Anterior Chest Wall Anatomy PDF

Anterior Chest Wall Bi-Hung Peng, PhD Department of Neurobiology  Topics Surface Anatomy & Reference lines Bony landmarks Vertebra anatomy Rib cage anatomy Breast – Normal and abnormal Anatomy Pectoral Wall – Muscles, nerves, vessels & function Surface Anatomy of Anterio...

Anterior Chest Wall Bi-Hung Peng, PhD Department of Neurobiology  Topics Surface Anatomy & Reference lines Bony landmarks Vertebra anatomy Rib cage anatomy Breast – Normal and abnormal Anatomy Pectoral Wall – Muscles, nerves, vessels & function Surface Anatomy of Anterior Thoracic Wall  Lines of reference mid-sternal - mid-clavicular - subcostal - Axillary Lines axilla Anterior axillary line Mid-axillary line Posterior axillary line Back (posterior) Lines Scapular lines Posterior median line Thoracic Skeleton Modified from Netter (2003), Plates 174 & 178  Thoracic Skeleton (Anterior View) 1 Manubrium 2 3 true ribs (1-7) Sternum Body 4 Ribs (12) Xiphoid 5 process 6 7 11 floating 8 floating 12 9 False ribs (8-10) 10 Modified from Netter (2003), Plate 178  T1 T1 T7 T7  Thoracic Skeleton Mid-Thoracic Rib (Posterior View) Articular facets Neck for vertebral body Ribs 3-9 Tubercle Inferior costal Superior costal facet facet All other ribs articulate with only their own vertebral body. Head Articular facet for transverse process Modified from Netter (2003), Plate 179 Thoracic Skeleton Mid-Thoracic Vertebra (Superior and Left Lateral Views) Transverse costal facet Superior costal facet Inferior costal facet Modified from Netter (2003), Plate 147 Anterior chest wall - male Anterior chest wall - female Anterior chest wall – female Surface Anatomy Mammallary crease areola nipple areolar glands (of Montgomery) Female breast Female breast  Female breast - blood supply SubclavianArtery Axillary Artery Lateral thoracic Internal thoracic (mammary)  Female breast - lymphatic Axillary Nodes Parasternal Abdominal Clavicular Nodes Receives lymph from axillary & parasternal nodes. Dumps into large veins in neck  Physical findings on breast exam. Anatomical Basis Lump –cyst, fibrocystic disease, mass Dimpling – injury/inflammation, mass Retracted nipple – injury/inflammation, mass, congenital (10% of females have inverted nipples as a normal condition) Peau d‘ orange – lymphatic blockage Warmth/Redness – pregnancy, menstrual cycle, inflammation Less mobile – injury, implant, muscular development Lump - mass Dimpling – suspensory ligaments Dimpling Retracted Nipple – lactiferous ducts Peau d’ orange – obstruction of lymphatics Warm – Vascular signs Detection of breast cancer Breast quadrants: percentage of malignant tumors  “Milk Line” Polymastia – supernumerary breasts Polythelia – supernumerary nipples Gynecomastia – male breasts (feminization) Pectoralis Major  Pectoralis Major Origin: Deltoid Clavicular The clavicular head medial head half of the clavicle Insertion: The sternocostal head  The bicipital groove of the humerus anterior surface of the sternum, sternocoastal head superior six costal cartilages, aponeurosis of external oblique muscle Cephalic vein  Proximal Attachment Distal Attachment Muscle Innervation Main Actions (Origin) (Insertion) Clavicular head: anterior surface of medial half of clavicle Lateral and medial Adducts and medially rotates Crest of greater humerus at shoulder joint pectoral nerves; Sternocostal head: anterior tubercle of clavicular head (C5 Acting alone: clavicular head Pectoralis major surface of sternum, superior six intertubercular and C6), flexes shoulder joint, and costal cartilages sulcus (lateral lip of sternocostal head sternocostal head extends it from bicipital groove) Abdominal part: aponeurosis of (C7, C8, and T1) the flexed position external oblique muscle Deltopectoral triangle Clavicular head Sternocostal head Cephalic Vein (between pec minor and subclavius)  Cephalic Vein Pectoralis Major Serratus Anterior The pectoralis major receives dual motor innervation by the medial pectoral nerve and the lateral pectoral nerve, also known as the lateral anterior thoracic nerve.  