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Questions and Answers
What is the primary function of the thoracic cage?
What is the primary function of the thoracic cage?
- To enclose the thoracic cavity and support the shoulder girdle (correct)
- To store calcium and phosphorus
- To produce red blood cells
- To protect the brain
Which structures are part of the skeletal framework of the thoracic cage?
Which structures are part of the skeletal framework of the thoracic cage?
- Pelvis, femur, and humerus
- Ribs, clavicles, and scapulae
- 12 pairs of ribs, sternum, and 12 thoracic vertebrae (correct)
- Skull, vertebrae, and costal cartilages
Which landmark is associated with the junction between the manubrium and the body of the sternum?
Which landmark is associated with the junction between the manubrium and the body of the sternum?
- Xiphoid process
- Intercostal space
- Clavicular notch
- Sternal angle (of Louis) (correct)
At what age does the xiphoid process typically ossify?
At what age does the xiphoid process typically ossify?
Which of the following structures articulates with the clavicle at the sternum?
Which of the following structures articulates with the clavicle at the sternum?
What is the term used for the notch felt at the base of the throat?
What is the term used for the notch felt at the base of the throat?
Which ribs articulate with the costal notches on the body of the sternum?
Which ribs articulate with the costal notches on the body of the sternum?
What clinical procedure can be performed using the sternum?
What clinical procedure can be performed using the sternum?
What condition is caused by the introduction of air due to a defect in the pleura?
What condition is caused by the introduction of air due to a defect in the pleura?
What is the primary reason for inserting a needle at the upper border of the rib during a pleural tap?
What is the primary reason for inserting a needle at the upper border of the rib during a pleural tap?
What feature differentiates healthy lungs in living individuals from cadaveric lungs?
What feature differentiates healthy lungs in living individuals from cadaveric lungs?
What can irritation of the phrenic nerve present as?
What can irritation of the phrenic nerve present as?
Why is it important to recognize the levels of pleural reflection during a thoracocentesis?
Why is it important to recognize the levels of pleural reflection during a thoracocentesis?
What is the main action of the external intercostal muscles?
What is the main action of the external intercostal muscles?
What type of innervation do the external intercostal muscles receive?
What type of innervation do the external intercostal muscles receive?
Which muscle is primarily responsible for depressing the ribs?
Which muscle is primarily responsible for depressing the ribs?
Where do the internal intercostal muscles attach superiorly?
Where do the internal intercostal muscles attach superiorly?
Which of the following muscles acts similarly to the internal intercostals?
Which of the following muscles acts similarly to the internal intercostals?
What role does the neurovascular bundle located between the inner and innermost intercostal muscles serve?
What role does the neurovascular bundle located between the inner and innermost intercostal muscles serve?
Which of the following structures is located on the posterior surface of the lower sternum?
Which of the following structures is located on the posterior surface of the lower sternum?
How do the actions of the serratus posterior inferior differ from those of other thoracic muscles?
How do the actions of the serratus posterior inferior differ from those of other thoracic muscles?
Which artery directly supplies the anterior intercostal arteries in the upper six spaces?
Which artery directly supplies the anterior intercostal arteries in the upper six spaces?
Where do the posterior intercostal veins drain into on the left side of the body?
Where do the posterior intercostal veins drain into on the left side of the body?
Which artery supplies the lower intercostal spaces?
Which artery supplies the lower intercostal spaces?
What is the consequence of obstruction of the thoracic aorta in relation to the arteries?
What is the consequence of obstruction of the thoracic aorta in relation to the arteries?
Which artery accompanies the phrenic nerve and supplies the sternum?
Which artery accompanies the phrenic nerve and supplies the sternum?
What is the origin of the internal thoracic artery?
What is the origin of the internal thoracic artery?
The anterior primary rami of which spinal nerve forms the subcostal nerves?
The anterior primary rami of which spinal nerve forms the subcostal nerves?
How many pairs of thoracic spinal nerves are there in total?
How many pairs of thoracic spinal nerves are there in total?
