By Chris Sevilla

 Muscles of the thoracic wall - Pectorals - Serratus anterior - Intercostal muscles  Mechanism of respiration  Intercostal veins, arteries and nerves  VAN bundle

 Most superficial  Origin:  Clavicular head-anterior medial half of clavicle  Sternocostal head- sternum and upper 6 costal cartilages  Insertion: Lateral lip of intertubercular sulcus of humerus  Innervation: Medial AND lateral pectoral nerves (C5-8, T1)  Action: Adducts and medially rotates humerus. CH flexes humerus, SH extends from flexed position Clavicular head Sternocostal head

 Deep to Pec major  Origin: anterior surfaces of ribs III-V  Insertion: coracoid process of the scapula  Innervation: Medial pectoral nerves only (C8- T1)  Action: Stabilises scapula by drawing it anteriorly and inferiorly.

 Origin: External surfaces of ribs 1-8.  Insertion: Anterior surface of medial scapula border.  Innervation: Long thoracic nerve (C5-C7)  Action: Protracts scapula

MuscleOriginInsertionInnervationAction Pectoralis MajorClavicular head- anterior medial half of clavicle Sternocostal head- sternum and upper 6 costal cartilages Lateral lip of intertubercular sulcus of humerus Medial AND lateral pectoral nerves (C5-8, T1) Adducts and medially rotates humerus. CH flexes humerus, SH extends from flexed position Pectoralis Minor anterior surfaces of ribs III-V coracoid process of the scapula Medial pectoral nerves only (C8- T1) Stabilises scapula by drawing it anteriorly and inferiorly. Serratus anteriorExternal surfaces of ribs 1-8. Anterior surface of medial scapula border. Long thoracic nerve (C5-C7) Protracts scapula

 For breathing  Located between ribs  Innervated by corresponding thoracic nerves (T1-T11)

 External - Anteroinferior direction - Action: Contract during forced INSPIRATION and raise the ribs  Internal and innermost - Posteroinferior direction - Action: Contract during forced expiration and lower the ribs

 Pump handle movement - Increases anterior- posterior dimension. - Sternum moves up and forwards.  Bucket handle movement - Increases transverse dimension. - Shafts of ribs elevate.

 Anterior intercostal vv drain into internal thoracic vein.  Posterior intercostal vv drain into azygos/hemi- azygos vein

 Internal thoracic arteries give rise to anterior intercostal aa.  Thoracic aorta and costocervical trunks gives rise to posterior intercostal aa Internal thoracic aa and costocervical trunks are branches of the subclavian artery

 Dermatome  area of skin supplied by a single spinal nerve  Myotome  the muscles supplied by a single spinal nerve

 Intercostal aa, vv and nn in the intercostal space.  Lies in costal groove of superior rib.  In between internal and innermost intercostal muscles.

 Chest drain/Thoracentesis  Need to remove blood, fluid/air from pleural cavity.  Insert needle close to inferior rib to avoid damaging VAN bundle

 The pectoralis major is the largest and most superficial muscle of the thoracic wall. It is responsible for adducting and medially rotating the humerus.  The pectoralis minor is a small muscle that allows protraction of the scapula.  The serratus anterior is innervated by the long thoracic nerve and is responsible for protracting the scapula.  The intercostal muscles are responsible for respiration by moving the ribs. These movements are known as the pump and bucket handle movements.  The external intercostal muscles have fibres that run in the anteroinferior direction. The other two run in the posteroinferior direction.  The blood supply of the thoracic wall is from the internal thoracic aa/vv anteriorly and the aorta/azygos system posteriorly.  The VAN bundle consists of the intercostal aa/vv/nn running in the costal groove of the superior rib.

Pectoralis major has 2 heads: a clavicular head and a sternocostal head. True! The lateral pectoral nerve innervates pectoralis minor. False! The MEDIAL pectoral nerve does this! The pump handle movement increases the A/P diameter of the thorax. True! The thoracic aorta provides arterial supply to the anterior thoracic wall. False! It supplies the posterior thoracic wall! The VAN bundle lies in the costal groove of the inferior rib. False! They DO lie in the costal groove, but of the SUPERIOR rib. BEWARE! Some exam questions ARE this picky!

 Either Gray’s Anatomy or Moore’s Clinically Oriented Anatomy.  An anatomy atlas (e.g. Netter’s, McMinns)  CAL packages on Moodle  Aclands Video Atlas of Human Anatomy (access via UoN library NUSearch)

 Moore, K., Agur, A., Daley, A.(2011) Essential Clinical Anatomy.4 th Edition. Chapter 1: Thorax.  Drake, L. Vogl, W. Gray’s Anatomy for Students. 2 nd Edition. Chapter 3.  Netter’s anatomy  Google images

 Any questions? me at