Thorax Flashcards
(49 cards)
What are the contents of the superior mediastinum?
thymus, phrenic nerves, aortic arch: great veins (brachiocephalic trunk, right subclavian and r common carotid; left subclavian and left common carotid, left and brachio, left and right subs, left and right common carotids), main lymphatic trunks (thoracic), vagus nerve, great arteries, trachea and main bronchi, upper oesophagus
superior mediastinum runs from superior thoracic aperture bordered by clavicle, level of t1/2; to t4/5 transverse throacic plane, marked by sternla engal
BATS & TENT
Brachiocephalic veins
Arch of aorta
Thymus
Superior vena cava
Trachea
Esophagus
Nerves (vagus & phrenic)
Thoracic duct
(and main broc=nchi, )
What are the two great veins?
The superior and inferior venae cavae*
List the true ribs
1-7
True ribs attach directly to sternum
8List the false rib
8-12
False ribs do not attach to sternum directly
Note also 11 and 12 (Sometimes 10) are floating. 8-10 (usu.) connect via costal cartilages ofribs above.
Floating ribs insert into the muscles of the posterior abdominal wall
What are the components of the intervertebral disc?
- Annulus fibrosus
- Nucleus pulposus
see footnote:
https://www.physio-pedia.com/Intervertebral_disc
The intervertebral disc (IVD) is important in the normal functioning of the spine. It is a cushion of fibrocartilage and the principal joint between two vertebrae in the spinal column. There are 23 discs in the human spine: 6 in the cervical region (neck), 12 in the thoracic region (middle back), and 5 in the lumbar region (lower back).
They consist of three major components: the inner, nucleus pulposus (NP), the outer, annulus (AF) and the cartilaginous endplates that anchor the discs to adjacent vertebrae.
Nucleus pulposus sits at centre, It is made of 66% to 86% water with the remainder consisting of primarily type II collagen (it may also contain type VI, IX, and XI) and proteoglycans.
AF: Consists of “lamellae” or concentric layers of collagen fibres [2]. The fibre orientation of each layer of lamellae alternate and therefore allow effective resistance of multidirectional movements. The AF contains an inner and an outer portion. They differ primarily in their collagen composition. While both are primarily collagen, the outer annulus contains mostly type I collagen, while the inner has predominantly type II
List the anatomical structures of the thoracic cavity
a million…
ribs
lungs and pleura
heart, pericardium/sac
diaphragm
vessels: all the biggies including azygos, hemiazgos, and accessory hemiazygos
thymus
vagus, phrencu, l recurrent laryngeal,
vertebrae
oesophagus
aorta(thoracic)
List and describe the structures of the mediastinum
see fill in blank for answers
Describe the structure of the heart
see fill in blanks for layers
Atria: two
Ventricles: two
Describe the structure of the lungs
R and L
superior, middle (hor)/oblique/inferior
superior/oblique/inferior
Hilum: bronchus, R and L, pulmonary arteries, veins, phrenic nerve
Apex
Base
Costodiaphragmantic recesses, costopherenic angles
Cardiac notch
Surrounded by visceral and parietal pleura
The three surfaces of the lung include the costal, medial, and diaphragmatic surfaces. The costal surface is covered by the costal pleura and is along the sternum and ribs. It also joins the medial surface at the anterior and posterior borders and diaphragmatic surfaces at the inferior border. The medial surface is divided anteriorly and posteriorly. Anteriorly it is related to the sternum, and posteriorly it is related to the vertebra. The diaphragmatic surface (base) is concave and rests on the dome of the diaphragm; the right dome is also higher than the left dome because of the liver.
