Thoracic Cavity 2024 MSPC PDF

Thoracic Cage NK3 Video resource https://www.youtube.com/watch?v=3TPHXcY-rS0 At the end of this lecture, you will be able to: Describe the components of the thoracic cage Discuss the components that make up the thoracic cage Identify the parts of the sternum and define the s...

Thoracic Cage NK3 Video resource https://www.youtube.com/watch?v=3TPHXcY-rS0 At the end of this lecture, you will be able to: Describe the components of the thoracic cage Discuss the components that make up the thoracic cage Identify the parts of the sternum and define the sternal angle Discuss the parts of a rib and rib classifications Discuss the parts of the thoracic vertebrae Discuss the intercostal space and the neurovascular bundle Discuss the relationship between the components of the thoracic cage Discuss some medical relevance associated with the thoracic cage  The Thorax Region in the trunk of the body that lies between the neck and abdomen Inner thoracic cavity Thoracic wall Thoracic cavity divided into three compartments Right and left pulmonary cavities Lungs and Pleurae Central Mediastinum Compartment intervening and separating the two pulmonary cavities Heart Thoracic part of great vessels Thoracic part of the trachea Esophagus Thymus Lymph nodes Thoracic wall Bony (rib cage) and muscular tissues The Thorax Region in the trunk of the body that lies between the neck and abdomen Function Action of respiration Protects major organs or respiration and circulation Provide attachment for and support the eight of the upper limb Provide the anchoring attachment for upper limb, abdomen, neck and back  The Thorax Thoracic inlet/Superior thoracic aperture Superior opening into the space surrounded by ribcage Bounded posteriorly by T1 Laterally by 1st pair of ribs and costal cartilages Anteriorly by superior border of the manubrium Trachea, oesophagus, nerves and vessels Thoracic outlet/Inferior thoracic aperture Diaphragm separates the thoracic cavity from abdominal cavity Bounded by Posteriorly by 12th thoracic vertebrae Posterolaterally, 11th and 12th pairs of ribs Anterolaterally, costal cartilages of ribs 7 to 10 forming the costal margins Anteriorly by xiphisternal joint Esophagus, inferior vena cava, aorta Skeletal and Cartilaginous Framework Rib cage Sternum in front Ribs at the sides Thoracic vertebrae and intervertebral disc posteriorly Skeletal and Cartilaginous Framework Study the parts of a vertebra The thoracic vertebrae Study the different vertebrae Body Vertebral arches Processes Vertebral body the anterior part of each vertebrae Weight bearing portion Spinous processes centred posteriorly at the point of the arch. Transverse process extend laterally and posteriorly from the vertebral body. Lamina connect the transverse and spinous processes Pedicle connect the vertebral body to the transverse processes How many processes does a thoracic vertebra have? Skeletal and Cartilaginous Framework The thoracic vertebrae Characteristic features Long inferiorly slanting spinous process Prominent and palpable Tip of the spinous process lies approximately at the level of the body of the vertebra below it Costal facets on transverse process Articulation with the tubercles of the rib With the exception of the last 2 or 3 thoracic vertebrae Transverse processes Demifacets on vertebral bodies Superior costal facets on the upper sides of the body Inferior costal facets on lower sides of the body T2-T9 Skeletal and Cartilaginous Framework Skeletal and Cartilaginous Framework Skeletal and Cartilaginous Framework Sternum Flat elongated bone Consist of three flat bones Manubrium (handle of a sword) Level with the third and fourth thoracic vertebrae Jugular notch (Suprasternal) Clavicular notches form sternoclavicular joints with ……… Lateral border??? Body (blade of a sword) Level with fifth to ninth vertebrae Three transverse ridges anteriorly (what do they signify) Facets on lateral aspect Needle biopsy of hematopoietic bone marrow in adult patients Xiphoid process Found in the epigastrum Demifacet for seventh costal cartilage Skeletal and Cartilaginous Framework Manubriosternal joint Lies opposite inferior border of fourth vertebral body Symphysis joint Articulation between manubrium and body Sternal angle/Angle of Louis Prominent: Posterior angle between manubrium and body is less than 180 The manubrium and body lie in different planes It marks the point at which the costal cartilages of the second rib articulate with the sternum  C Skeletal and Cartilaginous A D Framework Muscle attachment Pectoralis major Sternal ends attached to anterior surface of manubrium and anterior surface of body B E Sternocleidomastoid Sternal ends attached to anterior surface of manubrium Sternothyroid Attached to posterior surface, opposite first costal cartilage Sternohyoid Medial fibres are attached Transversus thoracis (sternocostalis) Attached to posterior surface Skeletal and Cartilaginous Framework Muscle