Thorax

What is the primary muscle of inspiration

The primary muscle of inspiration is the diaphragm

What are the other muscles that may assist in inspiration

The scalenus, serratus dorsalis cranialis and the external intercostal muscles

What is the primary muscle for forced expiration

The external and internal intercostal muscles and the abdominal muscles

What muscles may assist in the forced expiration

Serratus dorsalis caudalis m. and Transverse thoracic m.

How does the diaphragm move during inspiration and expiration

The diaphragm contracts and moves downwards during inspiration, increasing thoracic cavity volume, and relaxes and moves upwards during expiration, reducing thoracic cavity volume.

What are the main foramen in the diaphragm and what their locations

The caval foramen lies on the right side at the junction and is where the caudal vena cava enters the chest from the abdomen. The oesophageal hiatus is located more centrally in the muscular part just dorsal and medial to the caval foramen. The aortic hiatus is dorsal to this, between the crura of the diaphragm.

What are difference in fibre direction of the internal and external intercostal muscles

The external intercostal muscles run towards a caudoventral direction and the internal intercostal muscles run to a caudodorsal direction

What is the difference in the direction of serratus dorsalis cranialis and caudalis muscle fibres

Serratus dorsalis cranialis is directed caudoventrally. The serratus dorsalis caudalis m. has fibres directed cranioventrally.

Where does the transverse thoracic muscle lie

The internal ventral surface of the thorax that lies between the regions of the costochondral junctions of the sternal ribs either side and runs across the dorsal aspect of the sternum

What is the mediastinum

The double layered serous membrane that contains all the midline thoracic structures

Where does the mediastinum sit

The cranial mediastinum is the mediastinum that lies cranial to the heart, and the caudal mediastinum lies caudal to the heart. The middle mediastinum contains the heart.

What is the plica venae cavae

The fold of pleura that contains the caudal vena cava

What is the ligamentum arteriosus

A short fibrous band that connects the pulmonary artery to the descending aorta, remnants of the ductus arteriosus in fetal circulation.

What are the two main branchings off the aorta

The right brachiocephalic trunk and the left subclavian artery.

What branches off the brachiocephalic trunk

The left and right common carotid artery and the right subclavian artery.

What are the 4 main branches off the left subclavian artery. How do they branch off

First branch is the more medial vertebral artery and then the more lateral and really close costocervical trunk artery. Then comes off the ventral internal thoracic artery and then opposite that a little more cranially is the superficial cervical artery

What branches off the internal thoracic artery

The cranial epigastric artery which continues as the superficial cranial epigastric

Where do the intercostal arteries come off and how many pairs are there

After the origin of the left subclavian artery and gives off nine pairs

Which side is the azygous vein on

The right side

What is the major route of lymphatic return to the circulation

The thoracic duct

Where do the tracheobronchial lymph nodes sit

They are located around the tracheal bifurcation, lying either side of the trachea and between the diverging bronchi.

Where do the cranial mediastinal lymph nodes sit

They are located in the cranial part of the mediastinum, near the trachea and dorsal to the subclavian artery

What are the left lung lobes

The left lung is divided into two lobes: the left cranial lobe which has a cranial and caudal portion and the left caudal lobe.

What are the right lung lobes

The right lung is divided into four lobes: the right cranial lobe, right middle lobe, the right caudal lobe and the accessory lobe

What are the different parts of the parietal pleura

The parietal pleura is costal when it covers the internal surface of the rib cage, diaphragmatic when it covers the thoracic surface of the diaphragm, mediastinal when it lines the left or right sides of the mediastinum

What does the phrenic nerve innervate and its function

The phrenic nerve innervates the diaphragm causing it to contract

Describe the pathway of the sympathetic trunk as it moves caudally to cranially

The sympathetic trunk runs alongside the vertebral column where it merges with the stellate ganglion before it splits to form the ansa subclavia and moves down to join with the middle cervical ganglion. The rest of the sympathetic trunk runs up the neck as the vagosympathetic trunk.

Where do the right and left recurrent laryngeal nerves emerge from and what is the difference between their pathways

The right recurrent laryngeal nerve emerges from the right vagus nerve, looping under the right subclavian artery, while the left recurrent laryngeal nerve arises from the left vagus nerve, looping under the aortic arch.

What are the landmarks used for cardiac puncture

Puncture occurs in the 3rd intercostal space just caudal to the caudal border of the brachium, at the level of the costochondral junctions