Thorax Anatomy Flashcards
Regions of the Anterior Thorax
The Five Trunk Lines
Midsternal line (anterior median) is a vertical line through the midline of the sternum.
Midclavicular lines run through the midpoint of the clavicles parallel to the midsternal line.
Midaxillary line is a vertical line that runs inferiorly from the deepest part of the axilla.
Midvertebral line (posterior median) is a vertical line through the vertebral column.
Scapular lines are parallel to the midvertebral line and cross the inferior angle of the scapula.
Anterior Thorax Vasculature
Lateral Thorax Vaculature
Posterior Thorax Vasculature
The major lymph nodes of the upper trunk are the. . .
axillary lymph nodes
The skin above the manubriosternal joint is supplied by sensory fibers from
the lower cervical plexus (C3, C4 and C5)
Below the manubriosternal joint and to the upper epigastric region is innervated by
the intercostal nerves (anterior primary rami of the T1-T12)
There is considerable ___ between neighboring dermatomes.
There is considerable overlap between neighboring dermatomes.
Auscultating the Aortic Valve
right 2nd intercostal space, just lateral to the sternum.
Auscultating the Pulmonary Valve
left 2nd intercostal space, just lateral to the sternum.
Auscultating the Tricuspid Valve
left 5th intercostal space, just lateral to the sternum.
Auscultating the Mitral Valve
left 5th intercostal space, midclavicular line.
The costal cartilages of ribs ____ articulate with the sternum via sternocostal joints, while the costal cartilages of ribs ____ articulate with one another at interchondral joints to form the costal margin.
The costal cartilages of ribs 1-7 articulate with the sternum via sternocostal joints, while the costal cartilages of ribs 8-10 articulate with one another at interchondral joints to form the costal margin.
symphesis (plural sympheses)
immovable joint
“False ribs”
Ribs 8-10, which are conjoined by cartilage to one another but are not conjoined directly to the sternal body.
“Floating ribs”
Ribs 11-12, which have no joints with other ribs or the sternal body and are mostly posterior.
Sections of thoracic wall muscle
Outer layer: External intercostal muscles
Middle layer: Internal intercostal muscles
Inner layer: Innermost intercostal muscles (and transversus thoracis, subcostal muscles)
Accessory Respiratory Muscles
Not shown is the abdominal wall muscle, also an accessory respiratory muscle.
Intercostal neurovasculation
Blood supply and nerve innervation resides in each intercostal segment just inferior to the superior rib of the intercostal space. They run in the following order:
Vein
Artery
Nerve
(VAN)
Intercostal Nerves
Intercostal nerves run below each rib and they are distributed to the thoracic wall, intercostal muscles, parietal pleura, periosteum of the ribs, abdominal wall and the peritoneum.
Intercostal arteries
posterior intercostal arteries (main intercostal arterial supply) are branches of the thoracic aorta; anterior intercostal arteries arise from the internal thoracic artery and anastomose with the respective posterior intercostal artery. Intercostal arteries run below each rib and supply the intercostal muscles - with additional branches from the subclavian and axillary arteries - the pectoralis muscles, the breast and the skin.
Intercostal veins
Intercostal veins accompany the intercostal arteries. They drain into the azygos system and internal thoracic veins.
Intercostal lymphatics
The lymph vessels of the intercostal spaces follow the intercostal vessels.
Internal Thoracic Artery
The internal thoracic artery arises from the subclavian artery; it is a paired artery, each runs on the side of the sternum. It supplies the anterior chest wall and the breasts.
Subdermal view of the anterior thoracic wall
Internal view of the anterior thoracic wall
A patient has fluid in the pleural space (underneath the thoracic cage). You are considering inserting a needle to drain the fluid. Where would you insert the needle?
Just above the rib that forms the lower boundary of the intercostal space
Points of attachment of the diaphragm
The false ribs (7, 8, 9, 10), the floating ribs (11, 12), the 12th thoracic and upper lumbar vertebra, ligaments to the upper thoracic wall (as high as the axillary T4), and the xiphoid process.
Palpable points of attachment are shown.
The costodiaphragmatic recess
The inferior and posterior area of the thorax which extends to the T12-L2 area of the spine. This area experiences the greatest vertical movement of the diaphragm as it contracts and relaxes during respiration.
Abnormal fluid accumulation of the thorax tends to collect here.
Diaphragm Tendons
The right crus is fixed to the upper L3, the left crus to the upper L2, and the central tendon is a trifoliate in which diaphragm muscles converge radially.
The superior aspect of the tendon is ___ with the inferior aspect of the ___.
The superior aspect of the tendon is continuous with the inferior aspect of the fibrous pericardium.
