Introduction to the Respiratory System

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Questions and Answers

What is the primary function of the diaphragm and chest wall?

To act as a bellows for the lungs (correct)

To protect the heart from injury

To filter the air we breathe

To aid in digestion

What is the significance of the thoracic inlet and outlet?

They are the boundaries of the thoracic cavity (correct)

They are responsible for regulating blood pressure

They are the attachment sites for the ribs

They are the primary sites of gas exchange

What is the role of the pleural fluid in the respiratory system?

To absorb oxygen from the air

To regulate body temperature

To lubricate the movement of the lungs within the thoracic cavity (correct)

To remove carbon dioxide from the blood

What is unique about the thoracic volume in patients with emphysema?

It is increased due to lung overinflation Signup and view all the answers

What is the primary mechanism of increasing thoracic volume during inspiration?

Contraction of the diaphragm Signup and view all the answers

What is the innervation of the diaphragm?

Phrenic nerve and intercostal nerves Signup and view all the answers

What is the attachment site of the diaphragm?

Vertebral column and ribs Signup and view all the answers

What is the primary function of the pleural membranes?

To reduce friction between the lungs and chest wall Signup and view all the answers

What structure forms the superior boundary of the thoracic cavity?

Suprapleural membrane Signup and view all the answers

What is the term for the space between the visceral and parietal pleura?

Pleural cavity Signup and view all the answers

Which of the following structures is NOT part of the thoracic cavity?

Kidneys Signup and view all the answers

What is the inferior boundary of the thoracic cavity?

Diaphragm Signup and view all the answers

What is the function of the pleural fluid?

To maintain the lungs in an inflated state Signup and view all the answers

What is the term for the space between the two lungs?

Mediastinum Signup and view all the answers

What structures bound the thoracic cavity laterally?

Ribs Signup and view all the answers

What structure lines the space surrounding the lungs?

Parietal pleura Signup and view all the answers

Which of the following structures forms the bony-cartilaginous ring that the suprapleural membrane attaches to?

1st thoracic vertebra, 1st rib, 1st costal cartilage and upper margin of the manubrium Signup and view all the answers

Where does the suprapleural membrane rise up to and extend?

2.5 cms above the medial end of the clavicle Signup and view all the answers

What is the diaphragm?

A bi-domed muscular sheet that inserts into a central tendon Signup and view all the answers

What is the function of the hemi-diaphragm?

Enabling us to breathe in Signup and view all the answers

What structures pass through the thoracic inlet?

Trachea, oesophagus, vessels of the head and neck, and vessels of the upper limb Signup and view all the answers

What type of fascia do the vessels of the head and neck take as they pass through the thoracic inlet?

Carotid sheath Signup and view all the answers

What is the thoracic outlet bounded by?

Costal margin in front, the tips of the 11th ribs, the 12th ribs and the inferior margin of the 12th thoracic vertebra Signup and view all the answers

What passes through the thoracic outlet?

Thoracic structures destined for the abdomen Signup and view all the answers

Study Notes

Boundaries of the Thoracic Cavity

The thoracic cavity is the space occupied by the lungs and their covering of visceral pleura.
The lungs almost completely fill this space, leaving a tiny gap between the visceral pleura and the parietal pleura.
The enclosed space between the pleural membranes is called the pleural cavity.
The thoracic cavity is bounded posteriorly by the thoracic vertebral column, laterally by the ribs, and anteriorly by the sternum.

Thoracic Apertures

The thoracic inlet, or superior thoracic aperture, is a bony-cartilaginous ring defined by the 1st thoracic vertebra, 1st rib, 1st costal cartilage, and upper margin of the manubrium.
The suprapleural membrane attaches to this ring and rises upwards, extending 2.5 cm above the medial end of the clavicle.
The thoracic outlet, or inferior thoracic aperture, is the space bounded by the costal margin in front, the tips of the 11th and 12th ribs, and the inferior margin of the 12th thoracic vertebra.
The diaphragm closes off the thoracic outlet and is a bi-domed muscular sheet inserting into a central tendon.

Structures Passing Through the Thoracic Inlet

Structures that pass through the thoracic inlet, such as the trachea, oesophagus, carotid artery, and internal jugular vein, take a sleeve of the fascial membrane as they do so.
The trachea and oesophagus take pre-tracheal fascia, the vessels of the head and neck take the carotid sheath, and the vessels of the upper limb take the axillary sheath.

Diaphragm

The diaphragm is the principal muscle of breathing.
Each side of the diaphragm is referred to as a hemi-diaphragm.
The diaphragm descends to enable inspiration and relaxes to allow expiration.
The thoracic outlet transmits thoracic structures destined for the abdomen and permits passage of venous blood from the lower half of the body back into the heart.

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Description

Learn about the boundaries of the chest and the respiratory system in this introductory lecture, covering the thoracic inlet and outlet.