Thoracic_Wall_1&_2_slides (1).pdf

Thoracic wall 1 & 2 Mr Fraser Chisholm [email protected] Where this fits: Anatomy Lectures Dissection Guided studies Thoracic Wall 1&2 Osteology of the thoracic cage Overview of the thoracic cage Thoracic cavity 1&2 Removal of the anterior thoracic wall Changes to circulation at birth...

Thoracic wall 1 & 2 Mr Fraser Chisholm [email protected] Where this fits: Anatomy Lectures Dissection Guided studies Thoracic Wall 1&2 Osteology of the thoracic cage Overview of the thoracic cage Thoracic cavity 1&2 Removal of the anterior thoracic wall Changes to circulation at birth Heart and pericardium Cross-sectional anatomy of the thorax Heart: internal structure and surface anatomy Surface anatomy of the neck Superior Mediastinum Coronary circulation and conduction Posterior mediastinum Foetal circulation Development of heart and great arteries Nerves of the thorax 2 Learning Outcomes: After this lecture, time spent in the dissecting room, and further private study you should be able to: 1. Describe how the ribs, vertebrae, costal cartilages and sternum form the “thoracic cage” with particular reference to the anterior and posterior articulations of the ribs 2. List the functions of thorax 3. List the relations of the sternal angle 4. Define the borders of the thoracic inlet and thoracic outlet 5. List the structures that pass through the thoracic inlet 6. Explain the signs and symptoms of thoracic outlet syndrome 7. Describe anatomy, neurovascular supply and lymphatic drainage of the breast 8. Explain the boundaries and clinically important relations of the breast 9. Remember the functions of muscles attached to the thoracic cage 10. Explain the anatomical basis of movements of the thorax 11. Describe the organization and functions of the intercostal musculature 12. Describe the arrangement, blood supply, venous and lymphatic drainage and innervation of the thoracic wall 13. Describe the features of intercostal nerves and their cutaneous distribution 14. List the structures through which a needle must pass when inserting a chest drain 15. Identify anatomical structures on medical images of the thorax 3 ILOs 1. Describe how the ribs, vertebrae, costal cartilages and sternum form the “thoracic cage” with particular reference to the anterior and posterior articulations of the ribs 2. List the functions of thorax 3. List the relations of the sternal angle 4. Define the borders of the thoracic inlet and thoracic outlet 5. List the structures that pass through the thoracic inlet 6. Explain the signs and symptoms of thoracic outlet syndrome 7. Describe anatomy, neurovascular supply and lymphatic drainage of the breast 8. Explain the boundaries and clinically important relations of the breast 4 ILOs 9. Remember the functions of muscles attached to the thoracic cage 10. Explain the anatomical basis of movements of the thorax 11. Describe the organization and functions of the intercostal musculature 12. Describe the arrangement, blood supply, venous and lymphatic drainage and innervation of the thoracic wall 13. Describe the features of intercostal nerves and their cutaneous distribution 14. List the structures through which a needle must pass when inserting a chest drain 15. Identify anatomical structures on medical images of the thorax 5 Recommended Reading, Related elements • MD2001 lecture “Back: Bones, Joints, Ligaments and Muscles” in week 9 • MD2002 lecture “Pectoral and scapular regions” in week 1 • MD2002 guided study “Cervical rib” in week 5 • MD3001 Practical notes of “Osteology of the thoracic cage” in week 1 • MD3001 Practical notes “Removal of the Anterior Thoracic Wall” in week 2 • Moore et al. Clinically Oriented Anatomy 8th Ed, 2018 © Wolters Kluver. • Chapter 4 – section: “Overview of Thorax” and “Thoracic wall” 6 Thorax – Region, Organ or structure? Protection?: • Heart and great vessels, lungs and major airways • Liver, stomach, spleen, kidneys Rigidity and elasticity Respiration: • Resists negative intra-thoracic pressure • Works in partnership with the diaphragm