References: M1 700-713, 722-723, 793-802; N 407-410; N424-427 ; R 370-371, 384, 389-393
AT THE END OF THIS LABORATORY PERIOD YOU WILL BE RESPONSIBLE FOR THE
IDENTIFICATION AND DEMONSTRATION OF THE STRUCTURES LISTED BELOW :
1. Bones and bony features: scapula (spine, supraspinous fossa, infraspinous fossa, acromion, acromial angle, medial border, lateral border, superior border, inferior angle, superior angle, glenoid cavity, scapular notch, coracoid process, supraglenoid tubercle) and humerus (greater tubercle, lesser tubercle, intertubercular groove, surgical neck, deltoid tuberosity).
2. Muscles : trapezius, latissimus dorsi, levator scapulae, rhomboideus minor, rhomboideus major, serratus anterior, deltoid, supraspinatus, infraspinatus, teres minor, teres major, subscapularis, long head of triceps, tendon of long head of biceps.
3. Nerves: accessory, long thoracic, suprascapular, dorsal scapular, upper, middle (thoracodorsal), and lower subscapular, axillary.
4. Arteries: transverse cervical, suprascapular, subscapular, thoracodorsal, scapular circumflex, posterior humeral circumflex.
5. Ligaments: suprascapular, articular disc of sternoclavicular joint, acromioclavicular, coracoclavicular, glenoid labrum, coracoacromial.
YOU SHOULD ALSO BE ABLE TO DO THE FOLLOWING THINGS:
1. Identify on diagrams or on marked bones the muscular attachments of the scapula.
2. List the muscles that produce the various movements of the scapula.
3. List the components of the musculotendinous cuff, their actions, and their innervation.
4. Give the boundaries of the quadrangular and triangular spaces and list the structures that pass through them.
5. Demonstrate understanding of the collateral circulation about the shoulder.
6. Give the innervation and actions of the muscles in the shoulder region and list the deficits that occur following injury to their nerves .
Before beginning the dissection, study the bones and bony features listed above, using a skeleton or your bone set. The cadaver should then be placed in the prone position and any skin remaining over the shoulder, axilla, or upper arm should be reflected and removed. Identify the

