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Questions and Answers
What structure marks the level of the lower border of the right lung?
Which type of epithelium is found in the alveolar ducts and alveoli?
Which arteries are responsible for the blood supply to the bronchi?
What type of nerve supply causes bronchoconstriction?
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What is the function of surfactant produced by type II pneumocytes?
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What is the origin of the diaphragm's sternal part?
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Which structures are transmitted through the esophageal opening of the diaphragm?
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What role do the muscle fibers of the right crus play around the esophageal orifice?
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Where is the vena caval opening located?
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Which blood vessels are transmitted through the greater splanchnic nerve?
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What is the aortic opening's position relative to the crura?
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What forms the minor openings in the diaphragm?
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What do the arcuate ligaments form?
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What does the foramen of Morgagni represent?
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Which structure aids in connecting diaphragm actions with the lumbar vertebrae?
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What is the primary function of the thoracic cage?
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Which part is not a component of the sternum?
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How many pairs of true ribs are there in the human body?
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Which characteristic is not associated with typical thoracic vertebrae?
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Which statement is true regarding the atypical ribs?
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What are the boundaries of the thoracic cage primarily defined by?
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What feature distinguishes the 10th to 12th ribs?
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Which structure does not traverse through the apertures of the thoracic cage?
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What shape describes the inlet of the thorax?
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Which structure does NOT pass through the inlet of the thorax?
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What is the primary function of the diaphragm?
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Which of the following is a boundary of the thoracic outlet (inferior aperture)?
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Which structure is located posteriorly at the inlet of the thorax?
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What distinguishes the right cupola of the diaphragm?
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Which nerve is part of the structures passing through the inlet of the thorax?
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The central part of the diaphragm is primarily made up of what type of tissue?
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What is the shape of the inlet of thorax described as?
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Which muscle is NOT associated with the structures passing through the inlet of the thorax?
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What is the primary motor nerve supplying the diaphragm?
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Which artery is NOT a branch of the internal thoracic artery?
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What condition is characterized by an inward growth of the ribs and sternum?
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What is the potential consequence of severe funnel chest?
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Which of the following nerves provides sensory supply to the peripheral part of the diaphragm?
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In case of a deformity known as pigeon chest, what is a common underlying cause?
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Which of the following vessels correspond with the veins that drain into the systemic veins?
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Which of these is a symptom of severe funnel chest?
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Which artery supplies the diaphragm and is derived from the descending thoracic aorta?
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What nerve provides sympathetic supply to the diaphragm?
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Study Notes
Thoracic Cage
- The thoracic cage is the bony framework of the chest
- Consists of the vertebral column posteriorly, ribs and intercostal spaces laterally, sternum and costal cartilages anteriorly
- Protects heart, lungs and other organs
Bones Forming the Thoracic Cage
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Sternum:
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Composed of fused sternebrae
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Includes manubrium, body, and xiphoid process
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Manubrium:
- Contains jugular (sternal) notch
- Articulates with ribs 1 & 2
- Clavicular articular facets
