Muscles of the Shoulder Girdle Anterior

Muscles of the Shoulder Girdle Anterior

 

The muscles of the anterior shoulder girdle include:

(Click on the thumbnails for a larger view)

anatomy-chart-muscles-that-position-the-pectoral-girdle-anterior-view-start.

Helpful hints:

  • deltoid – (delta = triangular)
  • pectoralis major – (pectus = chest; major = larger) Often called “The Pecs.”
  • pectoralis minor – (pectus = chest; minor = lesser)
  • serratus anterior – (serratus = saw)  A muscle with 8 or 9 ‘saw-like’ projections extending toward the anterior thorax via the ribs 1-8 (or 9).

     The muscles of the shoulder girdle are extremely important for the diverse actions of the shoulder.  As you think of the activities of our daily lives, the shoulder joint and associated muscles, bones, and ligaments undergo a wide variety of contortions in order to produce the activities we desire. 

When compared to the pelvic girdle, the shoulder girdle has much less boney structure to give stability.  The lack of boney structure and support must be accompanied by great muscle and ligamentous support in order to stay stable.

     It must be noted that the deltoid (or deltoideus) muscle is not solely on the anterior portion of the shoulder.  This muscle encompasses the majority of the shoulder joint.  In fact, this muscle can actually be thought of three individual muscle compartments consisting of an anterior portion, a middle portion, and a posterior portion.  Therefore, when studying most movements at the shoulder joint it is important to include the action of the deltoid muscle.

Origin: 

  • Deltiod – This muscle originates from the clavicle, and the acromion process and spine of the scapula.
  • Pectoralis major – This muscle originates from the clavicle, the sternum, and cartilages of ribs 1-7.
  • Pectoralis minor – This muscle originates from ribs 3-5.
  • Serratus anterior – This muscle originates from ribs 1-8 (or 9).

Insertion:

  • Deltoid – This muscle inserts onto the deltoid tuberosity of the humerus.
  • Pectoralis major – This muscle inserts onto the lateral crest of the intertubercular groove of the humerus.
  • Pectoralis minor – This muscle inserts onto the coracoid process of the scapula.  (Note: Do not confuse the corocoid process of the scapula with the coroniod process of the ulna.)
  • Serratus anterior – This muscle inserts onto the entire medial border of the scapula.

Action:

  • Deltoid – The action of this muscle includes shoulder joint abduction, flexion, extension, medial and lateral rotation.  (Note: action does not include adduction)
  • Pectoralis major – The action of this muscle includes shoulder joint flexion, adduction, and medial rotation.  (May also aid in shoulder extension if beginning from a flexed position)
  • Pectoralis minor – The action of this muscle includes glenoid cavity depression; or elevation of ribs 3-5.
  • Serratus anterior – The action of this muscle includes abduction of the scapula, and elevation of the glenoid cavity.

download-videosand charts

anatomy-chart-Muscles_that_Move_the_Humerus

anatomy-chart-Shoulder-girdle-muscles-diagram.

anatomy-chart-shoulder

anatomy-chart-Muscles_that_Position_the_Pectoral_Girdle

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