Anatomy: The Thorax

Front 1

Three parts of the sternum (and three structures of clinical importance)

Back 1

1. manubrium
2. body
3. xiphoid cartilage

clinically relevant:
1. suprasternal notch (border of manubrium)
2. sternal angle (fromed by manubriosternal joint)
3. xiphisternum (at the subcostal angle)

Front 2

Articulations at the head of each rib:

Back 2

a) upper and lower articular facets covered w/ cartilage for articulation w the vertebra above and the one at the same (corresponding) level
b)interarticular crest (not covered with cartilage) is between the upper and lower facets

Front 3

Articulations at the tubercle of each rib

Back 3

the tubercle has got an articular facet (covered w/ cartilage) articulating w/ the transverse process of the vertebra; and a non articulating tough portion.

Front 4

Directions of ribs from posterior to anterior:

Back 4

LIP: lateral, inferior, posterior
ALI: anterior, lateral, Inferior
AIM: anterior, inferior, medial

Front 5

Costal Margin:

Back 5

cartilage off the ribs (7-12) and the 12th rib contribute to the formation of the costal margin

Front 6

Costal Groove:

Back 6

runs along the inferior border of all the ribs (except the first and the last) lodging the intercostal neurovascular bundle:
VAN (from superior to inferior)

Front 7

Unique aspects of the 1st rib:

Back 7

-No costal groove or angle
-it has the most curved body
-it is the shortest rib
-it has superior and inferior surfaces instead of medial and lateral
-has landmarks: scalene crest and tubercle: anterior groove for subclavian vein and posterior groove for subclavian artery and T1 ventral ramus... the scalene muscle is attached to the tubercle

Front 8

Unique aspects of the 12th rib:

Back 8

-one of two floating ribs (the other is the 11th)
-only a single facet (instead of 2) on its head to articulate with the body of the 12th thoracic vertebra
-it has no neck, tubercle, angle, nor a groove
-its cartilage is short and pointed: ending between abdominal muscles

Front 9

Boundaries of the thoracic inlet:

Back 9

-1st thoracic vertebra
-1st rib
-manubrium

Front 10

Boundaries of the thoracic outlet:

Back 10

-the xipohoid cartilage
-costal margin
-T12

Front 11

Ribs:
1. longest:
2. farthest:
3. obliquest:

Back 11

longest = 7th
farthest = 8th
obliquest = 9th

Front 12

costochondral junction

Back 12

each rib unites with its costal cartilage at a costochondral junction

Front 13

True Ribs

Back 13

ribs 2-7

their costal cartilage joins the sternum directly at a sternocostal joint: all of them are synovial, except the first which is cartilaginous

Front 14

False Ribs

Back 14

ribs 8-10

their costal cartilage meets the costal cartilage of the rib above it to be indirectly connected to the sternum

Front 15

Floating Ribs

Back 15

ribs 11 and 12

The costal cartilage of these ribs are free (neither directly nor indirectly attached to the sternum)

Front 16

Sternal Angle

Back 16

The costal cartilage of the 2nd rib meets the sternum at the sternal angle: very useful anatomical landmark (for dividing mediastinum, numbering ribs and intercostal space to locate signs and symptoms in clinical examination)

Front 17

joints between the heads of rubs and the body of the vertebra

Back 17

-the head of each rib (2nd to 9th) articulates w/ the body of the corresponding vertebra, as well as the body of the one above: the inferior facet of the head articulates with the body of the corresponding vertebra, and the superior facet articulates with the body of the vertebra above.
-a non-articular crest extends between the two facets on the head of each rib.

*the rest of the ribs only have one facet to articulate with the body of the vertebra at the corresponding level

*all of these joints are synovial

Front 18

Intra-articular ligament

Back 18

inside the joint (between head of rib and body of vertebra).

helps fasten the head to the intervertebral disc

Front 19

Radiate ligament

Back 19

outside the joint (between the head of the rib and body of vertebra)

attached to the anterior surface of each head

it also helps fasten the head to the intervertebral disc, the body of the vertebra above, and that of the one below

Front 20

The costotransverse joints

Back 20

*synovial

from the 1st to the 10th rub: each has a tubercle which is formed of 2 areas: a medial smooth area, and a lateral rough one:

1. smooth (articular): for articulation w/ the transverse process of the corresponding vertebra

2. rough (non-articular): for the attachment of the lateral cosotransverse ligament (between it and the top of the transverse process of the corresponding vertebra)

Front 21

Costotransverse Ligament:

Back 21

between the superior aspect of the neck of the rib and the transverse process of the vertebra at the same level.