P. Major Lateral pectoral nerve T1 T2 Median and ulnar nerve T3 P. Minor Thoraco epigastric vein T4 External intercostal T5 membrane  Deep Layer Muscle Proximal Attachment Distal Attachment Innervation Main Actions Medial border and 3rd–5th ribs in Medial and lateral Stabilizes scapula by drawing superior surface of Pectoralis minor midclavicular line near pectoral nerves (C6– it inferiorly and anteriorly coracoid process of their costal cartilages T1) against thoracic wall scapula Inferior surface of Anchors and depresses Junction of 1st rib and Nerve to subclavius Subclavius middle third of clavicle at sternoclavicular its costal cartilage (C5 and C6) clavicle joint External surfaces of Anterior surface of Protracts scapula and holds Long thoracic nerve Serratus anterior lateral parts of 1st to medial border of it against thoracic wall; (C5, C6, and C7) 8th–9th ribs scapula rotates scapula Anterior Thoracic Wall (Deep Dissection) Subclavius Pectoralis minor Long thoracic External nerve and lateral intercostals thoracic artery Internal intercostals Serratus anterior Modified from Netter (2003), Plate 183  Pectoralis Minor Muscle Clavipectoral fascia Neurovascular Bundle Thoracoacromial (a & v) Lateral Pectoral nerve Medial Pectoral nerve Cephalic vein Blood Supply & Innervation Thoracoacromial trunk Lateral pectoral n Medial pectoral n  Intercostal Muscles Superior Inferior Muscles Innervation Main Actiona Attachment Attachment During forced inspiration: External intercostal elevate ribsa Internal intercostalb Inferior border of Superior border Intercostal During forced respiration: ribs of ribs below nerve interosseous part depresses Innermost ribs; interchondral part intercostalb elevates ribsa b Internal and innermost intercostal muscles are essentially the same muscle: Muscle fibers passing superficial to the intercostal neurovasculature are “internal” and those passing deep to the neurovasculature are “innermost.” Muscles of Chest Wall deep pectoral region Pectoralis minor Axillary vessels Ribs Intercostal spaces Intercostal muscles costochondral junction Intercostal muscles external internal innermost costochondral junction  Internal intercostal External muscle intercostal A. Combination of movements with diaphragmatic excursion. The primary movement of inspiration is contraction of the diaphragm, which increases the vertical dimension of the thoracic cavity (arrows). B. Forced inspiration. The thorax widens during forced inspiration ( arrows). C. Forced expiration. The thorax narrows during forced expiration ( arrows).  Muscles of Respiration Inspiration Expiration Major Diaphragm (active contraction) Passive (elastic) recoil of lungs and thoracic cage Tonic contraction of muscles of anterolateral Tonic contraction of external Normal (Quiet) abdominal walls (rectus abdominis, external and intercostals and interchondral Minor internal obliques, transversus abdominis) to portion of internal intercostals to antagonize diaphragm by maintaining intraabdominal resist negative pressure pressure In addition to the above, active contraction of In addition to the above, active muscles of anterolateral abdominal wall contraction of sternocleidomastoid, (antagonizing diaphragm by increasing descending (superior) trapezius, intraabdominal pressure and by pulling inferiorly and pectoralis minor, and scalenes to fixing inferior costal margin): rectus abdominis, elevate and fix upper rib cage external and internal obliques, and transversus Active (Forced) abdominis External intercostals, interchondral portion of internal intercostals, Internal intercostal (interosseous part) and serratus subcostales, levatores costarum, and a posterior inferiora to depress ribs serratus posterior superior to elevate ribs Internal costal mm : intercartilagenous portion Questions?