Anatomy Flashcards
What is the function of arteries, capillaries and veins?
Arteries = take blood away from the heart Capillaries = exchange nutrients Veins = collect and return blood to heart
What is the function of the lymphatics?
Drain excess extracellular fluid from tissues - blood goes into tissues and plasma leaks out of capillaries into ECF - lymphatic channels return this ‘lymph’ to the venous circulation
What splits into the right and left pulmonary artery?
Pulmonary trunk
Where does the inferior mediastinum begin and what is it split into?
T4 - sternal angle
Anterior, middle and posterior
What is contained within the middle mediastinum?
Heart, origins of the great vessels
Where is the mediastinum found?
Between the 2 pleural cavities
What is the function of the azygos vein?
Transports deoxygenated blood from the posterior walls of the thorax and abdomen into the superior vena cava - it enters the vena cava at T4
What does the heart sit on top of?
The diaphragm
What are the 3 parts to the aorta and what is their vertebral levels?
Ascending Aortic arch (begins and ends at T4) Descending (descends from T4 downwards - thoracic then abdominal aorta)
What are the two main circulations?
Pulmonary and systemic
What vertebral level does the pulmonary trunk split?
T4
How many vessels enter the LA posteriorly?
2 left and 2 right pulmonary veins
What drains into the RA?
Superior and inferior vena cava (one single channel)
Does the right side of the heart face the front or back?
Right side of the heart faces the front and left faces the back
What are the coronary arteries?
Surround the heart on the surface (pericardium) and dive into the myocardium and feed it with oxygenated blood
What are the three branches that come of the aortic arch?
Brachiocephalic trunk - right subclavian artery and right common carotid artery
Left common carotid
Left subclavian artery
What does ‘common’ mean?
That its going to split - e.g. common carotid splits into external and internal carotid artery (the external carotid supplies the face and the internal carotid supplies the brain), common illiac splits into internal and external illiac artery (external illiac goes onto form the femoral artery)
What lies at the base (back) of the heart?
LA (and the LV)
Where does the apex beat lie?
Mid-clavicular line, 5th intercostal space (just below nipples)
What chamber makes up the apex?
LV
Where does the trachea bifurcate?
T4
In a cross section through the chest, what will you find?
The thoracic cavity contains principally two pleural cavities with, between them, the mediastinum
What chamber is most anterior in a cross section of the thorax?
RV
What chamber is most posterior in a cross section of the thorax?
LA
what way does the apex point in a cross section of the thorax?
Into the left lung (top right hand corner)
Where is the RA located?
It is the most right part of the heart
What structures sit behind the LA?
The LA is entirely posterior
Oesophagus
Descending aorta
Azygos vein
Where is the thymus located?
Just below the sternum
When lying down, what vertebral levels does the heart lie between?
T5-T8
What is located in the anterior mediastinum?
Sternum and costal cartilages 4-7
Anterior edges of lungs and pleura
Thymic remnants
Internal thoracic vessels
What is located in the posterior mediastinum?
Oesophagus Descending aorta Thoracic vertebrae 5-8 (middle as there is 12) Sympathetic chain Azygos vein
What is located laterally to the heart?
Lungs
Phrenic nerve
What is located inferiorly to the heart?
Central tendon of diaphragm
What is located in the superior mediastinum?
Trachea Oesophagus Vagus and phrenic nerve SVC Left and right brachiocephalic veins (form left and right subclavian veins) Internal jugular vein Common carotid artery
What are the layers of the heart from inside to outside?
Endocardium Myocardium Epicardium (visceral layer of serous pericardium) Pericardial cavity Parietal layer of serous pericardium Fibrous pericardium
What is another name for the epicardium?
Pericardium
What is the endocardium?
Simple squamous epithelium sitting on a basement membrane, sitting on connective tissue
What is the myocardium made up of?
Cardiac muscle
What is the epicardium?
Outer layer of the heart wall
Simple squamous epithelium (outermost layer) + BM + connective tissue
What forms the heart valves and lines the heart chambers?