Major openings of the diaphragm
- Aortic opening, level of T12
- Esophageal opening (also vagus nerve), level of T10
- Inferior Vene Cava (also right phrenic nerve), level of T8
Smaller openings also exist, mostly for nerve fibers.
Superior diaphragm vasculation
Inferior diaphragm vasculation
Diaphragm innervation
Only innervated from the abdominal surface.
Mediastinal box
Made by drawing the midclavicular lines, then drawing two axial planes: one at the level of the xiphoid process, the other at the beginning of the midclavicular lines.
Any injury in the mediastinal box is assumed to have punctured the heart until proven otherwise.
Mediastinal regions
Major structures of the superior mediastinum
- L and R brachiocephalic veins
- Aortic arch
- Pulmonary Trunk
- Trachea and R/L Main Stem Bronchi
- Esophagus
- Azygos vein
Ligamentum arteriosum
Why is the right lung more likely to be filled with fluid than the left?
Because the angle between the right bronchus and trachea is more accute than that between the left bronchus and trachea due to the postion of the heart inferior to the left bronchus
Location of the thoracic duct
Superior mediastinum radiograph
Major structures of the posterior mediastinum
“Four birds resting on a tree”, where the “tree” is the descending thoracic aorta. The branches are the intercostal arteries, right/left bronchial arteries.
The four birds are:
The vagus nerve (“vagoose”)
The esophagus (“esophagoose”)
The Azygos vein (“azygoose”)
The thoracic duct (“thoracic duck”)
Posterior mediastinum diagram
Trachea
The trachea is a hollow cylinder in the middle of the respiratory tract; it connects the larynx with the lungs. The trachea descends in the midline of the thoracic cavity between the level of the C6 vertebra and T4-T5 vertebrae.
It is comprised of about 20 C-shaped hyaline cartilages that provide structural rigidity to the trachea. The trachea bifurcates in the superior mediastinum into the right and left main bronchi. The right main bronchus is shorter, wider and more vertical than the left main bronchus.
Trachea neurovasculation
Pleura
Formed from mesodermal tissue and stays with the embryonic endodermal lung through its development.
The parietal layer is fixed via a loose connective tissue (endothoracic fascia) to the inner thoracic wall, lower cervical vertebra, costovertebral area, mediastinum, and diaphragm. The visceral layer is attached to the lungs; it is continuous with the parietal pleura.
Subdivisions of parietal pleura
Relative height of the pleura and lung
During quiet respiration the inferior borders of the lungs are two ribs higher than the borders of the pleural cavity. The borders of the pleural cavity are:
Anterior: 8th rib at the level of the midclavicular line.
Lateral: 10th rib at the level of the midaxillary line.
Posterior: 12th rib at the level of the scapular line.
Lung Lobes
Lobes of the left lung
The inferior lobe is larger than the superior lobe. It contains most of the left lung base, a large part of the posterior border, and the lower posterior part of the medial and lateral surfaces.
The superior lobe includes the apex, most of the costal and medial surfaces, the entire anterior border and the cardiac notch as well as the lingula, which is a tongue-like projection of the left lung below the cardiac notch.
Right lung lobes
Lung Dual Blood Supply
1) the pulmonary vascular system -> pulmonary artery, pulmonary vein
2) the bronchial (systemic) vascular system -> bronchial arteries, bronchial veins, azygos and hemiazygos veins
Lung Lymphatics
Innervation of the lung
The sympathetic preganglionic fibers originate from the lateral horn of the T2-T4 segments of the spinal cord relay in the upper thoracic ganglia. The postganglionic fibers are part of the pulmonary plexuses. They innervate the bronchial tree and the pulmonary vessels. Activation of the sympathetic fibers results in bronchodilation, vasoconstriction and inhibition of glandular secretion.
The vagal afferent fibers transmit information for the coughing reflex, stretch reception, blood pressure and chemoreception.
The vagal efferent fibers innervate the smooth muscle in the airways and pulmonary vessels and regulate the secretion of the bronchial glands. Activation of the parasympathetic fibers results in bronchoconstriction, vasodilation and glandular secretion stimulation.
Heart Diagram
Location of the phrenic neurovascular bundles
In the white ovals, running between the parietal mediastinal pleura and parietal pericardium.
pericardial reflections
Curvatures of the serous pericardium (at around the great vessels), that is formed by the parietal pericardium (attached to the fibrous pericardium) as it changes direction (reflects) and continues as visceral pericardium and covers the heart.
Oblique and Transverse Sinuses
Important for cardiac surgery.
Heart atria
Heart valves cross section
Heart arteries
Heart veins
Heart Innervation