- Sternal angle at the level of the 2nd rib
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Body: Articulates with ribs 2-7
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Xiphoid process:
- Cartilage that calcifies over time
- Partial attachment of various muscles
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Ribs:
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12 pairs
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7 True ribs: Direct attachment to the sternum
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5 False ribs: Indirect or no attachment to the sternum
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Floating ribs: Last two false ribs, no ventral attachment
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Typical ribs: Ribs 3-9
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Atypical ribs: Ribs 1, 2, 10, 11, 12
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Rib Anatomy:
- Typical ribs: Head, neck, tubercle, angle, shaft, subcostal groove
- Atypical ribs: First rib is short, flat, wide, and supports subclavian vessels; second rib is long and flat; Ribs 10-12 articulate only with the vertebrae; Ribs 11 & 12 don't articulate with transverse processes posteriorly or sternum anteriorly
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Vertebrae:
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12 thoracic vertebrae
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Identified by:
- Transverse costal facets
- Costal facets on vertebral body
- Long spinous processes pointing inferiorly
- Superior articular facets facing dorsally (posteriorly)
- Inferior articular facets facing ventrally (anteriorly)
- Circular vertebral foramen
- Heart-shaped body
Boundaries of the Openings of the Thoracic Cage
- The thoracic cage is osseo-cartilaginous (bony and cartilaginous)
- Elastic and allows for respiration
- Shapes a truncated cone
Inlet of Thorax (Superior Aperture)
- Narrow and kidney shaped
- Boundaries:
- Anteriorly: Manubrium sterni
- Posteriorly: T1 body
- Laterally: 1st rib + cartilage
- Structures passing:
- Viscera:
- Trachea
- Esophagus
- Lung apices
- Remnants of the thymus
- Large vessels:
- Brachiocephalic artery
- Left common carotid artery
- Left subclavian artery
- Right and left brachiocephalic veins
- Muscles:
- Sternohyoid
- Sternothyroid
- Longus colli
- Nerves:
- Right & left phrenic nerves
- Right & left vagus nerves
- Right & left sympathetic trunks
- Right & left 1st thoracic nerves
- Viscera:
Thoracic Outlet (Inferior Aperture)
- Presents with the diaphragm
- Boundaries:
- Anteriorly: Infrasternal angle
- Posteriorly: T12 body
- Laterally: Costal margin (7th to 12th ribs)
Diaphragm
- Dome-shaped musculo-aponeurotic partition between thorax and abdomen
- Convex superior surface faces the thorax
- Depressed in the middle, summits are called cupolae
- Right cupola is higher due to the presence of the liver
- Peripheral part is muscular (striated)
- Central part is tendinous, occupied by central tendon
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Origin:
- Sternal part arises from the posterior surface of the xiphoid process
- Costal part arises from the deep surfaces of the lower six ribs and their costal cartilages, forming the right and left domes
- Vertebral/lumbar part arises from the upper three lumbar vertebrae, forming the right and left crura and the arcuate ligaments (medial & lateral)
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Insertion:
- Central tendon. Some right crus muscle fibers pass up to the left, surrounding the esophageal orifice in a sling-like loop, potentially acting as a sphincter to prevent regurgitation
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Openings:
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Major openings:
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Vena Caval opening:
- Level of T8 vertebra in the central tendon
- Transmits inferior vena cava & branches of the right phrenic nerve
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Esophageal opening:
- Level of T10 vertebra
- Transmits esophagus, right and left vagus nerves, esophageal branches of the left gastric vessels, and lymph vessels
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Aortic opening:
- Anterior to the body of T12 vertebra between the crura
- Transmits aorta, thoracic duct, and azygos vein
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Vena Caval opening:
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Minor openings:
- Space of Larrey: Between sternal origin and 7th costal cartilage, transmits superior epigastric vessels and a few lymphatics from the liver. When enlarged, it's called "foramen of Morgagni"
- Greater and lesser splanchnic nerves: Right and left crura
- Left phrenic nerve: Piercing the left cupola
- Sympathetic trunk, least splanchnic nerve: Medial arcuate ligament
- Musculophrenic vessels:
- Subcostal vessels and nerve:
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Major openings:
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Nerve supply:
- Motor: Phrenic nerve
- Sensory: Central part by phrenic nerve, peripheral part by lower 6 or 7 intercostal nerves
- Sympathetic: Celiac plexus
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Blood supply:
- Arteries: Musculophrenic and pericardiophrenic arteries (branches of internal thoracic artery), lower 5 or 6 posterior intercostal arteries, superior phrenic artery (branch of descending thoracic aorta), inferior phrenic artery
- Veins: Corresponding with the arteries, draining into the systemic veins
Clinical Significance of Sternum
