Upper Extremity

Chapter 11: Upper Extremity

Learning Objectives

  • Define action, origin, and insertion of listed muscles

  • Articulate location of listed muscles

  • Describe relationships of muscles to other muscles and structures

  • Identify synonyms and antagonists for listed muscles

Muscles Acting on the Pectoral Girdle

1. Levator Scapulae

  • Action: Elevates and retracts (adducts) the scapula; inferiorly rotates the scapula; flexes neck to the same side when the scapula is fixed.

  • Origin: Transverse processes of C1-C4 vertebrae.

  • Insertion: Superior part of the medial border of the scapula.

2. Rhomboid Major

  • Action: Elevates and retracts (adducts) the scapula; inferiorly rotates the scapula.

  • Origin: Spinous processes of T2-T5 vertebrae.

  • Insertion: Medial border of the scapula.

3. Rhomboid Minor

  • Action: Same as rhomboid major.

  • Origin: Spinous processes of C7-T1 vertebrae.

  • Insertion: Medial border of the scapula near the spine.

4. Serratus Anterior

  • Action: Stabilizes, superiorly rotates, and protracts the scapula (prime mover of scapula protraction).

  • Origin: Ribs 1-8 (or 9).

  • Insertion: Medial border of the scapula.

5. Trapezius

  • Action:

    • Superior fibers: Elevate and superiorly rotate the scapula.

    • Middle fibers: Retract (adduct) the scapula.

    • Inferior fibers: Depress the scapula and superiorly rotate the scapula.

  • Origin: Occipital bone; ligamentum nuchae; spinous processes of C7 to T12.

  • Insertion: Clavicle; acromion process and spine of the scapula.

6. Pectoralis Minor

  • Action: Protracts and depresses the scapula.

  • Origin: Ribs 3-5.

  • Insertion: Coracoid process of the scapula.

Muscles Acting on the Arm at the Glenohumeral Joint

1. Deltoid

  • Origin: Acromial end of clavicle; acromion and spine of scapula.

  • Insertion: Deltoid tuberosity on humerus.

  • Action:

    • Anterior fibers: Flex and medially rotate the arm.

    • Middle fibers: Prime mover of arm abduction.

    • Posterior fibers: Extend and laterally rotate the arm.

2. Coracobrachialis

  • Origin: Coracoid process of scapula.

  • Insertion: Middle medial shaft of the humerus.

  • Action: Adducts and flexes the arm.

3. Pectoralis Major

  • Origin: Clavicular head: medial half of the clavicle; sternal head: sternum; cartilage of ribs 1-6.

  • Insertion: Lateral part of the intertubercular sulcus of humerus.

  • Action: Adducts, medially rotates, and flexes the arm (prime mover of arm flexion).

4. Latissimus Dorsi

  • Origin: Spinous processes of T7-T12; ribs 9-12; iliac crest; thoracolumbar fascia.

  • Insertion: Intertubercular sulcus of the humerus.

  • Action: Adducts, medially rotates, and extends the arm (prime mover of arm extension).

5. Teres Major

  • Origin: Inferior angle of scapula.

  • Insertion: Lesser tubercle of the humerus.

  • Action: Extends, adducts, and medially rotates the arm.

6. Supraspinatus

  • Origin: Supraspinous fossa of the scapula.

  • Insertion: Greater tubercle of the humerus.

  • Action: Abducts the arm.

7. Infraspinatus

  • Origin: Infraspinous fossa of the scapula.

  • Insertion: Greater tubercle of the humerus.

  • Action: Laterally rotates the arm.

8. Teres Minor

  • Origin: Upper dorsal lateral border of the scapula.

  • Insertion: Greater tubercle of the humerus.

  • Action: Laterally rotates the arm.

9. Subscapularis

  • Origin: Subscapular fossa of the scapula.

  • Insertion: Lesser tubercle of the humerus.

  • Action: Medially rotates the arm.

Muscle Compartments of the Upper Limb

1. Anterior Compartment

  • General Function: Flexes the shoulder or arm.

  • Key Muscles:

    • Biceps Brachii: Flexes and supinates forearm; long head also flexes arm.

    • Brachialis: Flexes forearm.

    • Brachioradialis: Flexes forearm.

2. Posterior Compartment

  • General Function: Extension of the arm.

  • Key Muscle:

    • Triceps Brachii: Primary extensor of the forearm; long head also extends and adducts the arm.

Forearm Muscle Layers

A. Anterior Forearm Muscles
1. Superficial Layer

  • Key Muscles:

    • Flexor Carpi Ulnaris: Flexes wrist and adducts hand.

    • Palmaris Longus: Weak wrist flexor.

    • Flexor Carpi Radialis: Flexes wrist and abducts hand.

    • Pronator Teres: Pronates the forearm.

2. Intermediate Layer

  • Key Muscle:

    • Flexor Digitorum Superficialis: Flexes wrist and 2nd-5th MP joints and PIP joint.

3. Deep Layer

  • Key Muscles:

    • Flexor Digitorum Profundus: Flexes wrist and 2nd-5th MP joints, PIP joints, and DIP joints.

    • Pronator Quadratus: Prime mover of forearm pronation.

B. Posterior Forearm Muscles
1. Superficial Layer

  • Key Muscles:

    • Extensor Carpi Radialis Longus: Extends wrist, abducts hand.

    • Extensor Carpi Radialis Brevis: Extends wrist, abducts hand.

    • Extensor Digitorum: Extends wrist and 2nd-5th MP joints, PIP joint, and DIP joint.

    • Extensor Carpi Ulnaris: Extends wrist, adducts hand.

C. Figures and Diagrams

  • Figures illustrating muscle locations, such as deltoid, teres major, and triceps brachii, enhance understanding of muscle anatomy and relations in the upper limb. Diagrams show interrelationships among the muscles, their origins, insertions, and actions

  • Figure 11.17b and 11.18a-d provide various views and examples of muscle groups and specific muscle actions.