Structure of the heart Flashcards
Fibrous skeleton aka
Cardiac skeleton
Fibrous skeleton definition
Complex framework of dense collagen rings that connects the annuli of all 4 cardiac valves
Between the 4 annuli are
the right and left trigones as well as the membraneous portions of the interatrial, inter-ventricular and atrioventricular septa
(links between rings)
The annuli of the 2 ventricular valves are attached to form a
figure 8
Functions of the fibrous skeleton
- Keeps orifices of valves open
- Prevents distortion of openings
- Attachment for leaflets and cusps
- Attachment for myocardium
- Separate impulses originating from the atria and ventricles
Fibrous skeleton
External surfaces of the heart
Base of the heart
- Fixed posteriorly to the pericardial wall opposite the bodies of the T6-T9 vert. bodies
- Consists of the left atrium
immediately posterior to the base of the heart is
the oesophagus
Apex of the heart location
Located deep to the left 5th IC space
+/- 8cm from the central line
Apex of the heart formed by
formed by the inferolateral part of the left ventricle
Anterior surface of the heart
Aka…
sternocostal surface of the heart
Anterior surface of the heart direction
Directed anteriorly, superiorly and slightly to the left
Anterior surface of the heart Consists of:
Mostly the right ventricle and a part of the right atrium and left ventricle
Diaphragmatic surface
The heart rests on the diaphragmatic surface in its anatomical position which faces inferiorly and lies on the diaphragm.
What forms the diaphragmatic surface
Formed by the left ventricle and a small part of the right ventricle, separated by the posterior inter-ventricular groove
What separates the diaphragmatic surface from the base of the heart
the coronary sinus
R and L pulmonary surfaces
- Are broad and convex
- They face the lungs
L pulmonary surface is formed by the
left ventricle
Right pulmonary surface is formed by the
right atrium
Right border of the heart
Formed by the RA
- From the SVC to the IVC
Inferior border of the heart
Mostly formed by the RV and slightly by the LV
left border of the heart
Formed by LV and slightly by the left auricle
Sup. border of the heart
formed by the R and L atria and the L/R auricle
Forms the transverse pericardial sinus
Sup. border of the heart
Internal partitions that form the 4 chambers of the heart produces grooves on the external surface of the heart
= external sulci/grooves
External sulci/grooves
- Coronary sulci
- anterior interventricular sulci
- posterior interventricular sulci
Coronary sulci AKA
atrioventricular sulci
Coronary sulci
is a groove that circles the heart, making the seperation between the atria and the ventricles
Coronary sulci contents
- right coronary artery
- the small cardiac vein
- coronary sinus
- circumflex branch of the left coronary artery
Anterior and posterior interventricular grooves mark the
separation of the two ventricles
Anterior interventricular groove contents
- anterior interventricular artery
- Great cardiac vein
posterior interventricular groove Location
- on the diaphragmatic surface
posterior interventricular groove contents
- posterior inter ventricular artery
- middle cardiac vein
All the external sulci are ________ with each other, just to the _____ of the _____ of the heart
continuous
right
apex
The area on the lower backside of the heart where the coronary sulcus and posterior inter-ventricular sulcus meet
= cardiac crux/ crux of the heart/ crux cordis
Forms the entire right border of the heart
Right atrium
The right atrium receives O2 poor blood from the systemic circuit via 3 structures:
- SVC
- IVC
- Coronary sinus
ear shaped structure on heart
= oracle
Internally, the right atrium has 2 parts
- The smooth part
- The rough part - has horizontal ridges on it
The rough part of the internal right atrium - has horizontal ridges on it.
what are these ridges?
Pectinate muscles
Internally, the right atrium has 2 parts. The rough and smooth part.
How are they separated?
By a large C shaped ridge
= crista terminalis
Posterior to the end of the crista is a structure/ depression
Fossa ovalus
Fossa ovalus
In the inter-arterial septum, that marks the spot where an opening existed in the foetal heart (foramen ovalus)
Inferiorly and anteriorly, the right atrium opens into the right ventricle, through the
tricuspid valve/ right atrioventricular valve
Atrioventricular valves
LAB RAT
- Left atrium: Bicuspid
- Right atrium: Tricuspid
The right ventricle receives ________ blood from the ______ and pumps it through the __________ which is guarded by the ________ into the pulmonary artery
deoxygenated
RA
pulmonary orifice
pulmonary valve
The right ventricle
Triangular in shape and forms the majority of the anterior border of the heart
Pillars
= Papillary muscles
The RV can be divided into
- Inflow portion
- And an outflow portion
The inflow portion and outflow portion of the RV is separated by a
muscular ridge = Supra-ventricular crest
The interior of the inflow portion of the RV is covered by a series of irregular muscular elevations
= Trabeculae carneae
Trabeculae carneae give the R ventricle sponge like appearance and can be grouped into 3 main types:
Ridges
Bridges
Pillars
Ridges
attach along entire length on one side to form ridges along the interior surface of the R ventricle
Bridges
Attach to the ventricle at both ends, but are free in the middle
Most NB example of bridges in the RV
= moderator band
= septomarginal trabecula
Moderator band/ septomarginal trabecula location
Spans between the interventricular septum and the anterior wall of the RV
Moderator band/ septomarginal trabecula function
Has an important conductive function containing the right bundle branches
Papillary muscles are anchored by their _____ to the _____.