Describe the connections between the heart and the lungs
Pulmonary circulation is the system of transportation that shunts de-oxygenated blood from the heart to the lungs to be re-saturated with oxygen before being dispersed into the systemic circulation. Deoxygenated blood from the lower half of the body enters the heart from the inferior vena cava while deoxygenated blood from the upper body is delivered to the heart via the superior vena cava. Both the superior vena cava and inferior vena cava empty blood into the right atrium. Blood flows through the tricuspid valve into the right ventricle. It then flows through the pulmonic valve into the pulmonary artery before being delivered to the lungs. While in the lungs, blood diverges into the numerous pulmonary capillaries where it releases carbon dioxide and is replenished with oxygen. Once fully saturated with oxygen, the blood is transported via the pulmonary vein into the left atrium which pumps blood through the mitral valve and into the left ventricle. With a powerful contraction, the left ventricle expels oxygen-rich blood through the aortic valve and into the aorta
Pulmonary arteries Right ventricle -> pulmonary trunk -> right and left pulmonary arteries
Purpose: deliver deoxygenated blood to the respective lung
Pulmonary veins Lung capillaries -> 4 pulmonary veins (2 from each lung) -> left atrium
Purpose: deliver oxygenated blood to the left ventricle which will distribute it to the body
List the great vessels
The large arteries and veins directly connected with the heart are termed the great vessels, consisting of the inferior vena cava, superior vena cava, pulmonary arteries, pulmonary veins, and root of the aorta (The ascending aorta begins at the aortic valve, approximately at the level of the third costal cartilage, as the continuation of the left ventricular outflow tract, and is usually up to 2.1cm wide [6] [7], carrying newly oxygenated blood to the body. It ascends for about 5cm before becoming the aortic arch at the sternal angle, which continues superiorly, curving slightly to the left and posteriorly over the hilum of the left lung before descending again in the posterior mediastinum where, at the level of T4, it continues as the thoracic aorta.
The apex of the aortic arch is where its three branches are given off: the brachiocephalic trunk, the left common carotid artery, and, latterly, the left subclavian artery. Just anteriorly to these near vertical branches, the left superior intercostal vein is draped obliquely across the aortic arch. As it travels horizontally from posterolateral to anteromedial, it first crosses over the left vagus nerve, then under the left phrenic nerve, before draining into the left brachiocephalic vein.)
List the main branches of the great vessels
see question below
Describe the supply territory of the great vessels and their branches
Aorta
The aorta is the largest artery in the body. It carries oxygenated blood (pumped by the left side of the heart) to the rest of the body.
The aorta arises from the aortic orifice at the base of the left ventricle, with inflow via the aortic valve. Its first segment is known as the ascending aorta, which lies within the pericardium (covered by the visceral layer). From it branch the coronary arteries. The second continuous segment is the arch of the aorta, from which branch the major arteries to the head, neck and upper limbs. These are:
Brachiocephalic trunk Left common carotid artery Left subclavian artery
After the arch of the aorta, the aorta then becomes the descending aorta which continues down through the diaphragm into the abdomen.
The pulmonary arteries receive deoxygenated blood from the right ventricle and deliver it to the lungs for gas exchange to take place.
The arteries begin as the pulmonary trunk, a thick and short vessel, which is separated from the right ventricle by the pulmonary valve. The trunk is located anteriorly and medially to the right atrium, sharing a common layer of pericardium with the ascending aorta. It continues upwards, overlapping the root of the aorta and passing posteriorly.
At around the level of T5-T6, the pulmonary trunk splits into the right and left pulmonary arteries. The left pulmonary artery supplies blood to the left lung, bifurcating into two branches to supply each lobe of the lung. The right pulmonary artery is the thicker and longer artery of the two, supplying blood to the right lung. It also further divides into two branches.
Pulmonary Veins
The pulmonary veins receive oxygenated blood from the lungs, delivering it to the left side of the heart to be pumped back around the body.
There are four pulmonary veins, with one superior and one inferior for each of the lungs. They enter the pericardium to drain into the superior left atrium, on the posterior surface. The oblique pericardial sinus can be found within the pericardium, between the left and right veins.