Endocardium
What are myocytes connected by?
Intercalated discs
What is the thickest layer of the heart wall?
Myocardium
What is a functional syncytium?
All the cells function as a unit
What is the most outer layer of the heart?
Fibrous pericardium
What is the fibrous pericardium fused with?
The central tendon of the diaphragm
What is the function of the fibrous pericardium?
Holds the heart in place and protects the heart against sudden overfilling
What pierces the fibrous pericardium?
The aorta, pulmonary trunk and the SVC
The tunica adventitia of these vessels becomes fused with the fibrous pericardium
What is the direction of blood flow in the heart controlled by?
Valves - they work passively
What is located on the right border of the heart?
Right atrium
What is located on the inferior border of the heart?
Right and left ventricle
What is the function of the chordae tendineae and papillary muscles?
Prevent valve failure (prevents inverting)
What are some clinically important valve scenarios?
Abnormalities - incompetence/stenosis
Infection (bacterial endocarditis)
What valve is bicuspid?
Mitral valve (LA -> LV)
2 cusps =
2 papillary muscles and 2 sets of chordae tendinae
What are the types of atrio-ventricular valves?
Tricuspid and bicuspid valves
What are the semi-lunar valves?
Aortic and pulmonary valves
What is the fibrous cardiac skeleton?
Anchors the valves if the heart - consists of four fibrous rings each surrounding one of the valves
What is the function of the fibrous cardiac skeleton?
Provides and semi-rigid support for the valve leaflets
What is the fibrous cardiac skeleton made up of and where does it lie?
Dense connective tissue
The plane between the atria and the ventricles
What arises from the right aortic sinus?
Right coronary artery
What arises from the middle aortic sinus?
Left coronary artery
Why are the coronary arteries only perfused in diastole?
Because in systole, aortic sinuses are shielded by aortic valve cusps
Where are the coronary arteries located?
In the epicardium
What happens if a coronary artery is blocked?
Heart attack
What does the right coronary artery split into?
Right marginal artery
Posterior descending artery
What does the left coronary artery split into?
Left anterior descending (or inter-ventricular) artery
Left marginal artery
Left circumflex artery
Whats different about the right and left coronary arteries?
The left coronary artery splits into 2 and the right just stays as 1
What is an important function of the serous pericardium?
Secretes fluid into the pericardial space - lubricant which allows the heart to move (i.e. in diastole allows the heart to stretch)
What are the two types of arteries?
Elastic artery - lots of elastic fibres
Muscular artery - more smooth muscle
What do arterioles contain and why is this important to them?
Smooth muscle - this allows them to expand and contract to control blood flow to capillary bed
What is the order, starting from the aorta, back round to the VC?
Aorta Arteries Arterioles Capillaries Venules Veins Vena cava
What are the the layers of an artery wall?
Tunica intima Tunica media Tunica adventitia (externa)
What is the tunica intima made up of?
Epithelium (simple squamous) + BM + connective tissue
What is the tunica media made up of?
Smooth muscle
Elastic tissue
What is the tunica externa made up of?
Fibrous connective tissue
What are some differences between arteries and veins?
Arteries have a smaller diameter than accompanying vein
Arteries have a thicker wall than accompanying vein
Comparing arteries to capillaries, which has the greater individual diameter? which has the greatest total cross-sectional area?
Arteries
Capillaries
What are examples of elastic arteries in the body?
Aorta
Common carotid arteries
Pulmonary artery
Subclavian arteries
What are examples of muscular arteries in the body?
Coronary arteries
Radial arteries
Femoral arteries
what is the function of elastic arteries?
Expand and contract to push blood
What is the function of muscular arteries?
They control the distribution of blood to different regions
What is the mechanism by which elastic arteries work?
Pressure reservoir
Stretched during systole
During diastole the heart relaxes -> pressure falls, the artery recoils thereby maintaining pressure on the blood
What is the recoil and stretchability due to?
The extensive amounts of elastic fibres in the tunica media in the form of layers = laminae
Where do the elastic fibres come from?
