OIAN 11

Question 1

Serratus Anterior

Answer 1

Origin:
- Anterolateral surface of the upper 8 or 9 ribs
Insertion:
- Costal aspect of the medial border of the scapula
Action:
- Protracts the scapula
- Assists to upwardly rotate the scapula
- Functionally prevents winging
Nerve:
- Long Thoracic
- C5, 6, 7

Question 2

Deltoid

Answer 2

Origin:
- Anterior portion: lateral portion of the clavicle
- Middle portion: acromion process
- Posterior portion: scapular spine
Insertion:
- Deltoid tuberosity
Action:
- Anterior portion: flexes and internally (medially) rotates the arm
- Middle portion: abducts the arm (all)
- Posterior portion: extends and externally (laterally) rotates the arm
Nerve:
- Axillary

Question 3

Supraspinatus

Answer 3

Origin:
- Supraspinous fossa
Insertion:
- Uppermost of three facets of the greater tubercle of the humerus
- Capsule of the shoulder joint
Action:
- Abducts the arm (almost solely for first 20 degrees)
- Helps guide humeral head into central glenoid with elevation of shoulder
Nerve:
- Suprascapular
- C5, 6

Question 4

Infraspinatus

Answer 4

Origin:
- Infraspinous fossa
Insertion:
- Middle facet of the greater tubercle of the humerus
- Capsule of the shoulder joint
Action:
- Externally rotates the arm
- Helps produce inferior translation and compression into glenoid during arm elevation (along with the other rotator cuff muscles)
Nerve:
- Suprascapular
- C5, 6

Question 5

Teres Minor

Answer 5

Origin:
- Middle half of the scapula’s lateral border
Insertion:
- Lowest of three facets of the greater tubercle of the humerus
- Capsule of the shoulder joint
Action:
- Externally rotates the arm
- Helps produce inferior translation and compression into glenoid during arm elevation (along with the other rotator cuff muscles)
Nerve:
- Axillary
- C5, 6