CHEST MUSCLES

1) PECTORALIS MAJOR

 
Origin : FROM
– Anterior medial half of clavicle.
– Half of manubrium and sternum.
– costal cartilage ( second to sixth ).
  
Insertion : ON
– Lateral lip of bicipital groove.
 
Action : MAINLY
– Adduction and medial rotation of shoulder
– Flexion of arm .
Nerve supply:
– Medial and lateral pectoral nerve.

 

2) PECTORALIS MINOR

Origin : FROM 3 – 5 rib near costoclavicular junction.
Insertion : ON Corocoid process ( medial border and upper surface )
Action : MAINLY Depresses shoulder.

Nerve supply : Medial and lateral pectoral nerve.

 

3) SERRATUS ANTERIOR

Origin : From 8 digitations and from upper 8 ribs .
 
Insertion : ON
1st – Superior angle to root of spine.
2 nd – Medial border of scapula.
3 rd – inferior angle of scapula.
Action : MAINLY Scapular protraction
 

Nerve supply : Brachial plexus

 

4) DIAPHRAGM 

Origin : FROM Xiphoid process, costal margin , fascia over quadratus lumborum and psoas major.
Insertion : ON Central tendon of diaphragm.
Action : MAINLY Pushes abdominal viscera inferiority.

Nerve supply : phrenic nerve.

 


5) EXTERNAL INTERCOSTAL

Origin : FROM Lower border of rib with in an intercostal space.
 
Insertion : ON upper border of rib below.
 
Action : MAINLY Keep intercostal  space from blowing out or sucking .
 

Nerve supply : Intercostal nerve.

 


6) INTERNAL INTERCOSTAL

 
Origin : FROM Upper border of rib.
 
Insertion : ON Lower border of rib above.
 
Action : MAINLY Keeps intercostal space from blowing out or sucking in during respiration.

Nerve supply : Intercostal nerve.

7) INNER MOST INTERCOSTAL

 
Origin : FROM Upper border of a rib
 
Insertion : ON Fibers course up and medial to insert on the inferior margin of the rib above.
Action : MAINLY keeps intercostal space from blowing out or sucking in during respiration.

Nerve supply : Intercostal nerve.

8) LEVATOR COSTARUM

 
Origin : FROM Transverse process C7 , T11.
Insertion : ON Rib below its origin , medial to the angle.
Action : MAINLY Elevates the rib.
 
Nerve supply : from Dorsal primary Rami of spinal nerve.


9) SUBCOSTALIS

Origin : FROM Angle of ribs
Insertion : ON Angle of a rib 2 -3 rd ribs above origin.
Action : MAINLY Compresses the intercostal spaces.
 
Nerve supply : Intercostal nerve.


10) TRANSVERSE THORACIC

Origin : FROM Posterior surface of sternum.
Insertion : ON Inner surface of costal cartilage 2-6 .
Action : MAINLY Compress the thorax for forced expiration.
Nerve supply : Intercostal nerve.

 

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