Lecture 7
What are the effects of force on a joint?
There is compression force that brings it together and there is distraction force that pulls it apart.
Both give full joint range.
What are the functions of the elbow complex?
- allows for functional placement of the hand (closer to and further away from the body)
- forearm rotation is an important component (supination and pronation)
- serves to stabilize the hand for skilled or forceful movements (iso co contraction)
What are the bones and joint of the elbow complex?
Bones= humerus, ulna, radius
Joints= humeroulnar (hinge), humeroradial (pivot), superior (proximal radioulnar joint
What is a carrying angle?
- axis of movement at elbow joint is not horizontal
- 5 to 15 degrees (typical)
- allows objects to be carried away from body
- valgus= (inward) if greater than 5 to 15 degrees
- varus= (outward) if less than 5 to 15 degrees
females have a wider carrying angle
What is valgus?
What is varus?
valgus= involving oblique displacement of the distal part of a limb away from the midline ex: turners
varus= involving oblique displacement of the distal part of a limb towards the midline
what is the elbow joint capsule?
- humeroradial, humeroulnar, and superior radio ulnar joints all encoded in single joint capsule
What are the radioulnar joints?
- superior (proximal) radioulnar joint= proximal articulation of radius w/ the ulna
- inferior (distal) radioulnar joint: distal articulation of the radius w/ the ulna
What are the ligaments by the humeroulnar and humeroradial joints?
- medial (ulnar) collateral ligament: anterior portion primary stabilizer (3 parts) ex: Tommy John surgery
- lateral (radial) collateral ligament: reinforces the humeral radial articulation, protecting against distraction of the joint (2 parts)
What are the ligaments by the superior radioulnar joint?
- annular ligament: closely binds the radial head to the ulna
- oblique cord: runs just inferior to the radial arch (ulna) to inferior portion of bicipital tuberosity (radius)
What are the ligaments by the radioulnar joints?
- interosseous membrane: binds the radioulnar joint together, transmits forces from the hand and distal end of radius to the ulna
- anterior and posterior radioulnar ligaments: reignforce the inferior radioulnar joint anteriorly and posteriorly
What are the motions of the elbow?
- joint is where the humerus articulates with the ulna and radius
- active range of motion: 0 degrees (full extension) to between 130 degrees and 150 degrees
- passive range of motion: 0 degrees to between 150 degrees and 160 degrees
What are the motions of the radioulnar joints?
- pronation
-supination
- active and passive range of motion: 0 drees (neutral position/ resting on ulnar border) to 90 degrees
What are the movements at the elbow and forearm?
- flexion:occurs at the humeroulnar joint, ulna slides along the trochlea of the humerus until the coronoid process of the ulna reaches coronoid fossa of the humerus
- extension: during extension, the ulna slides in the opposite direction until the olecranon process enters the olecranon fossa (reaching end range), when the elbow s extended, there is no contact between the capitulum of the humerus and the radial head
- supination/ pronation: in anatomical position (supinated), the radius and ulna are parallel to each other, during pronation, the radius crosses over the ulna (the radius does 90% of the motion over the ulna; the ulna only pivots slightly
What is the bicep brachii?
movements?
-two heads, two joint muscle
- simultaneously flexes elbow and supinates forearm
- active in all flexion activities with supination
- tends not to be active when forearm is pronated
What is the brachialis?
-not influenced by oration of radius (pronation/ supination)
- active in elbow flexion with or without resistance
- active in all positions, all types of contractions, with or without resistance
What is the brachioradialis?
- most active as flexor in 24 to 1120 degrees of flexion
- functions as both a pronator and supinator (to neutral)
-has the ability to pronate (to neutral) and supinate (to neutral) the forearm- as an assist
- active as a prime mover throughout range with increased speed, force, or resistance through the full ROM
- most force as a flexor at mid range (not a prime mover until between 24 degrees and 120 degrees)
What is the tricep?
-three heads, two joint muscle
- covers the entire posterior surface of the upper arm
- prime mover for elbow extension
- assists with shoulder extension and adduction
What is the ancones?
- initiation of extension of elbow and maintaining a position of extension
What is the supinator?
- prime mover for supination
- active in supination under all conditions
- functions best and independently when elbow is fully extended
- biceps and supinator are a force couple, and are prime movers for supination
-active under all conditions but best when elbow in extension
- when elbow is flexed to 90 degrees, biceps is 4x stronger doing supination than the supinator
-biceps will not be effective for supination when elbow is in full flexion or extension
- supinator works alone to supinate when elbow full extended
What are the pronator muscles?
- pronator quadratura: pronates forearm by pulling radius over the ulna and turn palm downward
- pronator teres primarily pronates forearm forearm but assists with elbow extension
List flexor muscles
biceps brachii, brachialis, brachioradialis
list supinators
- supinator
- biceps
list extensors
- triceps
- anconeus
list pronators
- pronator quadratus
- pronator teres
analyze pushup at the elbow
movement: extension
contraction: concentric
muscles: triceps and anconeus