Thorax: Breast Flashcards
Anterior Axillary Line
- Vertical line through anterior axillary fold
Posterior Axillary Line
- Vertical line through posterior axillary fold
Midaxillary Line
- Vertical line midway between the anterior and posterior axillary lines
Anterior Median Line
- Vertical line down the midline
Midclavicular Lines
- Parasagittal vertical lines through midpoint of the clavicle
Breast
- Accessory reproductive organ
- Glandular tissue embedded in fat (connective tissue)
- Located in the superficial fascia
- Anterior to deep fascia
- Located from mid-axillary line to sternum, ribs 2-6
- Axillary process (tail of Spence)
Areola
- Pigmented area of skin
Montgomery Tubercles
- Sebaceous glands located in areola
Nipple
- Lacks hair, fat, and sweat glands
- Smooth muscle
- Fissured by lactiferous duct openings
Retromammary Space
- Between the superficial and deep fascia
- Allows for breast movement on pectoral fascia
Glandular Tissue
- 15-20 lobes of glandular tissue (parenchyma of the breast)
- Each lobe contains 20-40 terminal ductal lobular units
Terminal Ductal Lobular Unit (TDLU)
- Each lobe drained by a lactiferous duct
- Supported by suspensory ligaments (of Cooper)
- Form fibrous septa, anchored to skin and deep fascia
Lactiferous Sinus
- Dilated portion of duct
Parenchyma
- Refers to functional tissue of an organ (breast in this case)
Medial Breast Arterial Supply
- Perforating branches of internal thoracic artery (medial mammary arteries)
Lateral Breast Arterial Supply
- Superior thoracic artery (lateral mammary arteries)
- Lateral thoracic artery (lateral mammary arteries)
- Pectoral branch of thoracoacromial artery
Anterior and Posterior Intercostal Arteries
- Mammary branches
Cutaneous Innervation of Breast
- 2nd – 6th Intercostal nerves
- Lateral & anterior branches
- Nipple is supplied by 4th intercostal nerve (ventral ramus of T4)
Lymph Nodes of the Breast
- Axillary lymph nodes
- Anterior (pectoral) nodes
- Posterior (subscapular) nodes
- Central nodes
- Apical nodes
- Parasternal nodes
- Interpectoral nodes
Axillary Lymph Nodes
- Anterior (pectoral) nodes
- Posterior (subscapular) nodes
- Central nodes
- Apical nodes
Lymph Drainage
- Axillary pathway: 75% of lymph
- Axillary nodes (anterior axillary nodes)
- Can bypass the axillary nodes and drain directly - Internal thoracic pathway(mammary) to the parasternal lymph nodes
- Can communicate with lymph vessels of the opposite breast - Retropectoral and Transpectoral pathways
- Subdiaphragmatic pathway
Tumors
- Can invade through retromammary space and deep fascia
- Breast fixation
Shortened Suspensory Ligaments
- Skin dimpling and nipple retraction
Pectoral Fascia
- Covers anterior and posterior of pectoralis major
becomes axillary fascia (floor of axilla)
Clavipectoral Fascia
- Attaches to clavicle
- Envelopes subclavius and pectoralis minor muscles - Pierced by cephalic vein, thoracoacromial artery, lateral pectoral nerve
- Called suspensory ligament of axilla below pec minor
- Connects to and supports axillary fascia
Anterior Axio-Appendicular Muscles
- Connect the pectoral girdle and humerus to the axial skeleton
- Primarily function in moving the pectoral girdle and humerus
Move the Pectoral Girdle and Humerus
- Pectoralis major
- Pectoralis minor
- Subclavius
- Serratus anterior
Pectoralis Major
- 2 heads
- Forms anterior axillary fold
Proximal Attachment of Pectoralis Major
- Medial ½ clavicle, anterior sternum, upper 6 costal cartilages, aponeurosis of external oblique muscle
Distal Attachment of Pectoralis Major
- Lateral lip of intertubercular sulcus
Pectoralis Major Innervation
- Lateral and medial pectoral nerves
Pectoralis Major Function
- Adduct, medial rotation, flexion and extension of humerus
Aponeurosis
- Flat tendon that part of the muscle attaches to
Flexion vs. Extension
- Muscle can act both ways depending on body position in gravity
Pectoralis Minor
- Deep to pec major
- Important landmark (axillary artery, brachial plexus)
- Subcoracoid space
Subcoracoid Space
- Brachial plexus, axillary vessels
Proximal Attachment of Pectoralis Minor
- Ribs 3-5
Distal Attachment of Pectoralis Minor
- Coracoid process
Pectoralis Minor Innervation
- Medial pectoral nerve
Function of Pectoralis Minor
- Stabilize scapula, pulls against thoracic wall (lateral angle moves inferiorly)
- Accessory muscle of respiration
Proximal Attachment of Subclavius
- 1st rib/costal cartilage jxn
Distal Attachment of Subclavius
- Inferior, middle 1/3 of clavicle
Innervation of Subclavius
- Nerve to subclavius
Function of Subclavius
- Stabilize SC joint, depress clavicle
Serratus Anterior
- Boxer’s muscle
- Scapula protractor
Proxima Attachment of Serratus Anterior
- Lateral aspect of ribs 1-8 (9)
Distal Attachment of Serratus Anterior
- Anterior surface of medial scapular border
Innervation of Serratus Anterior
- Long thoracic nerve
Function of Serratus Anterior
- Scapular protraction and rotation, stabilizes against thorax
Long Thoracic Nerve Injury
- Branch of the brachial plexus
- This nerve has a superficial location
- Injured in: mastectomy, knife injury, chest tube
Causes of Long Thoracic Nerve Injuries
- Weakness or paralysis of serratus anterior
Effects of Long Thoracic Nerve Injuries
- Winging of the scapula
- Difficulty with arm elevation (abduction)
Winging of Scapula
- Medial border of scapula will no longer be against thorax and will stick out toward the back