attachment External intercostal membranes Attached to the borders of the body between the costal facets Rectus abdominis Most medial fibres of rectus abdominis attached to anterior surface of xiphoid process Linea alba Attached its lower end Aponeurosis of External and Internal oblique attached to anterior surface of xiphoid process Transversus abdominis Diaphragm Are there any unique features of the ribs in this image? Skeletal and Cartilaginous Framework Ribs Cancellous interior of hematopoietic marrow throughout adulthood 12 pairs of ribs and each rib is identified by it’s number Articulate posteriorly with the vertebral column True ribs: First seven pairs are connected to the sternum by costal cartilages False ribs Floating ribs Intercostal spaces Spaces between the rib Identified by it’s number The number corresponds to that of the rib bordering the upper margin of the space Eg: the intercostal space between the 5th and 6th ribs on the right is called the right fifth intercostal space  Skeletal and Cartilaginous Framework Ribs Typical ribs third to ninth rib Head: slightly enlarged posterior end of the rib Wedged shape Two facets Neck: short segment from head to the point where a small prominence (tubercle) projects Body: longest segment Extends backwards and laterally before curving sharply forward Angle: region where the body turns sharpy forward Upper body is gently curved and lower body is grooved Costal groove  Skeletal and Cartilaginous Framework Ribs Typical ribs Second to ninth rib Two synovial joints Costovertebral joint Head of rib articulates with both the superior costal facet on the body of the thoracic vertebrae at its own level and inferior costal facet on the body of the vertebrae above Costotransverse joint Tubercle of the rib articulate with the costal facet of the transverse process of the vertebrae at its own level Skeletal and Cartilaginous Framework Ribs Atypical ribs First rib Short and broad Flat above and below Head bears a single articular facet (articulates only with the body of the first thoracic vertebrae Two wide shallow grooves on the middle of the upper surface Anterior groove for the subclavian vein Posterior groove for subclavian artery Grooves are separated by a scalene tubercle No costal groove Relationship between the first rib, clavicle and subclavian vessels Skeletal and Cartilaginous Framework Ribs Atypical ribs Second rib Twice as long as first rib Rib is not twisted so it will rest evenly on a flat surface Near the middle, its outer surface is a roughened area for attachment of part of the serratus anterior muscle Head has two facets for articulation with body of T1 and T2 10th 11th 12th ribs Has a single facet on its head 11th and 12th do not possess a tubercle or neck and anterior ends are pointed and tipped with cartilage Skeletal and Cartilaginous Framework Costal cartilages Hyaline cartilage Caps anterior tips of the ribs Provide flexible attachment for their anterior ends Costochondral junction Avascular tissues Low reparative capacity Physically traumatized costal cartilages heal relatively slowly Skeletal and Cartilaginous Framework Costal cartilage of the first ribs forms a synchondrosis with the manubrium (no movement is possible) Costal cartilage of third to seventh ribs form synovial joints with the body of the sternum Costal cartilage of eighth, ninth and tenth form synovial joints with costal cartilages of the rib above Articulation among costal cartilages of seventh, eighth, ninth and tenth form a scalloped cartilaginous margin referred to as costal margins Costal cartilages of eleventh and twelfth ribs do not form any articulation Intercostal muscles Intercostal muscles The intercostal spaces of the chest wall contain three overlapping layers of muscles These muscles are muscles of respiration (muscles of breathing) External intercostal muscle Internal intercostal muscle Innermost intercostal muscle Muscles are innervated by intercostal nerves Intercostal muscles External Intercostal muscle Most superficial Origin: lower border of the body of the rib above Insertion: upper border of the body of the rib blow Muscle fibres extend downward and forward from their origin (inferoanteriorly) Extends posteriorly as far as the tubercle of the ribs and anteriorly as far as the tips of the ribs Replaced by external intercostal membrane at the interchondral interval Elevation of ribs during inspiration Intercostal muscles Internal Intercostal muscle Middle layer Origin: Upper border of the lower rib Insertion: floor of costal groove of upper rib Muscle fibres extend upward and forward from their origin Extends anteriorly as far as the lateral border of either the sternum or costal margin and posteriorly as far as the angles of the rib Replaced by internal intercostal membrane at the posterior end (the interval between the rib angles to the vertebral column) Depression of ribs during forced expiration Intercostal muscles Deepest Intercostal muscle