Michael Chung, MD Assistant Professor Cardiothoracic Radiology Mount Sinai World Congress of Thoracic Imaging June 2017 Disclosures There are no disclosures pertinent to this presentation Mount Sinai Department of Radiology Introduction • The chest wall muscular anatomy is an aspect of chest CT that can be often overlooked by the cardiothoracic radiologist • Goals: • Review the normal chest wall anatomy on CT • Highlight the common normal variations in chest wall anatomy and shape • Focus on a few conditions which may distort the normal anatomy • Review common chest wall surgeries, including their indications and imaging appearance on CT Mount Sinai Department of Radiology 16 1 8 / 4 14 15 9 11 KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Sternocleidomastoid (16) 2. Pectoralis minor 11. Deltoid • Divides neck into anterior and posterior triangles 3. Subscapularis 12. Serratus Anterior • Will often see a portion of the SCM as it attaches to its 4. Teres Major 13. Rhomboid origin on the manubrium 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae • Platysma 7. Infraspinatus 16. Sternocleidomastoid • Not visualized here, but can be seen on chest CTs as a 8. Latissimus Dorsi 17. Rectus Abdominis broad sheet of thin muscle covering the anterior neck 9. Trapezius Mount Sinai Department of Radiology 1 8 / 4 14 15 11 13 9 NOTES: KEY: 1. Pectoralis major 10. Long Head of Triceps • Deltoid (11) 2. Pectoralis minor 11. Deltoid • Largest shoulder muscle, will commonly see on chest 3. Subscapularis 12. Serratus Anterior CTs with patient’s arms elevated 4. Teres Major 13. Rhomboid • Innervated by the axillary nerve (C5-6) 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae • Levator Scapulae (15) 7. Infraspinatus 16. Sternocleidomastoid • Connects pectoral girdle to the cervical spine (originates 8. Latissimus Dorsi 17. Rectus Abdominis on C1-4 transverse processes) 9. Trapezius Mount Sinai Department of Radiology 1 2 3 8 4 12 5 14 7 13 6 11 10 9 NOTES: KEY: • Teres Major (4) 1. Pectoralis major 10. Long Head of Triceps • Will often be confluent with the latissimus dorsi (8) 2. Pectoralis minor 11. Deltoid 3. Subscapularis 12. Serratus Anterior • Assists in medial shoulder rotation and shoulder 4. Teres Major 13. Rhomboid adduction 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae • Teres Minor (5) 7. Infraspinatus 16. Sternocleidomastoid • Part of the rotator cuff, assists in external rotation 8. Latissimus Dorsi 17. Rectus Abdominis • Can be difficult to differentiate with infraspinatus in 9. Trapezius younger, thinner patients Mount Sinai Department of Radiology 1 2 8 3 12 4 5 14 7 13 6 10 9 11 KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Supraspinatus (6) 2. Pectoralis minor 11. Deltoid • The most commonly ruptured rotator cuff muscle 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid • Can degenerate in elderly patients leading to instability 5. Teres Minor 14. Erector Spinae in the glenohumeral joint 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid • Infraspinatus (7) 8. Latissimus Dorsi 17. Rectus Abdominis • Assists in laterally rotating the arm 9. Trapezius • Innervated by suprascapular nerve (C5 and C6) Mount Sinai Department of Radiology 1 2 8 4 3 5 14 7 6 10 13 9 NOTES: • Pectoralis Major (1) KEY: • Covers much of the anterior chest, inserts on the lateral 1. Pectoralis major 10. Long Head of Triceps lip of the bicipital groove of the humerus 2. Pectoralis minor 11. Deltoid 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid • Pectoralis Minor (2) 5. Teres Minor 14. Erector Spinae • Divides the axillary artery into 3 parts 6. Supraspinatus 15. Levator Scapulae • Divides axillary lymph nodes into levels 7. Infraspinatus 16. Sternocleidomastoid • I: below inferior edge of p. minor 8. Latissimus Dorsi 17. Rectus Abdominis • II: underneath/posterior to p. minor 9. Trapezius • III: above/medial to p. minor Mount Sinai Department of Radiology 1 2 8 3 7 14 9 10 NOTES: 13 • Rhomboid (13) • Q uadrilateral shaped, helps retract scapula KEY: 1. Pectoralis major 10. Long Head of Triceps • Innervated by dorsal scapular nerve, injury can lead to a 2. Pectoralis minor 11. Deltoid winged scapula 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid • Long Head of Triceps (10) 5. Teres Minor 14. Erector Spinae • Arises from infraglenoid tubercle of the scapula 6. Supraspinatus 15. Levator Scapulae • Extends distally anterior to the teres minor and posterior 7. Infraspinatus 16. Sternocleidomastoid to the teres major 8. Latissimus Dorsi 17. Rectus Abdominis • Acts in extending forearm; long