Dissection SSC

Question 1

The muscles in the chest wall and there nerve innervation

Answer 1

Pec Major - medial and lateral pectoral nerves C5-T1

• Lateral pectoral nerve innervates the clavicular head (C5 and C6).
• Medial pectoral nerve innervates the sternal head (C7, C8 and T1).

pec minor - pectoral nerves C5-T1 (specifcially medial pectoral nerves C8-T1- innervates both as it passess through pec minor)

Serratus anterior - Long thoracic nerve C5-C7

External intercostal muscles - - Intercostal nerves T2-T11

rectus abdominis - Intercostal and subcostal nerves T7-T12

Question 2

Lung anatomy

Answer 2

on the right

• superior
• middle
• inferior
• horizontal and oblique between

on the left

• superior and inferior
• oblique between

anterior

• on the right superior and middle
• on the left superior and inferior

Question 3

structures in the hilum

Answer 3

• pulmonary artery
• pulmonary vein
• bronchus

Question 4

What are the two heads of pec major

Answer 4

• clavicular and sternal head

Question 5

describe the brachial plexus

Answer 5

• roots are C5 C6 C7 C8 T1
• trunks are superior, middle, inferior
• cords are lateral, posterior and medial
• lateral and medial pectoral nerves come of the lateral and medial cord
• then the branches are
• musculotaneous -C5, C6, C7.
• axillary - C5 and C6.
• medial - C6 – T1
• radial - C5-T1
• ulnar - C8 -T1

Question 6

when does the subclavian become the axillary vein

Answer 6

subclavain continues from the axillary vein and becomes the axillary vein at the outer border of the 1st rib

Question 7

name the true and false floating ribs

Answer 7

1-7 true
8-10 false
11 and 12 floatig

Question 8

what is the relation of the phrenic nerve and the brachial plexus to the anterior scalene muscle

Answer 8

the phrenic nerve is on the anterior surface

brachial plexus is behind it

Question 9

where is the suprasternal notch found

Answer 9

T2

Question 10

where is the angle between the xiphoid process and sternum

Answer 10

T9

Question 11

where is the angle of louis

Answer 11

T4

Question 12

what innervates the SCM

Answer 12

CN XI - spinal accessory nerve

Question 13

where is the subclavius

Answer 13

• Subclavius (between 1st rib and clavicle) = Subclavian nerve.

Question 14

describe how the branches of the vessels change name in the arm

Answer 14

• The subclavian vessels become known as the axillary vessels after passing over the 1st rib.
• The axillary artery and vein passes under pectoralis minor, but before this the thoracoacromial branch is given off.
• After passing over teres major, the axillary vessels become known as the brachial vessels.

Question 15

where does the internal thoracic artery branch from

Answer 15

• The internal thoracic artery branches from the subclavian arteries

Question 16

what does the intenral throacic artery supply

Answer 16

• The internal thoracic artery is also known as the mammary artery, as it supplies the breasts in addition to the anterior chest wall.

Question 17

what epigastric artery does the internal thoracic artery become

Answer 17

• The internal thoracic arteries form the superior epigastric artery.
• The internal thoracic vein arises from the superior epigastric vein.

Question 18

where does the internal thoracic artery drain

Answer 18

brachiocephalic veins

Question 19

what are the 1st choice for coronary artery bypass grafts

Answer 19

• internal thoracic arteries

Question 20

where does most of the bodies lymphatic drain into and what does it contain

Answer 20

• Most of the body’s lymphatics drain into the thoracic duct.
• The thoracic duct is about 40cm long, and contains chyle.
• Chyle is a mixture of emulsified fats and lymph fluid.

Question 21

where is the cistera chyli found

Answer 21

• The cisterna chyli is a dilated sac found at L1/2, forming the beginning of the thoracic duct.