Which layer of the pleura is associated with the walls of the pleural cavity?
Which layer of the pleura is associated with the walls of the pleural cavity?
Where does the cervical pleura project into the body?
Where does the cervical pleura project into the body?
What is the primary function of the fluid in the pleural cavity?
What is the primary function of the fluid in the pleural cavity?
Which statement about the borders of the pleura is correct?
Which statement about the borders of the pleura is correct?
Which type of pleura reflects from the medial wall onto the surface of the lung?
Which type of pleura reflects from the medial wall onto the surface of the lung?
The costal pleura is separated from which anatomical structure?
The costal pleura is separated from which anatomical structure?
What is the singular term for the space between the visceral and parietal pleura?
What is the singular term for the space between the visceral and parietal pleura?
Which pleura covers the upper surface of the diaphragm?
Which pleura covers the upper surface of the diaphragm?
What is the primary source of blood supply to the lungs?
What is the primary source of blood supply to the lungs?
Which nerve supply function results in bronchial muscle relaxation?
Which nerve supply function results in bronchial muscle relaxation?
How are bronchopulmonary segments characterized in terms of their independence?
How are bronchopulmonary segments characterized in terms of their independence?
What structure primarily drains lymph from the lungs?
What structure primarily drains lymph from the lungs?
During inspiration, how do the dimensions of the thorax change?
During inspiration, how do the dimensions of the thorax change?
Which ribs are classified as floating ribs?
Which ribs are classified as floating ribs?
What type of joint is formed between the head of the rib and the bodies of two adjacent vertebrae?
What type of joint is formed between the head of the rib and the bodies of two adjacent vertebrae?
What is the main function of costal cartilages in the thoracic cage?
What is the main function of costal cartilages in the thoracic cage?
Which structure is associated with the junction of the neck and shaft of a rib?
Which structure is associated with the junction of the neck and shaft of a rib?
What type of joint exists between costal cartilages 2-7 and the sternum?
What type of joint exists between costal cartilages 2-7 and the sternum?
How do the costal cartilages of ribs 8-10 articulate?
How do the costal cartilages of ribs 8-10 articulate?
What is the role of the subcostal groove on the rib's shaft?
What is the role of the subcostal groove on the rib's shaft?
Which of the following joints is classified as fibrocartilaginous?
Which of the following joints is classified as fibrocartilaginous?
What is the primary function of the hilum of the lung?
What is the primary function of the hilum of the lung?
Which structure is found within the root of the lung?
Which structure is found within the root of the lung?
What is the orientation of the pulmonary veins in relation to the bronchi within the hilum?
What is the orientation of the pulmonary veins in relation to the bronchi within the hilum?
Which of the following correctly describes the inferior border of the lung?
Which of the following correctly describes the inferior border of the lung?
How is the oblique fissure of the lung oriented?
How is the oblique fissure of the lung oriented?
What structures are positioned anteriorly and superiorly in the root of the right lung?
What structures are positioned anteriorly and superiorly in the root of the right lung?
What relationship does the left lung's root have with the arch of the aorta?
What relationship does the left lung's root have with the arch of the aorta?
What is the function of the pulmonary ligament?
What is the function of the pulmonary ligament?
Which of the following best describes the costal surface of the lung?
Which of the following best describes the costal surface of the lung?
What is the primary distinction between the structures surrounding the right and left lung roots?
What is the primary distinction between the structures surrounding the right and left lung roots?
What separates the superior and middle lobes from the inferior lobe in the right lung?
What separates the superior and middle lobes from the inferior lobe in the right lung?
Which of the following statements about the right lung is correct?
Which of the following statements about the right lung is correct?
Where are breath sounds from the superior lobe of the right lung best heard?
Where are breath sounds from the superior lobe of the right lung best heard?
Which structure is part of the significant relationships of the medial surface of the left lung?
Which structure is part of the significant relationships of the medial surface of the left lung?
What is the primary reason aspirated materials are more likely to enter the right lung?
What is the primary reason aspirated materials are more likely to enter the right lung?
