Muscles that move humerus:forearm

Muscles That Move the Humerus

• The muscles responsible for arm movement and shoulder strength are primarily the pectoralis major and latissimus dorsi.

  • Pectoralis Major: Covers the chest's front.

  • Latissimus Dorsi: Located in the lower back, connects to a strong aponeurosis.

• These muscles are essential for moving and stabilizing the shoulder.

Figures Overview

• Figure 1 depicts various muscles involved in arm and shoulder movement:

  • Pectoralis Major and Latissimus Dorsi: Key players in humeral movement.

  • Deltoid: Responsible for different arm movements, including abduction and rotation.

  • Other muscles: Engage in roles such as stabilization and extension of the shoulder joint.

Muscles and Their Actions

• A detailed table outlines the prime movers and their origin/insertion, detailing actions such as flexion, extension, and rotation of the humerus.

  • Pectoralis Major: Flexion, adduction, medial rotation (Origin: Clavicle; Insertion: Humerus).

  • Latissimus Dorsi: Extension, adduction, medial rotation (Origin: Thoracic and lumbar vertebrae; Insertion: Humerus).

  • Deltoid: Abduction (Origin: Scapula and clavicle; Insertion: Humerus).

  • Rotator Cuff Muscles: Enhance stability and movement, including the subscapularis, supraspinatus, infraspinatus, and teres major.

Anatomy of Shoulder Muscles

• Deltoid Muscle: A thick muscle creating the rounded shape of the shoulder, responsible for:

  • Arm abduction, flexion, medial rotation, and extension.

• Subscapularis: Medially rotates the arm; originates from the anterior scapula.

• Supraspinatus: Facilitates arm abduction; located above the scapular spine.

• Infraspinatus: Laterally rotates the arm; positioned below the scapular spine.

• Teres Major: Functions in adduction and medial rotation of the arm.

• Coracobrachialis: Assists in arm flexion and adduction.

• Rotator Cuff: A group of tendons providing shoulder stability; prone to injuries from repetitive motions (e.g., baseball pitching).

Muscles That Move the Forearm

• Forearm is composed of radius and ulna and enables key movements at the elbow:

  • Flexion (bending), extension (straightening), pronation (palm-down), supination (palm-up).

Forearm Flexors

1. Biceps Brachii

   • Two-headed muscle, involved in flexing the forearm and assisting in shoulder movements.

2. Brachialis

   • Lies deep to the biceps; enhances flexion power.

3. Brachioradialis

   • Effective in quick flexion and stabilizing during lifting.

Forearm Extensors

• Triceps Brachii: Major extensor, crucial for pushing and throwing actions.

• Anconeus: Aids in extending the forearm.

Forearm Pronators and Supinators

• Pronator Muscles: Turn hand palm down.

  • Pronator Teres: Helps with pronation (Origin: Medial epicondyle).

  • Pronator Quadratus: Extends the action of the pronator teres.

• Supinator Muscle: Turns the forearm palm up; works opposite to pronators.

Important Tables

• Tables in the content provide specifics about muscle actions, origins, insertions, and roles in various movements of the humerus and forearm.

• Clinical Importance: Understanding these muscles aids in diagnosing and treating injuries, especially related to repetitive motion and strain.