Question 22

what is the clinical signfiicance of the throacic duct

Answer 22

• The clinical significance of the thoracic duct is the presence of Virchow’s node, a lymph node in the left supraclavicular space indicating the first sign of malignancy

Question 23

where is the other part of the bodies lymph drainage

Answer 23

• The only regions NOT drained by the thoracic duct are the right side of the head/neck and the right arm.
• These regions are drained by the right lymphatic duct.

Question 24

what does the thoracic duct cross

Answer 24

• The thoracic duct cross the azygos and hemiazygos veins anteriorly.

Question 25

what is the safe zone

Answer 25

* The anatomical safe zone is a region on the lateral chest wall, that is deemed safe to enter tubing into the thoracic cage for drainage. * It is found in the 5th intercostal space between T4 and T5.

Question 26

what are the borders of the safe zone

Answer 26

- Anterior = Lateral pectoralis major. - Posterior = Anterior boarder of latissimus dorsi. - Superior = Apex below the axilla. - Inferior = Horizontal line corresponding to the height of the nipples.

Question 27

what are the external intercostal muscles used as

Answer 27

- Used for forced and quiet inhalation. | - Fibres run downwards and forwards (as if putting hands in pockets).

Question 28

what are the internal intercostal muscles used as

Answer 28

- Used for forced exhalation (as quiet expiration is passive). - Fibres run downwards and backwards.

Question 29

where is the neurovascular bundle in terms of intercostal muscels

Answer 29

• The neurovascular bundle is between the internal and innermost layers.

Question 30

what are the roots of the intercostal nerves

Answer 30

T1-T11

Question 31

WHERE DOES THE AZYGOUS VEIN RUN

Answer 31

* A vein running up the vertebral column on the right side between the SVC and IVC. * It drains into the superior vena cava.

Question 32

Where does the hemiazygous run and where does it cross into the azygous

Answer 32

* The hemiazygos veins run in the left side and drains into the azygous vein. * The hemiazygos and accessory hemiazygos cross to the azygos at T8 and T9.

Question 33

describe the pathway of the phrenic nerve

Answer 33

- The phrenic nerve descends with the internal jugular vein. - It descends and passes over the anterior scalene muscle. - The left phrenic passes over the subclavian artery, but under the subclavian vein. - But the right phrenic nerve passes over the brachiocephalic artery, and under the brachiocephalic vein. - The right phrenic then passes anterior to the lung root and over the RA, piercing the diaphragm. - The left phrenic nerve passes over the pericardium and inserts into the diaphragm.

Question 34

what is the difference between the position of the phrenic and vagus nerve

Answer 34

• The phrenic nerves are more lateral and anterior than the vagus nerves.

Question 35

describe the pathway of the vagus nerve

Answer 35

- The vagus nerves leave the skull via the jugular foramen. - Both travel between the internal carotid artery and internal jugular vein while passing through the carotid sheath. - The right vagus nerve passes over the right subclavian artery, but posterior to the superior vena cava. - It passes posterior to the right main bronchus before it innervates the organs. - The left vagus nerve enters the thorax between the left common carotid artery and left subclavian artery. - It passes over the aortic arch and posterior to the left main bronchus. - Both vagus nerves enter the abdomen through the oesophageal hiatus.

Question 36

describe the nerve supply of the viseral and parietal pleura

Answer 36

• The visceral pleura (autonomic nerves), covers the lung, while the parietal pleura (somatic nerves) covers the inner thoracic wall.

Question 37

what happens if fluid enters the pleural cavity

Answer 37

have a pneumothorax

Question 38

how many bronchopulmonary segements are there

Answer 38

• There are 10 bronchopulmonary segments on the right lung, and 8-9 on the left lung

Question 39

what are the bronchopulmonary segemnets

Answer 39

• A bronchopulmonary segment is a portion of the lung supplied by the same bronchus and arteries.

Question 40

describe the thymus

Answer 40

* A primary lymphoid organ of the immune system, where T cells mature. * It is found in the anterior mediastinum, anterior to the heart but posterior to the sternum. * The thymus begins to atrophy by the early teens.