base
ventricle
The apexes of the papillary muscles are attached to
fibrous chords
= Chordae tendineae
The chordae tendineae are attached to
the three tricuspid valve cusps:
Ant. cusp
Septal cusp
Post. cusp
By contracting, the papillary muscles pull on the
chordae tendineae
- to prevent prolapse of the valve leaflets during the ventricular systole
The outflow portion of the RV is the portion
that leads the pulmonary artery
The outflow portion of the RV is the portion is located in the __________ of the ventricle.
superior aspect
superior aspect of the RV
contains the
conus arteriosus
conus arteriosus
= smooth walled part of the outflow portion of the RV that goes into the pulmonary trunk
makes up most of the hearts posterior surface
Left atrium
Left atrium receives _______ blood, returning from the lungs from the ________
O2 rich
2 R and L pulmonary veins
The only part of the left atrium visible anteriorly is its
triangular left oracle
Internally, most of the left atrial wall is _______ with ______ muscles lining the ______.
smooth
pectinate
oracle only
The LA opens into the LV through the
mitral valve/ Left atrioventricular valve/ bicuspid valve
Left atrium
Forms the apex of the heart and dominates the inferior surface of the heart
Left ventricle
the LV pumps blood into the
systemic circulation
like the right ventricle, the LV contains
trabeculae carneae, papillary muscles, chordae tendineae, the cusp of the bicuspid valve
______, the left ventricle opens into the artery of the systemic circulation =
Superiorly
aorta through the aortic valve
LV
4 heart valves divided into 2 kinds
- atrioventricular valves
= Tricuspid and bicuspid
= Mitral and tricuspid - Semi-lunar valves
= pulmonary valves and aortic valves
4 heart valves divided into 2 kinds
- atrioventricular valves
= Tricuspid and bicuspid
= Mitral and tricuspid - Semi-lunar valves
= pulmonary valves and aortic valves
Tricsupid valve located
Between the RA and RV
atrioventricular/ tricuspid valves consist of
3 cusps
- Anterior
- Septal
- Posterior cusp
The mitral/ bicuspid valve is located between the
LA and LV
Mitral/ bicuspid valves consists of
Anterior and posterior cusp
Semilunar valves located
Between the ventricles and outflow vessels
Pulmonary valve located
Between the RV and pulmonary trunk
Pulmonary valve consists of
3 cusps
- Left
- Right
- Anterior
The aortic valve is located
between the LV and the ascending aorta
The aortic valve consists of
3 cusps
- Right - opening of R coronary artery
- Left - opening of L coronary artery
- posterior
The R and L cusps of the aortic valve contain the opening of R and L coronary arteries which
Marks the origin of the left and right coronary arteries
the sides of the leaflets of the cusps of the pulmonary and aortic valves are attached to
The walls of the outflow vessel, which is slightly dilated to form a sinus
the free superior end of the 3 leaflets are thickened
Lunule
the conducting system
generates and transmits the impulses that produce the co-ordinated contractions of the cardiac cycle.
the conducting system consists of
highly specialised conducting fibres for conducting impulses rapidly in the different areas of the heart
The pacemaker of the heart
The sinoatrial node (SA)
SA node location
- anterio-laterally, just deep to the epicardium at the junction of the SVC and the RA, near the superior end near the christa terminalis
SA node location
- anterio-laterally, just deep to the epicardium at the junction of the SVC and the RA, near the superior end near the christa terminalis
The pacemaker of the heart (SA node) functions
Initiates and regulates the impulses of the heart
AV node
Atrioventricular node
- Is a smaller collection of nodal tissue than the SA node
AV node location
- posterio-inferior region of the interatrial septum near the opening of the coronary sinus
The AV node distributes the signal to the ventricles through structures/ bundles
= AV bundle
At the junction of the membraneous and muscular part of the inter-ventricular septum, the AV bundle divides into _____
These branches proceed on each side of the muscular inter ventricular septum, deep to _____ and then ramify into the _______
the right and left bundles.
endocardium
fibres of purkinje
Extrinsic innervation of the heart
Cardiac plexus
the Cardiac plexus is
Autonomic
The cardiac plexus lies on the
anterior surface of the bifurcation of the trachea.
The cardiac plexus is divided into
a superficial and deep portion
The cardiac plexus is formed by
Sympathetic fibres:
- T1-T5/6
- Stimulates SA node
Parasympathetic fibres:
- Vagus nerves
- Inhibits SA node
