Muscles of the thorax

The muscles of the chest wall, neuro-vascular bundle and lymphatic drainage of the thorax

Learning objectives

• At the end of this session, a student should be able to:-
• Identify the muscles making the thoracic wall
• Identify the main and accessory muscles of respiration
• Identify the neurovascular bundles of the thorax

Describe the lymphatic drainage of the thorax

Muscles of the thoracic wall

• External intercostal muscles (accessory m. of Inspiration)
• Internal intercostal m. (expiration)
• Diaphragm m. (Major m. of Inspiration)
• Subcostalis m. ( accessory m of expiration-forced)

Transversus thoracis m. (accessory expiration)

Other accessory muscles of expiration/Inspiration

• Serratus anterior m. (inspiration)
• Rectus abdominis m. (expiration)
• Sternocleidomastoid m. (inspiration)
• Scalenius m.(inspiration)
• Transversus abdominis (expiration)
• Internal oblique m.(expiration)

External oblique (expiration)

The diaphragm

Innervation of diaphragm

The neuro-vascular bundle

The intercostal nerves

The intercostal nerves arise from the anterior rami of the thoracic spinal nerves from T1 to T11 and are situated between adjacent ribs.

• Located in the costal groove
• Supply the intercostal muscles.

Occur in the order VAN

Innervation to diaphragm

The phrenic nerve originates from the anterior rami of the C3,C4 and C5 nerve roots and consists of motor, sensory, and sympathetic nerve fibers. It provides complete motor innervation to the diaphragm and sensation to the central tendon aspect of the diaphragm.

Blood supply and drainage

The T. wall muscles receives blood from internal thoracic artery (a branch of subclavian artery).

Venous drainage is through Azygous and hemiazygous veins into right and left subclavian veins

Lymphatic drainage

THANK YOU