5. Lecture Notes on the Pumping Mechanism and Thoracic Anatomy

Flashcards covering the pumping mechanism, thoracic cavity, thoracic cage, intercostal muscles, blood supply, and diaphragm anatomy.

Pumping Mechanism

Air is drawn into the lung at inspiration by expansion of the lungs, and expelled at expiration by contraction of the lungs.

Thoracic Cavity

Space cranial to the diaphragm containing the lungs, thoracic trachea, heart, major vessels and other important organs.

Thoracic Cage

Has the shape of a laterally flattened cone.

Thoracic Inlet

Cranial extremity of the thoracic cage.

External Intercostals

Muscle fibre direction downwards and backwards; involved in inspiration.

Internal Intercostals

Muscle fibre direction downwards and forwards; action controversial, possibly involved in inspiration also.

Deep Cervical Artery

First pair of intercostal arteries arise from this artery in the horse.

Costocervical Trunk

The blood supply to the first three ribs in the dog is from this trunk

Internal Intercostal Muscle

The intercostal arteries course down the deep face of this muscle.

Dorsal Costo-Abdominal

Runs caudal to the last rib and not inside the intercostal space.

Aortic Hiatus

Located between the two crura and contains the descending aorta, right azygos vein and cisterna chyli.

Oesophageal Hiatus

An opening in the right crus at its junction with the tendinous centre, slightly to the left of the median plane containing the oesophagus, vagus nerve trunks and oesophageal vessels.

Caval Foramen

An opening in the tendinous centre near the muscle on the right side a little above the dorso-ventral middle of the muscle containing the posterior vena cava.

Phrenic Nerve

Motor and sensory nerve supply to the diaphragm.

Cervico-Thoracic (Stellate) Ganglion

Located on the lateral surface of the longus colli muscle at the level of the 1st intercostal space.

Embryological Development of Diaphragm

Forms from several structures that eventually divide the thorax from the abdomen.