Anatomy Thoracic Wall and Mediastinum PDF

ANATOMY Thoracic Wall, Mediastinum, and Breast Block 2 Alfred Philip De Dios, MD | September 10, 2023...

ANATOMY Thoracic Wall, Mediastinum, and Breast Block 2 Alfred Philip De Dios, MD | September 10, 2023 Trans 2.01 OVERVIEW I. Thoracic Cage B. Anterior Mediastinum B. Surface Landmarks A. Function C. Middle Mediastinum B. Surface Landmarks D. Posterior Mediastinum Lines of the Chest Significance of Wall Compartments Anterior Chest Wall III. Breast Lines A. Mammary Gland Lateral Chest Wall Surface Anatomy Lines Types of Breasts C. Bony Components B. Nipple-Areolar Complex Superior Aperture Areola Sternum Nipple Figure 2. Surface landmarks of the thoracic cage. Ribs C. Nipple Abnormalities Source: Doc AP’s PPT Typical Ribs E. Breast Support Atypical Ribs F. Blood Supply Palpable bony landmarks and reference lines Joints Venous Drainage II. Mediastinum G. Innervation ○ For anatomic orientation A. Superior Mediastinum H. Lymphatic Drainage ○ Guide to locate deep structures LEARNING OBJECTIVES Table 2. Surface landmarks of the thoracic cage. Identify important surface landmarks in the chest Surface Landmark Definition Identify the bony and muscular components of the thoracic Separates the neck from the thorax Clavicle cage Located superiorly Explain the chest wall movement Where the two clavicles meet Suprasternal notch Identify pertinent surface landmarks of the breast Superior border of the sternum Discuss anatomy and significance of the parts of the breast Indication of the 2nd rib Sternal angle Reference point for physical examination I. THORACIC CAGE Horizontal line across the nipple Nipple line T4 level posteriorly Inferior border of the sternum and thorax at the midline Xiphoid process For orientation of probes during heart ultrasound Palpable margin oblique to the xiphoid process Costal margin Corresponds to the costal cartilages of 7th-10th ribs Landmark for interventional lung Intercostal spaces procedures Figure 1. Thoracic cage. Source: Doc AP’s PPT Lines of the Chest Wall Thoracic cage is made up of: ○ Anteriorly: Sternum ○ Posteriorly: Thoracic vertebrae (12)[2027 trans] 12 pairs of ribs with their costal cartilage ○ Connects the sternum and the thoracic vertebrae These bony structures delineates the extent of the thorax Clavicle and Scapula (pectoral girdle bones) ○ Attached to the thorax Widest diameter: T7 level; due to: ○ Anterior curving of the sternum ○ Kyphosis of thoracic spine Figure 3. Lines of the anterior (L) and lateral (R) chest wall (1: Anterior A. Function axillary; 2: Mid-clavicular; 3: Mid-sternal). Table 1. Functions of the thoracic cage. Source: Doc AP’s PPT Protection Breathing Correlated with the surface landmarks for better localization Protects vital structures of a particular structure or finding Lungs, heart, heart great Bones and muscle vessels, esophagus, and Responsible for creating a trachea negative pressure that is Partial protection of some organs required in respiration in the abdominal cavity Liver, stomach, spleen Page 1 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN,  ANA 2.01 Thoracic Wall and Mediastinum Anterior Chest Wall Lines Sternum Table 3. Anterior chest wall lines. Definition Vertical line along the axillary fold Marks the lateral border of the anterior Anterior axillary chest line Separates the anterior and lateral chest wall Vertical line midpoint to the clavicle Medial to the nipple Midclavicular line Landmark for access to subclavian vessels Line that runs through the midpoint of Midsternal line the sternum Figure 5. Sternum. Source: Moore’s Clinically Oriented Anatomy (8th version) Separates the left and right chest Initially composed of four separate bones that fuses during Lateral Chest Wall Lines adolescence Table 4. Lateral chest wall lines. Consists of the: Definition ○ Manubrium Anterior axillary Anterior border of the lateral chest wall ○ Body line ○ Xiphoid process Runs from the apex (deepest part) of the Midaxillary line axillary fossa (armpit) Table 6. Components of the sternum. Posterior axillary Definition Posterior border of the lateral chest wall line Located superiorly Several notches C. Bony Components ○ Superior: Suprasternal/jugular Superior Aperture Manubrium notch ○ Lateral: Clavicular notch (clavicle attachment) Angle of Louis Junction of the manubrium