Thoracic Wall Muscles Overview
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Questions and Answers

Which of the following is NOT part of the thoracic wall framework?

  • Suprapleural membrane
  • Sternum and costal cartilages
  • Diaphragm
  • Thoracic part of the vertebral column
  • Rib & intercostal spaces
  • Clavicle (correct)

    • What is the name of the dense fascial layer that surrounds the cervical pleura?

  • Intercostal membrane
  • Diaphragm
  • Endothoracic fascia
  • Suprapleural membrane (correct)
  • Parietal pleura

    • What is the function of the endothoracic fascia?

  • Maintains the shape of the lungs
  • Allows the lungs to expand and contract
  • Connects the parietal pleura to the thoracic wall
  • Protects the visceral pleura
  • Separates the parietal pleura from the thoracic wall (correct)

    • What is the primary muscle of respiration?

    <p>Diaphragm (E)</p> Signup and view all the answers

    The subcostals share the action of the internal intercostals.

    <p>True (A)</p> Signup and view all the answers

    Name the three layers of intercostals?

    <p>External, Internal, and Innermost intercostals.</p> Signup and view all the answers

    The internal intercostals are ______ with the internal oblique muscle of the abdominal wall.

    <p>continuous</p> Signup and view all the answers

    What does the innermost intercostal muscle share its space with?

    <p>Intercostal neurovascular bundle (B)</p> Signup and view all the answers

    What are the two main functions of the diaphragm?

    <p>Separating the thoracic cavity from the abdominal cavity and aiding in inspiration and expiration (A)</p> Signup and view all the answers

    The diaphragm has attachments to the costal cartilages of ribs 7-12.

    <p>True (A)</p> Signup and view all the answers

    What is the name of the opening through which the esophagus and vagus nerves pass through the diaphragm?

    <p>Oesophageal hiatus (B)</p> Signup and view all the answers

    What level is the aortic opening of the diaphragm?

    <p>T12 level (A)</p> Signup and view all the answers

    The left and right crura of the diaphragm originate from the lumbar vertebrae.

    <p>True (A)</p> Signup and view all the answers

    When the diaphragm contracts, it creates a dome shape, which increases the volume of the thoracic cavity.

    <p>False (B)</p> Signup and view all the answers

    The diaphragm is innervated by which nerve?

    <p>Phrenic nerve (B)</p> Signup and view all the answers

    What are the names of the intercostal muscles that are not part of the main five muscles?

    <p>A and B (D)</p> Signup and view all the answers

    Flashcards

    Thoracic Wall

    The structure containing skin, muscles, ribs, and diaphragm surrounding the thoracic cavity.

    Muscles of Thoracic Cage

    Include intercostals, subcostals, and transversus thoracis, involved in respiration.

    Intercostal Muscles

    Muscles located between the ribs in three layers: external, internal, and innermost.

    External Intercostals

    11 pairs that elevate ribs to increase thoracic volume during inhalation.

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    Internal Intercostals

    Muscles that depress the rib cage and reduce thoracic volume during exhalation.

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    Innermost Intercostals

    Deepest intercostal muscles, acting similarly to internal intercostals.

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    Transversus Thoracic

    Muscle attaching sternum to ribs, weakly depresses ribs.

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    Subcostals

    Muscles running from lower ribs to hold and depress ribs during exhalation.

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    Diaphragm

    Muscle separating thoracic and abdominal cavities, vital for respiration.

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    Diaphragm Attachments

    Peripheral attachments include lumbar vertebrae, costal cartilages, and xiphoid process.

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    Oesophageal Opening

    T10 opening in the diaphragm for the esophagus and nerves.

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    Aortic Opening

    T12 level opening for aorta and thoracic duct in the diaphragm.

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    Caval Opening

    T8 opening transmitting the inferior vena cava through diaphragm.

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    Diaphragm Function

    Flattens and relaxes to change thoracic cavity volume during respiration.

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    Innervation of Diaphragm

    Phrenic nerve (C3-C5) controls diaphragm movement.

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    Vasculature of Diaphragm

    Supplied mainly by inferior phrenic arteries and includes others.

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    Suprapleural Membrane

    Dense layer protecting cervical pleura, resists intrathoracic pressure changes.

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    Endothoracic Fascia

    Thin connective tissue layer between parietal pleura and thoracic wall.

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    Intercostal Neurovascular Bundle

    Contains nerves and vessels between ribs, found between internal and innermost intercostals.

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    Inspiration

    Process of inhaling, diaphragm contracts, increasing thoracic cavity volume.

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    Expiration

    Process of exhaling, diaphragm relaxes, reducing thoracic cavity volume.

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    Right Crus of Diaphragm

    Arises from lumbar vertebrae, acts to prevent reflux during swallowing.

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    Left Crus of Diaphragm

    Arises from lumbar vertebrae, assisting diaphragm structure.

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    Central Tendon

    Muscle fibers of diaphragm fused at the center, attaching to pericardium.

