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41 Cards in this Set
- Front
- Back
Four Bones of elbow and forearm complex |
1. Scapula 2. Distal Humerus 3. Ulna 4. Radius |
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Distal Humerus: Trochlea |
Spool shaped-medial side of distal humerus-articulates with the ulna-humeroulnar (elbow) joint |
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Distal Humerus: Capitulum |
Lateral to the trochlea-articulates with the head of the radius to form the humeroradial joint |
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Medial epicondyle |
Prominent projection of dista humerus-medial side-proximal attachment for most wrist flexor muscles, pronator teres and medial collateral ligament of the elbow |
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Lateral epicondyle |
Proximal attachment for most wrist extensor muscles, supinator muscle and lateral collateral elbow ligament |
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Medial & Lateral Supracondylar Ridges |
Immediately proximal to both epicondyles |
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Olecranon Fossa |
Relatively deep, broad pit located on posterior side of the distal humerus |
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Four joints in elbow/forearm complex |
1. Humeroradial joint 2. humeroulnar joint 3. proximal radioulnar joint 4. distal radioulnar joint |
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Olecranon Process |
Large, blunt, proximal tip of the ulna, rough posterior surface is distal attachment for triceps muscle |
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Trochlear Notch |
Large, jaw like curvature of proximal ulna articulating with trochlea: inferior tip comes to a point, forming the coronoid process. |
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Coronoid Process |
Strengthens articulation of humeroulnar joint by firmly "grabbing" trochlea |
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Radial Notch |
Slightly inferior and lateral to the trochlear notch. Articulates with radial head to form proximal radioulnar joint |
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Styloid Process |
Pointed projection of bone that arises from ulnar head |
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Radius: Radial Head |
Shaped like a wide disc on proximal end of radius. Superior surface consists of shallow, cup shaped depression called the fovea that articulated with humeral capitulum, forming the humeroradial joint |
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Bicipital tuberosity / Radial Tuberosity |
Enlarged ridge of bone on anterior medial aspect of proximal radius. Primary distal attachment for biceps brachii |
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Ulnar notch |
Small depression on medial side of distal radius that articulates with the ulnar head |
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Humeroulnar Joint
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provides most of elbow's structural stability by trochlear notch interlocking with trochlea. Limits motion of elbow to flexion and extension
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Humeroradial Joint
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Formed by the capitulum articulating with the fovea. Permits continous contact between radial head and capitulum during supination, pronation, flexion and extension
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Cubitus Valgus orientation
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Natural outward angulation of the forearm within the frontal plane. Called the CARRYING ANGLE because of its function of keeping a carried object away from the body. Elbow trauma can result in either excessive cubitus valgus or cubitus varus
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Supporting structures of the elbow
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1. annular ligament 2. articular capsule 3. medial collateral ligament (MCL) 4. lateral collateral ligament (LCL) |
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articular capsule |
thin, expansive band of connective tissue enclosing humeroulnar, humeroradial and radioulnar joints |
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medial collateral ligament (MCL) |
attaches proximally to medial epicondyle and distally to medial aspects of coronoid and olecranon processes, provides stability by resisting cubitus valgus producing forces |
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lateral collateral ligament (LCL) |
originates on the lateral epicondyle and splits into two fiber bundles known as the RADIAL COLLATERAL LIGAMENT, which attaches to the annular ligament and the LATERAL (ULNAR) COLLATERAL LIGAMENT which attaches to lateral aspect of the proximal ulna.
Provides elbow stability by resisting cubitus varus producing forces. |
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Supporting structures of elbow joint |
Collateral ligaments limit excessive varus and valgus deformities of the elbow. Medial collateral ligament is most often injured during attempts to 'catch' oneself from a fall. Because these ligaments also become tight at the extremes of elbow flexion and extension, these motions can also damage the collateral ligaments, if very forceful |
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Elbow joint kinematics |
Elbow flexion and extension occur in the sagittal plane around a medial lateral axis of rotation, which courses through both epicondyles.
Elbow range of motion normally spans from 5 degrees of hyperextension to 145 degrees of flexion.
Most activities use a more limited 100 degree arc of motion, between 30 and 130 degrees (Functional ROM) |
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Arthrology of the forearm complex |
composed of the proximal and distal joints.
Pronation and supination occur as a result of motion at each of these two joints. Pronation and supination DO NOT OCCUR AT THE HAND.
Firm articulation between distal radius and carpal bones requires that the hand follows the rotation of the radius. |
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Proximal and Distal Radioulnar Joint: ANNULAR LIGAMENT |
Thick, circular band of connective tissue that wraps around the radial head and attaches to either side of the radial notch of the ulna.
Holds the readial head firmly against the ulna, allowing it to spin freely during supination and pronation |
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Distal Radioulnar Joint capsule |
Reinforced by palmar and dorsal capsular ligaments. Provides stability to the distal radioulnar joint |
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Interosseous membrane |
helps bind radius to ulna
serves as a site for muscular attachments and a mechanism to transmit forces proximally through forearm |
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Supination |
occurs in many functional activities that require the palm to be turned up. ex. holding a bowl of soup |
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Pronation |
occurs with activites that require the palm turned down.
ex: pushing up from a chair |
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Supination and Pronation |
occur as the radius rotates around an axis of rotation that travels from the radial head to the ulnar head |
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0 degree or neutral position |
the thumb up position. From this position, normally 80-90 degrees of supination and 80-90 degrees of pronation |
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Arthrokinematics of supination & pronation |
With humerus fixed and forearm free:
Radius moves...Ulna stationary
Radial head spins in place in direction of moving thumb
Distal radius rolls and slides in the same direction relative to the ulnar head. (Concave on Convex=Same direction) |
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During supination |
the radial head spins in the direction of the thumb.
Spinning head of the radius also makes contact with the capitulumof the humerus.
At the distal radioulnar joint, the concave surface of the distal radius rolls and slides in the same direction across the stationary ulna |
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Force transmission through the interosseous membrane |
Most introsseous membrane fibers are oriented 45 degrees from the long axis of the forearm, helping transmit compressive forces from the hand to the upper arm |
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Push up actions |
create a compressive force passing through the hand to the wrist, 80% of which is transmitted through the radius at the radiocarpal joint |
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Proxial directed force |
passes up radius and because of angulation of interosseous membrane, is transferred partly to ulna |
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As a result |
compressive force that entersdistal forearm at radius exits proximal forearm through both humeroulnar and humeroradial joints and is transferred up to the shoulder |
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Distally |
radius is more able to accept force |
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proximally |
ulna is more able to accept force |