Posterior Shoulder - Muscles and Bones

Question 1

Scapula

Answer 1

Question 2

Attachment sites for rotator cuff muscles

Answer 2

Greater & Lesser tubercles

Question 3

Humerus

Answer 3

Question 4

Shoulder movements

Answer 4

Question 5

Scapula movements

Answer 5

Question 6

scapular sliding along thoracic wall occurs along…

Answer 6

scapulothoracic joint (hypothetical joint)

Question 7

abduction of humerus above head cuases…

Answer 7

lateral rotation of scaupla

Question 8

Serratus Anterior Muscle

Answer 8

Origin: lateral parts of ribs 1-8

Insertion: anterior surface of medial border of scapula

Function: Stabilizes scapular, laterally rotates scapula, protracts scapula

Innervation: Long thoracic nerve (C5-C7)

Question 9

Winged Scaupla

Answer 9

• Long thoracic nerve trauma
• unable to clamp/stabilize scaupla against thoracic wall
• unable to abduct arm above head b/c glenoid cavity cannot be laterally rotated

Question 10

General groups of shoulder muscles

Answer 10

1. Superficial posterior shoulder muscles
2. Deep posterior shoulder muscles
3. Scapulohumeral muscles

Question 11

Superficial posterior shoulder muscles (Extrinsic shoulder muscles)

Answer 11

1. Trapezius
2. Latissimus

Question 12

Deep Posterior Shoulder Muscles

Answer 12

1. Levator scapula
2. Rhomboids (major/minor)

Question 13

Levator Scapula

Answer 13

Function: elevates, rotates scapula; tilts glenoid cavity inferiorly

Innervation: dorsal scapular nerve (C5)

Question 14

Rhomboids (major and minor)

Answer 14

Function: retract and rotate scapula; tilt glenoid cavity inferiorly

Innervation: dorsal scapular nerve (C5)

Question 15

Scapulohumeral muscles

Answer 15

1. Deltoid
2. Teres Major
3. Supraspinatus
4. Infraspinatus
5. Subscapularis
6. Teres Minor

• All muscles pass from scapula to humerus and act on shoulder joint
• stabilize humerus head in glenoid cavity

Question 16

Deltoid

Answer 16

Origin: Clavicle, acromion, spine of scapula

Insertion: deltoid tuberosity of humerus

Function: principal abductor of arm

Innervation: Axillary nerve (C5-C6)

Question 17

Teres Major

Answer 17

Origin: Scapula

Insertion: intertubercular groove (bicipital groove) of humerus

Function: adducts and medially rotates arm

Innervation: lower subscapular nerve (C5-C6)

Question 18

Muscles of Rotator Cuff

Answer 18

1. Supraspinatus
2. Infraspinatus
3. Teres minor
4. Subscapularis

• Insertion: musculotendinous rotator cuff
• Function: protect shoulder joint; stabilize humeral head
• Mnemonic: SITS

Question 19

Supraspinatus Muscle

Answer 19

Origin: supraspinous fossa

Insertion: superios facet of greater tubercule

Function: arm abduction

Innervation: suprascauplar nerve (C5&C6)

Question 20

Infraspinatus Muslce

Answer 20

Origin: Infraspinous fossa

Insertion: middle facet of greater tubercle

Function: Lateral rotation of arm

Innervation: suprascauplar nerve (C5&C6)

Question 21

Teres Minor

Answer 21

Origin: Lateral border of scaupla

Insertion: inferior facet of greater tubercle

Function: Laterally rotates arm

Innervation: Axillary nerve

Question 22

Subscapularis

Answer 22

Origin: Subscapular fossa

Insertion: Leser tubercle

Function: Medially rotates and adducts arm

Innervation: Upper and lower subscapular nerves (C5 & C6)

Question 23

Subacromial Bursae (subacromial and subdeltoid bursae)

Answer 23

• synovial fluid filled sacs that helps reduce friction btwn muscles/bone during shoulder movements

Question 24

Gateways to Posterior Scapular Region

Answer 24

1. Suprascapular notch/foramen
2. Quadrangular space
3. Trigangular Space
4. Triangular interval

• These allow neurovascular structures to move between anterior and posterior scapular/arm regions

Question 25

Suprascapular Notch

Answer 25

* located on **superior border of scapula** * **superior transverse scapular ligament** spans the roof of this forming a foramen * **Suprascapular nerve** passes _through_ foramen and **innervates infraspinatus muscles** * **Subscapular artery** passes _over_ this ligament * ligament can **ossify** and compress scauplar nerve --\> shoulder pain

Question 26

Quadrangular Space

Answer 26

* Bounded by * Teres Major * Teres Minor * Long head of triceps * Surgical neck of humerus * Contains **Axillary nerve** and **Posterior circumflex humeral artery**

Question 27

Triangular Space

Answer 27

* Bounded by * Teres Major * Teres Minor * Long head of triceps * Contains **circumflex scapular artery** (branch of subscauplar artery)

Question 28

Dermatome

Answer 28

* Representations of which spinal nerve root innervates which region of skin * tell you which level **dorsal root** accepts sensory information from a particular part of body * **cell bodies** of these sensory neurons reside in **dorsal root ganglion**

Question 29

Shingles

Answer 29

* **Herpes zoster** is virus that makes chicken pox in children * in some patients remains dormant in **dorsal root ganglion ** * can become active, travel along nerve fibers to dermatome supplied by that nerve * rash erupts --\> painful shingles

Question 30

Important Dermatomes to Remember

Answer 30