Podcast
Questions and Answers
Following an injury affecting the medial and lateral pectoral nerves, which shoulder motion would be MOST affected?
Following an injury affecting the medial and lateral pectoral nerves, which shoulder motion would be MOST affected?
- Abduction beyond 90 degrees.
- Extension.
- Lateral rotation.
- Adduction and medial rotation. (correct)
A patient presents with 'winged scapula' after a surgical procedure. Which muscle is MOST likely paralyzed due to nerve damage?
A patient presents with 'winged scapula' after a surgical procedure. Which muscle is MOST likely paralyzed due to nerve damage?
- Latissimus dorsi.
- Rhomboids.
- Trapezius.
- Serratus anterior. (correct)
A surgeon is performing a procedure in the axilla and needs to identify the nerve responsible for protracting the scapula. Which nerve should the surgeon locate?
A surgeon is performing a procedure in the axilla and needs to identify the nerve responsible for protracting the scapula. Which nerve should the surgeon locate?
- Dorsal scapular nerve.
- Axillary nerve.
- Long thoracic nerve. (correct)
- Suprascapular nerve.
Which of the following best describes the anatomical location of the long thoracic nerve in relation to the serratus anterior muscle?
Which of the following best describes the anatomical location of the long thoracic nerve in relation to the serratus anterior muscle?
A bodybuilder is performing a bench press. Which action primarily involves the sternocostal head of the pectoralis major?
A bodybuilder is performing a bench press. Which action primarily involves the sternocostal head of the pectoralis major?
During a diagnostic procedure, a physician needs to access a vein that runs through the clavipectoral fascia. Which vein are they MOST likely targeting?
During a diagnostic procedure, a physician needs to access a vein that runs through the clavipectoral fascia. Which vein are they MOST likely targeting?
Which action at the shoulder can still be performed if the medial pectoral nerve is damaged, but the lateral pectoral nerve is intact?
Which action at the shoulder can still be performed if the medial pectoral nerve is damaged, but the lateral pectoral nerve is intact?
What is the primary function of the subclavius muscle during shoulder movements?
What is the primary function of the subclavius muscle during shoulder movements?
A patient is diagnosed with Poland syndrome. Which of the following muscles is MOST likely affected by this condition?
A patient is diagnosed with Poland syndrome. Which of the following muscles is MOST likely affected by this condition?
Which rib serves as the origin for the subclavius muscle?
Which rib serves as the origin for the subclavius muscle?
The clavipectoral fascia encloses which of the following muscles?
The clavipectoral fascia encloses which of the following muscles?
What is the insertion point of the pectoralis minor muscle?
What is the insertion point of the pectoralis minor muscle?
Beyond stabilizing the clavicle, what secondary function does the subclavius muscle assist with?
Beyond stabilizing the clavicle, what secondary function does the subclavius muscle assist with?
A patient has difficulty raising their arm above 90 degrees and has noticeable asymmetry in their shoulder girdle. Which muscle is MOST likely affected, considering its role in upper limb abduction beyond 90 degrees?
A patient has difficulty raising their arm above 90 degrees and has noticeable asymmetry in their shoulder girdle. Which muscle is MOST likely affected, considering its role in upper limb abduction beyond 90 degrees?
A patient is experiencing difficulty breathing, and the physician suspects a muscle of the pectoral region is involved. Which muscle assists in respiration when its insertion is fixed?
A patient is experiencing difficulty breathing, and the physician suspects a muscle of the pectoral region is involved. Which muscle assists in respiration when its insertion is fixed?
Flashcards
Pectoralis Major Origin (Clavicular Head)
Pectoralis Major Origin (Clavicular Head)
Medial half of the front of the clavicle.
Pectoralis Major Origin (Sternocostal Head)
Pectoralis Major Origin (Sternocostal Head)
Sternum and upper 6 costal cartilages.
Pectoralis Major Insertion
Pectoralis Major Insertion
Lateral lip of the bicipital groove.
Pectoralis Major Nerve Supply
Pectoralis Major Nerve Supply
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Pectoralis Major Action
Pectoralis Major Action
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Pectoralis Minor Origin
Pectoralis Minor Origin
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Pectoralis Minor Insertion
Pectoralis Minor Insertion
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Pectoralis Minor Nerve Supply
Pectoralis Minor Nerve Supply
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Pectoralis Minor Action
Pectoralis Minor Action
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Subclavius Origin
Subclavius Origin
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Subclavius Insertion
Subclavius Insertion
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Subclavius Nerve Supply
Subclavius Nerve Supply
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Subclavius Action
Subclavius Action
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Serratus Anterior Origin
Serratus Anterior Origin
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Serratus Anterior Insertion
Serratus Anterior Insertion
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Study Notes
- Muscles of the pectoral region cover the anatomy
- The objectives are to describe the gross anatomy of pectoral muscles and how primary muscles affect shoulder motion, including adduction, abduction, flexion, and extension
Case Scenario
- An 18-year-old injured the lateral wall of their right chest during a knife fight
- After healing, the scapula moves away from the thoracic wall when leaning on their right hand
- This presentation suggests damage to the long thoracic nerve
Pectoralis Major
- Originates from the medial half of the front of the clavicle (clavicular head), sternum, and upper 6 costal cartilages (sternocostal head)
- Inserts on the lateral lip of the bicipital groove
- Receives nerve supply from the medial and lateral pectoral nerves
- Responsible for flexion, adduction, and medial rotation of the arm
- Aids in respiration when its insertion is fixed
- Acts on the shoulder
Pectoralis Minor
- Originates from the 3rd, 4th, and 5th ribs
- Inserts on the coracoid process
- Innervated by the medial pectoral nerve
- Causes protraction and depression of the scapula
- Assists in respiration when insertion is fixed
Subclavius
- Originates from the 1st rib
- Inserts on the subclavian groove on the inferior surface of the clavicle
- Receives nerve supply from the nerve to subclavius
- Works to steady (fix) the clavicle during shoulder movement
Clavi-pectoral Fascia
- Connective tissue sheet that extends from the clavicle to the floor of the axilla
- Encloses the subclavius and pectoralis minor muscles
- Fills the gap between them
- Pierced by the cephalic vein, acromio-thoracic artery, lateral pectoral nerve, and lymphatics (CALL)
Serratus Anterior
- Originates from the upper 8 or 9 ribs
- Inserts on the ventral surface of the medial border of the scapula
- Innervated by the nerve to serratus, specifically the long thoracic nerve
- Main protractor of the scapula, functioning as the "boxer's muscle"
- Lower 5 digitations assist in raising the arm above the head (abduction > 90°) when working in conjunction with the trapezius
- Keeps the scapula close to the thoracic wall
- Assists in respiration
Injury of Long Thoracic Nerve
- Root value is C5,6,7
- The long thoracic nerve runs superficially on the serratus anterior muscle, making it susceptible to damage
- Common causes: mastectomy
- Results in paralysis of the serratus anterior, leading to a "winged scapula" deformity
- Winged Scapula causes the medial border and inferior angle of the scapula project away from the thoracic wall when pushing forward with the arm
Poland Syndrome
- Congenital condition characterized by the absence of the pectoralis major muscle
- Can present as a partial or complete absence
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