The superior pulmonary veins return blood from the upper lobes of the lung, with the inferior veins returning blood from the lower lobes. The inferior left pulmonary vein is found at the hilum of the lung, while the right inferior pulmonary vein runs posteriorly to the superior vena cava and the right atrium.
Superior Vena Cava
The superior vena cava receives deoxygenated blood from the upper body (superior to the diaphragm, excluding the lungs and heart), delivering it to the right atrium.
It is formed by merging of the brachiocephalic veins, travelling inferiorly through the thoracic region until draining into the superior portion of the right atrium at the level of the 3rd rib.
As the superior vena cava makes its descent it is located in the right side of the superior mediastinum, before entering the middle mediastinum to lie beside the ascending aorta.
Inferior Vena Cava
The inferior vena cava receives deoxygenated blood from the lower body (all structures inferior to the diaphragm), delivering it back to the heart.
It is initially formed in the pelvis by the common iliac veins joining together. It travels through the abdomen, collecting blood from the hepatic, lumbar, gonadal, renal and phrenic veins. The inferior vena cava then passes through the diaphragm, entering the pericardium at the level of T8. It drains into the inferior portion of the right atrium.
Define the boundaries of the mediastinum and the pleural cavities
thoracic aperture to diaphragm
sternum to verterbral column
plural cavities: Superior: root of the neck, 2-3 cm above the level of rib one. Inferior: The thoracic surface of the diaphragm inferiorly. Medial: The mediastinum medially.
Describe the pleura
Consists of
- visceral pleura
- pleural cavity (and fluid)
- parietal pleura
- endothoracic fascia
- diaphragm
Describe the pericardium
Consists of the following structures:
- visceral pericardium or epicardium
- pericardial cavity and fluid
- parietal pericardium
- fibrous pericardium
- central tendon of the diaphragm
Describe the nerve supply of the thoracic cage
Somatic:
- - intercostal nerves (posterior, priperal 6, sensory; branches of c345 phrenic, cnetral)
Note on intercostals:
During their course, collateral, lateral cutaneous, and anterior cutaneous branches branch off. The anterior ramus branches innervate the skin over the ribs and muscles of the thoracic wall. The posterior ramus branches go on to innervate the skin over the posterior thoracic wall and the muscles of the spine.
i.e. contents:
-motor ohrenic nerves, phrenic 345 (pericardium, diaphramg, lung via hila)
Contents:
Autonomic:
sympatheically: trunk, t1-l2
parasymapttic: vagus, dorsal nucleus in medilla— enters via common carotids and int jugular veins, branches to plexuses in cardia, pulmo and oseo, out via eso hiatus in diaphragm
The left recurrent laryngeal nerve branches off the left vagus nerve at the level of the aortic arch.[17][22] It traverses medially, inferior to the aortic arch, and ascends to enter the neck. The right recurrent laryngeal nerve does not enter the thoracic cavity but traverses under the right subclavian artery from the right vagus nerve. Palsy of the recurrent laryngeal nerve affects the laryngeal muscles.[23]
The brachial plexus originates from C5 to T1 spinal nerves and is situated superior to the thorax.[19] As trunks, divisions, and cords form, nerves branch off to supply muscles superficial to the thoracic wall; this includes the dorsal scapular, medial and lateral pectoral, long thoracic, and thoracodorsal nerves.
List the layers of the thoracic wall
Skin
Superficicla fascia and fat
muscle e.g. serratus anterior
rib
external intercostal
internal intercostal
– intercostal artery vein and nerve, and collatral branches
inner most
endothoraic fascia
partierl pleura
(pericardium– fibrous, serous partieal and viscaeral)
pleural cavity
visceral
lung
Describe the pulmonary and systemic circulation
The pulmonary system connects the heart and the lungs and its primary function is gas exchange. The pulmonary trunk arise from the right ventricle and carry de-oxygenated blood to the lungs trough the left and right pulmonary arteries. Following gas exchange at the pulmonary alveoli, pulmonary veins return to the left atrium of the heart to deliver oxygenated blood.