Front 22

superior costotrasnverse ligament (aka suspensory ligament)

Back 22

between the superior aspect of the neck of the rib and the transverse process of the vertebra just above its level

Front 23

External Intercostals:

Back 23

-from: lower border of rib above
-fibers run downward and medially to upper border of rib below

(think of putting your hands in your pockets.. this is the direction of external intercostals)

Front 24

Internal Intercostals:

Back 24

-from: upper border of rib below
-fibers run upward and medially to lower border of rib above
-deep to external intercostal muscle

Front 25

Innermost Intercostals:

Back 25

-direction of fibers is similar to internal intercostal muscle
-deep to internal intercostal

Front 26

Inspiration:

Back 26

active movement served mostly by the diaphragm
-aided mainly by the external intercostal muscles (and the medial part of the internal intercostal muscles- the interchondral part of the internal intercostal).

Front 27

Expiration:

Back 27

-at rest, expiration is passive (result of the relaxation of the diaphragm and the external intercostals allowing the recoil of the lung tissue)

forced and forced controlled expirations (ex. talking, coughing) us internal intercostal muscles.

also during forced expiration the anterolateral muscles of the abdomen contract, pushing the abdominal contents, causing elevation of diaphragm and a decrease in vertical dimension of the thoracic cavity

Front 28

How do we prevent herniation of the lung?

Back 28

internal and innermost intercostal muscles are considered to tighten intercostal spaces during respiration.

Front 29

3 parts of the diaphragm (and their origin and insertions):

Back 29

1. STERNAL:
origin: back of the xiphoid process two short (nearly horizontal) muscular bands
insertion: to the middle of the anterior (convex) border of the central tendon

2. COSTAL
origin: from the inner (deep) surface of the lower 6 cartilages and the adjacent rib
insertion: a continuous insertion along the anterior convex border, and the right and left ends of the central tendon

3. VERTEBRAL
origin: from 3 sites on each side: right and left lateral arcuate ligament (fascia of quadratus lumborum m.), right and left medial arcuate ligament (fascia of psoas m.), the right side of the body of L1-L3 for the right crus, and the left side of the body of L1-L2 for the left crus
insertion: the muscle sheets from the arcuate ligaments, and the crural muscles are inserted into the concave (posterior) border of the central tendon.

Front 30

Which side of the diaphragm is higher? why?

Back 30

The top of the right side of the diaphragm is higher than the left
-right extends to 4th intercostal space
-left extends to the 5th intercostal space

*this is to make room for the liver!

Front 31

What nerve innervates the diaphragm?

Back 31

the phrenic nerve: "C3, 4, 5 keep the diaphragm alive!"

Front 32

3 Major openings in the diaphragm:

Back 32

1. inferior vena cava: passes through the right part of the central tendon at level of T8

2. Esophagus: passes through the muscular part at level of T10

3. Aorta: passes behind diaphragm (between right and left crura) at level of T1

Front 33

Mediastinum

Back 33

tissue separating the the chest region into 2 cavities (left and right)

all thoracic tissues except the lungs are in the mediastinum.

Front 34

Visceral and Parietal Pleura

Back 34

Visceral Pleura: intimately applied to the lungs

Parietal Pleura: intimately applied to the chest wall

between the two there is "potential space"

*the parietal pleura is continuous with the visceral at the REFLECTION of "the pleura covering the mediastinum" onto the covering of the stalk of the lung.

Front 35

Mechanism of inspiration

Back 35

the potential space around the lung is sub-atmospheric (negative).. this keeps the lung inflated at all times.

an increase in the volume of the chest cavity will obviously be accompanied by an increase in the pleural cavity (sac/space) causing further decrease in the pleural (intrapleural) pressure (which is already lower than the atmospheric) increasing the suction of air by the lung.

Front 36

Accessory muscles to inspiration include:

Back 36

-scalene
-sternocleidomastoid
-subclavius
-pectoralis major and minor
-serratus anterior
-serratus posterior inferior
-anterolateral wall of the abdomen

Front 37

The dynamics of respiration: 2 ways to increase chest volume.

Back 37

1. the descent of the diaphragm: the descent of the diaphragm is solely (exclusively) responsible for the increase in the vertical diameter of the chest cavity (it also contributes to the increase in the other 2 diameters)

2. the expansion of the chest wall: the result of the increase in its anteroposterior, and its transverse diameters.

