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Questions and Answers
Which muscle forms the deepest layer of the intercostal spaces and extends anteriorly to the sternum?
Which muscle forms the deepest layer of the intercostal spaces and extends anteriorly to the sternum?
What anatomical structures are found in each intercostal space?
What anatomical structures are found in each intercostal space?
Which muscle forms the superficial layer of the intercostal spaces and attaches superiorly to the inferior border of the rib above?
Which muscle forms the superficial layer of the intercostal spaces and attaches superiorly to the inferior border of the rib above?
From its origin at the floors of the costal grooves, which direction do the fibers of the internal intercostal muscle run?
From its origin at the floors of the costal grooves, which direction do the fibers of the internal intercostal muscle run?
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What are the spaces between the ribs and costal cartilages called?
What are the spaces between the ribs and costal cartilages called?
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Which muscle forms the middle layer of the intercostal spaces and runs downwards, backwards, and laterally from its origin at the floors of the costal grooves?
Which muscle forms the middle layer of the intercostal spaces and runs downwards, backwards, and laterally from its origin at the floors of the costal grooves?
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To which structures do the external intercostal muscles attach superiorly and inferiorly?
To which structures do the external intercostal muscles attach superiorly and inferiorly?
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Where are the muscle fibers of external intercostal muscles directed?
Where are the muscle fibers of external intercostal muscles directed?
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What replaces the muscle fibers of external intercostal muscles anteriorly?
What replaces the muscle fibers of external intercostal muscles anteriorly?
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Which muscle extends anteriorly to the sternum and is replaced posteriorly by the posterior intercostal membranes?
Which muscle extends anteriorly to the sternum and is replaced posteriorly by the posterior intercostal membranes?
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Which muscle arises from the roots of the transverse processes, the sides of the vertebral bodies, and the intervertebral discs, from the 12th thoracic to the 5th lumbar vertebrae?
Which muscle arises from the roots of the transverse processes, the sides of the vertebral bodies, and the intervertebral discs, from the 12th thoracic to the 5th lumbar vertebrae?
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Which muscle arises from the adjacent parts of the bodies of the last thoracic vertebra and the first lumbar vertebra?
Which muscle arises from the adjacent parts of the bodies of the last thoracic vertebra and the first lumbar vertebra?
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Which muscle passes deep to the inguinal ligament to reach the lesser trochanter of the femur?
Which muscle passes deep to the inguinal ligament to reach the lesser trochanter of the femur?
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Which muscle originates from the iliac fossa and inserts into the lesser trochanter of the femur?
Which muscle originates from the iliac fossa and inserts into the lesser trochanter of the femur?
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Which muscle contributes to the superior part of the posterior abdominal wall and is part of the posterior abdominal wall muscles?
Which muscle contributes to the superior part of the posterior abdominal wall and is part of the posterior abdominal wall muscles?
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Study Notes
Intercostal Muscles and Spaces
- The innermost intercostal muscle forms the deepest layer of intercostal spaces and extends anteriorly to the sternum.
- Each intercostal space contains 3 main structures: intercostal muscles, intercostal nerves, and intercostal vessels (arteries and veins).
- The external intercostal muscle is the superficial layer, attaching superiorly to the inferior border of the rib above.
- Internal intercostal muscle fibers run downward and forward from their origin at the floors of the costal grooves.
- The spaces between ribs and costal cartilages are called intercostal spaces.
- The internal intercostal muscle forms the middle layer, running downwards, backwards, and laterally from its origin at the floors of the costal grooves.
Attachments and Fiber Directions
- External intercostal muscles attach superiorly to the inferior border of the rib above and inferiorly to the superior border of the rib below.
- Muscle fibers of external intercostal muscles are directed downward and forward.
- Anteriorly, muscle fibers of external intercostal muscles are replaced by anterior intercostal membranes.
Other Important Muscles
- The sternocleidomastoid muscle extends anteriorly to the sternum and is replaced posteriorly by the posterior intercostal membranes.
- The psoas major muscle arises from the roots of the transverse processes, sides of the vertebral bodies, and intervertebral discs from T12 to L5.
- The quadratus lumborum muscle originates from the adjacent parts of the bodies of the last thoracic vertebra (T12) and the first lumbar vertebra (L1).
- The iliopsoas muscle passes deep to the inguinal ligament to reach the lesser trochanter of the femur.
- The iliacus muscle originates from the iliac fossa and inserts into the lesser trochanter of the femur.
- The psoas major muscle contributes to the superior part of the posterior abdominal wall and is part of the posterior abdominal wall muscles.
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Description
Test your knowledge of the anatomy of the thoracic wall and diaphragm, including intercostal spaces, muscles, vessels, and nerves. Learn about the anatomical structures found in the 11 intercostal spaces on each side.