and body 5 cm from the suprasternal notch Marks the attachment of the 2nd rib (highest rib that can be palpated) Sternal angle ○ Landmark for the identification and counting of the lower ribs At the level of the T4 vertebrae ○ Tracheal bifurcation Figure 4. Superior aperture (red border) ○ Beginning and end of the aortic Source: Doc AP’s PPT arch At the level of the T5-T9 vertebrae Thoracic inlet or outlet (depends on the orientation) Covers a significant portion of the Located superiorly mid-chest Kidney-shaped Body Very strong Serves as a passageway Contains a hematopoietic marrow ○ Structures from the neck to chest (lifetime) Carotid arteries ○ Site for bone marrow aspiration Jugular vein At the level of the T10 vertebrae ○ Structures from the upper extremity to chest Variable in length, shape, and structure Xiphoid process Subclavian vessels pass through the 1st rib and Cartilaginous (early life) to ossified clavicle (middle age) Table 5. Boundaries of the superior aperture. Location Boundary Anterior Manubrium Lateral 1st rib Posterior Body of T1 Page 2 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Ribs costovertebral joints ○ (1) Attached to its corresponding vertebrae ○ (2) Attached to the vertebrae above it Ex. 7th rib attaches to T7 and T6 Has a tubercle ○ With an articular facet Part of the costotransverse Neck joint between the rib and transverse process of the Figure 6. Ribs. vertebra Source: Doc AP’s PPT Angle ○ Start of the rib body Largest part of the bony wall of the chest ○ Greatest degree of rib curvature Numbered according to their vertebral attachment ○ Most posterior extent of the Length increases caudally until the 7th rib thoracic cage ○ After the 7th, length becomes progressively shorter ○ Aligns with the medial border of As the rib moves inferiorly as they come anteriorly, posterior the scapula rib level is higher Body Costal groove Costal cartilage length varies from 2cm (1st) to 10cm (7th ○ At the lower edge of the rib rib) ○ Where the intercostal vessels and the intercostal nerve run Table 7. Classification of ribs according to attachment. ○ VAN (superior to inferior) Definition Intercostal Vein 1st to 7th Intercostal Artery True ribs Directly attached to the sternum via Intercostal Nerve cartilaginous portion 8th to 10th Atypical Ribs False ribs Attaches to the costal cartilage of the rib above 11th and 12th ○ 12th not always present Floating ribs No anterior attachments End in the musculature of the lateral chest wall Typical Ribs Figure 8. Atypical rib (L: 1st rib; R: 2nd rib). Source: Doc AP’s PPT 1st, 2nd, 10th, 11th, 12th Table 9. Atypical ribs. Rib Definition Shortest, broadest, flatest, most angulated Very strong (fracture indicates that a significant force was applied to the chest) Figure 7. Typical rib. Head has only 1 facet Source: Doc AP’s PPT Anteromedial part 3rd to 9th rib 1st ○ Beneath the clavicle Curved, flattened bone Has grooves Parts: ○ For the subclavian artery and vein ○ Head ○ Passes between the clavicle and ○ Neck 1st rib ○ Body Prominence between the grooves ○ Attachment site for scalene Table 8. Components of a typical rib. muscles Definition 2nd No intercostal groove Has a slightly enlarged posterior end Head has only 1 facet Head 11 and 12 Normally has two hemi facets for No prominent transverse tubercle Page 3 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum ○ Why? It does not articulate with Table 11. Extrinsic Muscles the transverse process of the Neck Muscles vertebra Scalene Muscles No neck, no angle, no costal groove ○ Attached to the 1st rib ○ flexion of upper spine; lifting of ribs (during inspiration) Joints Sternocleidomastoid ○ Attached to the clavicle Figure 9. Joints of the thoracic cage. Source: Moore’s Clinically Oriented Anatomy (8th version) Figure 11. Muscles of the Neck Source: Lecturio Abdomen Muscles These compress the abdominal cavity thereby pushing the diaphragm upwards and increasing intrathoracic pressure = forced expiration. External oblique ○ Covers the eight lower ribs Internal oblique ○ Attaches to the lower three ribs Rectus abdominis ○ Inserts in the xiphoid process and the 5th-7th costal cartilages Figure 10. Costovertebral joints (right anterolateral aspect). Source: Prohealthsys Table 10. Joints of the thoracic cage. Joint Description Joint between the sternum and each costal