They are secreted by the smooth muscle cells
How do we identify an elastic artery?
The tunica media will be completely blue/purple - this is due to the presence of elastic fibres
OSPE question - why is this an elastic artery?
The very high amount of elastic fibres in the tunica media
What does the tunica media contain in muscular arteries?
Thick tunica media contains smooth muscle cells
Is there any elastic laminae between muscle cells in the tunica media?
No
Do you have any elastic fibres in muscular artery walls?
Yes, you have an internal and external elastic lamina
What are the elastic fibres in muscular arteries wall?
Elastic fibres are concentrated in 2 well defined sheets called:
- The internal elastic lamina (IEL) just under the epithelium (surrounding lumen)
- The thin external/outer elastic lamina (OEL) between the tunica media and the tunica adventitia
How do we tell a muscular artery from an elastic artery?
In a muscular artery the media is pink and the internal and external elastic is blue (on surface and mid-way down image - i.e. there is not elastic fibres everywhere)
What kind of epithelium is the endocardium, epicardium and the tunica intima?
Simple squamous
What makes up the tunica adventitia?
Fibrous connective tissue
What is the relationship between elastic and muscular arteries?
Elastic arteries include the largest arteries in the body, those closest to the heart, and give rise to the smaller muscular arteries. The pulmonary arteries, the aorta, and it’s branches together comprise the body’s system of elastic arteries.
What do the small muscular arteries become?
Arterioles
Do arterioles have smooth muscle?
1-2 layers in tunica media, no tunica adventitia
What constricts and dilates arterioles?
Rich sympathetic innervation - causes vasoconstriction
What is the importance of sympathetic innervation of arterioles?
Controls blood flow to capillaries beds (local) and controls blood pressure (systemic) - resistance vessels (TPR)
Why are capillaries important?
Main exchange site for nutrients, gases = therefore, very thin walled
What is a capillary wall made up of?
Tunica intima only - endothelium on BM (endothelial cells - 1 cell thick)
What are pericytes?
Incomplete layer of cells surrounding BM - have contractile properties which help control flow of blood in the capillaries
Is blood pressure in capillaries low or high?
Low
What are the three types of capillaries?
Continuous
Fenestrated
Discontinuous
What are the differences between the three types of capillaries?
Continuous - complete basal lamina and continuous endothelial lining
Fenestrated - complete basal lamina and fenestrated endothelial lining
Discontinuous - incomplete basal lamina and fenestrated endothelial lining
How would you identify a continuous capillary and where in the body would you find it?
Wall is solid surrounding the lumen, selective transport mechanisms (can control what is exchanged), e.g. in muscle
How would you identify a fenestrated capillary and where in the body would you find it?
Bumpy wall surrounding lumen and found in e.g. endocrine glands, kidney renal corpuscle
How would you identify a discontinuous capillary and where in the body would you find it?
See clear gaps in the wall surrounding the lumen, allows free passage of fluid and cells, found in e.g. liver, spleen, bone marrow
What are sinusoids?
Large diameter discontinuous capillaries and they are found where a large amount of exchange takes place - e.g. liver and some endocrine glands
What are AV shunts and how are the performed?
Bypasses capillary beds e.g. in skin for thermoregulation
Pre-capillary sphincters are at the start of the capillary from the arterioles and they can shut down the capillary - increase/decrease blood flow through it
How do we identify veins on histology?
Their walls are all squiggly
Tunica intima is thin, tunica media is very thin or absent and the tunica adventitia - collagenous tissue
What are valves made of?
Endothelial projections into the the lumen (to prevent the back flow of blood)
What is the difference between superficial and deep veins?
Superficial are thick walled with no surrounding support
Deep veins are thin walled with surrounding support from deep fascia and muscles - they run next to major arteries e.g. femoral artery and vein
What is oedema caused by?
A build up of fluid in the tissues
Where are the two major places in the body that lymph drains?
Thoracic duct and right lymphatic duct - drain into venous system at jugular/subclavian region
How do you tell a vein from a lymphatic vessel - histology?