The primary role of the systemic arterial system is to deliver oxygenated blood to all regions of the body to supply bones, muscles, viscera. The aorta arises from the left ventricle of the heart and produces a number of branches that deliver blood to target regions in the body. De-oxygenated blood returns to the right atrium of the heart via 3 veins: superior vena cava, inferior vena cava drain blood from the body, while the coronary sinus drains blood from the heart tissue directly.
Artery - from the Greek word aeirein=to raise, typically describe blood vessels that move blood away from the heart.
Vein - from the Latin word venā=blood vessel. To come in Latin is coming is veni, the vessels that deliver blood towards the heart are nominated as veins.
Please note, that this anatomical distinction is always true for every vessel, however, categorisation by blood content is not. In the systemic circulation arteries carry oxygenated blood to the body, while veins carry de-oxygenated blood back to the heart. In the pulmonary system arteries deliver de-oxygenated blood to the lungs for gas exchange and pulmonary veins return oxygen-rich blood to the heart.
List the valves of the heart
The location of the valves is easy to remember using the mnemonic All Patients Trust Me (APTM). As one looks at the heart, starting from the left, the first valve to be found is the Aortic, followed by the Pulmonary, followed by the Tricuspid/right AV/, followed by the Mitral/left AV (APTM).
The easy way to remember the bicuspid/tricuspid order is to remember that you ride a tricycle before you ride a bicycle. The tricuspid always comes first. It’s on the right side and separates the right atrium from the right ventricle. The bicuspid separates the left atrium from the left ventricle.
Semi-lunar valves:
Aorta:The aortic valve normally has three cusps however there is some discrepancy in their naming.[2] They may be called the left coronary, right coronary and non-coronary cusp– small proportion of population are biscusp
Pulmonary: tricusp
Describe the location of the thymus
Superior mediastinum
NB atrophies with age
List the key types of blood vessels and how their structure is related to function
Artery - from the Greek word aeirein=to raise, typically describe blood vessels that move blood away from the heart.
Vein - from the Latin word venā=blood vessel. To come in Latin is coming is veni, the vessels that deliver blood towards the heart are nominated as veins.
Please note, that this anatomical distinction is always true for every vessel, however, categorisation by blood content is not. In the systemic circulation arteries carry oxygenated blood to the body, while veins carry de-oxygenated blood back to the heart. In the pulmonary system arteries deliver de-oxygenated blood to the lungs for gas exchange and pulmonary veins return oxygen-rich blood to the heart.
tructure of vessel walls
Despite varying sizes and functions, most blood vessels share a similar structure being composed of three layers or “tunics”: from the lumen to the outside, these are the endothelium (a thin layer of endothelial cells), which sits on a basal lamina, the sub-endothelial connective tissue, and an internal elastic membrane.
Tunica intima – the innermost layer. Consists, from lumen out, of the endothelium (a thin layer of endothelial cells), which sits on a basal lamina, subendothelial connective tissue, and an internal elastic membrane.
Tunica media – the middle layer. Consists of multiple layers of smooth muscle cells arranged circumferentially, and contains varying amounts of elastic tissue.
Tunica adventitia – the outermost layer. Consists of connective tissue. Varies in thickness, and in collagen and elastin content.
Elastic (conducting) arteries
Elastic arteries include the aorta, pulmonary, common carotid, brachiocephalic, subclavian, and iliac arteries.
The tunica media is the thickest layer, consisting predominantly of sheets of elastic tissue separated by thin layers of collagen fibers and smooth muscle cells.
These vessels are too thick to obtain oxygen and nutrients from their lumen by diffusion – instead they have their own small arteries (called the vasa vasorum) present in the tunica adventitia.
Muscular (distributing) arteries
Muscular arteries arise from the elastic arteries and are the most abundant type of artery in the body.