Front 38

Pump-handle mechanism:

Back 38

responsible for the increase of the anteroposterior diameter of the chest.

mainly in the upper ribs (1-6)

Front 39

Bucket-handle mechanism:

Back 39

responsible for the increase in the transverse diameter of the chest

mainly in the lower ribs (7-11)

Front 40

Diaphragmatic inspiration:

Back 40

inspiration using largely or entirely the diaphragm:
old age, men, young children

Front 41

Thoracic inspiration:

Back 41

inspiration using largely or entirely intercostals

a.k.a. "rib inspiration

in pregnancy, esp. the last trimester

(there isn't room for the diaphragm to expand into with the baby there)

Front 42

How does the first rib elevate during inspiration?

Back 42

1st rib is indirectly elevated by sternum (since the others will elevate the sternum) at resting inspiration.

Front 43

Hyperpnoea:

Back 43

hyperventilation: forced inspiration and expiration (deep) and rapid.

-both pump handle and bucket handle
-upper and lower chest
-all diameters are increased

Front 44

Tachypnoea:

Back 44

the main increase is in the anteroposterior diameter in the upper chest
-shallow hyperventilation

use of accessory muscles: scalenus and sternocleidomastoid work on first and second rib and the sternum (ribs 3-6 follow indirectly)

Front 45

Eupnoea and Euventilation:

Back 45

Eupnoea = normal, resting breathing

Euventilation = not hypoventilation nor hyperventilation.. slight increase in all diameters, but main increase is in anteroposterior diameter (in young healthy individuals)... mainly transverse/vertical in older people.

Front 46

Respiration during pregnancy:

Back 46

-thoracic at rest
-tachypnoea at stress (cannot use diaphragm bc pregnant uterus opposes it)
-in deep inspiration the accessory muscles are accompanied only by the intercostals working at maximum: diaphragm is not involved...
-if woman learns to breathe properly during pregnancy, delivery will be much easier and less painful

Front 47

Trachea

Back 47

-formed of successive C-shaped cartilages (open part faced posteriorly and is covered by a membrane) starting at C6 (inferior to cricoid)

-located anterior to esophagus

-bifurcates at level of T4/T5 (about the level of the sternal angle) into a wider and shorter right primary bronchi and a longer and narrower left primary bronchi

Front 48

The 4 surfaces and 3 borders of the lungs:

Back 48

Surfaces:
1. costal: laterally, opposite rib cage
2. diaphragmatic: inferiorly (base of lung)
3. mediastinal: medially, contains the hilum
4. superior: in the neck; apex of the lung

Borders:
1. anterior (sharp)
2. posterior (rounded)
3. inferior (continuous)

Front 49

The fissures of the lungs:

Back 49

1. Each lung has an oblique fissure separating it into superior and inferior lobes

2. the right lung has an additional transverse fissure resulting in a third lobe (middle lobe)

Front 50

2 distinct anatomical landmarks on the left lung:

Back 50

Lingula: tongue-shaped portion on the superior lobe of the left lung

Cardiac Notch: above the lingula

Front 51

HAS and HAD

Back 51

Right Lung = HAS
-Heart
-Arch of azygous vein (superior to hilum)
-Superior vena cava (inferior to hilum)

Left Lung = HAD
-Heart
-Arch of Aorta (superior to hilum)
-Descending Aorta (posterior to hilum)

Front 52

Valves of the heart:

Back 52

atrioventricular valves:
right = tricuspid
left = mitral

aortic valve = preventing regurge from aorta to the left ventricle

pulmonary valve = preventing regurge from the pulmonary trunk to the right ventricle

Front 53

auricles:

Back 53

an appendage on each atrium

Front 54

systole vs. diastole

Back 54

diastole: atrioventricular valves are open to allow blood to go from atriums to ventricles (when ventricles contract the av valves close and the pulmonary valves open)

systole: semilunar (pulmonary valves) open and atrioventricular valves close and blood goes to the rest of body.