Lymph channel will not contain any RBC
What is the vasa vasorum?
Vessels of the vessels - big blood vessels need little blood vessels to supply them
Does the tunica adventitia have lymphatics?
Yes
Where does the mediastinum lie?
It lies between the right and left pleura, it extends from the sternum in from to the vertebral column behind, and contains all the thoracic organs except the lungs
What is the mediastinum divided into?
Superior
Inferior
What is the inferior mediastinum subdivided into?
Anterior - in front of the pericardium
Middle - pericardium and its contents
Posterior - behind the pericardium
What is the pericardium?
The membrane enclosing the heart, consisting of an outer fibrous layer and an inner double layer of serous membrane
How do we remember what is in the superior mediastinum?
Glandular plane - thymus Venous plane - brachiocephalic vein, SVC Arterial-nervous plane - branches of aortic arch, vagus nerves, phrenic nerves Visceral plane - trachea, oesophagus Lymphatic plane - thoracic duct
What is contained in the anterior mediastinum?
Thymus
Lymph nodes
Fat
What is contained in the posterior mediastinum?
Oesophagus and vagus nerve Azygos vein sympathetic trunk Thoracic duct Descending aorta Splanchnic nerve
What is the inner visceral layer of the serous pericardium called?
Epicardium
Where is the pericardial cavity?
Between the parietal and visceral layers of the serous pericardium - filled with fluid
What is the epicardium composed of?
Epithelial cells and a thin layer of fat and connective tissue
How many serous cavities are there in the body?
3
What are the main identification features of the right atrium?
6! Openings for IVC, SVC Coronary sinus Fossa ovalis (in interatrial septum - depression) Tricuspid valve Right auricle Muscle pectinati
What are the main identification features of the right ventricle?
5! Tricuspid valve (3 cusps, chordae tendinae, papillary muscles) Trabeculae carnea Moderator band Opening for pulmonary trunk Interventricular septum
What are the main identification features of the left atrium?
Openings for - right and left superior and inferior pulmonary veins
Bicuspid mitral valve
Smooth-walled, small chamber, lying wholly postero-superiorly against the oesophagus (immediately behind it is the oesophagus)
Forms base of heart
What is the main identification features of the left ventricle?
Bicuspid (mitral) valve (2 valve cusps, chordae tendineae, papillary muscles)
Trabecular carneae
Opening for aorta
Interventricular septum
Wall 3x as thick as right ventricular wall
Forms apex of the heart
The heart is situated anterior to which vertebrae in the recumbent (lying down) position?
T5-T8
What makes up the right border of the heart?
SVC and right atrium
What makes up the left border of the heart?
Aortic arch and left ventricle
What makes up the anterior surface of the heart?
RA (1/4)
RV (2/4)
LV (1/4)
Heart sits 1/3 to the right of the sternum and 2/3 to the left
What are the main arteries of the trunk and chest wall?
Internal thoracic arteries (2) - gives of anterior intercostal arteries = internal mammary artery
Descending aorta
Where do the internal thoracic arteries originate from?
Subclavian arteries
What are the main veins of the trunk and chest wall?
Internal thoracic veins (2) - receive anterior thoracic veins
Inferior vena cava
Azygos vein
Where do the internal thoracic veins drain into?
Brachiocephalic veins
What is the main lymphatics of the trunk and chest wall?
Thoracic duct
What side of the vertebrae does the azygos vein lie on?
Right
Where does the thoracic duct sit in relation to the azygos vein and the aorta?
In between
What side do the IVC and the SVC lie in comparison to the aorta?
Right hand side - right mediastinum is essentially the venous side
What does subclavian artery arise from?
Aortic arch
When does the subclavian become auxiliary artery?
Lateral border of 1st rib
When does the auxiliary artery become the brachial artery?
Inferior border of the teres major muscle
When does the brachial artery divide?
Cubital fossa - divides into the radial and ulnar artery
What happens regarding arteries in the hand?
