10 Questions
What are the three osseous segments that comprise the shoulder?
Humerus, Clavicle, and Scapula
What type of joint is the AC joint, and what type of ligaments support it?
A plain synovial joint supported by the Superior acromioclavicular ligament, Inferior AC ligament, Coracoclavicular ligament, Trapezoid ligament, and Conoid ligament.
What are the three degrees of freedom of the Glenohumeral joint?
Flexion/Extension, Abduction/Adduction, and Medial/Lateral rotation or Internal/External rotation
What are the four rotator cuff muscles, and what actions do they perform?
Supraspinatus (abducts the arm), Infraspinatus (externally rotates the arm), Teres minor (externally rotates the arm), and Subscapularis (internally rotates the humerus)
What is the action of the Latissimus Dorsi muscle in the shoulder?
Adduction/Extension/Medial rotation of the Glenohumeral joint and depression of the scapula
What is the origin of the deltoid muscle?
Lateral end of the clavicle, acromion of scapula at top of the shoulder, and spine of the scapula
What is the function of the rhomboids muscle?
Depression and upward rotation of the scapula
Which muscle is responsible for protraction and upward rotation of the scapula?
Serratus anterior
What actions are caused by the contraction of the posterior deltoid muscle?
Extension and external rotation
Which muscles are responsible for flexion of the shoulder joint?
Pec major, anterior deltoid, biceps brachii, and coracobrachialis
Study Notes
Shoulder Anatomy
- Comprises of 3 osseous (bony) segments: Humerus, Clavicle, and Scapula
- Linked through 3 joints: Glenohumeral (GH) joint, Sternoclavicular (SC) joint, and Acromioclavicular (AC) joint
Sternoclavicular (SC) Joint
- Strong fibrous capsule
- 3 ligaments: Sternoclavicular ligament, Costoclavicular ligament, and Interclavicular ligament
- 3 rotary degrees of freedom: Elevation/Depression, Protraction/Retraction, and Anterior/Posterior rotation
Acromioclavicular (AC) Joint
- Attaches the scapula to the clavicle
- Plain synovial joint
- Joint capsule
- Weak capsule supported passively by various ligaments
- 3 motions: Internal/External Rotation, Depression/Elevation, and Upward/Downward Rotation
Glenohumeral (GH) Joint
- Surrounded by large loose capsule
- Ligaments: Superior GH, Middle GH, Inferior GH, and Coracohumeral
- 3 degrees of freedom: Flexion/Extension, Abduction/Adduction, and Medial/Lateral rotation or Internal/External rotation
- Dynamic stability provided by Deltoid and Rotator cuff muscles
Rotator Cuff Muscles
- Supraspinatus: elevates the arm
- Infraspinatus: externally rotates the arm
- Teres minor: externally rotates the arm
- Subscapularis: internally rotates the arm
Other Shoulder Muscles
- Teres major: extension, adduction, and internal rotation
- Trapezius: scapular elevation, upward rotation, and retraction
- Latissimus dorsi: adduction, extension, and internal rotation
- Pectoralis major: flexion, adduction, and internal rotation
- Rhomboids: depression, upward rotation, and extension
- Serratus anterior: protraction and upward rotation
Exercises
- Demonstrated exercises for strengthening rotator cuff muscles and shoulder muscles
- Exercises include using exercise machines, own body weight, tubing, and dumbbells
This quiz covers the bones and joints that make up the shoulder, including the humerus, clavicle, and scapula, as well as the ligaments and motions of the sternoclavicular joint.
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