Muscles of the Scapular Region Part 2

Question 1

When do muscles fibers spiral?

Answer 1

On the way to their insertion

Question 2

What is the Origin, insertion, insertion, and action of the Latissimus Dorsi?

Answer 2

Origin: Spinous Process of inferior 6 thoracic vertabrae,thoracolumbar fascia,iliac crest, and inferior 3 and 4 ribs

Insertion: Floor of intertubercular groove of humerus

Innervation: Thoracodorsal nerve

Action: Extends,adducts,medially rotates humerus; raises trunk when climbing

Question 3

What is the Origin, insertion, insertion, and action of the teres major?

Answer 3

origin: Posterior surface, inferior angle of scapula

Insertion:Medial lip of intertubercular groove

Innervation: Lower subscapular nerve

Actions:adducts humerus, medially rotates humerus

Question 4

What do the rotator cuff muscles do?

Answer 4

Hold the head of the humerus in place at the shoudler joint

Question 5

What is common in rotator cuff and why?

Answer 5

Infero-anterior dislocation

common because rotator cuff tendons do not support the inferior aspect of the shoulder joint well, so the humeral head dislocates inferiorly easily

Question 6

What is at risk when the Humerus dislocates?

Answer 6

the axillary nerve

Question 7

What muscles abducts the humerus?

Answer 7

Supraspinatus abducts the humerus for first 15 degrees allowing deltoid to continue the abduction

However new research suggests suprascapularis can bring full ROM in arm but is not as strong as deltoid

Question 8

What muscles laterally rotate the humerus?

Answer 8

Infraspinatous
teres minor

Question 9

What muscles medially rotate the humerus?

Answer 9

Subscapularis

Question 10

What are the ligaments supporting the shoulder known for?

Answer 10

Their strength and the joint relies on the rotator cuff muscles/tendons to maintain their integrity