and abdominal muscles – more on this in respiratory lectures Movement: Provides attachment for muscles Haematopoiesis Connections with the neck, upper limbs and abdomen 7 Thorax • Shape of a truncated cone • Wider transversely than sagittal Sobotta Fig.831 Kelley Fig.6.18 8 Thoracic wall / Thoracic cage / Rib cage/ Thorax Thoracic Cage (rib cage) • Sternum, 12 pairs of ribs, costal cartilages,12 thoracic vertebrae and intervertebral discs Thoracic wall • • • • • Thoracic cage Skin and subcutaneous tissue Thoracic muscles and fascia Intercostal Muscles (3 layers) Mammary gland/ breast tissue • Guided Study: “An overview of the thoracic Wall” • Practical: “Osteology of the thorax” 9 Thoracic Vertebrae - Revision Remember general principals of vertebrae • Body, Pedicles, Laminae • Spinous processes, transverse processes Articular surface tubercle of rib Articular surfaces for head of rib • Superior and inferior articular facets • Intervertebral foramina Inferior and superior articular processes are vertical and articular facets form an arc allowing some rotation but no flexion 10 Ribs (L. Costae, adj. costal) 12 pairs of ribs • Numbered in ascending order from top to bottom • Rib and costal cartilage • Mobility and elasticity • True ribs (1-7) attach sternum directly through their own costal cartilages • False ribs (8-10) attach sternum indirectly through costal cartilage of 7th rib Costal cartilage • Floating ribs (11-12) do not articulate with sternum 11 Typical Rib Head Neck • Ribs 2-10 (3-9)* • Head, Neck, Tubercle, Body (shaft), Costal angle Tubercle Angle Shaft Ridge Costal groove on the inner surface and close to the inferior border. Covers the intercostal nerves and vessels 12 Atypical Ribs: First Rib • Deep and non-palpable Superior view of 1st Rib, on left side • Scalene tubercle; attachment for the anterior scalene muscle • Groove for subclavian vein • Groove for subclavian artery and the inferior trunk (C8 and T1) of the brachial plexus • Single facet on head to articulate with T1 vertebra only No Ridge Groove for subclavian artery Scalene Tubercle Groove for subclavian Vein • No costal groove 13 Atypical Ribs: 11 & 12 Are not attached to the sternum • Heads articulate only with corresponding vertebra o No Ridge • Do not articulate with the transverse processes o No Transverse facet (or real tubercle) Rib 12 is related to pleura 14 Sternum – breast bone 3 parts – Manubrium, Body, Xiphoid process (xiphisternum) https://radiopaedia.org/cases/segmented-sternum Moore Fig. 4.19d 15 Sternum – surface anatomy Sternal angle is at the level of: − 2nd Costal Cartilage (CC) − Intervertebral disc between T4 and T5 vertebra − The beginning and end of the aortic arch − The bifurcation of the trachea - carina − Superior limit of the pulmonary trunk − Azygos vein opening to SVC The sternum is also a site of bone marrow aspiration, in adults − Ligamentum arteriosum Xiphisternum: T6 dermatome Sobotta Fig. 802 16 Joints – Costovertebral Joint • Each typical rib articulates with the superior costal facet of its corresponding vertebra and the inferior costal facet of the vertebra above • The joints are synovial, supported by a capsule with ligaments Drake Fig. 3.24 Moore Fig. 4.8 17 Costovertebral joints T1 T2 Rib 1 Rib 2 Rib 3 T3 T4 Rib 4 Rib 5 T5 T6 • T1 vertebra has 1 and one half costal facet on its body • T11 and T12 have 1 oval costal facet each Rib 6 Rib 7 T7 • T2 – T9 vertebrae each have 2 half costal facets –demifacets * Variations occur 9/10 Full articular facet Rib 8 T8 T9 T10 Rib 9 Rib 10 T11 Rib 11 T12 Rib 12 L1 Demifacet T1 Vertebra 18 Joints – Costotransverse Joint Drake et al. Gray’s Anatomy for Students. 