10.1 Muscles of the Upper Limb and Scapula

Overview of Upper Limb Muscles

• The upper limb muscles are complex and differ from the lower limb.

• Important for movements involving the shoulder and elbow joints.

Scapula Movements

• Movements largely depend on muscle contractions.

• Stabilization occurs with simultaneous muscle contraction.

• Isolated contractions lead to specific scapula movements.

Key Muscles Moving the Scapula

• Trapezius:

  • Origin: Occipital bone, C1-7, T1-12

  • Functions: Elevates, depresses, and retracts scapula

• Serratus Anterior:

  • Origin: Ribs 1-9

  • Functions: Protracts and stabilizes scapula

• Levator Scapulae:

  • Origin: C1-4

  • Functions: Elevates scapula

• Rhomboids (Major & Minor):

  • Functions: Stabilizes, retracts, and elevates scapula

• Pectoralis Minor:

  • Origin: Ribs 3-5

  • Functions: Stabilizes, protracts, and depresses scapula

Sequential Scapula Movements

• Superior Rotation: Upper trapezius, lower trapezius, serratus anterior

• Inferior Rotation: Rhomboids, levator scapulae, pectoralis minor

Upper Limb Muscle Groups

• Muscles for shoulder movement insert on the humerus; for elbow movement, on ulna/radius.

• Muscles categorized as flexors (ventral) or extensors (dorsal).

Rotator Cuff Muscles

• Crucial for the stability and movement of the humerus:

  • Supraspinatus: Abducts humerus

  • Infraspinatus: Laterally rotates humerus

  • Teres Minor: Laterally rotates humerus

  • Subscapularis: Medially rotates humerus

Muscles Moving the Humerus

• Pectoralis Major: Adduction and flexion/extension of humerus

• Latissimus Dorsi: Extends, rotates, and adducts humerus

• Teres Major: Adducts and extends humerus

• Deltoid: Abducts humerus

Synergists and Antagonists

• Synergists: Latissimus dorsi, pectoralis major, and teres major (for adduction)

• Antagonists: Latissimus dorsi and pectoralis major (in flexion/extension)