cartilage Synovial joint ○ Allows movement Bones are not physically Sternocostal connected ○ Exception: Attachment of the 1st rib (synchondrosis joint) Enables chest to expand during inspiration Reinforced by sternocostal ligaments Joint between each costal cartilage and Costochondral their respective ribs Joint between ribs and vertebrae Costovertebral Figure 12. Muscles of the Abdomen Two attachments in typical rib Source: Britannica Joint between manubrium and clavicle Anterior Thoracic Wall Muscles Synovial joint: saddle type Synchondroses ⭐ Involved in the movement of the upper extremities; Sternoclavicular ○ Cause of immobility considered as auxiliary breathing muscles Only point where thoracic cage is Pectoralis major and Pectoralis minor attached to shoulder girdle ○ Lifts the chest Serratus anterior A. Muscular Components Extrinsic Muscles Thorax – supported by the muscles of the neck, shoulders, back, and abdominal wall Page 4 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Table 12. Intercostal muscles External Internal Innermost Oblique Similar in Inferoanterior Inferoposterior orientation: structure and orientation as Continuous External Internal internal with: oblique oblique intercostals Elevate the ribs (during Depress inspiration) Depress the the ribs Action: Spread out ribs (during (during medially to expiration) expiration) form an aponeurosis Figure 13. Anterior Thoracic Wall Muscles Source: Lecturio Posterior Thoracic Wall Muscles Increase thoracic volume and reinforce thoracic wall Trapezius Latissimus dorsi Serratus posterior Rhomboids Levator scapulae Figure 15. Intrinsic Muscles Source: Lecturio Transversus Thoracis Muscle Depresses the ribs (during expiration) Originates from the posterior aspect of the sternum to 2nd -6th costal cartilages Continuous with transversus abdominis muscle found inferiorly Figure 14. Muscles of the Back Source: Britannica Subcostalis Muscle Found at the inferior surface of the lower ribs and extends to Intrinsic Muscles the superior border of the rib 2 or 3 levels below it Intercostal Muscles Its fibers are parallel to the innermost intercostals (shares Attach ribs together the same action) ○ Attached to the inferior portion of the rib above and to the superior portion of the rib below B. Blood Supply Primary respiratory muscles Each intercostal space receives its blood supply from one ○ Responsible for expanding and decreasing the diameter posterior intercostal artery and two anterior intercostal of the thoracic cage arteries (3 arteries) wherein they link laterally forming Innervations: Intercostal nerves collaterals Oriented in different directions and counteract the movement of each other Table 13.1 Posterior Intercostal Arteries 11 pairs (for the eleven intercostal spaces) Posterior Intercostal Arteries ○ Arrangement from external to internal: Arise from two main vessels: External intercostal Subclavian artery supplies the 1st-2nd intercostal spaces Internal intercostal (costocervical trunk) Intercostal artery, vein, and nerve Descending aorta supplies the 3rd-7th intercostal spaces Innermost intercostal Drainage: azygos or hemiazygos veins Composed of three groups: ○ External intercostals Table 13.2 Anterior Intercostal Arteries ○ Internal intercostals Anterior Intercostal Arteries ○ Innermost intercostals Arise from two main vessels: Internal thoracic supplies the 1st-6th intercostal spaces Musculophrenic supplies the 7th-9th intercostal spaces Drainage: internal thoracic or musculophrenic veins Page 5 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum thymus regresses and may be entirely found in the II. MEDIASTINUM superior mediastinum. Central compartment in thoracic cavity Space between pleural cavities A. Superior Mediastinum Extends throughout entire length of thoracic cavity Functions as protective pathway for structures traversing from neck to abdomen Figure 18. Contents of Superior Mediastinum Source: Doc AP’s slides Posterior border: Extends from T1-T4 Figure 16. Blood Mediastinum Contains the following: Source: Kenhub ○ Major vessels supplying upper extremities, head, and Table 14. Borders of Mediastinum neck (e.g. subclavian and carotid vessels, brachiocephalic vein, subclavian vein, and jugular vein) Compartment Border ○ Thoracic duct Superior Thoracic inlet ○ Vagus , phrenic, cardiac, left