Breast, Pec, and Axillary Flashcards Preview

Anatomy Mini 1 > Breast, Pec, and Axillary > Flashcards

Flashcards in Breast, Pec, and Axillary Deck (29):

Sternal Angle (Angle of Louis)

Junction of the second rib with sternum at the levels of T4 & T5, and the second d costal cartilages


Sections of the sternum

Manubrium, body, Xiphoid process


Deltoid Fascia

Descends from clavicle, acromion, and scapular spine

Continuous with pectoral fascia anteriorly, infraspinous fascia posteriorly


Pectoral Fascia

Descends from clavicle and sternum, investing pectoralis major

Becomes axillary fascia laterally


Clavicopectoral Fascia

Descends from clavicle. Encloses subclavius and pectoralis minor.

Continuous with axillary fascia


Axillary Fascia

Continuation of pectoral fascia.

Forms the floor of the axilla.


Muscles of the pectoral region

- Pectoralis major
- Pectoralis minor
- Subclavius
- Serratus Anterior


Pectoralis major: Origin, insertion, Innervation, action

Origin: Clavicular head- anterior surface of medial clavicle. Sternocostal end- anterior surface of sternum and superior six costal cartilages.

Insertion: lateral lip of inter tubercular sulcus

Innervation: lateral and medial pectoral nerve.

Action: both adduct and medially rotate humerus. Clavicular head- flexes humerus. Sternocostal head- extends humerus from a flexed position


Pectoralis minor: origin, insertion, Innervation, action

Origin:Ribs 3-5 near costal cartilages.

Insertion: Coracoid process

Innervation: medial pectoral nerve

Action: stabilizes scapula by drawing it inferiorly against thoracic wall


Subclavius: Origin, insertion, Innervation, action

Origin: junction of the 1st rib and costal cartilage

Insertion: inferior, middle clavicle

Innervation: nerve to subclavius

Action: anchors and depressed clavicle


Serratus anterior: Origin, insertion, Innervation, action

Origin: lateral parts of the 1st-8th ribs

Insertion: anterior surface of medial border of scapula

Innervation: log thoracic nerve

1. Protracts scapula
2. Holds scapula against thoracic wall
3. Superior rotation of scapula.


Nerves of pectoral region

Median and lateral nerves are named for where they come off of brachial plexus. Not their anatomical position.

- Long Thoracic nerve (C5-C7)(laterally)
- Lateral pectoral nerve (C5-C7)(anteriorly)
-Medial pectoral nerve (C8-T1)(anteriorly)(pierces pec minor to reach pec major)


Fracture of clavicle

Medial fragment will be elevated due to sternocleidomastoid.

Lateral fragment will be depressed (weight of arm) and addicted and pulled medially (pec major)


Contents of the axilla: within &outside awry sheath

Within: axillary artery and branches, axillary veins and tributaries, brachial plexus (cords and branches)

Outside: axillary lymph nodes and lymphatic vessels, axillary fat


Subclavian artery

Arises from brachiocephalic trunk on right side and directly from aorta on left.

Becomes axillary artery at lateral border of first rib


Axillary artery: Boundaries and parts

Boundaries: superior- lateral border of 1st rib. Inferior- inferior border of teres major (becomes brachial artery)

Divided into 3 parts:
-1st rib and medial border of pec minor
-medial border to lateral border of pec minor
-lateral border of pec minor to inferior border of teres major


1st part of axillary artery

Between 1st rib and pec minor.
Enclosed within axillary sheath.

Has only 1 branch: superior thoracic artery


2nd part of Axillary artery

Posterior to pec minor (medial border to lateral border)

2 branches:
- Thoracoacromial artery (divides into 4 branches: Clavicular, Acromial, Deltoid, and Pectoral)
- Lateral thoracic artery


3rd part of axillary artery

Lateral border of pec minor to inferior border of teres major.

3 branches:
- Posterior circumflex humeral
- Anterior circumflex humeral
- Subscapular (2branches: Circumflex scapular and Thoracodorsal)


Cephalic vein

Superficial, subcutaneous vein of lateral aspect of upper limb.

Travels through deltopectoral groove, pierces clavipectoral fascia at deltopectoral triangle, feeds into axillary vein.


Axillary vein

Formed by union of brachial and basilic veins. Becomes subclavian vein at lateral border of 1st rib


External female breast

Tissue typically extends transversely from lateral border of sternum to midaxillary line and vertically from 2nd to 6th ribs


Polymastia, polythelia, amastia, gynecomastia

Polymastia: accessory breast
Polythelia: accessory nipples
Amastia: no breast development
Gynecomastia: breast in males


Vasculature of breast (arteries)

(Veins follow arteries)

Lateral thoracic - gives mammary branches.

Posterior intercostal- gives art branches from lateral cutaneous branches.

Internal thoracic-gives medial mammary branches from anterior intercostal arteries


Nerves of breast

Anterior and lateral cutaneous branches of 4th to 6th intercostal nerves.

Nipple sits at T4 dermatome


Lymphatic drainage of breast

From nipple, areola and lobules to subareolar plexus. >75% goes to axillary lymph. Parasternal lymph collects medially. Subdiaphragmatic lymph collects inferiorly.

Important in metastasis of cancer


Axillary lymph nodes

3 sets of lymphs form base (humeral- lateral, Subscapular- posterior, pectoral- anterior, closest to breast). All drain into central lymph --> drain into apical lymph.


Presentation of breast cancer

-Invades glandular tissue: large dimples, shortening of suspensory ligaments.

- interference with lymph drainage: lymphadema (excess fluid in subcutaneous space), Peau d'orange (orange peel appearance).

-invades lactiferous ducts (retraction of nipple, shortened ducts)

- invades retro mammary space (breast elevates when muscle contracts)


Breast cancer surgery

Lumpectomy- usually followed by radiation.

Mastectomy- breast excision if tumor larger than 5cm (simple, modified radical, radical)