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Questions and Answers
What is the primary structure located in the costal groove of the rib?
What is the primary structure located in the costal groove of the rib?
Which layer is NOT part of the thoracic wall?
Which layer is NOT part of the thoracic wall?
Which structure provides the most superficial layer of the thoracic wall?
Which structure provides the most superficial layer of the thoracic wall?
What is the correct order of vessels in the costal groove from superior to inferior?
What is the correct order of vessels in the costal groove from superior to inferior?
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Which of the following structures does NOT innervate the muscles of the thoracic wall?
Which of the following structures does NOT innervate the muscles of the thoracic wall?
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Which fascia separates the thoracic cavity from the muscular layers of the thoracic wall?
Which fascia separates the thoracic cavity from the muscular layers of the thoracic wall?
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What type of muscle is primarily found in the intercostal spaces?
What type of muscle is primarily found in the intercostal spaces?
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Which muscle layer lies directly beneath the skin in the thoracic wall?
Which muscle layer lies directly beneath the skin in the thoracic wall?
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What is the main function of the intercostal muscles?
What is the main function of the intercostal muscles?
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The intercostal nerve primarily arises from which part of the nervous system?
The intercostal nerve primarily arises from which part of the nervous system?
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What is the significance of the median sagittal line in surface anatomy?
What is the significance of the median sagittal line in surface anatomy?
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Which structure is not part of the surface anatomy of the sternum?
Which structure is not part of the surface anatomy of the sternum?
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What do midclavicular lines connect?
What do midclavicular lines connect?
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Which line runs along the anterior axillary fold?
Which line runs along the anterior axillary fold?
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What anatomical landmark corresponds to the bottom of the sternum?
What anatomical landmark corresponds to the bottom of the sternum?
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Which of the following terms describes the intersection of the median plane with the anterior chest wall?
Which of the following terms describes the intersection of the median plane with the anterior chest wall?
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What does the posterior axillary line indicate?
What does the posterior axillary line indicate?
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Which anatomical line runs vertically down the midpoints of the clavicles?
Which anatomical line runs vertically down the midpoints of the clavicles?
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Which artery is a branch of the costocervical trunk?
Which artery is a branch of the costocervical trunk?
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What is the main drainage system for the posterior intercostal veins?
What is the main drainage system for the posterior intercostal veins?
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How many anterior intercostal spaces are mentioned?
How many anterior intercostal spaces are mentioned?
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Which of the following veins does NOT drain into the azygos system on the right side?
Which of the following veins does NOT drain into the azygos system on the right side?
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Which posterior intercostal veins drain into the brachiocephalic vein?
Which posterior intercostal veins drain into the brachiocephalic vein?
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Which arteries supply the intercostal muscles?
Which arteries supply the intercostal muscles?
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What is the total number of posterior intercostal spaces?
What is the total number of posterior intercostal spaces?
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What contributes to the formation of the azygos system of veins?
What contributes to the formation of the azygos system of veins?
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Which vessel drains the 2nd and 3rd intercostal veins?
Which vessel drains the 2nd and 3rd intercostal veins?
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From which artery does the musculophrenic artery branch?
From which artery does the musculophrenic artery branch?
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What connects the anterior and posterior intercostal veins?
What connects the anterior and posterior intercostal veins?
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What is the largest vein that drains the head?
What is the largest vein that drains the head?
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Which intercostal vein is classified as the smallest?
Which intercostal vein is classified as the smallest?
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Which artery indirectly supplies the intercostal muscles?
Which artery indirectly supplies the intercostal muscles?
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What is the primary function of the intercostal nerves?
What is the primary function of the intercostal nerves?
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Which type of fibers are found in intercostal nerves?
Which type of fibers are found in intercostal nerves?
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Where does the collateral branch of an intercostal nerve pass?
Where does the collateral branch of an intercostal nerve pass?
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What is the primary complication of an intercostal nerve block?
What is the primary complication of an intercostal nerve block?
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What anatomical structure do the intercostal arteries branch from?
What anatomical structure do the intercostal arteries branch from?
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Which intercostal nerve corresponds to the subcostal nerve?
Which intercostal nerve corresponds to the subcostal nerve?
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What type of pain management is achieved with an intercostal nerve block?
What type of pain management is achieved with an intercostal nerve block?
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How many pairs of intercostal nerves are there in the body?
How many pairs of intercostal nerves are there in the body?
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What is the function of the lateral cutaneous branch of intercostal nerves?
What is the function of the lateral cutaneous branch of intercostal nerves?
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What is indicated for an intercostal nerve block?
What is indicated for an intercostal nerve block?
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Which artery supplies blood to the intercostal spaces?
Which artery supplies blood to the intercostal spaces?
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From which larger artery do the posterior intercostal arteries typically branch?
From which larger artery do the posterior intercostal arteries typically branch?
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How many intercostal arteries supply each intercostal space?
How many intercostal arteries supply each intercostal space?
