Podcast
Questions and Answers
Which muscle is responsible for adduction, flexion, and medial rotation of the arm?
Which muscle is responsible for adduction, flexion, and medial rotation of the arm?
What is the primary action of the pectoralis minor?
What is the primary action of the pectoralis minor?
Which nerve is responsible for the innervation of the latissimus dorsi?
Which nerve is responsible for the innervation of the latissimus dorsi?
Which joint allows for movements of the pectoral girdle and is stabilized by ligaments?
Which joint allows for movements of the pectoral girdle and is stabilized by ligaments?
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What is the action of the serratus anterior muscle?
What is the action of the serratus anterior muscle?
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The trapezius muscle assists in which of the following actions?
The trapezius muscle assists in which of the following actions?
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Which muscle is NOT involved in the adduction of the arm?
Which muscle is NOT involved in the adduction of the arm?
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What structure provides stability to the acromio-clavicular joint?
What structure provides stability to the acromio-clavicular joint?
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Which of the following muscles helps hold the scapula against the thoracic wall?
Which of the following muscles helps hold the scapula against the thoracic wall?
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Which of the following is a characteristic action of the pectoralis major?
Which of the following is a characteristic action of the pectoralis major?
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Study Notes
Upper Limb Anatomy - Chapter A1
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Pectoral Region Muscles:
- Pectoralis Major: Originates from the sternum, upper six costal cartilages, and medial half of the clavicle. Inserts into the anterior axillary fold (lateral humerus). Actions include adduction, flexion, and medial rotation of the arm. Innervated by medial and lateral pectoral nerves (C5-T1)
- Pectoralis Minor: Originates from ribs 3-5 (3.5) and inserts into the coracoid process of the scapula. Actions include depressing the shoulder tip and stabilizing the scapula. Innervated by medial and lateral pectoral nerves (C8-T1).
- Trapezius: Originates from the occipital protuberance, cervical and thoracic vertebrae, and the spine of the scapula/lateral 1/3 clavicle. Inserts into the lateral 1/3 clavicle, spine of scapula. Actions include elevation, retraction, and rotation of the scapula; bracing the shoulder. Innervated by the spinal accessory nerve (CN XI).
- Latissimus Dorsi: Originates from the lower six thoracic vertebrae, lumbar spines, iliac crest, and thoracolumbar fascia. Inserts into the intertubercular groove of the humerus. Actions include adduction, medial rotation, and raising the body towards the arms (in climbing). Innervated by the thoracodorsal nerve (C6-C7).
- Serratus Anterior: Originates from the lateral surface of ribs 1-8 and inserts into the medial border of the scapula. Actions include scapular rotation (abduction), protraction, and holding the scapula against the thoracic wall. Innervated by the long thoracic nerve (C5-C7).
- Subscapularis: Originates from the subscapular fossa, inserts into the lesser tubercle of the humerus. Actions include medial rotation and adduction of the arm. Innervated by C5-7 subscapular nerves.
- Teres Major: Originates from the lower angle of the scapula, inserts into the intertubercular sulcus of the humerus. Actions include adduction and medial rotation of the arm. Innervated by C6-C7 lower subscapular nerve.
Pectoral Region Joints
- **Sterno-clavicular joint:** A fibrocartilage joint with articular discs. Significant in pectoral stability due to its ligaments
Axilla
- Acromioclavicular joint: Similar to sterno-clavicular, with fibrocartilage and ligaments providing stability. Susceptible to dislocation from direct force.
Axillary Muscles and Nerves
- Detailed descriptions of the muscles within the axilla (subscapularis, teres major), their origins, insertions, and nerve supplies are provided.
- Specific neuromuscular pathways and nerve arrangements relating to the axilla, such as the brachial plexus are shown.
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Description
Explore the muscles of the pectoral region in this quiz, including their origins, insertions, actions, and innervation. Test your knowledge on the Pectoralis Major, Pectoralis Minor, Trapezius, and Latissimus Dorsi. Perfect for students of anatomy and related fields.
