Muscles of the Shoulder and Arm

Muscles of the Shoulder and Arm

Overview

• Preparation for lab exam on muscles moving the shoulder and upper arm.
• Exam details: 42 questions on Thursday, with time allocated for a final review and quiz.

Muscles That Move the Shoulder

Rhomboid Major

• Description: Short, deep back muscle.
• Origin: Thoracic vertebrae.
• Insertion: Border of the scapula.
• Action: Retracts the shoulder (not required for tracking, but useful for understanding).

Serratus Anterior

• Description: Anterior muscle that appears serrated.
• Origin: Ribs.
• Insertion: Anterior aspect of the scapula.
• Identification: Look for it on the front side of the rib cage beneath the pectoralis major.

Pectoralis Major

• Description: Large chest muscle, superficial.
• Origin: Clavicle, sternum, and ribs.
• Action: Moves the shoulder joint, responsible for flexion and adduction of the arm.

Latissimus Dorsi

• Description: Large, flat muscle on the back.
• Origin: Lower spine, iliac crest.
• Insertion: Humerus.
• Action: Extension and rotation of the arm.

Muscles That Move the Arm

Deltoid

• Description: Superficial shoulder muscle; has three distinct parts.
• Origin: Clavicle and scapula.
• Insertion: Deltoid tuberosity of humerus.
• Action: Abducts arm (lifting away from the body).

Rotator Cuff Muscles

• Group of four muscles:
  1. Supraspinatus
  • Origin: Supraspinous fossa (above the spine of scapula).
  • Action: Initiates arm abduction.
  1. Infraspinatus
  • Origin: Infraspinous fossa (below the spine of scapula).
  • Action: Lateral rotation of the arm.
  1. Teres Minor
  • Description: Small round muscle above teres major.
  • Action: Lateral rotation of the arm.
  1. Subscapularis
  • Origin: Subscapular fossa (beneath scapula).
  • Action: Medial rotation of the arm.
• Commonality: All insert into the humerus and help in throwing motion.

Biceps Brachii

• Description: Muscle at the front of the upper arm.
• Origin: Scapula.
• Insertion: Radius.
• Action: Flexes the elbow (raises forearm).

Triceps Brachii

• Description: Located on the back of the upper arm.
• Origin: Scapula and humerus.
• Insertion: Olecranon process of ulna.
• Action: Extends the elbow (straightens the arm).

Study Recommendations

• Use flashcards for origin, insertion, and actions of muscles.
• Familiarize with models and/or visual aids.

Exam Preparation Tips

• Review all muscle actions and anatomical locations.
• Engage with class resources such as quizzes or instructor availability for questions.
• Remember to balance study time with breaks and inquiries.