TRAPEZIUS and reflect it laterally, cutting it away from its insertion into the SCAPULA . Leave the trapezius attached to the clavicle.
On the deep surface of the trapezius, identify the ACCESSORY NERVE and a branch of the TRANSVERSE CERVICAL ARTERY . Identify the LEVATOR SCAPULAE , the RHOMBOID MINOR , and the RHOMBOID MAJOR , and look for the
DORSAL SCAPULAR NERVE on the deep surface of the rhomboid muscles (A634, 635; G6.28, 8.3;
N407, 460; N424, 477 ). Lift the MEDIAL BORDER
OF THE SCAPULA away from the thoracic wall and identify the SERRATUS ANTERIOR muscle attached to the medial border (G4.29; N407;
N424 ).
Clean the DELTOID and note its attachments to the clavicle, scapula, and HUMERUS . Cut the deltoid from its attachment to the
SCAPULAR
SPINE and ACROMION ; turn it anteriorly, looking for the axillary nerve on its deep surface (A57;
G6.37; N415, N432 ). The AXILLARY NERVE is accompanied by the POSTERIOR HUMERAL
CIRCUMFLEX ARTERY , and both structures enter the region by passing through what opening?
Identify the INFRASPINATUS MUSCLE and clean the dense fascia from its surface all the way to its insertion into the GREATER TUBERCLE . Define the inferior border of the infraspinatus and separate it from the TERES MINOR (A35; G6.37;
N415; N432 ). Inferior to the teres minor, identify the
TERES MAJOR
and clean it medially to the point where it passes anterior to the LONG HEAD
OF THE TRICEPS . Separate the teres major from the triceps and continue cleaning it until its insertion into the crest of the LESSER TUBERCLE can be defined. Be careful not to damage the axillary nerve and posterior humeral circumflex artery where they pass above the teres major.
Now separate the long head of the triceps from the teres minor and clean it to its origin from the infraglenoid tubercle. The boundaries of the
QUADRANGULAR SPACE should now be well defined: superiorly, the teres minor, laterally, the
SURGICAL NECK OF THE HUMERUS , inferiorly, the teres major, and medially, the long head of the triceps (N409; N426 ). What structures pass through this space?
Finish separating the deltoid from its origin by cutting it away from the clavicle and turn it toward its insertion. Above the scapular spine identify the SUPRASPINATUS and clean its surface. Find the SUPRASCAPULAR NERVE and
ARTERY in the neck and trace them distally until they pass deep to the supraspinatus. Carefully cut through the supraspinatus at the point the nerve and artery pass deep to it and reflect the two parts of the muscle away from bone. Identify the
SUPRASCAPULAR LIGAMENT (superior transverse scapular ligament) and note the relationships of the suprascapular nerve and artery to this ligament (A32, 34; G6.27; N408, 409; N425,
426 ).
Cut through the infraspinatus and trace the course of the suprascapular nerve and artery.
Identify the CIRCUMFLEX SCAPULAR ARTERY and attempt to demonstrate its anastomosis with the suprascapular artery (A34; G6.11A; N410;
N427 ). From what artery does the circumflex scapular branch? Reflect the insertions of the supraspinatus, infraspinatus, and teres minor laterally and note their attachment to each other and to the capsule of the shoulder joint. Together with the tendon of the subscapularis, the tendons of these muscles form what is known as the musculotendinous (rotator) cuff.
The remainder of the dissection can be more easily done with the cadaver in the supine position. Identify the
SERRATUS ANTERIOR
, the
LONG THORACIC NERVE , and the
SUBSCAPULARIS and its nerves the UPPER and
LOWER SUBSCAPULAR . Identify the LATISSIMUS
DORSI and its nerve the THORACODORSAL
NERVE
(middle subscapular). Also identify the
THORACODORAL ARTERY supplying this muscle.
Clean the latissimus dorsi to its insertion into the humerus.
Clean the articular capsule of the sternoclavicular joint and then open the anterior part of the capsule. Identify the
ARTICULAR DISC and examine its attachments to the manubrium and to the clavicle (A147; G1.10B; N402; N419 ).

On the separate specimen provided
(dissected upper member from previous year) remove any parts of the deltoid and trapezius that conceal the joint. Identify the
ACROMIOCLAVICULAR LIGAMENT (A96;
G6.43A; N406; N423 ). Open the joint and see if an articular disc is present. Identify the
CORACOCLAVICULAR LIGAMENT which is the chief bracing ligament at the acromial end of the clavicle. It is subdivided into conoid and trapezoid parts (A96; G6.43A; N406; N423 ).
the supraspinatus, infraspinatus, and teres minor fuse with the capsule of the shoulder joint. Note the attachments of the articular capsule to the scapula and to the humerus (A96-102; G6.43B;
N406; N423 ). Open the posterior lamina of the capsule and examine the interior of the joint, noting the GLENOID LABRUM , which is the fibrocartilaginous rim about the GLENOID CAVITY , the
TENDON OF THE LONG HEAD OF THE BICEPS
, and the glenohumeral ligaments, which are three bands reinforcing the anterior part of the capsule
(A101, 102; G6.42, 46, 43B, 45A; N406; N423 ).
Identify the CORACOACROMIAL LIGAMENT , which helps to prevent upward displacement of the head of the humerus (A98; G6.46, 43A; N406;
N423 ).
Continue on the separate dissected specimen from last year. Note that the tendons of
1. Which muscles cause: a. elevation of scapula as in shrugging shoulders? b. protraction of scapula? c. retraction of scapula? d. depression of scapula?
1. a. Trapezius (upper part), levator scapulae b. Serratus anterior c. Trapezius (middle part), rhomboids d. Pectoralis minor, trapezius (lower part), latissimus
dorsi.
2. Sternoclavicular joint 2. What joint is involved in the movements listed above?
3. What is the musculotendinous or rotator cuff?
What is its main function?
3. The musculotendinous cuff is formed by the tendons of the subscapularis, supraspinatus, infraspinatus, and teres minor where they fuse together and fuse to the capsule of the shoulder joint. It covers all of the shoulder joint except its inferior aspect.
Its main function is to hold the head of the humerus in contact with the glenoid fossa.

