MUSCLES, MAMMARY GLANDS, CROSS-SECTION THORACIC WALL MUSCLES, MAMMARY GLANDS, CROSS-SECTION

THORACIC WALL MUSCLES

Surface Muscles (Anterior) Platysma Pectoralis major Pectoralis minor Subclavius Serratus anterior Refer in syllabus: Table 1, pp 47-49 Figure 13, p 50

Surface Muscles (Posterior) Latissimus dorsi Trapezius Rhomboideus major Rhomboideus minor Refer in syllabus: Table I; pp 47-9

Deltopectoral Triangle Boundaries: Anterior border of the deltoid. Superior border of the pectoralis major. Middle third of the clavicle.

Deltopectoral Triangle Contents: Cephalic vein. Deltopectoral lymph nodes. Deltoid branch of the thoracoacromial artery.

Clavipectoral Fascia Invests subclavius and pectoralis minor. Attached to clavicle and anterior thoracic wall. Pierced by: Cephalic vein Thoracoacromial artery Lateral pectoral nerve Become suspensory ligament of the axilla.

THORACIC WALL STRUCTURE (x.s.) Refer to Figure 15, p. 60 in syllabus as well as background material on pp 58-59.

MAMMARY GLAND

Mammary Glands Modified sweat glands 15-20 lobes Lobes separated by fibrous septa Lactiferous duct (1 per lobe) Lactiferous sinus (ampulla): Dilation as duct enters nipple

Mammary Glands Fibrous tela subcutanea: Fatty tela subcutanea: Connective tissue layer surrounding the entire gland. Fatty tela subcutanea: Adipose tissue deep to fibrous layer. Suspensory ligament of Cooper: Bundles of collagen fibers in dermis and hypodermis.

Mammary Glands Breast extends from 2nd-3rd rib superiorly to 6th-7th costal cartilage inferiorly. Extends from lateral border of sternum to beyond the anterior axillary fold.

Mammary Glands Retromammary space: Sinus mammarumis: Space between the gland and the pectoralis major muscle. Sinus mammarumis: Space between the two glands.

Mammary Gland Arteries Anterior perforating arteries: From internal thoracic artery To medial part of gland Medial mammary rami: From 2nd - 4th anterior perforating arteries To deep medial part of gland

Mammary Gland Arteries Lateral mammary artery: From lateral thoracic artery. To inferior part of gland. Lateral mammary rami: From lateral cutaneous branches of intercostal arteries. To lateral part of the gland.

Mammary Gland Veins Superficial and deep venous plexuses drain into internal thoracic, lateral thoracic, and intercostal veins.

Mammary Gland Nerves Lateral mammary nerve: T2-T6 Anterior branch of lateral cutaneous branch of intercostal nerves. Medial mammary nerve: Lateral branch of anterior cutaneous branch of intercostal nerves.

Mammary Gland Lymphatics Perilobular and interlobular lymphatic vessels: Into: Subareolar plexus: Lateral lymphatic trunk: From lateral and superior gland Medial lymphatic trunk: From medial and inferior gland

Mammary Gland Lymphatics Lateral lymphatic trunk and Medial lymphatic trunk: Into: Pectoral group of axillary lymph nodes: Subclavian lymphatic channels

Mammary Gland Lymphatics Accessory lymphatic drainage: Periphery of gland drains into apical group of axillary nodes and follows thoracoacromial trunk. Circumareolar channels drain into sternal chain.

THORACIC WALL LYMPHATICS

Lymphatic Drainage Subareolar plexus of nodes Axillary lymph nodes: Receive from: Superficial tissues, skin, breast, extrinsic limb muscles. Include: Pectoral group Lateral group Apical group Subscapular group

Lymphatic Drainage Infraclavicular nodes Parasternal nodes Abdominal nodes

MECHANICS OF RESPIRATION

Inspiration: “Bucket Handle” Involves contraction of intercostal muscles Results in raising of ribs Results in an increase in the lateral dimensions of the thoracic cage.

Inspiration: “Pump Handle” Results from raising of sternum Results in increase in anteroposterior dimensions of thoracic cage

Abdominal Breathing Results from lowering of diaphragm: Phrenic nerve Necessary when: Infant Costal cartilages are calcified

Expiration Mostly passive