Joint Actions - Mechanical Analysis

Mechanical Analysis of Joint Actions

Overview

• This document provides a comprehensive mechanical analysis of various joint actions across the human body, focusing on specific movements of the shoulder, hip, ankle, wrist, and elbow. Each section includes definitions, prime movers, and relevant anatomical details.

Shoulder Actions

Shoulder Flexion

• Definition: The action of raising the arm forward and upward.
• Prime Movers: Pectoralis major, anterior deltoid, and coracobrachialis.

Shoulder Extension

• Definition: The action of moving the arm backward.
• Prime Movers: Latissimus dorsi, posterior deltoid, and teres major.
• Common Muscle Involved: Pectoralis major can also adduct while extending.

Shoulder Abduction

• Definition: The movement of the arm away from the body in a lateral direction.
• Prime Movers: Deltoid (especially the middle fibers) and supraspinatus muscle.

Shoulder Adduction

• Definition: Moving the arm back towards the body.
• Prime Movers: Pectoralis major, teres major, and latissimus dorsi.

Shoulder Internal Rotation

• Definition: The inward turning of the shoulder joint.
• Prime Movers: Subscapularis, pectoralis major, and the anterior deltoid.

Shoulder External Rotation

• Definition: The outward turning of the shoulder joint.
• Prime Movers: Infraspinatus, teres minor, and posterior deltoid.
• Common Mistakes: Engaging the wrong muscles or limiting the range of motion.

Shoulder Horizontal Abduction

• Definition: The movement of the arm away from the body at shoulder level.

Shoulder Horizontal Adduction

• Definition: The movement of the arm toward the body at shoulder level.

Hip Actions

Hip Flexion

• Definition: The action of lifting the thigh or knee towards the chest.

Hip Extension

• Definition: Moving the leg backward from a flexed position.
• Standing Hip Extension: Focus on maintaining posture while extending the leg.

Hip Abduction

• Definition: Moving the thigh away from the midline of the body.

Hip Adduction

• Definition: Moving the thigh back toward the midline of the body.
• Standing Hip Adduction: Execution details to ensure correct form.

Hip Internal Rotation

• Definition: The rotation of the thigh inward towards the center of the body.

Hip External Rotation

• Definition: The rotation of the thigh outward, away from the center of the body.

Hip Horizontal Abduction

• Definition: The extension of the leg out to the side at hip level.

Hip Horizontal Adduction

• Definition: The movement of the leg toward the midline at hip level.

Ankle Actions

Ankle Plantar Flexion

• Definition: The movement pointing the toes or extending the ankle.
• Common Execution: Engage calf muscles for proper movement.

Ankle Dorsiflexion

• Definition: The action of pulling the toes towards the shin.

Ankle Inversion

• Definition: Moving the sole of the foot inward, towards the midline.

Ankle Eversion

• Definition: Moving the sole of the foot outward, away from the midline.

Wrist Actions

Wrist Flexion

• Definition: The action of bending the wrist so that the palm moves closer to the forearm.

Wrist Extension

• Definition: The straightening of the wrist, moving the back of the hand towards the forearm.

Wrist Ulnar Deviation

• Definition: The movement of the wrist towards the ulnar side (pinky side).

Wrist Radial Deviation

• Definition: The movement of the wrist towards the radial side (thumb side).

Radioulnar Joint Actions

Radioulnar Joints - Pronation

• Definition: The rotation of the forearm to turn the palm downwards.

Radioulnar Joints - Supination

• Definition: The rotation of the forearm to turn the palm upwards.
• Key Points: The action involves the radius crossing over the ulna in pronation.

Knee Actions

Knee Flexion

• Definition: The action of bending the knee, decreasing the angle between the thigh and the lower leg.

Knee Extension

• Definition: The straightening of the knee, increasing the angle between the thigh and lower leg.

Elbow Actions

Elbow Flexion

• Definition: The action of bending the elbow, bringing the forearm closer to the upper arm.

Elbow Extension

• Definition: The action of straightening the elbow to increase the angle between the forearm and upper arm.
• With Weight: Details on executing elbow extension while holding weight, focusing on form and muscle engagement.