recurrent laryngeal nerves Inferior Diaphragm ○ Note: Most lymphatic drainage in this region converges Lateral Pleura at the thoracic duct, which empties into the bloodstream Anterior Sternum at the left subclavian vein. Posterior Thoracic vertebrae ○ How to locate: Draw a line from the sternal angle; posteriorly to the junction of T4 or T5. Above this line is Transverse Thoracic Plane the superior mediastinum[2027 trans] ○ Important anatomical landmark that divides the mediastinum into superior and inferior compartment B. Anterior Mediastinum ○ Transverses through the sternal angle into the junction Border: extends from T4-T9 of T4-T5 Contains the following: ○ Lymphatic tissues ○ Parasternal lymph nodes C. Middle Mediastinum Border: extends from T4-T9 Contains the following: ○ Pericardial cavity ○ Roots of the great vessels D. Posterior Mediastinum Figure 17. Compartments of the Mediastinum Source: Doc AP’s slides Table 15. Compartments of the mediastinum Compartments of the Mediastinum Superior Inferior — Anterior Middle Posterior There are no physical barriers between compartments other than the pericardium. Note: In children, a substantial portion of the thymus is located in the anterior mediastinum. As individuals age, Figure 19. Sternal Angle of Posterior Mediastinum Source: Doc AP’s slides Page 6 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Surface Anatomy Posterior border: Extends from T5-T12 Contains the following: (Mnemonic: on the DATE, Vivian Slapped Larry) ○ Descending aorta ○ Azygos and hemiazygos veins ○ Thoracic duct (lower part) ○ Esophagus ○ Vagus nerve ○ Splanchnic nerves ○ Lymphatics (posterior mediastinal, prevertebral, retrocardiac and diaphragmatic lymph nodes) Very important area since this is where drainage from the neck goes Significance of Compartments Table 16. Significance of Mediastinum Compartments Figure 21. Surface Anatomy of the Female Breasts Compartment Significance Source: Doc AP’s slides Conduit space that serves as passageway for Superior structures from the neck and upper Extends from 2nd or 3rd rib to level of 6th or 7th rib extremities/thorax Extends medially from edge of the sternum, then laterally to Filled with connective and fatty tissues to anterior axillary line Anterior Defines the extent of dissection during breast surgeries protect the heart Middle Houses the heart and great vessels Tail of spence - superolateral extension of breast Serves as passageway of structures between Posterior thorax and abdomen III. BREAST Most distinguishing feature, paired organs of mammals Primary role: produce milk Secondary roles: ○ major female sexual characteristic ○ Key part of female body image Considered a specialized sweat gland. Located at the anterior chest wall and mainly supported by skin and connective tissues. Understanding vascular and lymphatic circulation will aid in the proper pathophysiologic analysis of breast diseases. Figure 22. Tail of Spence Sometimes, humans could have more than two breasts Source: NurseKey called a Supernumerary Breast. Intermammary cleft - breast cleavage A. Mammary Gland Figure 20. Mammary Gland Source: Doc AP’s slides Specialized sweat gland: apocrine More prominent in females Contains mostly fatty tissue Figure 23. Side View of Female Breast Source: Doc AP’s slides ○ Fibrocystic Breast Disease - lumpy breast tissue; very common finding among females in the second and third Breasts are located subcutaneously decade Rests on fascia of chest and abdominal muscle Made up of 15 to 25 lobes of glandular tissue, each ○ Pectoralis major emptying into a separate milk duct terminating in the nipple ○ Serratus anterior Produce milk; also the most common cause of cancer[2027 trans] ○ External oblique ○ Rectus abdominis Page 7 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Types of Breasts the area The size and shape of the breast vary with individual race Contains sweat and sebaceous glands and age. ○ Produces small elevations that you see at the surface of this structure Table 17. Types of Breasts and their Descriptions ○ Enlarge during pregnancy and secretes an oily substance Type Appearance that provides protective lubricant (Moore, 2017) ○ Montgomery glands - small elevations on the area of the areola (Batch 2027 trans) Secretes lubricants and pheromones to facilitate breastfeeding ⭐ Hemispherical Breasts