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Biomechanics of Elbow complex - Coggle Diagram
Biomechanics of Elbow complex
Mobility
Position of the forearm
Pronated or neutral position, ROM is less when compared to supinate forearm
Body mass index
High BMI has limited range of motion at the elbow
Type of motion
Active: From 135-145 degrees of flexion
Passive: From 150-160 degrees
Position of the shoulder
Depends on biceps brachii and triceps brachii that cross both shoulder and elbow
Limits ROM at elbow joint if full range of motion is attempted at both joints simultaneously
Muscle Action
Elbow flexors
Brachialis
Proximal Attachment: Anterior surface of the humerus
Distal Attachment: Coronoid process of the ulna
Moment Arm: 100°, indicating its efficiency in producing elbow flexion.
Biceps brachii
Proximal Attachment: Short head - Coracoid process of the scapula; Long head - Supraglenoid tubercle of the scapula
Distal Attachment: Radial tuberosity of the radius
Moment Arm: 90° showing its role in powerful elbow flexion
Brachioradialis
Proximal Attachment: Lateral supracondylar ridge of the humerus
Distal Attachment: Radial tuberosity of the radius
Moment Arm: 65° indicating its effectiveness in flexing the elbow
Triceps brachii
Proximal Attachment: Infraglenoid tubercle of the scapula (long head); posterior surface of the humerus (lateral and medial heads)
Distal Attachment: Olecranon process of the ulna
Moment Arm: High, showing effectiveness during push-ups
Anconeus:
Proximal Attachment: Lateral epicondyle of the humerus
Distal Attachment: Lateral surface of the olecranon and superior part of the ulna
Moment Arm: Moderate, supporting elbow extension during push-ups
Stability
Different flexion angles affect the stability of the humeroulnar and humeroradial joints
The lateral collateral ligament provides stability against varus stress
The medial collateral ligament provides resistance to valgus and varus stress at 90 degrees of flexion
Factors contributing to elbow joint stability include bony components, joint capsules, ligaments, and muscle tension at different flexion angles.
Axis
Axis of the elbow is in the middle of the trochlea on a line that intersects the longitudinal axis of the humerus.
Carrying angle
When the upper extremity is in the anatomical position the long axes if the humerus and forearm form an acute angle laterally at the elbow which is around 15 degree.