Cardiorespiratory Anatomy Flashcards
Thoracic cavity
- entrance is the thoracic inlet
- caudal border; diaphragm
- lined with serosa, pleura serous membrane
Thoracic cavity serosa
- the lining of the thoracic cavity and its organs
- smooth surfaces of pleura are lubricated with pleural fluid
- pleura is attached to the bony and muscular parts of the thorax by endothoracic fascia
- pleura consists of two separate sacs surrounding each lung
Pleural anatomy
- visceral pleura lines the lungs
- parietal pleura lines the thorax, consists of; costal pleura, diaphragmatic pleura and mediastinal pleura
- pleural cavity is between these
- pericardial pleura; part of mediastinal pleura on either side of the pericardium
- connecting pleura; connects visceral and parietal (pulmonary ligaments)
Mediastinum
- the junction of the two pleural sacs near midline of the thorax forms a double layer called mediastinum
- mediastinum is connective tissue that separates these cavities
- both parietal and visceral pleura meet with the mediastinal pleura
Types of mediastinum
- cranial; encloses oesophagus, trachea, great vessels, thoracic duct, lymph nodes, the thymus
- medial; pulmonary vessels, aortic arch, thoracic duct, azygous vein, lymph nodes, nerves, heart and pericardium
- caudal; aorta, vagus trunk, lymph nodes and left phrenic nerve
Mediastinum species differences
- DOGS; barrier is delicate but complete
- HORSE; ventral to oesophagus is fenestrated to allow communication between cavities
- RUMINANTS; openings occur rarely in sheep
Cranial vena cava
drains head and neck thoracic limbs and part of the thorax
Caudal vena cava
formed in the abdomen by the junction of the internal and external iliac veins
External jugular vein
formed near the angle of the jaw by the union of the linguofacial and maxillary veins
Lymphatic vascular system
- immunological defense
- network of one-way vessels
- return remaining interstitial fluid to the blood
- often run parallel to veins
- begin at lymph capillaries
- overlapping edges of endothelial cells create valve-like openings
- fluid is called lymph
Major lymphatic ducts
- right lymphatic duct; empties into right side of heart via jugular vein or cranial vena cava
- tracheal duct; empties into the thoracic duct or large veins near the heart
- thoracic duct; major lymph-collecting channel
The Thoracic Duct
- Drains from the cisterna chyli
- Left side, dorsal to the renal artery
- Both the intestinal and lumbar lymphatic trunks drain into cc
- pass through aortic hiatus into the mediastinum
- mostly enters the left jugular or cranial vena cava
Heart’s position in thoracic cavity
- middle part of the mediastinum
- 2/3 to 5/6 intercostal space
- tipped to left rests obliquely cranial to diaphragm
Pericardial sac
- made of fibrous pericardium and serous pericardium
- serous; has two layers, parietal and visceral
- between parietal and visceral; pericardial fluid
Layers of heart tissue
- visceral (epicardium); outer layer
- myocardium
- endocardium; inner layer
Ligaments from pericardium
- from the fibrous pericardium
- to the sternum; sternopericardial ligament
- to the diaphragm; phrenicocardial ligament
Hearts compartments
- auricular surface; small appendages of atrium
- auricles; next to pulmonary trunk
- atrial surface (right)
- atria; blood receiving chambers
- ventricles; blood pumping chambers
Heart valves
1) Right atrioventricular; tricuspid
2) Pulmonary valve
3) Left atrioventricular valve; bicuspid
4) Aortic valve
- valves anchored in ventricles by chordae tendineae
Branching of the coronary artery
- coronary groove encircles the heart
- branch of the aorta
- starts at aortic sinuses; pockets between valve cusps and vessel walls
Innervation of the heart
- autonomic
- sympathetic; through cervical and thoracic ganglia of the sympathetic trunk; increases HR
- parasympathetic; branch from vagus nerve (medulla oblongata)