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    Muscle Actions: External Intercostals

    Elevate ribs to expand thoracic volume during inhalation.

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    Muscle Actions: Internal Intercostals

    Depress ribs to reduce thoracic volume during exhalation.

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    Respiratory Muscles

    Muscles involved in changing volume of the thoracic cavity during breathing.

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    Muscles Attaching to Thoracic Wall

    Includes pectoralis major, minor, serratus anterior, and scalene muscles.

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    Intercostal Nerves (T1-T11)

    Nerves that innervate intercostal muscles, controlling breathing actions.

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    Study Notes

    Thoracic Wall Muscles and Layers

    • The thoracic wall is composed of several layers, including skin, muscles, and various membranes.
    • The framework of the thoracic wall includes the vertebral column posteriorly, the sternum and costal cartilages anteriorly, the ribs and intercostal spaces laterally, the suprapleural membrane superiorly, and the diaphragm inferiorly.
    • The thoracic wall is lined with parietal pleura internally.
    • The muscles that compose the thoracic cage are the intercostals, subcostals, transversus thoracis.
    • In addition, other muscles like the pectoralis major, minor; serratus anterior and scalene muscles attach to the thoracic wall.

    Intercostal Muscles

    • The intercostal muscles are organized into three layers: external, internal, and innermost.
    • The external intercostals run inferoanteriorly (from the rib above to the rib below).
    • The external intercostals originate at the lower border of a rib and insert into the superior border of the rib below.
    • The external intercostals elevate the ribs, increasing thoracic volume.
    • The external intercostals are innervated by intercostal nerves (T1-T11).
    • The internal intercostals lie deep to the external intercostals and run inferoposteriorly.
    • The internal intercostals originate at the lower border of a rib and insert into the superior border of the rib below.
    • The internal intercostals reduce the thoracic volume by depressing the ribcage.
    • The internal intercostals are innervated by intercostal nerves (T1-T11).
    • The innermost intercostals are the deepest layer; they are similar in structure to the internal intercostals.
    • The innermost intercostals run inferoposteriorly and are located in the most lateral portion of the intercostal spaces.
    • The innermost intercostals originate at the lower border of a rib and insert into the superior border of the rib below.
    • The innermost intercostals reduce the thoracic volume by depressing the ribcage.
    • The innermost intercostals are innervated by intercostal nerves (T1-T11).

    Subcostals

    • The subcostal muscles lie in the inferior portion of the thoracic wall.
    • They are thin slips of muscle running from the internal surface of a rib to the second or third rib below.
    • Their fibers run parallel to the innermost intercostal muscle.
    • The subcostals originate at the inferior surface of the lower ribs near the angle of the rib.
    • They then attach to the superior border of the rib two or three below.
    • The subcostals help in the actions of internal intercostals.
    • The subcostals are innervated by intercostal nerves.

    Transversus Thoracis

    • The transversus thoracis muscles are continuous with the transversus abdominis inferiorly.
    • They originate from the posterior surface of the inferior sternum to the interior surface of the costal cartilages (2-6).
    • The transversus thoracis are innervated by intercostal nerves (T1-T11).
    • Weakly depress the ribs.

    Diaphragm

    • The diaphragm is a double-domed sheet of skeletal muscle located at the inferior-most aspect of the rib cage.
    • The diaphragm separates the thoracic and abdominal cavities, and serves as the floor of the thoracic and roof of the abdominal cavity.
    • The diaphragm undergoes contraction and relaxation, altering thoracic volume and lung capacity.
    • This diaphragm has three peripheral attachments:
      • Lumbar vertebrae and arcuate ligaments
      • Costal cartilages of ribs 7-12
      • Xiphoid process of the sternum.
    • The right hemidiaphragm is slightly higher than the left, due to the liver.
    • The parts of the diaphragm that arise from the vertebrae are tendinous and are known as the right and left crura.
    • The right crus arises from L1-L3 and some fibers from it form the esophageal opening (physiological sphincter).
    • The left crus arises from L1-L2 and it forms the intervertebral discs.

    Suprapleural Membrane

    • The suprapleural membrane is a dense fascial layer, and a tent-shaped fibrous sheet.
    • It is attached laterally to the medial border of the first rib and costal cartilage.
    • The apex is attached to the tip of the transverse process of the seventh cervical vertebra.
    • Medially, it attaches to the fascia around structures that pass from the thorax into the neck.
    • It protects the underlying cervical pleura, and resists changes in intrathoracic pressure during respiratory movements.

    Endothoracic Fascia

    • The endothoracic fascia is a thin layer of loose connective tissue separating the parietal pleura from the thoracic wall.
    • An important fascia that underlies the suprapleural membrane.

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    Thoracic Wall Muscles and Layers PDF

    Description

    Explore the anatomy and layers of the thoracic wall, including the various muscles that contribute to its structure. This quiz covers the intercostal muscles and their organization, as well as other significant muscles related to the thoracic cage.

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