• mediastinum

Trunk Upper part of trunk being called

Chest 
 Chest walls 

More general Skin Superficial fascia Deep fascia Extrinsic muscles More front

Pectoralis major 

Pectoralis minor More lateral Serratus anterior More back Rhomboid Major Minor Serratus posterior Superior Inferior Levator scapulae More particular Framework Front chest Sternum Side chest Ribs Back chest Thoracic vertebra Thoracic wall proper Ribs

Spaces between ribs 
Intercostal space 
Anteriorly 
9 intercostal spaces 

Posterior 11 intercostal spaces

 Intercostal muscles 

External intercostal

From

Posteriorly tubercle of rib to Continuous with posterior fibres of superior costotransverse ligament

costochondral junction 

External or anterior intercostal membrane Fibres direction Downward , forward and medially

Internal intercostal From Lateral border of sternum Superior costotransverse ligament To Angle of rib Continuous with internal intercostal membrane Fibres Backwards , laterally Transversria thoracis

Parts 

Subcostalis Intercostalis intimi Sternocostalis Nerve supply

Intercostal nerves 

Anterior primary Rami of t1 to t11 Upper two supply upper limb Lower 5 supply abdominal wall Anterior primary Rami of t12 forms Subcostal nerve Course Runs in costal groove Ends near sternum Relations Passes below Neck of rib Costal groove Lies below posterior intercostal vessels Above downwards VAN posterior part of groove Nerve lies beneath pleura With endothoracic fascia and internal intercostal membrane Near sternum Nerve crosses infront of internal thoracic artery And sternocostalis muscle Pierces External and internal intercostal muscle

Branches Muscular branches Sensory branches Lateral cutaneous branch. Anterior cutaneous branch

Intercostal arteries Each intercostal space has a artery Posterior intercostal arteries

 First and second arise from superior intercostal artery 

Which arises from costocervical trunk of subclavian artery 3- 11 arise from descendng thoracic aorta

Course and relations

Actions of intercostal muscles

Chest cavity