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Questions and Answers
What is the primary action of the levator scapulae muscle?
What is the primary action of the levator scapulae muscle?
Which muscle primarily facilitates abduction of the upper limb from 0° to 15°?
Which muscle primarily facilitates abduction of the upper limb from 0° to 15°?
Which nerve innervates the deltoid muscle?
Which nerve innervates the deltoid muscle?
Where do the rhomboid muscles insert?
Where do the rhomboid muscles insert?
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Which muscle contributes primarily to retraction of the scapula?
Which muscle contributes primarily to retraction of the scapula?
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What is the range of motion of the upper limb at the shoulder joint during abduction, from 15° to 90°?
What is the range of motion of the upper limb at the shoulder joint during abduction, from 15° to 90°?
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Which of the following nerves innervates the supraspinatus muscle?
Which of the following nerves innervates the supraspinatus muscle?
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What is the primary function of the serratus anterior muscle?
What is the primary function of the serratus anterior muscle?
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Which muscle is primarily responsible for the retraction of the scapula?
Which muscle is primarily responsible for the retraction of the scapula?
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What movement is NOT associated with the trapezius muscle?
What movement is NOT associated with the trapezius muscle?
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Which structure primarily innervates the latissimus dorsi muscle?
Which structure primarily innervates the latissimus dorsi muscle?
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Which of the following muscles assists in shoulder adduction?
Which of the following muscles assists in shoulder adduction?
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What role does the levator scapulae muscle serve?
What role does the levator scapulae muscle serve?
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What is the primary action of the anterior part of the deltoid muscle?
What is the primary action of the anterior part of the deltoid muscle?
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Which muscle acts on the humerus at the glenohumeral joint?
Which muscle acts on the humerus at the glenohumeral joint?
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What is the innervation of the deltoid muscle?
What is the innervation of the deltoid muscle?
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Which of the following actions is NOT contributed by the pectoralis major muscle?
Which of the following actions is NOT contributed by the pectoralis major muscle?
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What is the insertion point of the pectoralis major muscle?
What is the insertion point of the pectoralis major muscle?
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Which heads of the pectoralis major muscle contribute to flexion?
Which heads of the pectoralis major muscle contribute to flexion?
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Which nerve primarily innervates the pectoralis major muscle?
Which nerve primarily innervates the pectoralis major muscle?
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Which action is primarily contributed by the posterior part of the deltoid muscle?
Which action is primarily contributed by the posterior part of the deltoid muscle?
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What is the primary function of the coracoacromial ligament?
What is the primary function of the coracoacromial ligament?
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What does a shoulder separation involve?
What does a shoulder separation involve?
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Which ligament helps limit superior dislocation of the humerus?
Which ligament helps limit superior dislocation of the humerus?
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What type of joint is formed where the head of the humerus articulates with the scapula?
What type of joint is formed where the head of the humerus articulates with the scapula?
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When the ligaments in the shoulder are torn, which of the following results?
When the ligaments in the shoulder are torn, which of the following results?
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Which component of the shoulder joint deepens the socket?
Which component of the shoulder joint deepens the socket?
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What injury is characterized by a grade 3 shoulder separation?
What injury is characterized by a grade 3 shoulder separation?
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Which structure is NOT associated with stabilizing the shoulder joint?
Which structure is NOT associated with stabilizing the shoulder joint?
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What type of dislocation occurs when the humerus moves from the glenoid cavity in an anterior/superior direction?
What type of dislocation occurs when the humerus moves from the glenoid cavity in an anterior/superior direction?
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Which nerve associated with the shoulder is impacted by dislocation of the humerus from the glenoid cavity?
Which nerve associated with the shoulder is impacted by dislocation of the humerus from the glenoid cavity?
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What is the primary function of muscles in relation to joints?
What is the primary function of muscles in relation to joints?
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Which muscle is identified as the primary muscle of the rotator cuff that originates from the anterior scapula?
Which muscle is identified as the primary muscle of the rotator cuff that originates from the anterior scapula?
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Where does the subscapularis muscle insert?
Where does the subscapularis muscle insert?
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Which of the following statements about muscle actions is true?
Which of the following statements about muscle actions is true?
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What is the role of the musculocutaneous nerve in relation to the shoulder?
What is the role of the musculocutaneous nerve in relation to the shoulder?
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Which structure is least likely to be directly affected by an anterior/superior dislocation of the humerus?
Which structure is least likely to be directly affected by an anterior/superior dislocation of the humerus?
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Study Notes
Shoulder Separations
- Coracoacromial and coracoclavicular ligaments help stabilize the bones of the shoulder
- When these ligaments tear, it results in a shoulder separation (not a dislocation)
- Coracoacromial ligament stretches between two parts of the scapula
- Coracoacromial ligament helps to deepen the joint socket, reducing the risk of superior dislocation of the humerus
Shoulder Dislocations
- The head of the humerus articulates with the glenoid cavity of the scapula within the glenohumeral (shoulder) joint
- Dislocation of the humerus from the glenoid cavity can impact neurovascular structures in the axilla
- Anterior/ superior dislocation and inferior dislocation are the most common types
Muscles of the Rotator Cuff
- Subscapularis muscle contributes to flexion, medial (internal) rotation, and abduction
- Deltoid muscle is a large muscle that contributes to abduction, flexion, extension, internal and external rotation
- Muscles can only cause an action at a joint if they cross that joint
Muscles of the Shoulder
- Pectoralis major muscle (sternocostal, clavicular, and abdominal heads) contributes to medial (internal) rotation, adduction, flexion, and transverse adduction
- Trapezius, levator scapulae, rhomboid major, and rhomboid minor muscles all act on the scapula at the sternoclavicular joint (and scapulothoracic 'joint')
- Levator scapulae, rhomboid major, and rhomboid minor muscles contribute to elevation and retraction of the scapula
Full Range of Motion
- Abduction of the upper limb at the shoulder joint involves 4 different muscles, supplied by 4 different nerves, to achieve the full range of motion from 0 - 180 degrees
- Supraspinatus muscle works from 0 - 15 degrees
- Deltoid muscle works from 15 – 90 degrees
- Trapezius muscle works from 90 - 160 degrees
- Serratus anterior muscle works from 160 - 180 degrees
Simplified Muscle Chart
- Subscapularis, latissimus dorsi, trapezius, levator scapulae, rhomboid major, and rhomboid minor muscles are all shoulder muscles that can be easily identified and remembered with the help of this chart
Learning Outcomes
- Identify and describe the bones, joints, and ligaments related to the shoulder
- Describe basic movements of the scapula and humerus
- Identify muscles that act to move the scapula and humerus, and describe their innervations and functions
- Predict functional implications of musculoskeletal injuries to the shoulder region
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Description
Test your knowledge on shoulder anatomy, including shoulder separations, dislocations, and the rotator cuff muscles. This quiz covers the ligaments involved, types of dislocations, and muscle functions related to shoulder movement.
