shoulder muscles

Question 1

What is the origin, insertion, and action of the Trapezius?

Answer 1

Origin: Occipital bone, nuchal ligament, spinous processes of C7–T12
Insertion: Lateral third of clavicle, acromion, spine of scapula
Action: Elevates, retracts, depresses, and rotates scapula

The Trapezius is a major muscle of the upper back and neck, involved in various shoulder movements.

Question 2

What is the origin, insertion, and action of Levator Scapulae?

Answer 2

Origin: Transverse processes of C1–C4
Insertion: Superior angle and medial border of scapula
Action: Elevates scapula, tilts glenoid cavity downward

The Levator Scapulae plays a crucial role in lifting the shoulder blade.

Question 3

What is the origin, insertion, and action of Rhomboid Major?

Answer 3

Origin: Spinous processes of T2–T5
Insertion: Medial border of scapula (below spine)
Action: Retracts and elevates scapula

Rhomboid Major aids in retracting the shoulder blades towards the spine.

Question 4

What is the origin, insertion, and action of Rhomboid Minor?

Answer 4

Origin: Nuchal ligament, spinous processes of C7–T1
Insertion: Medial border of scapula at the spine
Action: Retracts and elevates scapula

The Rhomboid Minor assists in stabilizing the scapula.

Question 5

What is the origin, insertion, and action of Serratus Anterior?

Answer 5

Origin: Lateral surface of ribs 1–8
Insertion: Anterior surface of medial border of scapula
Action: Protracts and stabilizes scapula, assists upward rotation

Serratus Anterior is essential for movements such as pushing.

Question 6

What is the origin, insertion, and action of Pectoralis Minor?

Answer 6

Origin: Ribs 3–5
Insertion: Coracoid process of scapula
Action: Depresses and protracts scapula

The Pectoralis Minor helps in movements that pull the shoulder forward and downward.

Question 7

What is the origin, insertion, and action of Subclavius?

Answer 7

Origin: First rib and costal cartilage
Insertion: Inferior surface of clavicle
Action: Anchors and depresses clavicle

Subclavius protects the underlying structures such as nerves and blood vessels.

Question 8

What is the origin, insertion, and action of Deltoid?

Answer 8

Origin: Clavicle, acromion, spine of scapula
Insertion: Deltoid tuberosity of humerus
Action:
* Anterior: flexion
* Middle: abduction
* Posterior: extension

The Deltoid is a key muscle for shoulder movement.

Question 9

What is the origin, insertion, and action of Supraspinatus?

Answer 9

Origin: Supraspinous fossa of scapula
Insertion: Superior facet of greater tubercle of humerus
Action: Initiates abduction (first 15°), stabilizes shoulder joint

Supraspinatus is part of the rotator cuff, crucial for shoulder stability.

Question 10

What is the origin, insertion, and action of Infraspinatus?

Answer 10

Origin: Infraspinous fossa of scapula
Insertion: Middle facet of greater tubercle of humerus
Action: Laterally rotates arm, stabilizes shoulder joint

Infraspinatus plays a vital role in shoulder rotation.

Question 11

What is the origin, insertion, and action of Teres Minor?

Answer 11

Origin: Lateral border of scapula
Insertion: Inferior facet of greater tubercle of humerus
Action: Laterally rotates arm, stabilizes shoulder joint

Teres Minor assists in lateral rotation of the arm.

Question 12

What is the origin, insertion, and action of Subscapularis?

Answer 12

Origin: Subscapular fossa of scapula
Insertion: Lesser tubercle of humerus
Action: Medially rotates arm, stabilizes shoulder joint

Subscapularis is also part of the rotator cuff, critical for shoulder function.

Question 13

What is the origin, insertion, and action of Teres Major?

Answer 13

Origin: Inferior angle of scapula
Insertion: Medial lip of intertubercular groove of humerus
Action: Adducts and medially rotates arm

Teres Major assists in bringing the arm closer to the body.

Question 14

What is the origin, insertion, and action of Pectoralis Major?

Answer 14

Origin: Clavicle, sternum, costal cartilages of ribs 1–6
Insertion: Lateral lip of intertubercular groove of humerus
Action: Adducts, flexes, and medially rotates arm

The Pectoralis Major is a large muscle involved in many upper body movements.

Question 15

What is the origin, insertion, and action of Latissimus Dorsi?

Answer 15

Origin: Spinous processes of T7–L5, iliac crest, thoracolumbar fascia
Insertion: Floor of intertubercular groove of humerus
Action: Extends, adducts, and medially rotates arm

Latissimus Dorsi is crucial for pulling movements and contributes to the V-shape of the back.