Week 9 Content Flashcards
Name the components of the thoracic cage.
12 thoracic vertebrae posteriorly
12 pairs of ribs and their costal cartilages
Sternum
Describe the facets of thoracic vertebrae.
Facets on the vertebral bodies articulate with the heads of the ribs
Facets on the transverse processes articulate with the rib tubercles
Describe the classification of ribs.
7 pairs of true ribs (1-7)
3 pairs of false ribs - do not directly articulate with the sternum via their own costal cartilage (8-10)
2 pairs of floating ribs - do not articulate with sternum at all (11-12)
Describe the components of a typical rib.
Head with 2 articular facets Neck Tubercle Body or shaft Angle Costal groove
Describe the costovertebral joint.
Articulation of the head of the rib with the superior part of the body of the corresponding thoracic vertebra, the inferior part of the body of the vertebra above, and the IVD
Synovial plane joint
Ligamentous support: radiate ligament (thickening of anterior capsule) surrounding the head of the rib and the 2 bodies of the vertebrae; intra-articular ligament attaches the head of the rib to the IVD
Describe the costotransverse joint.
Articulation of the tubercle of the rib with the associated transverse process\
Synovial plane joint
Ligamentous support: superiorly and laterally supported by the superior and lateral costotransverse ligaments
Describe the costochondral joint.
Articulation of the sternal ends of the ribs with the costal cartilage
Primary cartilaginous joint
Describe the sternocostal joint.
Articulation of the costal cartilages with the manubrium and sternum
1st rib is a primary cartilaginous joint
Ribs 2-7 are synovial plane joints supported by anterior and posterior radiate sternocostal ligaments
Describe how inspiration volume increases.
Vertical increase - contraction of the diaphragm causes the diaphragm to lower
Transverse increase - bucket handle movement of the ribs, primarily by ribs 8-10
Anterior/posterior increase - pump handle movement of the ribs, primarily by ribs 1-7
Name the muscles of the thorax.
Pectorals Serratus anterior Serratus posterior External intercostals Internal intercostals Innermost intercostals Subcostal muscles Transversus thoracis Levatores costorum
Describe the external intercostals.
11 pairs of muscles running obliquely from the rib above to the rib below
Fibers run inferiorly and medially/anteriorly
As they reach the costal cartilages, they become the external intercostal membrane
Muscular posteriorly, membranous anteriorly
Describe the internal intercostals.
11 pairs of muscles lying deep to the external intercostals
Fibers run obliquely at right angles to the external intercostals, run inferiorly and laterally/posteriorly
Posteriorly they form the internal intercostal membrane
Muscular anteriorly, membranous posteriorly
Describe the innermost intercostals.
11 pairs of muscles that run similar to the internal intercostals (inferolaterally)
Separated from the internal intercostals by the intercostal nerves and vessels
Muscular in the middle 3/4 of the intercostal space
Describe the subcostal muscles.
Thin muscular slips that extend from the angle of a rib on the internal surface to internal surface of rib below, crossing 2 intercostal spaces
Fibers run in the same direction as internal intercostals (inferolaterally)
Describe the transverse thoracis.
4 or 5 muscular slips that arise from the xiphoid and body of the sternum, spanning superiorly and laterally to costal cartilages 2-6
Describe levatores costarum.
12 fan-shaped muscles arising from the transverse processes of C7-T11, inserting inferiorly and laterally on the ribs below
Describe the intercostal nerves.
Ventral primary rami of the first 11 thoracic spinal nerves
12th thoracic spinal nerve is called the subcostal nerve
Describe the intercostal arteries.
Each intercostal space is supplied by a large posterior intercostal artery arising from the aorta and a small anterior intercostal artery arising from the internal thoracic artery, which arises from the subclavian artery
Describe the 2 pleura of the lungs.
Visceral pleura lines the lungs, parietal pleura lines the walls of the thoracic cavity. They come together and become continuous at the root of the lung
Parietal pleura has 3 parts - costal pleura (lines thoracic walls), diaphragmatic pleura (lines the diaphragm), and mediastinal pleura (lines the mediastinum)
Pleura cavities are 2 separate and closed potential spaces filled with fluid to reduce friction between parietal and visceral pleura
Describe the right and left lungs and their fissures.
Right lung has 3 lobes - superior, middle, and inferior - separated by horizontal and oblique fissures
Left lung has 2 lobes - superior and inferior - separated by an oblique fissure
Describe the bronchial tree.
Each lung receives a primary or principal bronchus from the trachea.
Each principal bronchus then divides into lobar bronchi which each supply a lobe of the lung.
Each lobar bronchus then divides into tertiary segmental bronchi, which each supply a specific bronchopulmonary segment.