Most common shape ○ Pheromones are for nursing a baby Nipple Greatest prominence of the breast (Moore, 2017) Found at center of the nipple-areolar complex Devoid of fat underneath Openings for the lactiferous ducts Tuberous Breasts Contains the following: Elongated Table 18. Structures of the Nipple-Areolar Complex Structures Function Sebaceous glands Lubrication Multiple sensory Stimulation nerve endings Pendulous Breasts Longitudinal Allow the nipple to be retracted Breasts look muscle “hanging” Nipple erection/ protrude More common in Circular muscle Compress the lactiferous ducts during obese and elderly lactation (Moore, 2017) C. Nipple Abnormalities Conical Breasts More evident in individuals with smaller breasts Figure 25. (Left) Flat nipples. (Right) Retracted nipples Source: Doc AP’s slides B. Nipple-Areolar Complex Although they do not appear normal, they still function properly Retracted nipples ○ May be a sign of malignancy ⭐ To differentiate physiologic to pathologic nipple retraction, stimulate the nipple. ○ Physiologic nipple - retracts normally ○ Pathologic nipple - doesn’t retract Figure 24. Nipple-areolar complex Source: Doc AP’s slides Areola Size and pigmentation varies Figure 26. Do not differentiate physiologic to pathologic nipple retraction ○ Under hormonal influence through this ○ Becomes evident when individual is pregnant Source: Doc AP’s slides (pigmentation at this time increases due to change in the balance of the female hormones) ○ Change in color makes it easier for the baby to visualize Page 8 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum D. Breast Support E. Blood Supply Figure 27. Transverse section of the breast. Source: Doc AP’s slides Develop within superficial fascia of anterior chest wall (subcutaneously) Lies between superficial and deep fascia Figure 29. Blood supply of mammary glands Source: Doc AP’s slides ○ Deep layer of the fascia lies on top of the pectoralis fascia and marks the posterior extent of dissection when Main blood supply removing the breast during surgery ○ ⭐ Breast is not attached to the deep fascia and hence, ○ Internal mammary artery - (60%) supplies the medial and inferior portions of the there is movement of the breast (Batch 2027 trans) breast Retromammary space The anterior perforating branches exit their ○ Between deep fascia and pectoralis fascia respective intercostal spaces approximately 2 cm ○ Allows the breast to move freely over the chest wall ○ ⭐ Where breast implants are placed during plastic laterally to the sternum 2nd and 3rd anterior perforating branches are surgery the most significant (Batch 2027 trans) Implants are not placed within the breast tissue, it’s ○ Lateral thoracic - (30%) placed behind the breast tissue (Batch 2027 trans) originates from the axillary artery, supplies the Linked by Cooper’s ligaments lateral and upper portions of the breast ○ Connective tissue that traverse the fats and separates ○ Intercostals - does not form collaterals the breast lobules Communicate with each other above and below the areola ⭐ Separates glandular structures (which are the origins ○ Branches from the internal mammary and lateral of breast cancer) (Batch 2027 trans) thoracic meet and form the collaterals around the areola ○ Help support the lobes and lobules of the mammary gland (Moore, 2017) Venous Drainage ○ Since they’re found near the lobules, any malignant Superficial tumor developing here can invade the ligaments causing ○ Transverse - (91%) internal mammary veins them to shorten ⭐ When that happens, the skin of the breast ○ Longitudinal - (9%) lower neck Deep appears to be like an orange rind called the Peau ○ Internal mammary d’orange. This is a sign of breast cancer Run medially in the subcutaneous tissues and join perforating vessels that empty into the internal mammary vein (Batch 2027 trans) ○ Axillary Ascend to the suprasternal notch and empty into the superficial veins of the lower neck (Batch 2027 trans) ○ Posterior intercostals Communicate with the vertebral veins and the azygos vein, which leads to the superior vena cava Figure 28. Peau D’orange Breast ⭐These are important hematogenous routes of metastasis (Batch 2027 trans) Source: Doc AP’s slides for breast cancer Page 9 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Important to know in order to understand the behavior