2005. Fig 3.24 © Elsevier Is the joint between the tubercle of rib (except 11 and 12) and the transverse process of its corresponding vertebra E.g. Rib #6 • articulates with the bodies of T6 and T5 • transverse process of T6 • Therefore its neck lies slightly obliquely Spratt p99 Fig. 7.04c 19 Costotransverse joints Costotransverse joints 1 to 7 have curved facets Costotransverse joints 8, 9 and 10 have flat facets allowing rotatory movement allowing gliding movement Important in respiratory movement – more to come later in MD3001 Moore Fig 4.9 20 Costochondral and Sternocostal joints • All ribs articulate anteriorly with a costal cartilage (CC) via a primary cartilaginous joint: costochondral joints • CC of ribs 1 – 7 articulate directly with the sternum via synovial joints to allow movement (except CC1) • CC of ribs #8 – 10 articulates with the costal cartilage above and, indirectly with the sternum • CC of ribs 7-9 articulate with each other at synovial joints NB. 10cc-9cc is a fibrous joint 21 Note the horizontal costal cartilages of ribs 1 to 4 And the increasingly oblique direction of costal cartilages 5 to 10 This orientation will be important when understanding respiratory movements 22 Thoracic Inlet (superior thoracic aperture) • Bound by T1 vertebra, 1st rib & CC and manubrium. • Slopes antero-inferiorly (to the level of T2/3) from the transverse plane. • Apex of lung extends 2 -3 cm above the anterior part of the 1st rib and clavicle Apex of lung 23 Thoracic inlet Structures that pass between the thorax and the neck: • Vessels that supply and drain the head and neck • Trachea • Oesophagus • Vagus + recurrent laryngeal nerves • Phrenic nerves Structures that pass between the thorax and the upper limb lie on the first rib: • Subclavian vein • Subclavian artery • (Inferior trunk of the brachial plexus) Drake Fig. 3.7 24 Thoracic Outlet (Inferior thoracic aperture) • Bound by T12 vertebra, 11th and 12th ribs, costal cartilages of Ribs #7-10 (costal margin, costal arch) and Xiphoid process • Closed incompletely by the diaphragm • Traversed by: • Oesophagus • Aorta • Inferior vena cava • Azygous Vein(s) • Various nerves 25 Thoracic outlet syndrome • A misnomer • The brachial plexus, the subclavian artery and the subclavian vein are closely related to the upper surface of the first rib and the inferior surface of the clavicle as they enter the upper limb. • The nerves and/or blood vessels may be compressed • What could the consequences be? • Compression by muscles or narrow bony passages. • OR pathology 26 Thoracic outlet Syndrome Symptoms: • Pain and parathaesia in upper limb • Weakening grip • Discolouration/ swelling in hand/ limb • Throbbing lump near clavicle • Upper limb fatigue • • • • Cold hands Raynaud’s phenomenon Pallor in hand/ fingers Waekness/ absence of pulses in upper limb • Various clinical tests • Imaging is diagnostic https://twitter.com/AvrahamCooperMD/status/1536880633 846407168 27 Breast • Is a structure consisting of mammary glands, skin and connective tissues Areola - hyperpigmented • Modified sweat gland • Similar structure in males and prepubertal females Nipple Sobotta Fig. 784 28 Milk Lines Supernumerary nipple are not uncommon (1:500) 29 Breast • Areolar glands (Montgomery glands): Sebaceous glands in the breast • Montgomery tubercles are the visible portions of Areolar glands on the skin surface, within the areola • Secreations assist in forming a seal during feeding http://classconnection.s3.amazonaws.com/813/flashcards/1549813/ png/glands_of_montgomery1338562345457.png 30 Breast • In adult females, base of it is located between the levels of 2nd – 6th (7th) ribs • From the lateral border of the sternum to the mid-axillary line • The upper lateral section may extend towards the axilla • Axillary process (axillary tail of Spence) • May perforate deep fascia and extend as far superiorly as the apex of the axilla Moore fig. 4.21 31 Breast Fascias • Found between the superficial and deep layers of superficial fascia • Sits on pectoralis major, serratus anterior and external oblique muscles • Between the superficial fascia and the muscles is the deep (pectoralis) fascia Figure from, https://anatomyofdiagram.com/breastanatomy-diagram/breast-anatomy-diagram-anatomy-andphysiology-of-a-breast-lifeinharmony/ 32 Breast structure • Consists of 15-25 lobes comprising lobules and ducts, surrounded by fat and a well developed, connective tissue stroma • In certain