Muscles of the Shoulder Girdle Posterior 

Muscles of the Shoulder Girdle Posterior 

 

The muscles of the posterior shoulder girdle include:

  • Supraspinatus

  • Infraspinatus

  • Subscapularis

  • Teres major

  • Teres minor

(Click on the thumbnails for a larger view)

anatomy-posterPectoral-shoulder-girdle-muscles

Helpful hints:

  • supraspinatus – (supra = above; spinatus = spine)
  • infraspinatus – (infra  = below)
  • subscapularis – (sub = deep; scapular = scapula)
  • teres major – (teres = round; major = larger)
  • teres minor – (teres = round; minor = lesser)

     The muscles of the shoulder girdle are extremely important for the diverse actions of the shoulder joint.  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 structural support must be accompanied by great muscle and ligamentous support in order to stay stable.  However, this lack of boney structural support allows a much wider range of motion than in the hip joint.

     The supraspinatus, infraspinatus, subscapularis, and teres minor compose the “rotator cuff muscle group.”  When an individual, usually an athlete, tears a muscle of this group it is often termed a ‘torn rotator cuff.’

Origin:

  • Supraspinatus – This muscle originates from the supraspinous fossa of the scapula.
  • Infraspinatus – This muscle originates from the infraspinous fossa of the scapula.
  • Suscapularis – This muscle originates from the subscapular fossa of the scapula.
  • Teres minor – This muscle originates from the lateral border of the scapula.
  • Teres major – This muscle originates from the lower 1/3 of the lateral border and inferior angle of the scapula.

Insertion:

  • Supraspinatus – This muscle inserts onto the greater tuberosity of the humerus.
  • Infraspinatus – This muscle inserts onto the greater tuberosity of the humerus.
  • Subscapularis – This muscle inserts onto the lesser tuberosity of the humerus.
  • Teres minor – This muscle inserts onto the greater tuberosity of the humerus.
  • Teres major – This muscle inserts onto the medial crest of the intertubercular groove of the humerus.  (Note: the inserting tendon of the teres major fuses with that of the latissimus dorsi.  Therefore, the two muscles share the same point of insertion.)

Action:

  • Supraspinatus – The action of this muscle includes shoulder joint abduction.
  • Infraspinatus – The action of this muscle includes shoulder joint extension, and lateral rotation.
  • Subscapularis – The action of this muscle includes shoulder joint extension, medial rotation, and adduction.
  • Teres minor – The action of this muscle includes shoulder joint extension, lateral rotation, and adduction.
  • Teres major – The action of this muscle includes shoulder joint, extension, adduction, and medial rotation. (These actions are also produced by the latissimus dorsi)

Charts:

anatomy-chart-Muscles_that_Position_the_Pectoral_Girdle-1

poster-chart-muscles-that-position-the-pectoral-girdle-posteriors

muscles-that-position-the-pectoral-girdle-posterior-view-chart

charts-muscles-that-position-the-pectoral-girdle-posterior




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