What feature characterizes the left lung compared to the right lung?
What feature characterizes the left lung compared to the right lung?
What anatomical structure does the trachea bifurcate into?
What anatomical structure does the trachea bifurcate into?
What is the orientation of the horizontal fissure in the right lung?
What is the orientation of the horizontal fissure in the right lung?
Which bronchus originates from the root of the right lung?
Which bronchus originates from the root of the right lung?
What structure is described as a medially directed tongue-like projection on the left lung?
What structure is described as a medially directed tongue-like projection on the left lung?
Which muscle is responsible for elevating the ribs during inspiration?
Which muscle is responsible for elevating the ribs during inspiration?
Where do the internal intercostal muscles attach superiorly?
Where do the internal intercostal muscles attach superiorly?
What is the innervation source for the intercostal muscles?
What is the innervation source for the intercostal muscles?
Which muscle primarily depresses the ribs and costal cartilages during forced expiration?
Which muscle primarily depresses the ribs and costal cartilages during forced expiration?
Which structure is located between the inner and innermost intercostal muscles?
Which structure is located between the inner and innermost intercostal muscles?
What is the action of the innermost intercostal muscles?
What is the action of the innermost intercostal muscles?
Which muscle acts primarily to depress the ribs?
Which muscle acts primarily to depress the ribs?
What distinguishes the external intercostal muscles from internal intercostals?
What distinguishes the external intercostal muscles from internal intercostals?
Where do the transversus thoracis muscles primarily attach?
Where do the transversus thoracis muscles primarily attach?
Which of the following muscles does not contribute to elevating the ribs?
Which of the following muscles does not contribute to elevating the ribs?
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Study Notes
Thoracic Cage Overview
- The thoracic cage comprises 12 pairs of ribs, corresponding thoracic vertebrae, costal cartilages, and the sternum.
- Encloses the thoracic cavity and supports the shoulder girdle.
- Provides attachment sites for neck, thorax, upper limbs, abdomen, and back muscles.
Key Landmarks of the Thorax
- Jugular (suprasternal) notch
- Sternal angle (of Louis) – palpable and important for counting ribs.
- Nipple
- Xiphoid process – ossifies by age 40 and descends into the infrasternal angle.
Skeletal Framework
- Composed of the sternum, 12 pairs of ribs with costal cartilages, and 12 thoracic vertebrae.
- Sternum consists of three parts: manubrium, body (four fused sternebrae), and xiphoid process.
Manubrium Details
- Contains the suprasternal notch and clavicular notches for sternoclavicular joint articulation.
Body of Sternum
- Articulates with costal notches for ribs 2 to 7.
Clinical Significance of the Sternum
- Sternal angle serves as a landmark for the second costal cartilage.
- Site for bone marrow biopsy and median sternotomy for heart access.
Intercostal Muscles
- Arranged in three layers: external intercostal, internal intercostal, and innermost intercostal.
- External intercostals elevate ribs during inspiration; internal intercostals lower ribs during forced expiration.
Thoracic Wall Musculature
- Other muscles involved in respiration: transversus thoracis, subcostal muscles, serratus posterior superior/inferior, and diaphragm.
Vasculature of the Thoracic Wall
- Anterior intercostal arteries arise from the internal thoracic artery; posterior intercostal arteries from thoracic aorta.
- Internal thoracic artery branches into musculophrenic and superior epigastric arteries.
- Posterior intercostal veins drain into azygous and hemiazygos veins, while anterior intercostal veins drain into internal thoracic veins.
Nerves of the Thoracic Wall
- Thoracic spinal nerves bifurcate into anterior (ventral) and posterior (dorsal) rami.
- Intercostal nerves run along intercostal spaces, with T12 forming the subcostal nerves.
Pleura and Lung Compartment
- Each lung has a pleural sac, consisting of visceral and parietal layers which facilitate lung movement.
- The pleural cavity contains fluid that reduces friction during respiration.
Types of Pleura
- Parietal pleura lines thoracic wall; visceral pleura covers lungs.
