Muscles of pectoral girdle

Muscles of Pectoral Girdle

Overview

  • The muscles of the pectoral girdle are essential for stabilizing and positioning the shoulder joint.

  • They facilitate the movements of the arm.

  • Divided into two groups: anterior muscles (front of the thorax) and posterior muscles (back of the thorax).

Anterior Muscles

Subclavius

  • Location: Anterior thorax.

  • Function: Stabilizes the clavicle by pushing it downward (depression).

  • Origin: First rib.

  • Insertion: Underside of the clavicle.

Pectoralis Minor

  • Location: Anterior thorax.

  • Function: Rotates the shoulder forward (important for throwing) and assists with inhalation.

  • Movement: Affects the scapula by moving it down; elevates ribs.

  • Origin: Anterior surfaces of ribs 2-4 or 3-5.

  • Insertion: Coracoid process of the scapula.

Serratus Anterior

  • Location: Anterior thorax.

  • Function: Moves the arm from the side of the body to the front; assists with inhalation.

  • Movement: Protracts scapula and elevates ribs.

  • Origin: Muscle slips from ribs 1-8 or 1-9.

  • Insertion: Anterior surface of the scapula's vertebral border.

Posterior Muscles

Trapezius

  • Location: Posterior thorax.

  • Function: Elevates shoulders (shrugging), pulls shoulder blades together, and tilts head backward.

  • Movement: Affects scapula and cervical spine by retracting, elevating, and extending the spine.

  • Origin: Skull and vertebral column.

  • Insertion: Acromion and spine of the scapula; clavicle.

Rhomboid Major

  • Location: Posterior thorax.

  • Function: Stabilizes shoulder blade (scapula) during pectoral girdle movement.

  • Movement: Retracts and rotates scapula downward.

  • Origin: Thoracic vertebrae (T2-T5).

  • Insertion: Medial border of the scapula.

Rhomboid Minor

  • Location: Posterior thorax.

  • Function: Also stabilizes shoulder blade during movement.

  • Movement: Retracts and rotates scapula downward.

  • Origin: Cervical and thoracic vertebrae (C7 and T1).

  • Insertion: Medial border of the scapula.

Table of Muscles That Position the Pectoral Girdle

  • Provides an overview of the primary muscles, their movements, origins, and insertions.

  • Highlights their roles in the stabilization and movement of the shoulder.

Importance

  • These muscles provide vital stability to the pectoral girdle.

  • They enable a wide range of movements in the arm and shoulder, facilitating various physical activities and tasks.

Additional Resource

  • Recommended video: "Shoulder (Pectoral) Girdle - Muscles and Movements" available through the provided link.