The Shoulder (Myology)

Question 1

Serratus Anterior

Answer 1

Action:
Protraction and upward rotation at the scapulathoracic joint

Origin: Superlateral surface of C1-T8

Insertion: Inferomedial border of the scapula

Innervation: Thoracic nerve C5-7

Question 2

Deltoid

Answer 2

Action:
Shoulder abduction
Stabiliser of humeral head

Origin:
Anterior;
Lateral third anterior surface of clavicle
Mid;
Acromion process
Posterior;
Scapular Spine

Insertion:
Deltoid tuberosity

Innervation: Axillary Nerve C5-6

Question 3

Pectoralis Major

Answer 3

Action:
Shoulder;
Adduction
Medial rotation
Arm;
Flexion/extension

Origin:
Clavicular head;
Anterior surface of the medial half of the clavicle
Sternocostal head;
Anterior manubrium

Insertion:
Greater tubercle of the humerus

Innervation:
Lateral pectoral nerve
Medial pectoral nerve

Question 4

Pectoralis Minor

Answer 4

Action:
Scapular;
Stabilisation
Depression
Abduction
Protraction
Internal and downward rotation

Origin:
Anterior ribs 3-5

Insertion:
Superomedial coracoid process of the scapula

Innervation:
Pectoral nerves C8 and T1

Question 5

Teres Minor

Answer 5

Action:
Shoulder;
External rotation
Adduction

Origin:
Lateral border of the upper 2/3 posterior scapula

Insertion:
Upper fibres;
Greater tubercle of the humerus
Lower fibres;
Humerus

Innervation:
Axillary nerve C5-6

Question 6

Supraspinatus

Answer 6

Action:
Arm abduction (0-15˚only)

Origin:
Supraspinatus fossa of the humerus

Insertion:
Greater tuberosity of the humerus

Innervation:
Suprascapular Nerve C5-6

Question 7

Infraspinatus

Answer 7

Action:
Shoulder;
External Rotation
Extension

Origin:
Infraspinatous fossa of the scapula

Insertion:
Posterior aspect of the greater tuberosity of the humerus

Innervation:
Suprascapular Nerve C5-6

Question 8

Subscapularis

Answer 8

Action:
Internal rotation of the humerus

Origin:
Medial 2/3 of the subscapular fossa

Insertion:
Lesser tubercle of the humerus and the anterior shoulder joint capsule

Innervation:
Upper and lower subscapular nerves C5-6

Question 9

Coracobrachialis

Answer 9

Action:
Humeral;
Flexor
Adductor
Stabiliser

Origin:
Apex of the coracoid process

Insertion:
A linear impression at the medial shaft of the humerus

Innervation:
Musculocutaneous nerve