Lecture #9: Shoulder, rotator cuff & axillary wall structures

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Lecture #9: Shoulder, rotator cuff & axillary wall structures
2015-10-09 16:28:22
Shoulder rotator cuff

Shoulder & rotator cuff
Show Answers:

  1. What are the three joints that make up the shoulder girdle?
    • sternoclavicular joint
    • acromial clavicular joint
    • glenohumeral joint
  2. True or flase: there are two bony articulations between the upper limb and the trunk. Provide the correct information if the answer is false.
    FALSE. There is only one bony articulation between the upper limb and the trunk: the articulation between the medial end of the clavicle, the 1st costal cartilage and the 1st rib.
  3. True or false: the upper limb is far more interesting and useful than the lower limb
    Absolutely true
  4. Describe the relationship between the suprascapular nerve, artery and the superior transverse ligament
    the suprascapular nerve travels under the superior transverse ligament while the suprascapular artery travels over the ligament.
  5. List the structures that reinforce the sternoclavicular joint capsule. Include which side or portion of the capsule each structure supports.
    • Anterior support: anterior sternoclavicular ligament
    • Posterior support: posterior sternoclavicular ligament
    • Interclavicular support: interclavicular ligament
    • Support between the medial clavicle, 1st rib and 1st costal cartilage: costoclavicular ligament
  6. List the muscles that directly act on the acromialclavicular joint.
    No muscles directly act on the acromialclavicular joint.
  7. The range of motion allowed at the acromionclavicular joint is:
    (A) 1-15 degrees
    (B) 15-25 degrees
    (C) 10-15 degrees
    (D) 15-20 degrees
    (E) no motion is allowed at the acromialclavicular joint.
    D: 15-20 degrees
  8. At the glenohumeral joint, what is sacrificed at the expense of  mobility?
  9. True or false: stability of the shallow glenoid cavity is reinforced by a tight fibrous joint capsule. Explain your answer if false
    FALSE. The joint capsule and fibrous membrane are very lax, particularly inferiorly, to facilitate movement of the humeral head within the gelnoid cavity. Stability is gained through the musculotendinous collar created by the rotator cuff tendons and the glenohumeral ligaments, the coracoacromial ligament, the coracohumeral ligament and the bony arch created by the acromion and coracoid processes
  10. Describe the insertion locations of the rotator cuff muscles relative to one another on the greater tubercle of the humerus.
    • Superior facet: supraspinatus
    • middle facet: infraspinatus
    • lower facet: teres minor
  11. Describe the anatomical difference(s) between the anatomical neck of the humerus and the surgical neck as well as the significance of this difference. Include a discussion of which structures are particularly in danger due to these differences and why they are in danger.
    The anatomical neck is immediately inferior to the head of the humerus. The surgical neck is inferior to the anatomical neck and lies approximately at the location where the wide head tapers into a narrower shaft. This tapering renders the surgical neck more susceptible to breaking. Breaks at this point on the humerus place the posterior circumflex humeral artery and the axillary nerve in danger b/c they pass into the posterior arm at the level of the surgical neck.
  12. List the structures that connect to the coracoid process.
    • 1) conoid ligament of the coracoclavicular ligament
    • 2) trapezoid ligament of the coracoclavicular ligament
    • 3) pectoralis minor
    • 4) superior transverse scapular ligament
    • 5) coracohrachialis muscle
    • 6) short head of biceps brachii
    • 7) coraco-acromial ligament
  13. True or false: the tendon of the short head of biceps brachii passes through the glenohumeral joint capsule. Provide the correct infomation if the answer is false.
    FALSE: the tendon of the long head of biceps brachii passes through the glenohumeral joint capsule. The tendon of te short head originates from the coracoid process.
  14. What is the functional significance of the inferior fold in the synovial membrane and fibrous joint capsule of the glenohumeral joint?
    Facilitates humeral abduction, but also renders the GH joint particularly unstable from the inferior direction.
  15. Describe the movements during arm abduction at the three joint that make up the shoulder girdle. Include the muscles involved in the movements.
    • Glenohumeral joint: humerus moves through the arc of abduction, 10-degrees of humeral abduction for every 5-degrees of scapular lateral rotation.
    • clavicle rotates inferiorly at the sternoclavicular joint and superiorly at the acromioclavicular joint and the scapula rotates laterally.
    • 1) Supraspinatus initiates  humeral abduction
    • 2) deltoid takes over after about 15 degrees
    • 3) Trapezius acts to elevate and laterally rotate scapula during abduction
    • 4) levator scapulae and the rhomboids may act to assist trapezius with scapular elevation
