Week 1
Explain what a true rib and a false rib is. (Try remember which ribs fall into which category too)
True rib - Independant rib (1-7)
False rib - floating or connected to the same costal cartilage (8-12)
This is the mediastinal surface of which lung? And name the visible impressions.
Refer to OneNote image
Left lung
- L subclavian artery
- aortic impression
- cardiac impression
Name the borders of the mediastinum
anterior - sternum
superior - thoracic inlet
posterior - thoracic vertebrae
inferior - diaphragm
laterally - lungs
What is a functional end artery vs an anatomical end artery?
Functional end artery: can anastomose to a degree if needed, but quite slowly
Anatomical end artery: single artery supplying a structure and does not anastomose
At what level does the oesophagus pierce the diaphragm?
T10
Name the 3 layers of deep muscles of thoracic wall. Describe the fibre orientation of the two outer layers.
Refer to onenote image
External intercostal - downward + medially (hand in pockets)
Internal intercostal - going upper + medially (hand over chest)
Innermost intercostals - transversus thoracis (ant), innermost intercostals (lat), subcostals (post)
Begins: inferior end of larynx (C5 or C6)
Ends: sternal angle (T4/T5)
Why is the wall of the LV thicker than the wall of the RV?
The left ventricle pumps blood for all the parts and tissues of the body, thus pumping at a higher pressure, whereas the right ventricle only pumps blood to the lungs which require less work (lower pressure).
Name the branches of the right coronary artery (4) and what it supplies (at least 4 things).
SA node branch, R marginal branch, AV node branch, posterior inter-ventricular branch
Supplies:
R atrium
Most of RV part of LV (diaphragmatic surface)
Post 1/3 of IV septum
SA node (60%)
AV node (90%)
Name the branches off the arch of aorta + where they're headed.
Refer to image.
From R to L on diagram:
Left subclavian -> UL
L common carotid -> Head
Brachiocephalic trunk
R common carotid -> head
R subclavian -> UL
Describe rib movement and which ribs are involved.
upper ribs (1-6) "pump handle" -> increase AP diameter
lower ribs (7-10) "bucket handle" -> increase lateral diameter
Nerve supply of each pleura layer and which is pain sensitive and which is pain insensitive>
Parietal pleura is pain sensitive -> phrenic and intercostal
Visceral pleura is pain insensitive -> autonomic nervous system
Describe the layers of pericardium.
Fibrous layer (single)
- fused with tunica adventitia of great vessels
- protects heart
- anchors heart to surrounding structures
Serous layer (double) -> visceral layer + parietal layer
- reflects to become deep layer
Name the branches of the left coronary artery (3), what it supplies (at least 4 things), and what important structure is innervated by one of its branches.
Branches: left marginal branch, anterior interventricular branch (Left anterior descending), circumflex branch
Supplies: L atrium, most of LV, part of RV, anterior 2/3 of IV septum, SA node (40%), AV node (10%)
The LAD supplies the AV bundle
Describe the course of the thoracic duct.
1. Begins at cisterna chyli
2. crosses posterior mediastinum and crosses left
3. ends where left brachiocephalic vein begins
Describe the arterial supply to the chest wall.
HINT: Three major arteries which have branches coming off them
Refer to onenote image
Subclavian artery:
-> axillary artery
-> Internal thoracic -> anterior intercostals
Thoracic aorta -> posterior intercostals (anastomose with anterior)
Axillary artery
-> superior thoracic
-> lateral thoracic
Describe the function of pulmonary veins and pulmonary arteries AND which is intrasegmental/intersegmental AND why one would be intersegmental
Pulmonary arteries -> taking blood away from heart (it is deoxygenated as it hasn't reached alveoli)
Pulmonary veins -> taking blood to heart (it has oxygen as it has reached alveoli)
Pulmonary veins are intersegmental (in between bronchi segments) for efficiency
refer to image
Describe what the valves are doing during blood flow
HINT: tricuspid, bicuspid (mitral), pulmonic and aortic.
1. When atrium contracts, tricuspid (R) and mitral/bicuspid (L) valves open and allow blood flow to ventricles
2. When ventricles contract, tricuspid and mitral valves are forced shut, but pulmonic and aortic valves are forced open by ventricular pressure
3. Blood leaving ventricles is prevented from flowing backwards by the seal of cusps
Explain the conduction system of the heart.
1. Electrical impulses from SA node (pacemaker of the heart) spread through both atria, causing them to contract
2. AV node is the electrical gateway to the ventricles, and delays the passage of electrical impulses to the ventricles
- This is important so that all blood has been ejected from atrium into ventricles before the ventricles contract
3. AV node receives the impulse from SA node and sends this to AV bundle/bundle of His
4. Bundle is divided into L and R branches which direct impulses to apex of heart
5. Impulses are then passed on to Purkinje fibres which travel upward and spread through ventricle myocardium
Contents of the superior mediastinum (there are 9 but name at least 6)
- SVC + tributaries
- Trachea (lower end)
- oesophagus (behind trachea)
- arch of aorta
- left vagus nerve + left recurrent laryngeal nerve
- thoracic duct + lymph nodes
- phrenic nerve
- cardiac plexus
- pre-vertebral muscles
Describe nerve supply to the chest wall and explain where you inject a needle and why?
HINT: ventral and dorsal rami, sympathetic trunk
ventral rami -> 11 pairs of intercostal nerves (in intercostal space) and 1 pair of subcostal nerves (T12 - because it is under 12th rib)
branches off the intercostal nerves:
collateral branch (runs on sup border of inf rib of intercostal space - inject here to avoid intercostal bundle)
lateral + anterior cutaneous branch (T1-T12 segmental skin innervation)
Sympathetic trunk:
Part of the ANS -> supplies visceral structures
sits on either side of vertebral bodies
paired organs = r sup r, L sup left
unpaired organs = bilateral sup = pain to midline
Describe the lymphatic system around the lungs
plexus (lymphatic vessels which drains tissue) -> tracheobronchial nodes (filters fluid) -> drains into bronchomediastinal trunk -> right lymphatic duct or thoracic duct -> venous system
Explain blood flow through heart (Right and Left side)
Right:
1. blood comes in from SVC, IVC, and CS into the RA
2. blood flows through R atrioventricular orifice to RV.
3. Blood enters RV through atrioventricular valve and heads up through fundibulum through pulmonary valve to lungs
Left:
1. Blood returns from 4 pulmonary veins (from lungs) into LA
2. Blood flows through L AV orifice to LV
3. Blood comes into LV from L AV valve
4. Blood heads out via aorta (aorta valve)
note -> atrium-orifice & ventricle-valve
Refer to image
Link the conduction system of the heart to ECG reading.
Refer to image if need.
P wave - when SA node fires and the electrical impulses cause the atria to depolarise
--- atrial systole (contraction) starts about 100 ms after P wave begins ---
PQ segment - time it takes for signal to travel from SA node to AV node
QRS complex - firing of AV node + represents ventricular depolarisation
Q wave - depolarisation of IV septum
R wave - depolarisation of main mass of ventricles
S wave - last phase of ventricular depolarisation at base of heart
--- atrial repolarisation also happens during this time but the signal is obscured from large QRX complex ---
ST segment - plateau in myocardial action potential (when the ventricles contract and pump blood)
T wave - represents ventricular repolarisation (which is right before ventricular diastole/relaxation)
Correctly draw the plane of louis tic tac toe diagram
Refer to image.