Scapulohumeral Muscles Flashcards
Where does the deltoid insert?
Deltoid tuberosity of the humerus
What is the origin of the deltoid?
Lateral third of the clavicle; acromion and spine of the scapula
What is the innervation of the deltoid?
Axillary nerve (C5, C6); main segmental innervation from C5
What actions does the deltoid perform?
Clavicular (anterior): flexes and medially rotates shoulder joint
Acromial (middle): abducts shoulder joint
Spinal (posterior): extends and laterally rotates shoulder joint
What is the origin of the supraspinatus?
The supraspinous fossa of scapula
Where does the supraspinatus insert?
Superior facet of greater tubercle of humerus
What is the innervation of the supraspinatus?
Suprascapular nerve (C4, C5, C6); main segmental innervation from C5
What action does the supraspinatus perform?
Initiates and assists deltoid in abduction of shoulder joint and acts with other rotator cuff muscles
What is the origin of the infrapsinatus?
The infraspinous fossa of the scapula
Where does the infraspinatus insert?
Middle facet of greater tubercle of humerus
What is the innervation of the infraspinatus?
Suprascapular nerve (C5, C6); main segmental innervation from C5
What action does the infraspinatus perform?
Laterally rotates shoulder joint; helps hold humeral head in glenoid cavity of scapula
What is the origin of the teres minor?
The middle part of the lateral border of the scapula
Where does the teres minor insert?
Inferior facet of greater tubercle of humerus
What is the innervation of the teres minor?
Axillary nerve (C5, C6); main segmental innervation from C5
What action does the teres minor perform?
Laterally rotates shoulder joint; helps hold humeral head in glenoid cavity of scapula
Where does the teres major originate?
The inferior part of the lateral border of scapula and posterior surface of inferior angle of scapula
Where does the teres major insert?
The medial lip of the intertubercular sulcus of the humerus
What is the innervation of the teres major?
Lower subscapular nerve (C5, C6); main segmental innervation from C6
What action does the teres major perform?
Adducts and medially rotates the shoulder joint
What is the origin of the subscapularis?
The subscapular fossa
Where does the subscapularis insert?
Lesser tubercle of humerus
What is the innervation of the subscapularis?
Upper and lower subscapular nerves (C5, C6, C7); main segmental innervation from C6
What action does the subscapularis perform?
Medially rotates and adducts shoulder joint; helps hold humeral head in the glenoid cavity