    • 5) serratus anterior may assist with lateral scapular rotation and to hold the scapula against the thorax during rotation
  16. What is the glenohumeral rhythm?
    During arm abduction there is 1 degree of lateral scapular rotation for every 2 degrees of humeral abduction rotation.
  17. Describe the anatomy of a type III shoulder separation.
    Complete separation of the acromioclavicular joint. The acromioclavicular ligament, the coracoclavicular ligament and the joint capsule are all torn. The shoulder falls in the inferior direction while the clavicle is pushed upward, resulting in a bumpy-looking shoulder.
  18. True or false: in a type I shoulder separation there may be partial tearing of the acromioclavicular ligament. Provide the correction information if the answer is false.
  19. True or false: the quadrangular space communicates the radial nerve and the posterior circumflex humeral artery from the anterior arm to the posterior arm. Provide the correct information if the answer is false.
    FALSE: the quadrangular space communicates the axillary nerve and the posterior circumflex humeral artery.
  20. True or false (if false, provide the correct information): the accessory nerve is CN XI and the motor component originates from spinal levels C1-C5, travels up into the skull via the jugular foramen and returns to its target muscles by passing back through the jugular foramen.
    FALSE. It enters the skull via the foramen magnus and exits via the jugular foramen.
  21. List the nerves that contribute to motor function of the shoulder and rotator cuff muscles that are NOT derived from the brachial plexus.
    • 1) accessory nerve
    • 2) Anterior ramus of C3
    • 3) Anterior ramus of C4
  22. True or false: C4 contributes fibers to the innervation of rhomboid major, but not to rhomboid minor. Provide the correction information if false.
    FALSE. C4 contributes to both rhomboid major and minor. The difference is that both C4 and C5 are primary for major and neither is primary for minor.
  23. Name the nerve that innervates the deltoid muscle and trace it back to its spinal origins and designate the primary level.
    • Axillary nerve:
    • Axillary nerve/posterior cord/posterior division/superior trunk/C5 & C6, C5 is primary
  24. Name the nerve that innervates the infraspinatus muscle and trace it back to its spinal origins, designating the primary.
    suprascapular nerve: suprascapular nerve/superior trunk/C5, C6, C5 is primary
  25. List all of the muscles in the shoulder region and rotator cuff that receive spinal contribution from C7.
  26. Drive the path of the primary blood supply for the middle portion of trapezius on the left side of the body back to the arch of the aorta. Provide all relevant landmarks and communicating regions.
    • 1) superficial cervical artery
    • 2) transverse cervical artery
    • 3) thyro-cervical trunk
    • 4) 1st part of subclavian (the first part is the portion from the origin of the artery to the medial border of the anterior scalene muscle)
    • 5) arch of the aorta
  27. True or false: there is one branch off of the first part of the axillary artery, two off of the second and three off of the third. Provide the correct information if the answer is false.
  28. If the posterior division of the middle trunk had a lesion on it rendering the fibers non-functional, which muscles in the shoulder/rotator cuff region would lose some or all of their nerve supply, and which fibers would be lost?
    Subscapularis would lose C7 fibers
  29. What is the difference between the ligamentum nuchae and the supraspinous ligament?
    The ligament nuchae runs from the external occipital protuberance on the occipital bone down to the spinous process of C7. It send fibers anteriorly between these landmarks that attach to the spinous processes of the cervical vertebrae. The supraspinous ligament is the inferior continuation of the ligamentum nuchae.
  30. Change one thing about the position (i.e., origin, insertion or path) of teres major to enable it to participate in flexion of the arm at the glenohumeral joint.
    It would have to originate somewhere on the anterior body, perhaps the clavicle like the clavicular portion of pec major or the rips like pec minor. Then it would be able to flex the extended arm.
  31. If the lateral cord had a lesion on it rendering it completely blocked, would it still be possible to medially rotate the arm in the glenohumeral joint? Explain your answer in terms of:
    A) affected muscles, nerves and spinal levels
    B) viable synergists and their nerves and spinal levels
    • Yes, medial rotation of the humerus would remain possible. 
    • A) pec major (both heads) is the only affected muscle. It is innervated (directly) by lateral and medial pectoral nerves. The clavicular head would be non-functional because it receives C5 and C6 fibers which travel through the lateral cord. The sternocostal head would be functional but would lose C6 and C7 because they travel through the lateral cord.
    • 2) viable synergists:
    • a) subscapularis (upper and lower subscapular nerves, C5, C6, C7)
    • b) latissimus dorsi (thoracodorsal nerve, C6, C7, C8)
    • c) teres major (lower subscapular nerve, C5, C6, C7)