head stabilizes humeral 9. Trapezius head in abduction Mount Sinai Department of Radiology 1 8 3 4 7 14 9 13 KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Erector Spinae (14) 2. Pectoralis minor 11. Deltoid • From lateral to medial: 3. Subscapularis 12. Serratus Anterior • Iliocostalis 4. Teres Major 13. Rhomboid • Longissimus 5. Teres Minor 14. Erector Spinae • Spinalis 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius Mount Sinai Department of Radiology 1 8 4 3 7 9 KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Subscapularis (3) 2. Pectoralis minor 11. Deltoid • Part of the rotator cuff 3. Subscapularis 12. Serratus Anterior • Inserts on the lesser tuberosity of the humerus and 4. Teres Major 13. Rhomboid assists in internal rotation 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius Mount Sinai Department of Radiology 8 4 3 7 9 KEY: NOTES: 1. Pectoralis major 10. Long Head of Triceps • Trapezius (9) 2. Pectoralis minor 11. Deltoid • Diamond shaped, superficial muscle of the posterior 3. Subscapularis 12. Serratus Anterior neck/back 4. Teres Major 13. Rhomboid • I nnervated by CN XI (accessory nerve) 5. Teres Minor 14. Erector Spinae • Acts to elevate, rotate and retract the scapula 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius Mount Sinai Department of Radiology 8 4 7 9 KEY: 1. Pectoralis major 10. Long Head of Triceps 2. Pectoralis minor 11. Deltoid 3. Subscapularis 12. Serratus Anterior 4. Teres Major 13. Rhomboid 5. Teres Minor 14. Erector Spinae 6. Supraspinatus 15. Levator Scapulae 7. Infraspinatus 16. Sternocleidomastoid 8. Latissimus Dorsi 17. Rectus Abdominis 9. Trapezius Mount Sinai Department of Radiology 8 12 4 8 14 KEY: 1. Pectoralis major 10. Long Head of Triceps NOTES: 2. Pectoralis minor 11. Deltoid • Latissimus Dorsi (8) 3. Subscapularis 12. Serratus Anterior • Assists in adduction, internal rotation, and extension of 4. Teres Major 13. Rhomboid the glenohumeral joint 5. Teres Minor 14. Erector Spinae • Innervated by thoracodorsal nerve 6. Supraspinatus 15. Levator Scapulae • Important to preserve this nerve in surgical flaps 7. Infraspinatus 16. Sternocleidomastoid involving the lattisimus 8. Latissimus Dorsi 17. Rectus Abdominis • Arises from posterior cord of brachial plexus 9. Trapezius Mount Sinai Department of Radiology 8 12 KEY: 1. Pectoralis major 10. Long Head of Triceps NOTES: 2. Pectoralis minor 11. Deltoid • Serratus Anterior (12) 3. Subscapularis 12. Serratus Anterior • Draws scapula anteriorly against chest wall 4. Teres Major 13. Rhomboid • Consists of 8 interdigitations of muscles 5. Teres Minor 14. Erector Spinae • Originates from ribs 1-8 and inserts on medial border of 6. Supraspinatus 15. Levator Scapulae scapula 7. Infraspinatus 16. Sternocleidomastoid • Innervated by the long thoracic nerve 8. Latissimus Dorsi 17. Rectus Abdominis • Injury to this nerve results in winged scapula 9. Trapezius Mount Sinai Department of Radiology 17 12 8 KEY: 1. Pectoralis major 10. Long Head of Triceps NOTES: 2. Pectoralis minor 11. Deltoid • Rectus Abdominis (17) 3. Subscapularis 12. Serratus Anterior • Paired muscles separated by the linea alba 4. Teres Major 13. Rhomboid • Attaches to the costal cartilages of ribs 5-7 and the 5. Teres Minor 14. Erector Spinae xiphoid process of the sternum 6. Supraspinatus 15. Levator Scapulae • Dual blood supply from the superior and inferior 7. Infraspinatus 16. Sternocleidomastoid epigastric vessels 8. Latissimus Dorsi 17. Rectus Abdominis • Can be used for muscle flaps in the chest 9. Trapezius Mount Sinai Department of Radiology 17 12 8 KEY: 1. Pectoralis Major 1. Long Head of Triceps 2. Pectoralis minor 2. Deltoid 3. Subscapularis 3. Serratus Anterior 4. Teres Major 4. Rhomboid 5. Teres Minor 5. Erector Spinae 6. Supraspinatus 6. Levator Scapulae 7. Infraspinatus 7. Sternocleidomastoid 8. Latissimus Dorsi 8. Rectus Abdominis 9. Trapezius Mount Sinai Department of Radiology Variant Anatomy: Sternalis • Muscle band extending from the jugular notch to the inferior aspect of the sternum • Lies adjacent to the medial edge of the pectoralis major • Can be mistaken for a pathologic lesion • Found in ~5% of the population Mount Sinai Department of Radiology Variant Anatomy: Sternalis • Muscle band extending from the jugular notch to the inferior aspect of the sternum • Lies adjacent to the medial edge of the pectoralis major • Can be mistaken for a pathologic lesion • Found in ~5% of the population • Often seen on mammography • Typically visible in the medial aspect of the breast on cranio-caudal (CC) view Mount Sinai Department