Scapulohumeral Muscles and the Glenohumeral Joint

Question 1

What is the origin, insertion, action and innervation of Deltoid

Answer 1

Origin: Acromion and spine of scapula, and the clavicle

Insertion: Deltoid tuberosity of the humerus

Action: abduct shoulder

Innervation: axillary nerve

Question 2

What is the origin, insertion, action and innervation of Supraspinatus

Answer 2

Origin: Supraspinatus fossa of the scapula

Insertion: greater tubercle of the humerus

Action:

• start abduction of the shoulder and then help deltoid with abduction
• makes up part of the rotator cuff

Innervation: suprascapular nerve

Question 3

What is the origin, insertion, action and innervation of Infraspinatus

Answer 3

Origin: Infraspinatus fossa of the scapula

Insertion: greater tubercle of the humerus

Action: laterally rotate arm at the shoulder and makes up part of the rotator cuff

Innervation: suprascapular nerve

Question 4

Injury to what nerve causes atrophy of the Supraspinatus and Infraspinatus muscles

Answer 4

The suprascapular nerve, typically caused by entrapment from transverse scapular ligament in the suprascapular notch

Question 5

What is the origin, insertion, action and innervation of Teres Minor

Answer 5

Origin: Middle lateral border of the scapula

Insertion: greater tubercle of the humerus

Action: laterally rotates shoulder and forms part of the rotator cuff

Innervation: axillary nerve

Question 6

What is the origin, insertion, action and innervation of Subscapularis

Answer 6

Origin: Subscapular fossa

Insertion: lesser tubercle of the humerus

Action: makes up part of the rotator cuff

Innervation: subscapular nerve

Question 7

What is the origin, insertion, action and innervation of Teres Major

Answer 7

Origin: inferior angle of the scapula

Insertion: intertubercle groove of the humerus

Action: adducts and dorsally extends arm

Innervation: subscapular nerve

Question 8

What 4 muscle make up the rotator cuff

Answer 8

Supraspinatus, Infraspinatus, Teres minor, and subscapularis

Question 9

What muscles attach to the intertubercle sulcus/groove

Answer 9

Subscapularis, Pectoralis Major, Lattissimus Dorsi

Question 10

What muscles attach at the greater tubercle of the humerus

Answer 10

Supraspinatus, Infraspinatus, and Teres minor

Question 11

How does the coracoacromial ligament effect the glenohumeral joint

Answer 11

It prevents the superior displacement of the head of the humerus from the glenoid cavity

Question 12

What leads to painful arc syndrome

Answer 12

inflammed subacromial bursa

Question 13

What muscle divides the axillary artery into 3 parts

Answer 13

pec minor

Question 14

What branch comes off the 1st segment of the axillary artery

Answer 14

Superior thoracic artery

Question 15

What 2 branches comes off the 2nd segment of the axillary artery

Answer 15

1. Thoracoacromial artery

2. Lateral thoracic artery

Question 16

What 3 branches comes off the 3rd segment of the axillary artery

Answer 16

1. Subscapular artery
2. Anterior circumflex artery
3. posterior circumflex artery

Question 17

What vessels form the axillary vein when it at the inferior border of Teres Major

Answer 17

The basilic and brachial vein

Question 18

Describe anterior scalene syndrome

Answer 18

rare form of thoracic outlet syndrome where the brachial plexus and veins are trapped between the scalene muscles