful pronation
-Prime mover for wrist extension during supination
Integrated Stability - Radioulnar Ligaments
Prevent separation of radius and ulna during loading
-allow approx. 5 mm of play
May contribute to force transmission from radius to ulna through DRUJ
-Dorsal: Taut in pronation
-Palmar: Taut in supination
Integrated Stability - TFCC
Helps bind ulna and radius together
Provides long-axis stabilization of radius and ulna by acting as a cushion
Integrated Stability - Interosseous membrane
Helps bind ulna and radius together
Provides long-axis stabilization of radius and ulna
How is force distributed form the wrist to the humerus?
Radius –> Interosseous membrane –> Ulna –> Humerus
