Shoulder Muscles

Question 1

Deltoid

Answer 1

O- Lateral 1/3 of anterior border of clavicle, acromion, spine of scapula
I- Deltoid tuberosity
A - Abduction of humerus
-Anterior (clavicle)→flexes and medially rotates humerus
-Posterior (spine)→ extends and laterally rotates humerus
Most powerful flexor
N- Axillary nerve

Question 2

Subdeltoid (subacromial bursa)

Answer 2

-located beneath deltoid muscle, acromion, and superficial to supraspinatus tendon; facilitates movement between tendons and bone or joint capsules

Question 3

Supraspinatus

Answer 3

O- Supraspinatus fossa of scapula
I- Deltoid tuberosity
Highest facet, posterior surface of greater tubercle of humerus
A- Initiates abduction of humerus
N- Suprascaular nerve
note
-Initiates abduction of humerus then deltoid takes over
-Also need upward rotation of glenoid for complete rotation

Question 4

Infraspinatus

Answer 4

O-Infraspinous fossa of scapula
I- Middle facet; posterior surface greater tubercle of humerus
A- Lateral rotation of humerus
N- Suprascapular nerve

Question 5

Deep fascia of shoulder muscle

Answer 5

• continuous across deltoid and infraspinatus

- helps for inter muscular septum between infraspiantus, trees minor, and trees major

Question 6

Suprascapular nerve and artery location

Answer 6

-approach scapula from ventral superior surface
- suprascapulr notch contains superior transverse scapular ligament
-suprascapular artery pases superior to ligament
-& suprascapular nerve passes inferior to ligament
to supply supraspinatus

-Nerve and artery send branches around neck of acrmion via greater scapular notch to supply infraspinatus

Question 7

Teres Minor

Answer 7

O- Middle 1/3 to upper 2/3 of lateral border of scapula
I- Lowest facet, posterior surface of greater tubercle of humerus
A- Lateral rotation of the humerus
N- Axillary nerve

Question 8

Teres Major

Answer 8

O- Dorsal surface inferior angle of scapula
I- Crest of lesser tubercle of humerus
A-Extension, adduction, and medial rotation of humerus
N- Lower subscapular nerve

Question 9

Tendons of supraspinatus, infraspinatus, and teres minor

Answer 9

blend with glenoidhumeral joint capsule to strengthen superiorly and posteriorly

Question 10

Subscapularis

Answer 10

O- Subscapular fossa
I- Lesser tubercle of humerus
A- Medial rotation of humerus
N- Upper and lower subscapular nerve

Question 11

Serratus Anterior

Answer 11

O- Outer surfaces of ribs 1-8 (9)
I- Vertebral costal surfaces of scapula from superior to inferior angle
A- Protracts scapula
-Upward rotates gleniod cavity
- Fixates scapula to thoracic wall
-Function as accessory muscle to respiration -Lying supine= action is to elevate ribs
N- Long thoracic nerve

Question 12

Rotator Cuff

Answer 12

• Supraspinatus, Infraspinatus, Teres Minor, Subscapularsis- stabilize head of humerus
• stabilize head of humerus
• refined movement
• superior muscles most likely to be injured

Question 13

Winged Scapula

Answer 13

injury to long thoracic nerve can cause winged scapula; inability to abduct upper limb; or push upper limb forward against resistance

Question 14

Quadrangle Space

Answer 14

Borders:
Superior- teres minor
Inferior- teres major
Lateral- humerus
Medial- long head of triceps

Contents:
axillary nerve and posterior circumflex artery
***pass anterior to posterior

Question 15

Triangular Space

Answer 15

Borders:
Superior- teres minor
Inferior- trees major
lateral- long head of triceps

Contents:
circumflex scapular artery
**pass anterior to posterior

Question 16

Scapular Anastomose

Answer 16

• union of arterial branches from subclavian and axillary origins
• 9 arteries involved
• blockages within axillary artery cause reversal flow within branches of subclavian and axillary aa
• anastomose are there to circumvent blockage

Question 17

Arteries Involved in Scapular Anastomoses

Answer 17

• deep branch of transverse cervical artery (dorsal scapular artery)
• suprascapular artery
• acromial branch (thoracoacromial a)
• circumflex scapular artery
• thoracodorsal artery
• anterior circumflex humeral artery
• posterior circumflex humeral artery

Question 18

3 Anastomoses of scapular artery

Answer 18

1. deep branch of transverse cervical and supra scapular artery with circumflex scapular and thoracodorsal arteries to bring blood to sub scapular artery
2. acromial branch with loop of anterior and posterior circumflex humeral arteries
3. deep branch of TC (or dorsal scapular) with intercostal arteries near scapula