Deepest layer Thin vestigial muscle Three groups of muscle Anterior: Transverse thoracis Lateral: innermost intercostal muscle Origin: inner surface of rib Insertion: upper surface of rib below Intercostal nerves Depression of ribs Posterior: Subcostal Neurovascular elements Intercostal vein Intercostal artery Intercostal nerve Lie partially under the cover of costal groove and between the two deepest intercostal layers Anterior ramus of nerve T12 coursing inferior to the 12 th rib is the subcostal nerve Posterior rami supply the joints, deep back muscles, and skin of the back Clinical relevance: Medical treatment involving the insertion of a needle through the tissue of an intercostal space, the needle is inserted just above the lower rib False Ribs A True Ribs Floating Ribs B C  C D A Tubercle Costal cartilage B Head Angle Costal groove E Neck F  A K B J Articular facets for ribs III-VI C Sternal angle (manubriosternal joint) Transverse ridges I Body of sternum Articular site for clavicle Xiphoid process D Articular demifacets for rib II Jugular notch Attachment site for rib I H E Manubrium of sternum Articular facets for rib VII G F  A B I Neck Area for attachment of middle scalene Head with articular facet H Costal cartilage Groove for subclavian artery G Groove for subclavian vein Scalene tubercle (attachment of anterior scalene) F Tubercle Area for attachment of serratus anterior E C D  Arterial Supply Arterial supply Thoracic aorta: Through the posterior and subcostal arteries Subclavian artery: through the internal thoracic and supreme intercostal arteries Axillary artery: Through the superior and lateral arteries  Arterial Supply Arterial supply Intercostal spaces 9 uppermost intercostal spaces is supplied by a pair of anterior intercostal (branches of internal thoracic artery, a branch of subclavian) and a single posterior intercostal 2 lowermost intercostal spaces are supplied by posterior intercostal Posterior intercostal artery of the 1st and 2nd intercostal space arise from the supreme (superior) intercostal artery Of the 3rd to 11th intercostal spaces (and subcostal space) arise posteriorly from the aorta  Arterial Supply Arterial supply Internal thoracic artery (Internal mammary arteries) Arise from inferior surfaces of subclavian Descend into thorax posterior to first clavicle and costal cartilage Lateral to sternum and posterior to upper six costal cartilages At the 6th intercostal space internal thoracic artery branches into musculophrenic and superior epigastric Anterior intercostal arteries of the 1 st to 6th intercostal spaces are branches of internal thoracic artery, 7th to 9th are branches of musculophrenic artery Inferior spaces are by posterior intercostal arteries  Venous drainage Intercostal veins accompany the intercostal arteries Lie most superior in costal groove 11 posterior intercostal and 1 subcostal vein Posterior intercostal vein (4-11) end up in the azygos and hemiazygos system which drains into superior vena cava Posterior intercostal vein of the first space drains into the right and left brachiocephalic vein Posterior intercostal vein of second and third intercostal space unite to form superior intercostal vein. Right superior intercostal I typically final tributary of the azygos vein and left superior intercostal empties into the brachiocephalic Internal thoracic vein Intercostal nerves Intercostal nerves are anterior Runs forward inferiorly to the rami of the first 11 thoracic spinal intercostal vessels in the subcostal nerves groove Anterior ramus off the twelfth First 6 nerves are distributed within thoracic nerve lies in the abdomen their intercostal spaces and runs forward in the abdominal Seventh to ninth intercostal nerves wall as subcostal nerve leave the anterior ends of the Each intercostal nerve enters the intercostal spaces by passing deep intercostal space between parietal to the costal cartilage to enter the pleura and posterior intercostal anterior abdominal wall membrane 10th and 11th nerves pass directly into the abdominal wall Why is pain referred along the medial side of the arm in coronary artery disease? Read on second intercostal nerve. Read Note that the lateral cutaneous branch of the second intercostal nerve is Rami communicantes known as the intercostobrachial nerve, which supplies the floor of the axilla Collateral branch and upper posteromedial region of the upper extremity. In acute cases of Lateral cutaneous branch coronary artery diseases (e.g. heart attack), patients usually feel left-sided Anterior cutaneous branch pain in their axilla and arm. This is cardiac referred pain that is mediated by Pleural sensory branch the intercostobrachial nerve. Peritoneal sensory branch Surface anatomy Suprasternal notch/Jugular notch Felt between the prominent medial needs of the clavicle in the midline It lies opposite the lower border of the body of the second thoracic vertebrae Sternal angle (Angle of Louis) Lies opposite the