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Study Notes
Thoracic Wall: Innervation & Vasculature
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Layers of Thoracic Wall:
- Skin
- Superficial Fascia
- Deep Fascia
- Muscles
- Intercostal
- External Intercostal Fascia
- Internal Intercostal Fascia
- Endothoracic Fascia
- Parietal Pleura
Intercostal Neurovascular Bundle
- Location: Costal Groove (Superior Border of Each Rib)
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Contents:
- Vein: Superior
- Artery: Middle
- Nerve: Anterior & Inferior
Intercostal Nerves
- Origin: Anterior Rami of Thoracic Spinal Nerves
- Number: 11 Pairs (1 Nerve/Intercostal Space)
- Nerve 12: Located in the Abdomen, Known as the Subcostal Nerve
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Main Branches:
- Collateral Branch: Mixed (Sensory & Motor), Passes Inferior to the Main Nerve on the Upper Border of the Rib Below
- Lateral Cutaneous Branch: Sensory, Located at the Midaxillary Line
- Anterior Cutaneous Branch: Sensory
- Muscular Branches: Motor, Supply Intercostal Muscles
- Pleural Branches: Sensory, Supply Parietal Pleura, Endothoracic Fascia (External, Internal, Innermost Intercostal Muscles)
Intercostal Nerve Block
- Objective: To relieve pain and allow pain-free respiratory movements
-
Indications:
- Rib Fractures
- Surgical Incisions
- Herpes Zoster Infection (Shingles)
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Procedure:
- Needle is inserted posteriorly near the rib (5-7 cm from midline)
- Needle is directed near the lower border of the rib
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Complications:
- Pneumothorax
- Hemorrhage
- Nerve Injury
Intercostal Arteries
- Number: 18 Pairs (11 Posterior & 11 Anterior)
-
Posterior Intercostal Arteries:
- 1st & 2nd: Branch directly from the Superior Intercostal Artery of the Costocervical Trunk (Subclavian Artery)
- 3rd - 11th: Branch from the Descending Thoracic Aorta
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Anterior Intercostal Arteries:
- 1st - 6th: Branch from the Internal Thoracic Artery
- Largest Branches: 5th & 9th Intercostal Arteries
- Collateral Branches: Run along the upper border of the rib below
Intercostal Nerve Block & Intercostal Arteries: Clinical Significance
- Clinical Significance: The Intercostal Arteries supply the intercostal muscles and the overlying skin. The Intercostal Nerve Block is used to relieve pain in the chest wall.
- Important to Note: Damage to the Intercostal Nerve can lead to loss of sensation & paralysis of the intercostal muscles.
Blood Supply to Muscles
- The superior epigastric artery, internal thoracic, and musculophrenic artery provide blood supply to the intercostal muscles.
- The costocervical trunk, a branch of the subclavian artery, also contributes to blood supply.
- The costocervical trunk divides into the deep cervical and superior intercostal arteries.
- The superior intercostal artery supplies the first two intercostal spaces.
- The musculophrenic artery supplies the lower intercostal spaces.
Intercostal Arteries
- The first two intercostal arteries originate from the superior intercostal artery, while the remaining ones arise from the thoracic aorta.
- The anterior intercostal arteries are branches of the internal thoracic artery.
- The posterior intercostal arteries directly supply the intercostal muscles and the skin of the chest wall.
Intercostal Veins
- There are three intercostal veins per space: one large posterior intercostal vein and two small anterior intercostal veins.
- The posterior intercostal veins drain into the azygos system of veins.
- The azygos vein collects venous blood from the right side of the thorax, while the hemiazygos and accessory hemiazygos veins collect from the left side.
- Exceptions to drainage:
- The first intercostal vein drains into the brachiocephalic vein.
- The second and third intercostal veins on the left side drain into the left superior intercostal vein, which then merges with the left brachiocephalic vein.
- The anterior intercostal veins drain into the internal thoracic vein.
- The internal thoracic vein drains directly into the brachiocephalic vein.
Surface Anatomy of the Thorax
- Clavicle: This bone lies horizontally across the superior part of the thorax.
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Sternum:
- Jugular notch: The superior depression on the sternum.
- Sternal angle: The point where the manubrium joins the body of the sternum. It is a clinically relevant landmark for counting ribs.
- Body of the sternum: The central portion of the sternum.
- Xiphoid process: The inferior, pointed end of the sternum.
- Costal margins: The inferior borders of the rib cage formed by the inferior ends of the ribs.
Surface Anatomical Lines
Anterior Lines
- Median sagittal line: This vertical line runs along the midline of the anterior chest wall.
- Midclavicular lines: These lines run vertically along the midpoints of the clavicles. They extend from the clavicles to the inguinal region.
Lateral Lines
- Anterior axillary line: This line runs vertically along the anterior axillary fold, which is formed by the lower border of the pectoralis major muscle.
- Posterior axillary line: This line runs vertically along the posterior axillary fold.
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Description
Test your knowledge on the layers and innervation of the thoracic wall, including the intercostal neurovascular bundle and intercostal nerves. This quiz covers the anatomical structures and their functions essential for understanding thoracic anatomy.
