Pectoral Region, Breast, Axilla Flashcards
Jugular notch
Notch in between the elevated sternal ends
Clavicle
Elongated, S-shaped bone that rests horizontally at the sternum across the upper part of the ribcage and the acromial end of the scapula
Sternal angle
- Synarthrotic joint formed by the articulation of the manubrium and the body of the sternum
- Also known as transverse thoracic plane
*Palpable clinical landmark in surface anatomy.
Sternum
Long flat bone over central chest
Xiphoid process
Smallest, most inferior part of sternum
Scapula
Triangle-shaped shoulder blade
Acromion process
Bony process of the scapula that extends laterally over the shoulder joint
Coracoid process
Small hook-like structure on the lateral edge of the superior anterior portion of the scapula
Medial pectoral nerve(s)
Supplies:
- Pectoralis minor + pectoralis minor
Origin:
- Medial cord
Lateral pectoral nerve(s)
Supplies:
- Pectoralis major
Origin:
- Lateral cord of brachial plexus
Anterior cutaneous nerves
Superior neurovasculature supplying skin/cutaneous aspects anteriorly
*changes planes
What does the thoracoacromial artery supply?
Supplies:
- Deltoid
- Pectoralis major
- Pectoralis minor
- Subclavius
Cephalic vein
- Superficial vein of UE
- Ascends into SC tissue
- Goes up lateral border of wrist + anterolateral surface of forearm + arm
- Passes between deltoid + pectoralis muscles
- Enters clavipectoral triangle
- Pierces costocoracoid membrane (part of clavipectoral fascia)
- Enters axillary vein
Subclavian vein
Right below subclavius muscle
*Brachial vein –> axillary vein (at inferior teres major border) –> subclavian vein (at lateral part of 1st rib)
Subclavius (origin + insertion)
Origin:
Junction + costocartilage of 1st rib
Insertion:
Inferior surface of mid third of clavicle
Nipple
Protuberance of breast through which lacteriferous ducts open
Areola
Circular pigmented area surrounding the nipple
Lactiferous ducts
- Ducts that converge + form branched system connecting the nipple to the lobules of the mammary gland
- Move milk to nipple by smooth muscle contractions along the ductal system
Pectoralis fascia
- Thin lamina covering the surface of pectoralis major
- Attachment to front of sternum, to the clavicle, + is continuous with fascia of the shoulder, axilla, + thorax
What is the retromammary space?
- Loose connective tissue plane between breast + pectoral fascia
- Allows for mobility of breast
What would a tumor in the retromammary space typically present as?
Immobility of the breast
Suspensory (Cooper’s) ligaments (of breast)
- Firmly attach mammary glands to dermis of overlying skin
- Help support mammary gland lobules
- Prevent breast from sagging
Axillary process (tail) of breast
Extension of mammary gland in the superolateral quadrant
Breast cancer is most common in which quadrant?
Upper outer (left or right)
What symptom presents when breast cancer interferes with the dermal lymphatics?
- Lymphedema in skin of breast
What is the most common site of metastasis in breast cancer?
Axillary lymph nodes
Orange-peel appearance of breast
Results from puffy skin between dimpled pores of breast in inflammatory breast cancer
Name common changes in appearance of breast due to presence of cancer
- Skin dimpling/retraction
- Orange-peel appearance
- Nipple retraction/deviation
- Abnormal contours
Mammary glands are what type of glands?
Modified sweat glands (apocrine)
Lactiferous sinus
Dilated area of the duct just deep to the areola
Terminal duct lobular unit (TDLU)
- Basic functional unit of breast
- Is the lobule
Polymastia
Supernumerary breast appearing as rudimentary nipple with underlying glandular tissue along milk line
Mammary ridges (milk lines)
- Origin of breast development
- Along either side of the body from axilla to inguinal canal
- Site of polythelia & polymastia
Polythelia
Supernumerary nipples (mistaken for moles)
Where does most lymphatic drainage of the breast go?
Most to axillary lymph nodes (75%)
Where does most breast lymph first drain to?
Pectoral (anterior) nodes
Where does lymph from medial breast typically drain to?
Parasternal lymph nodes or to opposite breast
Arterial supply of the breast
- Internal mammary artery (IMA)
- Lateral thoracic artery
Mediolateral oblique (MLO) view
- Superior top
- Inferior bottom
Craniocaudal (CC) view
- Lateral top
- Medial bottom
Pectoralis major (origin + insertion)
Origin:
- Clavicular head: Anterior surface of medial 1/2 of clavicle
- Sternocostal head: Anterior surface of sternum, costal cartilages 2-6, aponeurosis of external abdominal oblique muscle
Insertion:
- Lateral lip of intertubercular groove of the humerus
Pectoralis major (function + innervation)
Function:
- Flex arm
- ADduct arm
- Medial rotation of arm (in climbing, draws body upward)
Innervation:
- Lateral pectoral nerve
- Medial pectoral nerve
(C8, T1)
Pectoralis minor (origin + insertion)
Origin:
- Anterior aspect of the 3rd, 4th, and 5th ribs
Insertion:
- Coracoid process of the scapula
Pectoralis minor (function + innervation)
Function:
- Protract scapula
Innervation:
- Medial pectoral nerve (C8, T1)
Where is a pacemaker typically inserted?
- Infraclavicular area parallel to middle 1/3 of clavicle
- Subcutaneous pocket typically superficial to pectoralis major
Bony boundaries of axillary apex (cervicoaxillary canal)
- Clavicle (ant)
- Superior border of scapula (post)
- Lateral border of 1st rib (medial)
Boundaries of axillary fossa
- P. major, p. minor, clavipectoral fascia (ant)
- Scapula, subscapularis, t. major, lat. dorsi (post)
- Ribs 1-4, Intercostal muscles, serratus anterior (medial)
Where does the subclavian artery become the axillary artery?
Lateral border of 1st rib
Where does the axillary artery become the brachial artery?
Inferior border of teres major muscle
Name the branches of the axillary artery
First:
- Superior thoracic artery
Second:
- Thoraco-acromial
- Lateral thoracic artery
Third:
- Subscapular
- Anterior circumflex humeral
- Posterior circumflex humeral
What muscles does the axillary artery pass posterior to?
Pectoralis minor
What are the four branch of the thoraco-acromial artery?
1) Clavicular
2) Acromial
3) Deltoid
4) Pectoral
*Cadavers Are Dead People
How many lobes does the typical inactive adult mammary gland have?
15-20
Common sites of breast implant placement
- Subglandular position (on surface of the muscle but behind the gland)
- Sub muscular positon (behind Pectoralis major attachment is attached
- Bi plane implantation (below pectoralis major muscle but also in plane with the superficial fascia)
What incisions can be made for breast implant placement?
- Periareolar
- Inferior mammary fold (IMF)
- Transaxillary
What are the cells inside of mammary glands?
- Glandular cuboidal cells (produce milk)
- Myoepithelial cells (can contract and squeeze aveoli)
- Stromal cells (plasma produces IgA)
What 2 nerves does the subscapular nerve branch into?
- Thoracodorsal
- Circumflex scapular