- Preferred site for bone marrow aspiration because it's subcutaneous and readily accessible
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Funnel chest (pectus excavatum):
- Abnormality in the shape of the chest wall
- Also known as sunken chest or funnel chest
- Ribs and sternum grow inward, forming a dent in the chest. Can be mild or severe, and severe cases can impact the heart/lungs
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Pigeon chest (pectus carinatum):
- Abnormality in the shape of the chest wall
- Congenital deformation of the anterior chest wall
- Presents with an outward protrusion of the sternum or rib cage
- Also called "pigeon breast" when the sternal manubrium is prominent
- Might be caused by Rickets due to unmineralized osteoid deposition
Thoracic Viscera: Pulmonary Cavities and Mediastinum
- Pulmonary cavities: Spaces within the thorax containing the lungs
- Mediastinum: Central compartment of the thorax, located between the two pulmonary cavities, containing heart, great vessels, trachea, esophagus, thymus, and other structures
Anatomy of the Pleura and Pleural Cavity
- Pleura: Serous membrane that lines the thoracic cavity and covers the lungs
- Parietal pleura: Lines the thoracic cavity
- Visceral pleura: Covers the lungs
- Pleural cavity: Potential space between the parietal and visceral pleura, containing a small amount of lubricating fluid that reduces friction during lung movements
- Pleural fluid: Lubricates the pleural surfaces, allowing smooth gliding during respiration
Lungs
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Structure:
- Parenchyma: Functional tissue of the lungs, responsible for gas exchange
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Bronchial tree: System of branching airways that conduct air to and from the alveoli
- Trachea: Main airway, dividing at level of 5th thoracic vertebra
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Bronchi: Main branches of the trachea, transporting air to each lung
- Right bronchus: Wider, shorter, more vertical, and more likely to be obstructed by inhaled objects
- Left bronchus: Longer, narrower, and more oblique
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Lobar bronchi: Branches of the bronchi, supplying each lobe of the lung
- Right bronchus: Divides into 3 lobar bronchi
- Left bronchus: Divides into 2 lobar bronchi
- Segmental bronchi: Subdivisions of the lobar bronchi, supplying specific lung segments
- Bronchioles: Smallest airways, leading to the alveoli
- Terminal bronchioles: Last conducting airways before the respiratory bronchioles
- Respiratory bronchioles: Begin gas exchange, connecting to alveolar ducts
- Alveolar ducts: Small air passages with alveoli along their walls
- Alveoli: Tiny air sacs where gas exchange occurs
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Blood supply:
- Pulmonary arteries: Transport deoxygenated blood from the heart to the lungs for oxygenation
- Pulmonary veins: Carry oxygenated blood from the lungs back to the heart
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Nerve supply:
- Parasympathetic nerves: From the vagus nerve, cause bronchoconstriction
- Sympathetic nerves: From the sympathetic trunk, cause bronchodilation
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Function:
- Gas exchange: Primarily oxygen uptake and carbon dioxide removal
- Defense: Protective cells within the lung tissue, like plasma cells, macrophages, and lymphocytes, defend against microbes in the distal air passages
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Regulation:
- pH regulation: Lungs help regulate blood pH by removing carbon dioxide, a major contributor to acidity in the body
- Regulation of blood pressure: Lungs produce ACE (angiotensin-converting enzyme), which plays a role in blood pressure regulation
Respiratory Bronchioles and Alveoli
- Each lung is further divided into lobules by fine sheets of connective tissue
- Airway wall becomes thinner as it divides and becomes smaller, with a gradual decrease in smooth muscle and connective tissue
- Alveolar ducts and alveoli have a single layer of squamous epithelium
- Elastic fibers support these distal passages
- Dense network of capillaries surround the alveoli
- Respiratory membrane: Thin membrane between the alveoli and capillaries, where gas exchange occurs
- Septal cells (Type II pneumocytes): Located between squamous cells, producing surfactant
- Surfactant: Reduces surface tension, aiding in lung inflation and preventing alveolar collapse. Production begins between the 24th and 35th week of fetal life
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Nerve supply:
- Parasympathetic: Vagal nerve, triggers bronchoconstriction
- Sympathetic: Causes bronchodilation
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Function:
- Defense against microbes relies on protective cells like plasma cells, macrophages, and lymphocytes in the distal air passages
Blood supply
- Pulmonary arteries: Transport deoxygenated blood from the heart to the lungs.
- Pulmonary veins: Transport oxygenated blood from the lungs back to the heart.
Venous Drainage
- Right side: Empties into the azygos vein
- Left side: Empties into the superior intercostal vein
Nerve Supply
- Vagus nerve: Bronchoconstriction
- Sympathetic nerves: Bronchodilation.
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Description
Test your knowledge on the thoracic cage and its components, including the sternum and ribs. Explore the anatomy of the bony framework that protects vital organs such as the heart and lungs. This quiz will cover the details of rib structure, types, and articulations.