- Subdivisions include costal, diaphragmatic, mediastinal, and cervical pleura.
Pleural Recesses and Reflections
- Interactions between costal and mediastinal pleura create borders that can be affected by pneumothorax when compromised.
Clinical Procedures
- Thoracocentesis involves withdrawing fluid from the pleural cavity, with careful needle insertion to avoid injury.
- Parietal pleura irritation can cause pain perceived in the thoracic or abdominal walls due to somatic nerve innervation.
External Features of Lungs
- Lungs are vital for oxygenating blood and appear soft, light, and elastic in healthy individuals.
- They recoil to about one-third their size when the thoracic cavity is opened, highlighting their elastic nature.
Ribs
- Comprise 12 pairs of elongated, flattened, curved bones; articulate with thoracic vertebrae.
- Each rib has a body with a costal angle and anterior attachment to costal cartilage which connects to the sternum.
- The posterior portion articulates with thoracic vertebrae through a head and two facets.
- The tubercle on the rib is located at the neck and articulates with the transverse process of thoracic vertebrae.
- Contains a subcostal groove for a neurovascular bundle.
- True ribs (1-7) attach directly to the sternum; ribs 8-10 connect via costal cartilages forming the costal margin; ribs 11-12 are floating ribs, lacking anterior attachments.
Joint Structures
- Costovertebral joints are synovial, allowing rib articulation with vertebrae and intervertebral disc.
- Sternocostal joints are between costal cartilages and sternum, permitting flexibility.
- Costochondral joints connect bony ribs with costal cartilage.
- Interchondral joints exist between the cartilages of ribs 7-10.
- Manubriosternal and xiphisternal joints are fibrocartilaginous and cartilaginous respectively.
Musculature of Thoracic Wall
- External Intercostals: Attach from the lower border of ribs to upper border of the rib below; innervated by intercostal nerves; elevate ribs during inspiration.
- Internal Intercostals: Connect costal cartilage to the upper rib below; lower ribs during forced expiration.
- Innermost Intercostals: Function similarly to internal intercostals; innervated by intercostal nerves.
- Transversus Thoracis: Depresses ribs and attaches to costal cartilages.
- Subcostal Muscles: Located near lower rib angles; depress upper ribs.
- Back muscles involved in respiration include serratus posterior superior/inferior and diaphragm.
Lungs Structure
- Each lung features an apex, base, costal surface, mediastinal surface, anterior and posterior borders, and an inferior border.
- The hilum serves as the entry/exit point for vital structures (bronchi, pulmonary arteries and veins, autonomic nerves, lymphatics).
- Each lung root includes one pulmonary artery, two pulmonary veins, and one main bronchus.
Fissures of the Lungs
- Right lung: 3 lobes (superior, middle, inferior) and two fissures (oblique and horizontal).
- Left lung: 2 lobes (superior and inferior) and one oblique fissure; features a cardiac notch and lingula.
Bronchial Tree
- The trachea descends anterior to the esophagus and bifurcates at the sternal angle.
- Right main bronchus is shorter and wider, increasing the propensity for aspiration.
- Each lung has 10 bronchopulmonary segments, aerated by tertiary bronchi, making segments functionally independent.
Vasculature of the Lungs
- Pulmonary arteries carry deoxygenated blood from the heart; oxygenated blood returns via pulmonary veins.
- Bronchial arteries provide blood supply to the bronchial walls and visceral pleura.
- Bronchial venous blood partially enters the azygos system and pulmonary veins.
Nerve Supply of the Lungs
- Vagus nerves and sympathetic trunks influence bronchial muscle and glandular secretion.
- Sympathomimetic drugs and parasympathetic antagonists are used for asthma treatment.
Lymphatic Drainage
- Lymph drains from lungs to bronchopulmonary lymph nodes, then to tracheobronchial nodes, reaching either the thoracic or right lymphatic duct.
Movements of Respiration
- Inhalation expands thoracic diameters vertically, anteroposteriorly, and transversely through chest wall and diaphragm movement.
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