Describe the arterial supply to the lungs.
The branches of the pulmonary arteries supply venous blood to the lungs for aeration
Pulmonary arteries run with the bronchi and lie posterior to them
Each lobe and bronchopulmonary segment has a branch
Bronchopulmonary segments have no arterial anastomoses, SO removal of a pulmonary segment of the lung will not endanger the viability of adjacent segments
Describe the venous supply of the lungs.
Pulmonary vein drains oxygenated blood to the left atrium of the heart
Superior and inferior pulmonary veins are formed at the hilus of each lung
Superior pulmonary veins receive from the superior and middle lobes of the right lung and superior and lingula lobes of the left lung
Inferior pulmonary veins receive from the lower lobes of the right and left lungs
What is the root of the lung?
AKA the hilum of the lung, it is the attachment point of the lung to the heart and trachea, surrounded by the reflection of the parietal to visceral pleura
Provides a highway for the main bronchus, pulmonary vessels, bronchial vessels, lymph vessels, and nerves
Describe lymphatic drainage of the lungs.
Superficial lymphatic ducts drain to the surface and runs along the visceral pleura to the hilum
Deep lymphatic drainage follows the bronchi and collects at the hilum
At the hilum, all the lymphatic drainage is filtered by the tracheobronchial nodes
How does the parietal pleura relate to the thoracic wall?
Superiorly, pleura extends through thoracic inlet and is called the cupula
Inferiorly: 7th costal cartilage anteriorly, 10th costal cartilage mid-axillary, and 12th vertebral level posteriorly
What is the costo-diaphragmatic recess?
The separation of parietal pleura from visceral pleura where the costal and diaphragmatic pleura meet
How do the lungs relate to the thoracic wall?
Superiorly, lung extends through thoracic inlet as the apex of the lung
Anteriorly, lung extends down to the 6th costal cartilage
Mid-axillary, the lung extends down to the 8th costal cartilage
Posteriorly, the lung extends down the the 10th or 11th rib
Describe the boundaries of the mediastinum.
Superior - thoracic inlet Inferior - thoracic outlet Posterior - vertebral column Anterior - sternum Lateral - mediastinal pleura
Name the subdivisions of the mediastinum.
Superior mediastinum
Anterior mediastinum
Posterior mediastinum
Middle mediastinum
Describe the contents of the superior mediastinum.
Thymus Great veins Arch of the aorta and its 3 branches Parts of the trachea and esophagus Vagus and phrenic nerves Thoracic ducts
Describe the anterior mediastinum.
The region anterior to the pericardial sac and posterior to the sternum
Describe the posterior mediastinum and its contents.
The region posterior to the pericardial sac and anterior to the thoracic vertebrae
Contents: Esophagus Lower end of the trachea Descending aorta and its branches Azygos venous system Thoracic duct Thoracic part of sympathetic trunk
Describe the contents of the middle mediastinum.
Pericardial sac Heart Great arteries Main bronchi Phrenic nerve
What is the pericardium?
A double-layered fibroserous sac that encloses the heart and roots of the great vessels
Describe the layers of pericardium.
Fibrous pericardium
- dense fibrous outer layer of CT
- fused centrally to diaphragm and attached to sternum via sternopericardial ligaments
- keeps the heart within the thoracic cavity and limits its distention
- pierced inferiorly by the vena cava and posteriorly by the pulmonary veins
- superiorly blends with CT of the great vessels
Serous pericardium
- 2 layers - parietal that lines the pericardium, and visceral (epicardium) that lines the heart
- pericardial cavity between the 2 layers
Describe the pericardial sinuses.
During embryonic development, the pericardium forms folds resulting in sinuses
Transverse pericardial sinus - located anterior to the superior vena cava and posterior to the ascending aorta and pulmonary trunk
Oblique pericardial sinus - bounded on the right by the inferior vena cava and pulmonary veins and on the left by the pulmonary veins
How is the heart situated?
Obliquely in the middle of the mediastinum
Describe the base and apex of the heart.
Base - most posterior part of the heart, formed by the LA and a small portion of the RA
Apex - projects inferolaterally from the base of the heart, located at the 5th intercostal space just medial to the mid-clavicular line in a supine individual
Describe the surfaces of the heart.
Diaphragmatic surface - inferior surface of the heart formed by both ventricles (but mainly LV)
Sternocostal surface - anterior surface of the heart formed mainly by the RV
Pulmonary surface - left side of the heart formed mainly by the LV
Describe the borders of the heart.
Right border - RA, is in line with the superior and inferior vena cava
Inferior border - RV and a small part of the LV
Left border - LV and slightly by the LA
Superior border - both atria
Describe the RA.
