Pectoral Region and Breast

Question 1

platysma muscle

Answer 1

superficial muscle of neck

innervated by facial nerve

Question 2

cutaneous nerves

Answer 2

anterior = close to midline; or lateral = side of body
o Intercostal nerves – off anterior ramus from spinal ganglion to innervate costals, inferior
o Supraclavicular nerves – C3 and C4 over clavicle to superior thorax

Question 3

cephalic vein

Answer 3

drains into the axillary vein, comes from subclavian originating from right and left brachiocephalic trunks of the superior vena cava

Question 4

breast tissue

Answer 4

mammary gland, fat and fibrous tissue

Question 5

glandular breast tissue

Answer 5

parenchyma produces milk
 Axillary tail (of Spence) – prolongation of breast tissue that extends into axilla
 Lobes – drains into the ducts
 Lactiferous sinus – deep to nipple where small amount of milk can be stored
 Lactiferous duct – drains lobes to nipple
 Nipple – opening where milk can come out, where sinuses come out
 Areola – surround nipple, hyperpigmented, secretes lubrication during breastfeeding

Question 6

suspensory ligaments of cooper

Answer 6

support weight of breast, go through skin all the way back to retromammary fascia; cancer of these ligaments will cause a dimpling of the breast

Question 7

blood supply of breast

Answer 7

o Multiple sources of arterial supply and venous drainage
 Medial region – internal thoracic artery and vein
 Lateral region – lateral thoracic artery and vein, posterior intercostal arteries and veins
o Lymphatic drainage
 Medial region – parasternal
 Lateral region – axillary lymph nodes

Question 8

where do 60% of breast tumors occur?

Answer 8

upper outer quadrant

Question 9

pectoralis mahor

Answer 9

originiates at sternum, clavicle and costal margins
o Action - adduction, flexion and medial rotation of the shoulder joint
o Innervation - medial and lateral pectoral nerves
o Lateral just goes to pec major (over the top of minor, does not innervate)
o Insertion – humerus

Question 10

pectoralis minor

Answer 10

articulates at ribs 3-5 and coracoid process of scapula
o Action - depression of the scapula, and elevates ribs when scapula fixed
o Innervation - medial pectoral nerves – goes through pec minor

Question 11

lateral pectoral nerve

Answer 11

only innverates pec major, goes over top of minor

Question 12

medial pectoral nerve

Answer 12

innervates both pec major and pec minor

Question 13

serratus anterior

Answer 13

articulates at ribs 1-8 along midaxillary line to the scapula
o Action: upward rotation of the scapula
o Innervation: long thoracic nerve – prone to injury when breast surgery is done

Question 14

thoracoacromial artery

Answer 14

“PACD” divides into pectoral, acromial, clavicle and deltoid arteries; around/on top of pectoralis minor; originates from axillary artery

Question 15

lateral thoracic artery

Answer 15

travels with long thoracic nerve, along lateral thorax, innervates serratus anterior