Muscles of the pectoral girdle PART ONE (dave's notes)

Question 1

List the muscles of the pectoral girdle

Answer 1

Pec major
Pec minor
Sublavius
Trapezius
Lat dorsi
Rhom major
Rhom minor
Levator scapulae
Serratus anterior

Question 2

What is the origin of pec major?

Answer 2

Clavicular head from the medial 1/2 of the clavicle, sternocostal head from lateralmanubrium and sternum, six upper costal cartilages and external oblique aponeurosis

The muscle folds on itself with clavicular fibres lowest and sternal fibres highest

Question 3

What is the insertion of pec major?

Answer 3

The lateral lip of bicipital groove of the humerus, and the anterior lip of the deltoid tuberosity

Question 4

What is the action of pec major

Answer 4

clavicular head flexes and abducts arm, sternal head adducts and medially rotates the arm

Question 5

What is the nerve to pec major?

Answer 5

The medial? pectoral nerve (med cord) and the lateral pectoral nerve (lat cord)

Question 6

What is the origin and insertion of pec minor?

Answer 6

The anterior aspect of ribs 3,4,5 to the medial and upper surface of the coracoid process of the scapula

Question 7

What is the action of pec minor? innervation?

Answer 7

Elevates the ribs if scapular fixed.

The medial? pectoral nerve (med cord) and the lateral pectoral nerve (lat cord) - i.e. same as pec major

Question 8

What is pec minor a landmark for?

Answer 8

The axillary artery and cords of the plexus

Question 9

What is the origin and insertion of subclavius?

Answer 9

Subclavius originates from the costochondral origin of the first rib and inserts into the subclavian groove in the inferior surface of the middle 1/3rd of the clavicle

Question 10

What is the action and innervation to subclavius?

Answer 10

Depresses and steadies the clavicle. Nerve to subclavius (C5,6, upper trunk).

Question 11

What is the origin of trapezius?

Answer 11

medial 1/3rd to the superior nuchal line, ligamentum niche, spins process, and supraspinous ligaments to T12

Question 12

What is the insertion of trapezius?

Answer 12

the upper fibres are to the lateral 1.3rd of the posterior border of the clavicle, medial acromion, and the lateral spine of the scapula. Th slower fibres to medial end of scapula spine and as far as the deltoid tuberositie spine?
Migrates in during development

Question 13

What is the action of trapezius?

Answer 13

Elevates and retracts the scapula. Rotates it during abduction of the arm. If the scapula is fixed it extends and laterally flexes the neck

Question 14

What is the nerve supply to trapezius?

Answer 14

Spinal root of accessory nerve XI. Spinal nerve C3,4 for proprioception.