of breast diseases, specifically on how they spread to the axillary nodes and beyond Lymphatics are found within the entire breast parenchyma Each glandular structure has their own individual drainage ⭐ ○ Used to determine whether early breast cancer has spread to the axillary lymph nodes through sentinel node biopsy 75% lymphatics drains to axillary nodes ○ Especially from the lateral quadrants (Moore, 2017) 25% drains to the parasternal then internal mammary nodes Figure 30. Venous Drainage Source: Doc AP’s slides ○ From the medial breast quadrants (Moore, 2017) F. Innervation Supplemental Information From Batch 2027 trans: Sentinel node biopsy ○ Used for breast cancer, melanoma ○ Checks if dissection of axillary area can be avoided ○ Dye is injected around tumor → Wait to see if any lymph node will light up or absorb the dye → Remove and examine lymph node (+): Already spread to regional drainage area (-): No axillary dissection Nonspecific Lymphadenopathy ○ Benign enlargement of axillary node especially in neck area ○ If no signs of infection, there is no need to dissect, just observe ○ But nodal enlargement doesn’t recede quickly (at Figure 31. Innervation of mammary glands least 6 weeks) Source: Doc AP’s slides Innervation comes from the lateral and anterior cutaneous REFERENCES branches of 2nd - 6th intercostal nerves (4th - 6th in Dr. Alfred Philip O. De Dios, MD. Notes from Thoracic Wall, Moore’s) Mediastinum, and Breast [NEOLMS] Anterior branch ○ Innervates the medial portion BOOKS Lateral branch Moore, K.L., Dalley, K.F., Agur, A.M. (2017) ○ 4th: most constant Supplies nipple in 93% of breasts SYNTHESIS ○ 2nd: intercostobrachial nerve ⭐ Responsible for the sensory perception of the Thoracic Wall, Mediastinum and Breast To apply the external anatomy of the breast in medial aspect of the upper arm ⭐ Often sacrificed in the course of doing surgery for identifying clinical issues Lines and levels of the thoracic wall, mediastinum, and breast cancer especially when the patient has large breast are utilized to identify damage in the underlying axillary nodes structures CASE 1 G. Lymphatic Drainage Figure 1. (Downward) Stab Wound to the left nipple Location: Midclavicular line, Nipple line, 4th ICS Structures affected: lungs, chest cavity CASE 2 Figure 32. Lymphatics drainage of the breast. Source: Doc AP’s slides Page 10 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum If there is any injury in this area, suspect an injury to the heart. Bordered by clavicle and coastal region CASE 6 Figure 2. (Upward Lateral) Stab Wound to the Middle of Chest Figure 6. Enlarged Breast Tissues Location: Midsternal line, Subxiphoid area Structures affected: Cardiac Injury, Diaphragm, Lungs, Asymmetry of breast caused by a tumor Major Vessels It is not an increase of breast tissue but presence of a Clinical Findings: increased breath sounds and decreased tumor that causes the swelling heart sounds, any abnormalities in heart rate In cases of malignant tumors, it can also invasion of the CASE 3 overlying skin CASE 7 Figure 3. Stab Wound to the Upper Middle of Chest Location: Superior Mediastinum, Midclavicular line Structures affected: Great vessels CASE 4 Figure 7. Swelling and Dimpling of skin of Right breast Presence of dimpling due to the shortening of the ligaments affected by the tumor Also called Peau D’Orange REVIEW QUESTIONS Figure 4. Stab Wound below the right nipple Thoracic Wall Location: Anterior axillary line, Subcostal margin Structures affected: Lungs (If stab direction is perfectly _____1. The sternum consists of the following EXCEPT: perpendicular with the skin), Liver and Diaphragm (if stab A. Xiphoid Process direction is angled down) B. Body TIP C. Manubrium D. Mediastinum _____2. It is the landmark for access to subclavian vessels A. Midsternal Line B. Midclavicular Line C. Midaxillary Line D. Anterior Axillary Line _____3. These are considered as auxiliary breathing muscles: A. Neck muscles B. Abdomen muscles C. Anterior thoracic wall muscles D. Posterior thoracic wall muscles Figure 5. Cardiac Box Area _____4. This marks the attachment of the 2nd rib and is the landmark for the identification and counting of the lower ribs: Page 11 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Surface landmarks of the thoracic cage. A. Nipple line Surface Landmark Definition