Radial and ulnar arteries form palmar arches in pam of hand which give off digital arteries
What is the lateral vein in the arm?
Cephalic vein
What is the medial vein in the arm?
Basilic vein
What connects the basilic vein and the cephalic vein across the cubital fossa?
Median cubital vein
So cephalic vein travels up the limb on the lateral side - where does it drain?
Drains into auxiliary vein below clavicle
So basilic vein travels up the limb on the medial side - what does it become?
Becomes continuous within brachial veins (deep veins accompanying brachial artery)
What do the basilic vein and the cephalic vein become in the hand?
Dorsal venous arch
What does the internal iliac supply?
Genitalia
How do we revise arteries and veins of the legs?
OSPE mock - PowerPoint
What do the veins become in the feet?
Great saphenous vein and the small saphenous combine to give the dorsal venous arch
Where do we palpate pulses?
Common carotid artery Brachial artery Radial artery Femoral artery Popliteal artery Posterior tibial Dorsalis pedis
What does the right coronary artery become?
Right marginal artery
Posterior descending artery
What does the left coronary artery become?
Left anterior descending (or interventricular artery) artery
Left marginal artery
Left circumflex artery
What are the 2 major sulci that contain the branches of the coronary arteries?
Coronary (atrioventricular) sulcus - between atria and ventricles
Interventricular sulcus - between right and left ventricles
What does that RCA arise from?
Right aortic sinus of ascending aorta
What does the LCA arise from?
Left aortic sinus of ascending aorta
Where do the RCA and LCA run?
Coronary (atrioventricular) sulcus
What does the RCA give of the right marginal artery?
Inferior margin of heart
On the posterior surface of the heart what does the RCA become?
Posterior descending artery
Where does the left anterior descending artery lie in?
Inter-ventricular sulcus
Where are the anastomoses of the heart and what do they occur between?
Posterior surface of heart
Anterior and posterior descending arteries
Left circumflex and RCA
Anterior descending =
Anterior inter-ventricular
What does the coronary sinus do?
The coronary sinus drains into the right atrium
What vein lies alongside the anterior interventricualr artery?
Great cardiac vein
What vein lies alongside the posterior interventricular artery
Middle cardiac vein
What vein lies alongside the right marginal artery?
Small cardiac vein
Where do all three drain into?
The coronary sinus
What artery does the coronary sinus lie alongside?
Circumflex artery
Where do the anterior cardiac veins drain?
Directly into the RA
What can the vagus nerve (parasympathetic innervation) do to the heart?
Decreases heart rate
What can sympathetic innervation do to the heart?
Increase heart rate and force of contraction
What controls heart rate? (even though it can be influenced by the ANS)
Pacemaker cells in the SA node
What does the phrenic nerve innervate in the heart?
Innervates the fibrous pericardium and parietal layer of serous pericardium (carries pain sensation)
What does the vagus nerve innervate in the heart?
Innervates heart and visceral layer of serous pericardium (major external force that controls heart rate)
How do the sympathetic fibres innervate the heart?
From the cervical and upper thoracic sympathetic ganglia - innervate heart and visceral layer of serous pericardium
What is the difference between an artery and vein histologically?
Artery has a thick smooth muscular wall and lumen is smaller relative to wall than vein
Vein has much less smooth muscle
What are some features of cardiac muscle histologically?
Branching striated fibres
Central rounded nuclei (mono-nucleic)
Intercalated discs
Is a femoral artery muscular or elastic?
Muscular
What is the difference between muscular and elastic arteries?
Muscular arteries are smaller distributing arteries - they have thick smooth muscle in the wall and very few elastic fibres (they are split into two layers
Elastic arteries are larger conducting arteries receiving blood directly from the heart - they have numerous laminae of dark staining, wavy elastic fibres in wall amongst smooth muscle fibres (they need to contract and force blood through
Examples of elastic arteries?
Aorta and pulmonary arteries
What anatomical features allow arterioles to function as resistance vessels?
They have a relatively narrow lumen and a strong muscular wall