intervertebral disc between the fourth and fifth thoracic vertebrae A finger moved to the right or left will pass directly to the second costal cartilage Surface anatomy Xiphisternal joint Lies opposite of the body of the 9 th thoracic vertebrae Subcostal angle Inferior end of the sternum between sternal attchments of the seventh costal cartilages Costal margin Lower boundary of the thorax Formed by 7th, 8th, 9th, 10th ribs and ends of the 11th and 12th cartilages. Lowest part of the costal cartilage is formed by the 10th rib and lies at the level of the third lumbar vertebrae Surface anatomy Ribs First rib lies deep to the clavicle and cannot be palpated 12th rib can used to identify a particular rib by counting from below Nipple In male usually lies at the 4th intercostal space (about 4in (10cm)) In females the position is not constant Apex beat of the heart Formed by lower portion of the left ventricle Normally at the fifth intercostal space 3.5 inches (9cm) from the midline Lines of Orientation Midsternal line lies in the median plane over the sternum Midclavicular line runs vertically down from the midpoint of the clavicle Midaxillary line runs vertically downwards from a point situated midway between the anterior and posterior axillary folds Diaphragm Inferiorly thorax opens into abdomen by a wide opening Bounded by Xiphisternal joint Costal margin Body of the twelfth thoracic vertebrae Closed by muscular and tendinous septum (Diaphragm) Diaphragm is the primary muscle of respiration Diaphragm 3 parts Sternal part Costal part Vertebral part Central tendon Openings of the diaphragm Aortic opening Esophageal opening Caval opening Lymph nodes and associated vessels Act as surveillance for pathogenic invasion. Screen interstitial fluid that is being returned to the general circulation for potentially harmful agents. Sample questions The intercostal neurovascular bundle is particularly vulnerable to injury from fractured ribs because it is located a. Above the superior border of the ribs anteriorly b. Beneath the inferior border of the ribs, posterolaterally c. Between external and internal intercostal muscle layers d. Deep to the posterior intercostal membrane e. Superficial to the ribs anteriorly For each of the questions or incomplete statements below, one or more of the answers or completions are correct. Choose answer a. if only 1,2, and 3 are correct b. If 1 and 3 are correct c. If only 2 and 4 are correct d. If only 4 is correct e. If all are correct The sternal angle is at the level where 1. The second rib articulates with the sternum 2. The trachea bifurcates into right and left bronchi 3. The aortic arch both begins and ends 4. The inferior border of the superior mediastinum is demarcated Muscles that function to elevate the ribs in inspiration are 1. The sternocleidomastoid 2. The scalenus anterior 3. The external intercostals 4. The internal intercostals For each of the questions or incomplete statements below, one or more of the answers or completions are correct. Choose answer a. if only 1,2, and 3 are correct b. If 1 and 3 are correct c. If only 2 and 4 are correct d. If only 4 is correct e. If all are correct The posterior intercostal veins are tributaries to 1. The intervertebral veins 2. The azygos veins 3. The left subclavian vein 4. The brachiocephalic vein The azygos vein 1. Receives the left superior intercostal vein 2. Receives the right superior intercostal vein 3. Empties directly into the right brachiocephalic vein 4. Empties directly into the superior vena cava For each of the questions or incomplete statements below, one or more of the answers or completions are correct. Choose answer a. if only 1,2, and 3 are correct b. If 1 and 3 are correct c. If only 2 and 4 are correct d. If only 4 is correct e. If all are correct The third rib articulates posteriorly with the 1. Transverse process of the third thoracic vertebra 2. Body of the second thoracic vertebra 3. Body of the third thoracic vertebra 4. Transverse process of the second thoracic vertebra  Arterial Supply Arterial supply The posterior intercostal of the first two spaces are branches of superior/supreme intercostal (branch of costocervical which is a branch of subclavian) Posterior intercostal arteries for the lower nine intercostal spaces are branches of descending thoracic aorta  Venous drainage Venae comitantes of the anterior intercostal artery are tributaries of the venae comitantes of the musculophrenic and internal intercostals which are tributaries of the brachiocephalic vein Venae comitantes of the nine lowest posterior intercostal arteries are tributaries of the azygos system of veins. The venae comitantes of the two uppermost posterior intercostal arteries are drained by brachiocephalic vein. Posterior surface of the body is related a. on the right to the right pleura b. on the left the upper two segments of the body are related to the left pleura and lung c. and the lower two segments to the pericardium