Shoulder Joint:Anatomy,Movement & Muscle involvement

The shoulder is made up of three bones- the clavicle, the scapula, and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones make up the shoulder joints. It is a ball and socket type of synovial joint.Shoulder Joint bones

Movements of the shoulder joints

  • Flexion
  • Extension
  • Abduction
  • Adduction
  • Medial Rotation
  • Lateral Rotation
  • Circumduction

Flexion

Flexion-upper limb forwards in the sagittal plane.
Muscles involvement in flexion: pectoralis major, coracobrachialis, biceps brachii, anterior fibers of deltoid.

Extension
Extension-upper limb backward in the sagittal plane.
Muscles involvement in extension:latissimus dorsi, long head of triceps, teres major and posterior fibers of the deltoid

Abduction
Abduction-upper limb away from the midline in the coronal plane.
Muscles involvement in abduction: supraspinatus (initiates abduction of first 15 degrees), deltoid (up to 90 degrees), trapezius and serratus anterior muscle (scapular rotation, for abduction beyond 90 degrees).

Adduction
Adduction-upper limb towards midline in the coronal plane.
Muscles involvement in adduction: pectoralis major and minor, latissimus dorsi, teres major, gravity (depending on the body position), and even the lowest fibers of the deltoid (making deltoid its own antagonist)

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Medial Rotation
Medial Rotation-rotation towards the midline, so that the thumb is pointing medially.
Muscles involvement in medial rotation: subscapularis, latissimus dorsi, teres major, pectoralis major, anterior fibers of the deltoid

Lateral Rotation
Lateral Rotation -rotation away from the midline, so that the thumb is pointing laterally.
Muscles involvement in lateral rotation: infraspinatus and teres minor, posterior fibers of deltoid

Circumduction
Circumduction-Combination of all movements.
Muscles involvement in circumduction: pectoralis major, subscapularis, biceps brachii, coracobrachialis, supraspinatus, deltoid, teres major and minor, latissimus dorsi, infraspinatus, long head of triceps