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Questions and Answers
What is the origin of the Pectoralis Major muscle?
What is the origin of the Pectoralis Major muscle?
Which muscle is responsible for the rotation of the scapula?
Which muscle is responsible for the rotation of the scapula?
What is the insertion of the Pectoralis Minor muscle?
What is the insertion of the Pectoralis Minor muscle?
Which nerve innervates the Pectoralis Minor muscle?
Which nerve innervates the Pectoralis Minor muscle?
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What is the action of the Subclavius muscle?
What is the action of the Subclavius muscle?
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Which muscle is responsible for the abduction of the arm?
Which muscle is responsible for the abduction of the arm?
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What is the function of the costal cartilages in the chest wall structure?
What is the function of the costal cartilages in the chest wall structure?
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Which of the following muscles is located deep to the pectoralis major?
Which of the following muscles is located deep to the pectoralis major?
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What is the purpose of the intercostal spaces in the chest wall structure?
What is the purpose of the intercostal spaces in the chest wall structure?
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Which of the following bones forms the center of the chest?
Which of the following bones forms the center of the chest?
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What is the name of the muscle that covers the anterior chest wall?
What is the name of the muscle that covers the anterior chest wall?
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What is the location of the mammary gland in the chest wall structure?
What is the location of the mammary gland in the chest wall structure?
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How many pairs of ribs are present in the chest wall structure?
How many pairs of ribs are present in the chest wall structure?
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What is the name of the fold of skin and fascia that marks the boundary between the chest and arm?
What is the name of the fold of skin and fascia that marks the boundary between the chest and arm?
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Study Notes
Pectoral Muscles
The pectoral muscles are a group of muscles located in the pectoral region, which include:
Pectoralis Major
- Origin: Medial clavicle, sternum, and costal cartilages
- Insertion: Lateral lip of bicipital groove of humerus
- Actions:
- Adduction of the arm
- Flexion of the arm
- Medial rotation of the arm
- Innervation: Lateral and medial pectoral nerves
Pectoralis Minor
- Origin: Third to fifth ribs
- Insertion: Coracoid process of scapula
- Actions:
- Depression of the scapula
- Forward tilt of the scapula
- Innervation: Lateral pectoral nerve
Serratus Anterior
- Origin: First to ninth ribs
- Insertion: Costal surface of scapula
- Actions:
- Rotation of the scapula
- Abduction of the arm
- Innervation: Long thoracic nerve
Subclavius
- Origin: First rib
- Insertion: Inferior surface of clavicle
- Actions:
- Depression of the clavicle
- Stabilization of the clavicle
- Innervation: Nerve to subclavius
Pectoral Muscles
- Located in the pectoral region
Pectoralis Major
- Originates from the medial clavicle, sternum, and costal cartilages
- Inserts into the lateral lip of the bicipital groove of humerus
- Performs three main actions: • Adduction of the arm • Flexion of the arm • Medial rotation of the arm
- Innervated by the lateral and medial pectoral nerves
Pectoralis Minor
- Originates from the third to fifth ribs
- Inserts into the coracoid process of scapula
- Performs two main actions: • Depression of the scapula • Forward tilt of the scapula
- Innervated by the lateral pectoral nerve
Serratus Anterior
- Originates from the first to ninth ribs
- Inserts into the costal surface of scapula
- Performs two main actions: • Rotation of the scapula • Abduction of the arm
- Innervated by the long thoracic nerve
Subclavius
- Originates from the first rib
- Inserts into the inferior surface of clavicle
- Performs two main actions: • Depression of the clavicle • Stabilization of the clavicle
- Innervated by the nerve to subclavius
Chest Wall Structure in the Pectoral Region
Bony Landmarks
- Sternum is a long, flat bone located in the center of the chest
- There are 12 pairs of ribs that curve outward and backward from the spine to the sternum
- Costal cartilages connect the ribs to the sternum
- Thoracic vertebrae (T1-T12) form the posterior aspect of the chest wall
Muscles of the Chest Wall
- Pectoralis major is a large, fan-shaped muscle that covers the anterior chest wall
- Pectoralis major has two parts: sternal head and clavicular head
- Pectoralis minor is a small, triangular muscle located deep to the pectoralis major
- Serratus anterior is a muscle that originates on the surface of the scapula and inserts on the costal cartilages
- There are three layers of intercostal muscles between the ribs: external, internal, and innermost intercostal muscles
Other Key Structures
- Intercostal spaces are the spaces between the ribs where blood vessels and nerves pass
- The mammary gland is located in the subcutaneous tissue of the anterior chest wall
- The axillary fold is a fold of skin and fascia that marks the boundary between the chest and arm
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Description
Learn about the pectoral muscles, including their origin, insertion, actions, and innervation. Understand the functions of Pectoralis Major and Pectoralis Minor.
