Exam 3: Muscles of the Shoulder & Pectoral Girdle

What group of muscles attaches the upper extremity to the axial skeleton?

Pectoral Girdle

What muscles make up the Pectoral Girdle?

• Deltoid

• Serratus Anterior

• Pectoralis Major

• Pectoralis Minor

• Coracobrachialis

• Subclavius

Identify this muscle:

Deltoid

Deltoid Origin:

lateral 1/3 of the clavicle, acromion, and spine of the scapula

Deltoid Insertion:

deltoid tuberosity of the humerus

Deltoid Action(s):

abduction of the GH joint

What nerve is the Deltoid innervated by?

Axillary Nerve

Identify this muscle:

Serratus Anterior

Serratus Anterior Origin:

external surface of the upper 8 or 9 ribs

Serratus Anterior Insertion:

anterior surface of the medial border of the scapula

Serratus Anterior Action(s)—there are four:

• abduction

• upward rotation and depression of the scapula

• holds the medial border of the scapula against the ribs

• protraction of the scapula

What nerve is the Serratus Anterior innervated by?

Long Thoracic Nerve

Identify this muscle:

Pectoralis Major

Pectoralis Major Origin:

medial ½ of the clavicle, sternum, and cartilage of the 1-6 ribs

Pectoralis Major Insertion:

crest of the greater tubercle of the humerus

Pectoralis Major Action(s) of all the fibers—there are three:

• addduction

• internal rotation of the GH joit

• elevation of the thorax while breathing

Pectoralis Major Action(s) of the upper fibers—there are two:

• flexion of the GH joint

• horizontal adduction of the GH joint

Pectoralis Major Action(s) of the lower fibers—there is one:

extension of the GH joint

What nerve is the Pectoralis Major innervated by?

Pectoral Nerve

Identify this muscle:

Pectoralis Minor

Pectoralis Minor Origin:

3-5th ribs

Pectoralis Minor Insertion:

medial surface of the coracoid process of the scapula

Pectoralis Minor Action(s)—there are four:

• depresses the scapula

• abducts the scapula

• downward rotation of the scapula

• assist in elevation of the thorax while breathing when the scapula is fixed

What nerve is the Pectoralis Minor innervated by?

Pectoral Nerve