regions, connective tissue condenses to form Suspensory ligaments of the breast (Cooper’s ligaments) • Connect deep fascia to the dermis of the skin • Support the breast Suspensory ligaments 33 34 Retromammary space • Layer of loose connective tissue between the deep layer of superficial fascia and the deep fascia • Provides some degree of movement over underlying structures 35 Mammography Spratt p90 Fig.6.01 Spratt Fig.p91 6.02 Spratt p92 Fig.6.03 36 Spratt p93 Fig.6.05 37 Blood supply of the Breast 2 main supplies Internal thoracic artery Mammary branches Ant. Intercostal arteries Axillary Artery Lateral Thoracic artery Thoracoacromial artery Spratt p126 Fig. 8.06 • Veins follow the arteries and drain mainly to axillary and internal thoracic veins Moore Fig. 4.23 38 Lymphatic Drainage of the Breast • Areola + Lateral quadrants ➢ Axillary lymph nodes • Medial quadrants ➢ Parasternal lymph nodes ➢ Opposite breast • Inferior quadrants ➢ Inferior phrenic lymph nodes 39 Muscles of the thoracic wall 40 Intercostal spaces • 11 pairs of Intercostal Spaces • Each filled with 3 layers of muscles and membranes • If you needed to introduce a needle into the thoracic cavity for biopsy or for drainage of fluids, what structures would the needle pass through? • Is there anything you should avoid? 41 External Intercostal Muscle • • • • Extend from the inferior edge of the rib above, to superior edge of the rib below Anteriorly, muscle fibres are replaced by external intercostal membrane Raise ribs in forced inspiration, Prevent indrawing during inspiration 42 Internal Intercostal • Extend from the lateral edge of costal groove of the rib above, to superior edge of the rib below • Posteriorly, muscle fibres are replaced by internal intercostal membrane • Prevent indrawing during inspiration; Aids elastic recoil by moving ribs inferiorly in expiration 43 Innermost Layer Innermost intercostal • Thought to act with internal intercostal muscles • Deep surface is covered with endothoracic fascia Transversus thoracis • Lies posterior to sternum • Internal aspect of ribs and costal cartilages 3 to 6, to sternum, xiphisternum and costal margin • Maybe depresses ribs? Subcostalis • Lies on posterior wall • Lower ribs, internal surface, near angle down to inner surface of 2 to 3 ribs below 44 Intercostal summary Moore Fig 4.12 45 Spinal Nerve • Intervertebral foramen, formed by: • Spinal nerve may be at risk of compression by: Drake Fig. 2.12 46 Intercostal Nerves • Anterior rami of the thoracic spinal nerves do not form nerve plexus and maintain their segmental orientation and become intercostal nerves • Except T1 and lateral cutaneous branch of T2 • Intercostal nerves, together with the intercostal vein and artery (the order is VAN) lie in the costal groove at the inferior edge of the rib, between the internal and innermost intercostal muscles • Same arrangement in the abdomen wall 47 Intercostal nerves – cutaneous branches • First gives off lateral cutaneous branch • Travels in the costal groove • Becomes superficial parasternally, named anterior cutaneous branch 48 Dermatomes • Anterior thoracic wall is supplied not only by the intercostal nerves • Supraclavicular nerves (C3-4) descend over the clavicle as far as the 2nd costal cartilage • T1 has no cutaneous distribution over the anterior thoracic wall • Joins the brachial plexus, supplying the medial arm and forearm • (May be distributed only in a small region on the back) Moore 49Fig. 1.18 Dermatomes • T2 gives a large lateral cutaneous branch (the Intercostobrachial nerve) that supplies thorax wall in axilla and upper, medial part of upper limb(at risk in breast surgery) • T7 – T12 supply the skin and muscles of the abdominal wall as well 50 Intercostal nerve summary • Mixed spinal nerves • The ventral ramus of T1 joins the Brachial Plexus (inferior trunk) to supply • the small muscles of the hand • the skin of the medial aspect of the arm and forearm • muscles of the 1st intercostal space • Ventral rami of T2 – T11 • provide motor fibres to intercostal