Pectoral and Shoulder Region Flashcards
What are the superficial extrinsic muscles of the shoulder?
Trapezius and latissimus dorsi
What is the origin and attachments of the trapezius?
Origin - skull, muchal ligament and spinous process of C7-T12
Attaches to clavicle, acromion and scapula spine
What is the action of the trapezius muscle?
Upper fibres - elevate scapula and rotate it during abduction
Middle fibres - retract scapula
Lower fibres - pulls scapula inferiorly
What is the origin and attachment of the latissimus dorsi?
Origins - spinous process of T7-12, iliac crest, thoracolumbar fascia and scapular spine
Attachment - intertubercular sulcus of the humerus
What is the action of the latissimus dorsi?
Extension, adduction and medial rotation
What are the deep intrinsic muscles of the shoulder?
Levator scapula
Rhomboid major and minor
What is the attachment of the levator scapula and rhomboid major + minor?
Medial border of the scapula
What is the action of the rhomboids on the shoulder?
Retracts and rotates scapula
What are the origins and insertions of the deltoid?
Origin - spine of scapula, lateral 1/3 of clavicle and acromion
Insertion - deltoid tuberosity of the humerus
What is the origin and attachment of the teres major?
Origin - posterior surface of inferior angle of scapula
Insertion - medial lip of intertubercular groove of humerus
What are the actions of the deltoid muscle?
Anterior fibres - flex and medially rotate
Posterior fibres - extend and laterally rotate
Medial fibres - main adductor of arm
What is the action of the teres major?
Adduction, extension and medial rotation
What is the innervation of the teres major?
Lower subscapular nerve
What are the rotator cuff muscles?
Suprascapular, infraspinatus, subscapularis and teres minor
What is the insertions of the rotator cuff muscles?
Supraspinatus, infraspinatus and teres minor - greater tubercle of the humerus
Subscapularis - lesser tubercle of humerus
What is the action of the supraspinatus?
Abduction of UL
Performs the 0-15 degrees of abduction and assists with the deltoid until 90 degrees
What is the action of the infraspinatus?
Laterally rotates the arm
What is the action of the subscapularis?
Medially rotates the arm
What is the action of the teres minor?
Laterally rotates the arm
What is the innervation of the teres minor?
Axillary nerve
What is the innervation of the subscapularis and infraspinatus?
Suprascapular nerves
What is the origin and insertion of the pectoralis major?
Origin - anterior surface of medial clavicle , sternum, superior 6 costal cartilages and aponeurosis of external oblique muscle
Insertion - intertubercular sulcus of the humerus
What is the origin and insertion of the pectoralis minor?
Origin - 3-5th rib
Insertion - coracoid process of scapula
What is the origin and insertion of serratus anterior?
Origins - lateral ribs 1-8
Insertion - costal surface of medial border of scapula
What is the action of the pectoralis major?
Adducts and medially rotates UL and draws scapula anterior + inferiorly
What is the action of the pectoralis minor?
Stabilises the scapula
What is the action of the serratus anterior?
Holds scapula against rib cage and rotates scapula for upward movement
What muscles are involved in extension of the shoulder joint?
Latissimus dorsi, deltoid and teres major
What muscles are involved in flexion of the shoulder joint?
Pectoralis major, anterior deltoid and coracobrachialis
Weak flexion from biceps brachii
What muscles are involved in adduction of the shoulder joint?
Pectoralis major, latissimus dorsi and teres major
What muscles are involved in abduction of the shoulder joint?
First 15 degrees - supraspinatus
15-90 degrees - deltoid
After 90 degrees - trapezius and serratus anterior
What muscles are involved in internal rotation of the shoulder joint?
Subscapularis, teres major, pectoralis major, latissimus dorsi and anterior deltoid
What muscles are involved in external rotation of the shoulder joint?
Infraspinatus and teres minor
