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
Descends from clavicle, acromion, and scapular spine
Continuous with pectoral fascia anteriorly, infraspinous fascia posteriorly
Descends from clavicle and sternum, investing pectoralis major
Becomes axillary fascia laterally
Descends from clavicle. Encloses subclavius and pectoralis minor.
Continuous with axillary fascia
Continuation of pectoral fascia.
Forms the floor of the axilla.
Muscles of the pectoral region
- Pectoralis major
- Pectoralis minor
- 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
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)
- 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.
- Posterior circumflex humeral
- Anterior circumflex humeral
- Subscapular (2branches: Circumflex scapular and Thoracodorsal)
Superficial, subcutaneous vein of lateral aspect of upper limb.
Travels through deltopectoral groove, pierces clavipectoral fascia at deltopectoral triangle, feeds into 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)