They are characterized by a thick tunica media comprised of concentric layers of smooth muscle cells. The tunica media is bordered by the internal elastic lamina and external elastic lamina. These muscular and elastic components allow the arteries to contract and relax to regulate tissue blood supply.
Small arteries and arterioles (resistance arteries)
Arterioles are distinguished from small arteries by a lumen with a diameter smaller than 300 μm.
The tunica intima is very thin – comprised of endothelium, connective tissue and a thin internal elastic lamina.
The tunica media contains < 6 concentric layers of smooth muscle cells – this enables arterioles to control blood flow to the capillaries.
The tunica adventitia consists of elastin and collagen fibers arranged longitudinally and circumferentially.
Sympathetic nervous system and local changes in the tissue environment regulate their constriction and dilation thereby controlling the blood flow in an area (‘demand and supply’ principle)
Capillaries (exchange vessels)
Capillaries form extensive networks within tissues. There are several types of capillaries, but they all share similar characteristics:
The tunica intima consists of a single layer of endothelial cells.
The tunica media is missing and the tunica adventitia is greatly reduced or absent.
Gases, fluids and molecules are exchanged through their walls, to exchange between tissue and blood.
Three types of capillaries provide different rate of permeability. The majority of capillaries are continuous. Fenestrated capillary walls allow movement of larger molecules across the wall. They are found in the small intestine, to allow nutrient absorption, kidneys, choroid plexus and endocrine organs for blood filtration. Sinusoids are the rarest. The large gaps in the basement membrane and the endothelium allow movement of large molecules and even cells across the wall. They are found in the liver, spleen, bone marrow and lymph nodes.
Venules
Venules connect the capillary bed with veins, and share many structural characteristics with veins:
The tunica intima is very thin – comprised of endothelium, connective tissue and a thin internal elastic lamina.
The tunica media is poorly developed.
The tunica adventitia consists of fibrous connective tissue.
Medium veins
Medium veins are those with a diameter of
1–10 mm.
The tunica intima and tunica media are thinner than in similarly-sized arteries:
The tunica intima comprises a thin layer of endothelial cells.
The tunica media consists of 2 or more layers of circularly arranged smooth muscle. Because of the low luminal pressure, this is sufficient to produce appreciable changes in the radius of the veins and hence in the volume of blood held within them.
The tunica adventitia is the predominant layer, consisting of collagen and elastin fibers, and longitudinally arranged smooth muscle fibers.
Due to the thinner, less resistant vessel wall, veins are distensible and serve as blood reservoirs (~70% of blood is held in veins and venules).
Large muscular veins
Large veins include the vena cavae, splenic, portal, renal, external iliac and mesenteric veins.
The tunica intima comprises a thin layer of endothelial cells.
The tunica media is poorly developed, consisting of smooth muscle with some elastic and collagen fibers.
The tunica adventitia is the broadest layer, comprising bundles of collagen, elastin and smooth muscle fibers. In some veins (such as the vena cavae), the smooth muscle bundles are longitudinally arranged.
The tunica adventitia may also contain vasa vasorum.
all blod vessels have elastin exc caps
Which of the following statement regarding the thoracic wall is FALSE?
The intercostal vein, artery and nerve run in the costal groove between the the external and internal intercostal muscles
The posterior intercostal veins drain into the azygos vein on the right, and the hemiazygos on the left side
The anterior intercostal artery is a branch of the internal thoracic artery
The internal and innermost intercostal muscle are activated during forced/active expiration
Neck muscles attached to ribs are utilised during forced inspiration
The intercostal vein, artery and nerve run in the costal groove between the the external and internal intercostal muscles
THIS IS FALSE
Correct, this statement is false, as the intercostal neurovascular structures run in the costal groove that is bodered by the internal and innermost intercostal muscles
Structures that normally cross the diaphragm through the esophageal hiatus include the…
Posterior vagal trunk
The vagus nerve or cranial nerve X, that is responsible for the innervation of the thoracic, and the majority of abdominal viscera, crosses the diaphragm with the esophagus