B. Costal margin Separates the neck from the thorax C. Intercostal space Clavicle Located superiorly D. Sternal angle Where the two clavicles meet Suprasternal notch Superior border of the sternum Mediastinum Indication of the 2nd rib Sternal angle _____5.. Choose the correct association of mediastinum borders Reference point for physical examination to its contained anatomical part. Nipple line Horizontal line across the nipple A. Posterior: Thoracic Inlet Inferior border of the sternum and thorax B. Lateral: Diaphragm at the midline Xiphoid process C. Anterior: Sternum For orientation of probes during heart D. Superior: Pleura ultrasound Palpable margin oblique to the xiphoid _____6.Which mediastinum compartment serves as a process Costal margin passageway for structures from the neck and upper extremities? Corresponds to the costal cartilages of A. Superior 7th-10th ribs B. Anterior Intercostal spaces Landmark for interventional C. Middle D. Inferior Anterior chest wall lines. Definition Breast Vertical line along the axillary fold Marks the lateral border of the anterior Anterior axillary _____7.. What type of breast is evident in individuals with chest line smaller breasts? Separates the anterior and lateral chest A. Conical wall B. Hemispherical Vertical line midpoint to the clavicle C. Tuberous Medial to the nipple D. Pendulous Midclavicular line Landmark for access to subclavian vessels _____8. Everything is true about the Retromammary space Line that runs through the midpoint of EXCEPT: Midsternal line the sternum A. Allows the breast to move freely over the chest wall Separates the left and right chest B. Between deep fascia and superficial fascia C. Implants are placed behind the breast tissue Lateral chest wall lines. D. Where breast implants are placed during plastic surgery Definition Anterior axillary _____9. Which of the following is true? Anterior border of the lateral chest wall line A. The 4th lateral branch is usually sacrificed during Runs from the apex (deepest part) of the surgery of the breast cancer Midaxillary line axillary fossa (armpit) B. Sentinel node biopsy is used to detect late metastasis Posterior axillary of the breast cancer Posterior border of the lateral chest wall line C. Retracted nipples are always signs of breast cancer D. Orange peel-like appearance of the skin are signs of Posterior and Anterior Intercostal Arteries breast cancer Posterior Intercostal Arteries Arise from two main vessels: Subclavian artery supplies the 1st-2nd intercostal spaces ANSWER KEY: 1. D, 2. B, 3. C, 4. D, 5. C, 6. A, 7. A, 8. B, 9. D (costocervical trunk) Descending aorta supplies the 3rd-7th intercostal spaces Drainage: azygos or hemiazygos veins SUMMARY Anterior Intercostal Arteries Functions of Thoracic Cage Arise from two main vessels: Protection Breathing Internal thoracic supplies the 1st-6th intercostal spaces Protects vital structures Musculophrenic supplies the 7th-9th intercostal spaces ○ Lungs, heart, heart great vessels, Bones and muscle Drainage: internal thoracic or musculophrenic veins esophagus, and ○ Responsible for Significance of Mediastinum Compartments trachea creating a negative Partial protection of some pressure that is Compartment Significance organs in the abdominal required in respiration Conduit space that serves as passageway for cavity Superior structures from the neck and upper ○ Liver, stomach, spleen extremities/thorax Filled with connective and fatty tissues to Anterior protect the heart Page 12 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Middle Houses the heart and great vessels Serves as passageway of structures between Posterior thorax and abdomen FREEDOM WALL Figure 4. Superior aperture (red border). APPENDIX Figure 5. Sternum. Source: Moore’s Clinically Oriented Anatomy (8th version) Figure 1. Thoracic cage. Figure 7. Typical rib. Figure 2. Surface landmarks of the thoracic cage. Figure 8. Muscles of the Neck Source: Lecturio Figure 3. Lines of the anterior (L) and lateral (R) chest wall (1: Anterior axillary; 2: Mid-clavicular; 3: Mid-sternal). Page 13 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN  ANA 2.01 Thoracic Wall and Mediastinum Figure 9. Muscles of the Abdomen Source: Britannica Figure 13. Anterior Thoracic Wall Muscles Page 14 of 14 | TH: MARCELO, P. | AH TG 6 | LUCEÑO, MANALO, MANGULABNAN, MARASIGAN