Question 41

how many pulmonary veins carry blood back to the left atrium in the heart

Answer 41

4

Question 42

describe the pericardium

Answer 42

* The outer fibrous pericardium is made of dense CT that helps protect the heart. * The serous pericardium is divided into visceral and parietal layers. * In between these 2 layers is the pericardial cavity, filled with pericardial fluid.

Question 43

what is the pericardium innervated by

Answer 43

• The pericardium is innervated by the phrenic nerves, with the right passing lateral to it while the left passes over it.

Question 44

what is cardiac tamponade

Answer 44

* Fluid may collect within the pericardial cavity in pericardial effusion. * This can result in cardiac tamponade; compression of the heart within the pericardial sac. * Because the pericardium has a fibrous outer layer, it prevents expansion when the fluid collects. * This means that the pressure inside the sac is increased, and so the heart is compressed

Question 45

what can cardiac tamponade result in

Answer 45

• Cardiac tamponade may result in cardiogenic shock (inadequate circulation of blood), presenting as shortness of breath, light-headedness and a cough.

Question 46

How do you treat cardiac tamponade

Answer 46

• Cardiac tamponade is treated by draining the fluid from the sac; pericardiocentesis.

Question 47

what is the transverse pericardial sinus

Answer 47

• The transverse pericardial sinus is found anterior to the SVC, and posterior to the ascending aorta and pulmonary trunk.

Question 48

what are the 5 main veings that drain into the coronary sinus

Answer 48

- Great cardiac vein (anterior ventricular sulcus). - Middle cardiac vein (posterior ventricular sulcus). - Small cardiac vein (right atrioventricular sinus). - Posterior vein of the LV. - Oblique vein of the LA.

Question 49

what is the coronary sinus

Answer 49

* The coronary sinus is a collection of veins that join together to collect blood from the heart muscle (myocardium). * It delivers deoxygenated blood to the RA, at the coronary sinus orifice.

Question 50

where is the coronary sinus found

Answer 50

RA, at the coronary sinus orifice. | • The orifice is found between the inferior vena cava and the tricuspid valve

Question 51

describe the chest leads on an ECG and what part of the heart they look at

Answer 51

- V1 and V2 = Septal heart. - V3 and V4 = Anterior heart. - V5 and V6 = Lateral heart.

Question 52

what is the symapthetic trunk

Answer 52

• The sympathetic trunk is a collection of nerve fibres that runs from ribs 2-9.

Question 53

what is the differnece between preganglia and paraganglia fibres

Answer 53

• It transmits preganglionic fibres of the sympathetic NS to ascend to spinal levels >T1, and also spinal levels

Question 54

what is ramus used for

Answer 54

• Ramus communications are used to connect spinal nerves to the sympathetic trunk ganglia.

Question 55

what is the difference between white and grey ramus

Answer 55

* White rami communicans transport preganglionic fibres to the sympathetic trunk from T12 – L2, they appear white as they are more myelinated than grey rami. * Grey ramus communicans transport postganglionic sympathetic fibres from the sympathetic trunk, they appear grey as they are less than myelinated. * The white rami are found more lateral than the grey rami.

Question 56

name the splanchnic nerves and there nerve levels

Answer 56

• Greater splanchnic nerve: - T5-T9. - Synapses in the coeliac ganglion and innervates the foregut. • Lesser splanchnic nerve: - T9-T11. - Synapses in the SMA ganglion and innervates the midgut. • Least splanchnic nerve: - T12. - Synapses in the IMA ganglion and innervates the hindgut.

Question 57

what are the right and left crura

Answer 57

• The left and right crura are tendons that blend with the anterior longitudinal ligament of the vertebral column.

Question 58

describe each of the hiatus of the diaphrgam

Answer 58

* The IVC passes through the caval opening at T8. * The oesophagus passes through the diaphragm at T10 with the vagus nerve. * The abdominal aorta passes through the diaphragm a T12, but rather than piercing through it blends between the 2 crura.