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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

Distal Humerus: Trochlea

Spool shaped-medial side of distal humerus-articulates with the ulna-humeroulnar (elbow) joint

Distal Humerus: Capitulum

Lateral to the trochlea-articulates with the head of the radius to form the humeroradial joint

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

Lateral epicondyle

Proximal attachment for most wrist extensor muscles, supinator muscle and lateral collateral elbow ligament

Medial & Lateral Supracondylar Ridges

Immediately proximal to both epicondyles

Olecranon Fossa

Relatively deep, broad pit located on posterior side of the distal humerus

Four joints in elbow/forearm complex

1. Humeroradial joint

2. humeroulnar joint

3. proximal radioulnar joint

4. distal radioulnar joint

Olecranon Process

Large, blunt, proximal tip of the ulna, rough posterior surface is distal attachment for triceps muscle

Trochlear Notch

Large, jaw like curvature of proximal ulna articulating with trochlea: inferior tip comes to a point, forming the coronoid process.

Coronoid Process

Strengthens articulation of humeroulnar joint by firmly "grabbing" trochlea

Radial Notch

Slightly inferior and lateral to the trochlear notch. Articulates with radial head to form proximal radioulnar joint

Styloid Process

Pointed projection of bone that arises from ulnar head

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

Bicipital tuberosity / Radial Tuberosity

Enlarged ridge of bone on anterior medial aspect of proximal radius. Primary distal attachment for biceps brachii

Ulnar notch

Small depression on medial side of distal radius that articulates with the ulnar head

Humeroulnar Joint
provides most of elbow's structural stability by trochlear notch interlocking with trochlea. Limits motion of elbow to flexion and extension
Humeroradial Joint
Formed by the capitulum articulating with the fovea. Permits continous contact between radial head and capitulum during supination, pronation, flexion and extension
Cubitus Valgus orientation
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
Supporting structures of the elbow

1. annular ligament

2. articular capsule

3. medial collateral ligament (MCL)

4. lateral collateral ligament (LCL)

articular capsule

thin, expansive band of connective tissue enclosing humeroulnar, humeroradial and radioulnar joints

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

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.

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

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)

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.

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

Distal Radioulnar Joint capsule

Reinforced by palmar and dorsal capsular ligaments. Provides stability to the distal radioulnar joint

Interosseous membrane

helps bind radius to ulna

serves as a site for muscular attachments and a mechanism to transmit forces proximally through forearm


occurs in many functional activities that require the palm to be turned up. ex. holding a bowl of soup


occurs with activites that require the palm turned down.

ex: pushing up from a chair

Supination and Pronation

occur as the radius rotates around an axis of rotation that travels from the radial head to the ulnar head

0 degree or neutral position

the thumb up position. From this position, normally 80-90 degrees of supination and 80-90 degrees of pronation

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)

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

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

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

Proxial directed force

passes up radius and because of angulation of interosseous membrane, is transferred partly to ulna

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


radius is more able to accept force


ulna is more able to accept force