4. What are the actions of the muscles that form the rotator cuff?
4 Supraspinatus - abduction
Infraspinatus - lateral rotation
Teres minor - lateral rotation
Subscapularis - medial rotation
Together these muscles keep the head of the humerus in contact with the glenoid cavity when other muscles move the humerus.
5. What is the primary action of the teres major?
5. Medial rotation
6. What are the boundaries of the quadrangular space?
7. What structures pass through the quadrangular space?
8. What is the triangular space?
What separates it from the quadrangular space?
9. What passes through the triangular space?
10. Identify the muscles that attach to the scapula as indicated on the two diagrams that follow.
6. Superiorly the teres minor (also the capsule of the shoulder joint and anteriorly the subscapularis); laterally, the surgical neck of the humerus; inferiorly, the teres major; medially, the long head of the triceps.
7. The axillary nerve and the posterior circumflex humeral artery.
8. The triangular space is the interval bounded by the teres minor, the long head of the triceps, and the teres major.
It is separated from the quadrangular space by the long head of the triceps.
9. A branch of the circumflex scapular artery.
10a. a. Biceps, long head b. Coracobrachialis and short
head of biceps c. Pectoralis minor d. Omohyoid e. Serratus anterior f. Subscapularis g. Triceps, long head

10b. a. Levator scapulae b. Supraspinatus c. Omohyoid d. Trapezius e. Deltoid f. Biceps, long head g. Triceps, long head h. Teres minor i. Infraspinatus j. Teres major k. Latissimus dorsi (sometimes) l. Rhomboideus major m. Rhomboideus minor
11. What collateral circulation is available if the axillary artery is ligated proximal to the subscapular? Trace the route of blood flow from the subclavian to the brachial.
11. See G6.11, M
1
726-727 and H Figs. 15-18, 15-31.
12. What muscles are supplied by a) the suprascapular nerve? b) axillary nerve? c) lower subscapular nerve? d) thoracodorsal nerve (middle
subscapular)? e) upper subscapular nerve?
13. What is the action of the deltoid?
12. a. supraspinatus and infraspinatus b. deltoid and teres minor c. subscapularis and teres major
d. latissimus dorsi e. subscapularis
13. Its most important action is abduction, but its anterior part can also flex and medially rotate the arm and its posterior part can extend and laterally rotate the arm.
14. Sensory loss of skin over deltoid muscle and weakness of abduction of arm.
14. What deficits might one expect from injury to the axillary nerve?

15. What deficit is produced by injury to the long thoracic nerve?
15. Paralysis or weakness of the serratus anterior muscle, which results in winging of the scapula.
16. What nerve injury is likely to be associated with fracture of the surgical neck of the humerus?
What deficits would you expect to occur if this nerve is injured?
16. The axillary nerve is in direct contact with the surgical neck of the humerus and is the nerve most likely to be injured.
Since it supplies the deltoid and the teres minor muscles, the chief deficit would be great weakness or loss of abduction at the shoulder. There would also be generalized weakness in movements at the shoulder, since the deltoid also contributes to flexion and extension and to medial and lateral rotation. The teres minor is also a lateral rotator. There would also be diminished sensation in the skin overlying the deltoid because the axillary supplies a cutaneous branch (the upper lateral brachial cutaneous nerve) to this area.
17. Acromioclavicular, sternoclavicular, and distal radioulnar.
17. Name three joints in the upper member that commonly have articular discs.
18. What bones form the shoulder joint? 18. Scapula (glenoid fossa) and humerus (head)
LJ:bh revised 6/22/09