Receives blood from the IVC and SVC and the coronary sinus (main drainage of the heart)
Characterized by the pectinate muscles and fossa ovalis
Describe the RV.
Receives blood from the RA and pumps into the pulmonary arteries
Characterized by trabeculae camae and papillary muscles which are connected to the tricuspid valve via chordae tendinae
Walls of RV form a smooth surface, the infundibulum, in the upper medial part as it leads into the pulmonary trunk
Pulmonary trunk has pulmonary valves to prevent reflux of blood
Describe the LA.
Receives blood via 4 pulmonary veins from the lungs that is then passed to the LV through the mitral orifice which is guarded by the mitral (bicuspid) valve
Describe the LV.
Walls are 3x as thick as the RV
Blood is propelled from the the LV into the aorta through the aortic valves
Describe the arterial supply to the heart.
Right coronary artery
- arises form the aorta and passes inferiorly in the coronary sulcus
- gives off right marginal artery at the inferior border of the heart
- turns left at inferior border and gives rise to posterior interventricular artery which runs inferiorly to the apex of the heart in the posterior interventricular sulcus
Left coronary artery
- arises from the aorta and very quickly divides into anterior interventricular artery and the circumflex artery
- anterior interventricular artery descends to the apex of the heart where it anastomoses with the posterior interventricular artery
- circumflex artery passes around the left border of the heart in the coronary sinus and anastomoses with the termination of the right coronary artery
- left marginal artery arises from the circumflex artery
Describe the venous drainage of the heart.
Great cardiac vein - ascends in the anterior interventricular sulcus
Middle cardiac vein - ascends in the posterior interventricular sulcus
Small cardiac vein - runs in the coronary sulcus on the right side
All veins drain into the coronary sinus which empties into the RA
What forms the interscalene space and what passes through it?
Anterior and middle scalenes create the interscalene space and the subclavian artery and trunks of the brachial plexus pass through it
Which of the 3 scalene muscles attaches to the 2nd rib?
Posterior scalene - both the anterior and middle scalenes attach to the 1st rib
What is the action of the scalenes?
Lift the first 2 ribs
What are the attachments and actions of the SCM?
Attaches to clavicle and manubrium and lifts the sternum outward to increase chest volume (pump lever action)
What drains into the azygos vein?
The right superior intercostal vein and the posterior intercostal veins
Where does the T1 nerve sit and what plexus does it form?
It sits on top of the 1st rib and forms the brachial plexus
What pathway do the bundles of intercostal vein, artery, and nerve follow and why is this clinically important?
The bundles follow the costal grooves which are on the inferior side of each rib
Since the bundles sit UNDER the ribs, placing a needle into the chest for a chest tube of a thoracentesis requires that the clinician place the needle on the top of the rib to avoid bleeding
Where do the internal thoracic artery and vein run?
Under the costal cartilages and parallel to the sternum
Where does the internal thoracic artery originate from? To where does the internal thoracic vein empty?
ITA originates bilaterally from the subclavian artery
ITV empties bilaterally into the brachiocephalic vein
What is another name for the left internal thoracic artery, and why is it clinically important?
Left internal mammary artery (LIMA)
Generally used for CABG and is attached to the left anterior descending (LAD) coronary artery
What nerves innervate the parietal pleura and how is this important on assessing pain during breathing?
Innervated by somatic afferents from the intercosdtal nerves, so pain is felt as thoracic wall pain
This is different from the diaphragmatic and mediastinal somatic afferents which originate from the phrenic nerve (C2-C4), and therefore pain is felt in the lateral neck and supraclavicular regions
What would be the smallest part of the lung that could be easily removed during surgery?
A bronchopulmonary segment is the smallest functionally independent region of the lung. It is also the smallest area of the lung that can be removed and not affect an adjacent region of the lung
What is the relevance of the drainage of the lungs, thoracic wall, and the neck to the diagnosis and treatment of cancer?
Since the lymoh drainage of the lungs, thoracic wall, mediastinum, and the neck moves TOWARD the neck, often the first signs of cancer in the thorax manifests as enlargement of neck lymph nodes
Where does the thoracic duct begin and empty into?
Begins in the abdomen with the cisterna chyli and empties into the left brachiocephalic vein
What is unique about the azygos vein?
Unlike most veins which are bilaterally symmetrical, the azygos vein is not paired
What landmarks separate the superior mediastinum from the anterior and posterior mediastina?
Line between the sternal angle and the space between T4/T5
What is contained in the middle compartment of the mediastinum?
The pericardium which contains the heart
Through which mediastinal compartments does the esophagus pass?
superior and posterior mediastinal compartments
