SCAPULA AND DELTOID REGION
I. BONY LANDMARKS
A. Scapula
1. Acromion - "point of shoulder" - lateral end of spine
2. Spine - dorsal surface - divides scapula into anterior and posterior - continuous with acromion-palpable-T3
3. Superior and inferior angles-T2,T7
4. Coracoid process – attachment for 3 muscles and 3 ligaments
5. Supraspinous and infraspinous fossae
6. Supraglenoid and infraglenoid tubercles
7. Suprascapular notch - bridged by superior transverse scapular ligament
8. Body
9. Costal surface = subscapular fossa-R2-7
10. Groove for circumflex scapular vessels
11. Subscapular fossa
12. Glenoid fossa
B. Clavicle
1. Triangular-shaped medially (sternal)
2. Medial 2/3 is convex anteriorly - allows subclavian vessels and nn. to pass into arm
3. Lateral 1/3 flattened and concave anteriorly
4. Connections-Upper limb to axial skeleton
5. Palpable
6. First bone to ossify
7. Acts as strut - holds shoulder out at side of chest
C. Humerus
1. Head and greater tubercle
2. Lesser tubercle
3. Biceptal (intertubercular) groove
4. Deltoid tuberosity
5. Radial groove-radial nerve
6. Neck – anatomical and surgical-axillary nerve
II. MUSCLES OF THE SHOULDER
A. Scapular Muscles-"scapulohumeral muscles"-pass from the scapula to the humerus
1. Deltoid
a. Attachments: from lateral third of clavicle, acromion and spine of scapula to deltoid tuberosity of humerus - forms part of posterior axillary fold
b. Nerve: Axillary (C5-6) - from brachial plexus (posterior cord)
c. Artery: Posterior humeral circumflex (deltoid br. of thoracoacromial a.) - branch of axillary a.
d. Action: abducts arm, stabilize shoulder joint, rotates humerus medially - walking motion, three parts act together or alone
e. NOTE: the Deltoid m. is an important site of IM injections - anterior and lateral part - 2-3cm below acromion to miss axillary n.
2. Teres major
a. Attachments: from dorsal surface of inferior angle of scapula to intertubercular groove of humerus - with tendon of lat. dorsi form post. axillary fold
b. Nerve: Lower subscapular (brachial plexus-post cord)
c. Artery: Scapular circumflex (from axillary a.)
d. Action: adducts and medially rotates humerus and draws it back
B. Rotator Cuff Muscles
- mass of tendons fused with lateral part of the articular capsule of the shoulder joint
- all rotate humerus (except supraspinatus)
- give stability to shoulder joint
1. Supraspinatus
a. Attachments: Supraspinous fossa to greater tubercle of humerus - highest attachment-most commonly torn part of the rotator cuff
b. Nerve: Suprascapular (superior tr. of brachial plexus) - in notch, under ligament
c. Artery: Suprascapular (from thyrocervical tr.) - superior to ligament
d. Action: helps deltoid abduct arm - holds humerus in glenoid cavity of scapula
2. Infraspinatus
a. Attachments: infraspinous fossa to greater tubercle of humerus
b. Nerve: Suprascapular
c. Artery: Circumflex scapular, Post. Humeral circumflex
d. Action: lateral rotation of humerus - hold humerus in glenoid cavity
e. NOTE: this m. is the primary lateral rotator of the humerus
3. Teres minor
a. Attachments: superior lateral border of scapula to greater tubercle of humerus
b. Nerve: Axillary
c. Artery: Posterior humeral circumflex and circumflex scapular
d. Action: laterally rotates arm - holds humerus in glenoid cavity
4. Subscapularis - costal surface
a. Attachments: Subscapular fossa to lesser tuberosity of humerus - separated from T. major by long head of triceps
b. Nerve: upper and lower Subscapular
c. Artery: Lateral thoracic
c. Action: rotates humerus medially - draws it forward and down
C. Subacromial (subdeltoid) bursa
- directly under deltoid m.
1. between deltoid and supraspinatus tendon
2. facilitates movement of deltoid over joint capsule
3. forms lubricating mechanism between rotator cuff and coracoacromial arch
4. subscapular bursa
D. Triangular space - medial
1. Borders
a. teres minor - superior
b. teres major - inferior
c. long head of triceps - lateral
2. Contains circumflex scapular vessels
E. Quadrangular space - lateral landmark
1. Borders
a. teres minor
b. teres major
c. long head of triceps
d. humerus
2. Contains
a. posterior humeral circumflex vessels
b. axillary nerve
F. Blood supply to shoulder region
1. Suprascapular artery - br. of thyrocervical trunk - superior to suprascapular ligament
a. supraspinous br.
b. infraspinous br.
2. Subscapular artery - br. of axillary a.
a. circumflex scapular
b. thoracodorsal-latissimus dorsi
3. Posterior circumflex humeral artery – from 3rd part of axillary
4. Dorsal scapular artery - medial aspect of scapula - br. of subclavian
5. Arterial anastomoses - networks on both surfaces of scapula - important for establishment of collateral circulation
G. Nerves - branches of the brachial plexus
1.Axillary-Deltoid and T. minor
2.Suprascapular
3.Thoracodorsal and upper Subscapular
H. Lymphatic drainage of shoulder
1. Axillary lymph nodes > apical nodes > subclavian lymph trunk
2. Subscapular nodes > axillary nodes
3. Lateral nodes > apical nodes
a. paralysis of deltoid
b. teres minor