Anat 06

• The circulatory system provides for the metabolic requirements of the body cells via the blood, the interstitial fluid and the lymph.
• The circulatory system is divided into two divisions: the blood vascular system which includes the heart, arteries, and veins for the exchanges and transport gases, and the lymph vascular system which consists of lymph vessels, lymph nodes, and lymphatic organs for the removal of wastes and bacteria from the interstitial fluid and the return of protein-rich fluid to the bloodstream.
• The Cardiovascular System is divided into systemic circulation which begins in the left ventricle of the heart and passes by means of the systemic arteries to the entire body, returning by systemic veins to the right heart, pulmonary circulation which is smaller and begins in the right ventricle of the heart and transports (deoxygenated) blood by the pulmonary trunk and arteries to the alveolar capillaries of the lungs for gaseous exchange, and portal circulation which is hepatic portal circulation assuring the functional blood supply to the liver.
• Organs with dual blood supply supply the organ’s tissues as the nutritive blood supply and carry out its essential body functions as the functional blood supply.
• The branches of the brachial artery include the thoracodorsal artery to the teres major and latissimus dorsi, the caudal circumflex humeral artery which supplies the triceps, deltoideus, coracobrachialis, infraspinatus, and the shoulder joint capsule, the circumflex scapular artery which arises distal to the subscapular artery and courses cranially to supply the biceps brachii and the shoulder joint capsule, and the common interosseous artery which is the last branch of the brachial artery and dives through the interosseous space between the radius and ulna.
• The axillary artery is the continuation of the subclavian artery beyond the first rib and supplies the structure of the shoulder and continues as the brachial artery.
• The descending aorta is the part of the aorta caudal to the aortic arch, divided into two parts by the diaphragm (AORTIC HIATUS).
• The digital arteries include the palmar/dorsal common digital arteries which are superficial arteries on the palmar side of the metacarpus, the dorsal & palmar metacarpal digital arteries which are deep arteries of the metacarpus, and the proper digital arteries which are distal branches of the common digital arteries past the proximal end of the digits and extend as axial and abaxial proper digital arteries.
• The branches of the median artery include the deep antebrachial artery to the caudomedial muscles, the radial artery to the digits, and the superpalmar arch which gives off palmar metacarpal arteries (deep arch) and palmar common digital arteries (superficial arch) that supply the palmar aspect of forearm and manus.
• The branches of the axillary artery include the external thoracic artery which leaves the axillary near its origin to the superficial pectoral muscles, the lateral thoracic artery which arises distal to the external thoracic and supplies part of the latissimus dorsi, deep pectoral, and cutaneous trunci muscles, and the subscapular artery which is the largest and passes dorsocaudally between the subscapular and teres major muscles.
• The heart is the principal organ of the circulatory system, a central hollow muscular organ which functions as a suction and force pump.
• The heart is found obliquely placed in the middle mediastinum enclosed in a fibrosac, the pericardium.
• The long axis of the heart is directed caudally and ventrally.
• The heart has a base, an apex, two surfaces (atrial and auricular), and two borders (cranial and caudal).
• The heart has two grooves: the coronary groove, which divides the heart externally into the atria and ventricles, and contains the right coronary artery and circumflex branch of the left coronary artery, and the interventricular grooves, which are indistinct surfaces marking the external division of the ventricle into the right and left ventricles, corresponding to the interventricular septum internally.
• The right atrium consists of the sinus venarum cavarum, the main part, and the right auricle, the blind part projecting forward and downward.
• The wall of the right ventricle is thinner than the left because less pressure is required to move blood through the lungs than through the body.
• The heart has a left auricular surface, also known as the arterial side, where the auricles are seen with the pulmonary trunk in between them.
• The heart has a right atrial surface, also known as the venous side, where the vena cavae are seen entering the atria.
• The heart has two cavities: the atria (left and right) and the ventricles (left and right).
• The right atrium forms the right cranial part of the base of the heart and lies dorsal to the right ventricle, receiving deoxygenated blood from the body and most of the heart.
• Four chief openings found in the right atrium are the cranial vena cava, caudal vena cava, coronary sinus, and right atrioventricular orifice.
• The crista terminalis is a semilunar crest, thick-ridge of tissue placed between the entrance of the cranial vena cava and AV opening, the dorsal separation of the sinus venarum cavarum and the auricle.
• The right ventricle is composed of the right cranial part of the ventricular mass, receiving blood from the right atrium and pumping it, via the pulmonary circulation to the lungs.
• Pectinate muscles are freely branching, interlacing muscular bands radiating from the crista terminalis, strengthening the right auricle.
• The borders of the heart are cranial and caudal, with the cranial border being convex and the caudal border being nearly straight.
• The right ventricle has two openings: the right atrioventricular orifice and the pulmonary semilunar valve.
• Structures found inside the right atrium are the intervenous tubercle, which separates the openings of the two vena cavae, directing the flow of blood from the cranial vena cava to the atrioventricular orifice, and the oval fossa, a slit-like depression caudal to the intervenous tubercle on the medial wall of atrium, a remnant of the oval foramen at the interatrial septum.
• The base of the heart is up, the hilus of the organ facing dorsocranially (broad ‘top’) and always contains the major blood vessels: cranial vena cava, aorta, pulmonary arteries, and pulmonary veins.
• The large medial retropharyngeal lymph node is dorsal to the common carotid artery and ventral to the wing of the atlas.
• The pulmonary trunk arises from the right ventricle and its opening to the right ventricle, the pulmonary orifice, is guarded by the pulmonary valve consisting of 3 semilunar cusps.
• The ligamentum arteriosum (remnant of the fetal ductus arteriosus) connects the pulmonary trunk with the aorta.
• The aorta is divided into the ascending, arch, and descending (thoracic and abdominal) parts.
• The branches of the aortic arch include the brachiocephalic trunk and the left subclavian artery.
• Erectile tissue, also known as cavernous tissue, is a vascular specialization in which many closed-packed, endothelium-lined spaces are set in continuity with the bloodstream.
• The ligamentum arteriosum connects the pulmonary trunk with the aorta.
• The caudal laryngeal branch is a branch of the common carotid arteries.
• The branches of the left coronary artery include the paraconal interventricular branch, the circumflex branch, and the subsinuosal interventricular branch.
• A precapillary arteriovenous anastomosis is a connection between an artery and a vein.
• Small arterioles are located within the arterial branch of the cardiovascular system and are predirected to the proper arterial capillary bed.