anatomy of the shoulder

• pectoral girdle

  • Formed by the clavicle and scapula
  • Connects upper limb to axial skeleton
  • Mobile
  • Supported by muscles attached to ribs, sternum and vertebrae
• scapular

  • Lies on the posterolateral aspect of the thorax
  • Extends from the 2nd to 7th rib
  • Site for muscle attachment
• clavicle

  • Medial end forms the sternoclavicular joint
  • Lateral end forms the acromioclavicular joint
  • Acts as a strut
  • Transmits shock
  • Attachment points for muscles/ligament
• What is the only point of bony connection between the pectoral girdle and the trunk?


  Sternoclavicular Joint (SCJ)
• Where does the medial end of the clavicle articulate?


  With the clavicular notch at the superolateral angle of the sternum and the adjacent upper medial surface of the first costal cartilage
• What role does the intra-articular disc play in the SCJ?


  It provides cushioning between the articular surfaces and ligamentous support
• How does the joint capsule of the SCJ get its strength?


  It is strengthened by the anterior and posterior sternoclavicular ligaments and the interclavicular ligament
• What does the costoclavicular ligament do?


  It binds the clavicle to the first costal cartilage and limits elevation of the clavicle
• What type of joint is the Acromioclavicular Joint (ACJ)?


  Plane synovial joint
• What articulates in the ACJ?


  An oval flat facet on the lateral end of the clavicle and a facet on the anteromedial border of the acromion process
• What is the function of the coracoclavicular ligament?


  It anchors the lateral end of the clavicle to the coracoid process
• What are the two parts of the coracoclavicular ligament called?


  Conoid and trapezoid
• What is the scapulothoracic articulation?


  It is the articulation of the scapula with the thorax, depending on the integrity of the ACJ and SCJ
• What must happen for any movement of the scapula on the thorax?


  It must result in movement at either the AC joint, the SC joint, or both
• What is the purpose of scapular movement?


  To position the glenoid fossa for optimal contact with the arm
• What is scapulohumeral rhythm?


  It is the coordinated movement of the scapula across the thoracic cage with the movement of the humerus to the glenoid
• What is the ratio of scapulohumeral rhythm?


  1. 1
• What type of joint is the Glenohumeral Joint?


  Synovial ball and socket joint
• What does the glenoid fossa articulate with in the Glenohumeral Joint?


  The head of the humerus
• What is the role of the capsule in the Glenohumeral Joint?


  It forms a loose cylindrical sleeve and allows 2 cm translation
• How is the glenoid fossa deepened?


  By the presence of the glenoid labrum
• What are the three bands of fibers that reinforce the anterior part of the joint capsule called?

  Glenohumeral ligaments: Superior, Middle, and Inferior GHL
• What does the Transverse Humeral Ligament do?


  It bridges the gap between the greater and lesser tubercles
• What is the function of the trapezius muscle?


  It stabilizes the scapula.
• Where does the trapezius muscle originate and insert?


  It originates from the occiput and spinous processes C2-T12 and inserts into the lateral 1/3 clavicle, acromion, and spine of scapula.
• What is the function of the Coracohumeral Ligament?


  It attaches from the lateral border of the coracoid process to the upper part of the anatomical neck
• How does the upper part of the trapezius muscle function in relation to the serratus anterior?


  The upper part rotates the scapula obliquely upwards and works as a couple with the serratus anterior.
• What does the Coracoacromial Ligament form with the coracoid and acromion processes?


  A fibro-osseous arch above the head of the humerus
• What is the role of the middle and lower parts of the trapezius muscle?


  The middle part retracts the scapula, while the lower part supports the rotating action of the upper portion.
• What is the function of the Supraspinatus muscle?


  It abducts the arm
• What is the origin of the serratus anterior muscle?


  It originates from the first nine ribs.
• What is the primary function of the serratus anterior muscle?


  It protracts the scapula and the lower part rotates it with the trapezius.
• Where does the levator scapulae muscle originate and insert?


  It originates from the transverse processes C1-C4 and inserts into the superior angle of the scapula.
• Where does the Infraspinatus muscle attach?


  From the infraspinous fossa to the greater tuberosity
• What is the function of the levator scapulae muscle?


  It draws the scapulae upwards.
• What is the function of the Teres minor muscle?


  It laterally rotates the arm
• Where does the Subscapularis muscle attach?


  From the subscapular fossa to the lesser tuberosity
• What is the origin of the rhomboid major muscle?


  It originates from the spinous processes T1-T4.
• What is the function of the Subscapularis muscle?


  It medially rotates the arm
• What is the primary function of the rhomboid major muscle?


  It stabilizes and retracts the scapula.