L7 Shoulder and Proximal UE

Question 1

What are the anterior muscles of the shoulder?

Answer 1

• Pectoralis = pecs
• Broad origin: 2 heads (clavicula and sternum)
• Tapers towards the humerus
• Hooks onto the groove (lateral lip)
• Insertion to origin
• Glenohumeral flexion, medial rotation (bring the lateral lip closer) , …
• Subclavius
• O: First rib I: Subclavian groove
• Pectoralis minor
• O: Ribs 3-5 I: Corocoid process
• Depresses the scapula (corocoid process being a part of the scapula)
• Secondary function by fixing the scapula in place (elevates the rib, accessory breathing muscle)
• Origin to insertion

Question 2

What are the lateral muscles of the shoulder?

Answer 2

• Serratus Anterior (as opposed to SPS and SPI)
  
  • Lateral borders of rib to anteromedial border of scapula
  • Protraction of the scapula (boxers)
• Deltoid
  
  • Forms triangle when spread out
    
    • Horse shoe origin (clavicle, acromioclavicular joint and scapula) and inserts on deltoid tuberosity on humerus
    • Different muscle fiber groups
    1. Flexion (1 - ant.)
    2. Abduction (2 - mid)
    3. Extension (3 - post)

Question 3

What is the rotator cuff muscle that sits anteriorly?

Answer 3

• Subscapularis (superior to scapula)
  
  • Subscapular fossa to lesser tubercle of humerus
  • Bursa cushion under tendon
    
    • Subtendinous bursa of subscapularis
  • Allows for medial (internal) rotation

Question 4

What are the 3 posterior rotator cuff muscles?

Answer 4

• Supraspinatus
  
  • Supraspinous fossa to the greater tubercle of the humerus (superior facet)
  • Initiates the first 30 degrees of arm abduction at glenohumeral joint
    
    • Deltoid takes over past this point
• Infraspinatus
  
  • Infraspinous fossa to the greater tubercle (middle facet)
  • Lateral external rotation (attaches to the anterior side from posterior side so rotates it)
• Teres minor
  
  • Lateral scapular border (superior) to greater tubercle (inferior facet)
  • Lateral external rotation of the arm

Question 5

What are the three bursae of the shoulder joint?

Answer 5

• Subacromial bursa
  
  • Between acromium and tendon of the infraspinatus (middle facet of greater tubercle)
• Subcoracoid bursa
  
  • Between coracoid process and subscapularis muscle
• Subtendinous bursa of subscapularis
  
  • Under tendon of subscapularis
• • Subdeltoid bursa

Question 6

What are the posterior muscles of the shoulder?

Answer 6

• Teres major
  
  • Lateral scapularborder (inferior) to the medial lip of the intertubercular groove of humerus
  • Extension, adduction and medial (internal) rotation
    
    • Medial because it stretches from posterior side to the medial anterior side of humerus
• Levator Scapulae
  
  • TP of cervical spines to superomedial border of scapula
  • Elevation of scapula
• Rhomboid minor&major
  
  • SP of cervical and thoracic vertebrae to medial border of scapula
  • Retraction of scapula
• Trapezius
  
  • Posterior skull and cervical/thoracic vertebrae to HORSE SHOE
  • Different (3) fiber groups
    
    • 1. Elevation of scapula
    • 2. Retraction of scapula
    • 3. Depression of scapula
  • Innervated by SPINAL ACCESSORY (CN XI)
  • Blood supply by TRANSVERSE CERVICAL ARTERY
• ​Latissimus dorsi
  
  • Lower thoracic, lumbar, sacral and iliac crest to FLOOR (VALLEY) of intertubucular groove
  • Extension, adduction and medial (internal) rotation of the arm

Question 7

What are the muscles that attach to the intertubercular groove of the humerus?

Answer 7

“A Miss between two Majors”

• Medial lip - Pectoralis Major
• Valley/Floor - Latissimus Dorsi
• Lateral lip - Teres Major