Intrinsic Muscles of the Shoulder Flashcards
Which muscles make up the intrinsic muscles of the shoulder
Deltoid
Teres major
Rotator cuff muscles
What are the rotator cuff muscles
Supraspinatus
Infraspinatus
Subscapularis
Teres minor
Where does deltoid originate
Scapula
Clavicle
Where does deltoid insert
Deltoid tuberosity on the lateral surface of the humerus
Which nerves innervate deltoid
Axillary nerve
What is the action of the anterior fibres of deltoid
Flex the arm at the shoulder
What is the action of the posterior fibres of deltoid
Extend the arm at the shoulder
What is the action of the middle fibres of deltoid
Major abductor of the arm
What is the quadrangular space
The gap that the axillary nerve and posterior circumflex humeral artery pass through to reach the posterior scapula region
What forms the inferior border of the quadrangular space
Teres major
Where does teres major originate
Posterior surface of the inferior angle of scapula
Where does teres major insert
Medial lip of the intertubercular groove of humerus
Which nerves innervate teres major
Lower subscapular nerve
What is the action of teres maor
Adducts at the shoulder
Internal rotation of the arm
What is the collective function of the rotator cuff muscles
Pulls humeral head into the glenoid fossa providing stability to the glenohumeral joint
Where does supraspinatus originate
Supraspinous fossa of the scapula
Where does supraspinatus insert
Greater tubercle of the humerus
Which nerve innervates supraspinatus
Suprascapular nerve
What is the action of supraspinatus
Abducts the arm 0-15 degrees
Assists deltoid for 15-90 degrees abduction
Where does the infraspinatus originate
Infraspinous fossa of the scapula
Where does infraspinatus insert
Greater tubercle of the humerus
Which nerve innervates infraspinatus
Suprascapular nerve
What is the action of infraspinatus
Externally rotates the arm
Where does subscapularis originate
Subscapular fossa on the costal surface of the scapula
Where does subscapularis insert
Lesser tubercle of the humerus
Which nerves innervate subscapularis
Upper subscapular nerves
Lower subscapular nerves
What is the action of subscapularis
Internally rotates the arm
Where does teres minor originate
Posterior surface of the scapula, adjacent to its lateral border
Where does teres minor insert
Greater tubercle of the humerus
Which nerve innervates teres minor
Axillary nerve
What is the action of teres minor
Externally rotates the arm
Which rotator cuff muscle is most commonly affected with tendonitis
Supraspinatus - during abduction it rubs against the coraco-acromial arch