muscles, abdominal muscles • sensory supply to the skin and parietal pleura 51 Arteries of the thoracic wall • Subclavian artery: • Vertebral artery • Thyrocervical trunk • Costocervical trunk • Internal thoracic artery • • Lies along the margins of the sternum Terminates as the superior epigastric and musculophrenic arteries 52 Arteries of the Thoracic wall Thoracic aorta (between T4/5 - T12) Parietal branches: – 3rd - 11th posterior intercostal arteries – Subcostal artery (inferior to 12th rib, supply posterior abdominal wall) – Superior phrenic artery (diaphragm) 53 Intercostal arteries 54 Anterior intercostal arteries • Anterior intercostal arteries (from Internal thoracic [mammary] artery) • 2 per space in spaces 1-6 • 7th -10th Anterior intercostal arteries are branches of the musculophrenic artery • 11th intercostal space and subcostal area have no anterior supply 55 Intercostal anastomoses 56 Venous drainage of thoracic wall • Anterior intercostal veins drain to the internal thoracic vein then to brachiocephalic vein • Posterior intercostal veins drain either to the brachiocephalic vein or to the superior vena cava via azygos system 57 Azygous system • Drains the posterior wall of the thorax and part of the posterior abdominal wall • Begins from lumbar and subcostal veins and/or direct branch of the inferior vena cava • Passes behind the diaphragm, with the aorta and thoracic duct • Ascends in the posterior mediastinum, passes posterior to the right lung hilum, arches and opens into the superior vena cava • Connects superior and inferior vena cava 58 Azygous system Moore Fig. 3.72B 59 Hemiazygous • AKA Inferior hemiazygos vein • Has connections with the left renal vein • Passes through or behind the left crus of the diaphragm • Crosses to the right at approximately T9 and joins the azygos 60 Accessory Hemiazygos • AKA Superior hemiazygos • Descends from 4th intercostal space, crosses to the right at approximately T8 • Can open into • Azygos • Hemiazygos • Both 61 Superior and Supreme intercostal veins • Superior • Left and right • Drains spaces 2-4 • Right Drains to Azygous near its arch • Left drains to Left Brachiocephalic vein – very anteriorly • Supreme • Left and right • Drains rib space 1 • Drains (usually) to Brachiocephalic veins 62 • 1 Accessory hemi-azygos vein • 2 Azygos arch • 3 Azygos vein • 4 Hemi-azygos vein • 5 Intercostal veins Spratt p116- Fig. 8.05 63 Lymphatics of thoracic wall Anteriorly: • Parasternal nodes • Alongside internal thoracic artery • Bronchomediastinal trunks Posteriorly: • Intercostal nodes • Thoracic duct (inferiorly) or bronchomediastinal trunks (superiorly) Superficially: • Axillary • Inferior phrenic nodes 64 65 Rib fractures Fractures of the ribs are relatively common, and most frequently occur between ribs 4 and 10. Why not the first two pairs of ribs? Why not the last two pairs? Little can be done to assist the healing of broken ribs other than binding them tightly to limit movement. Plaster cast? Can cause hemothorax, pneumothorax with or without pulmonary injury, splenic injury https://radiopaedia.org/cases/28604/studies/28889?lang=gb&referrer=%2Farticles%2Fribfractures%3Flang%3Dgb%23image_list_item_6560525 66 https://radiopaedia.org/cases/14780/studies/14717?lang=gb&referrer=%2Farticles%2Fribfractures%3Flang%3Dgb%23image_list_item_1336466 67 Sources of figures and Images • DAFFNER: Daffner & Hartman. Clinical Radiology. The Essentials ,4th Ed, 2014 © Lippincott Williams & Wilkins. • DRAKE: Drake et al. Gray’s Atlas of Anatomy 2nd Ed, 2018 © Elsevier. • KELLEY: Kelly&Petersen. Sectional Anatomy for Imaging Professionals, 3rd Edition, 2013 © Mosby, Elsevier Inc • MOORE: Moore et al. Clinically Oriented Anatomy 8th Ed, 2018 © Wolters Kluver. • SNELL: Snell R. Clinical anatomy by Regions, 9th Ed, 2011 © Lippincott Williams & Wilkins • SOBOTTA: Putz&Pabst. Sobotta Atlas of Human Anatomy, 14th Edition, 2006 © Urban and Fischer Verlag, Elsevier Inc • SPRATT: Spratt et al. Weir and Abraham’s Imaging Atlas of Human Anatomy, 5th Edition, 2017 © • Elsevier Inc. 68