Front 55

the CAT of the heart:

Back 55

viewing the heart from the anterior position we can see three major vessels:

from left to right:
superior vena Cava
Aorta
pulmonary Trunk

Front 56

The four borders of the heart:

Back 56

INFERIOR: mainly right ventricle
RIGHT: mainly right atrium
LEFT: mainly the left ventricle
SUPERIOR: CAT of the heart (between the two auricles)

Front 57

Base and three surfaces of the heart

Back 57

BASE: faces posteriorly (not inferiorly). formed by the left atrium
ANTERIOR surface: right ventricle
INFERIOR surface: left ventricle
LEFT surface: left ventricle

Front 58

Pericardial Sac

Back 58

surrounds the heart and creates a "potential space" (called the pericardial cavity)

visceral pericardium= applied directly onto the heart

parietal pericardium= opposes the visceral and creates the potential space

points of reflection = where the visceral and the parietal pericardium are continuous

*note: there is also another layer on top of the parietal pericardium called the "fibrous pericardium" which is continuous with the central tendon

Front 59

cardiac tamponade

Back 59

since the parietal pericardium is fibrous and not very distensible... if there is an injury and bleeding in the potential space it will constrict the heart leading to limited venous return and critically low cardiac output

Front 60

Where is the apex of the heart?

Back 60

it is part of the left ventricle.. it is inferior (not superior)

Front 61

"Crown of the Heart"

Back 61

-Base:
-left atrioventricular groove (anterior part)
-left atrioventricular groove (posterior part) -occupied by coronary sinus
-right atrioventricular groove (anterior part)
-right atrioventricular groove (posterior part)

-Top of crown:
-apex
-anterior intraventricular groove
-posterior intraventricular groove

Front 62

Fossa Ovalis*

Back 62

a special feature on the interatrial septum.

In fetus: oxygenated blood comes from placenta (not from lungs)
-blood flows from right atrium to left atrium
-the little amount of blood that goes through pulmonary artery bypasses and goes to aorta (prevents blood going to lungs unnecessarily)
-this bypass gets blocked after birth
-in some babies this does not close

Front 63

The "infundibulum" and the "vestibule"

Back 63

infundibulum = the commencement of the big arteries in the right ventricle

vestibule = the commencement of the big arteries in the left ventricle

Front 64

which vessels drain into each atrium

Back 64

right atrium:
-superior vena cava
-inferior vena cava
-coronary sinus

left atrium:
-four pulmonary veins

Front 65

SA node

Back 65

in the right atrium, at the root of the superior vena cava

"pacemaker" of the heart

Front 66

Why are all surfaced of the inside of the heart smooth (even the ridged parts)>

Back 66

because if there were rough surfaces there would be an accumulation of bacteria which would lead to thrombus.

Front 67

What is the role of the papillary muscles?

Back 67

papillary muscles arise from the rough part; they are contractile; and their free ends have tendon-like structure (the chordae tendinae) which are inserted onto the free edges of the cusps of the corresponding atrioventricular valve.

failure of the papillary muscle to contract or rupture of the tendinous cords may lead to prolapse of the corresponding valve and blood regurge.

Front 68

septomarginal band

Back 68

*unique to humans

-comes from septum (a partition) to the margin of the heart
-like electrical wires
-takes hearts electrical impulse and has muscle fibers contract to open up “parachute” (tricuspid valve)

Front 69

which is thicker.. left or right ventricular wall?

Back 69

the left ventricular wall is 3X thicker than the right.

Front 70

The right coronary artery supplies:

Back 70

The right side of the heart including:
-SA node
-posterior half of the interventricular septum
-AV node

Front 71

The left coronary artery supplies:

Back 71

The left side of the heart and the and the anterior half of the interventricular septum

Front 72

coronary sinus

Back 72

most of the venous blood of the heart itself is drained by the coronary sinus.

it runs in the posterior part of the left atrioventricular groove

Front 73

Journey of the right coronary artery:

Back 73

travels through the right half of the AV (coronary) groove ending posteriorly giving off a posterior interventricular branch supplying the posterior half of the interventricular septum (and the AV node in 60% of the population)

Front 74

Journey of the left coronary artery:

Back 74

after a journey of less than 2cm it divides under the left auricle into 2 branches:

1. the anterior interventricular that runs in the anterior interventricular groove to supply the anterior part of the interventricular septum

2. circumflex that will take the journey of the left half circle of the AV (coronary) groove to end posteriorly near the posterior interventricular groove

Front 75

ostium

Back 75

the opening of the cusps of the semilunar valves

Front 76

Where do most coronary blocks occur?

Back 76

in the anterior interventricular artery

(if the block were to occur in the right coronary artery, there would be disaster since it supplies the SA node and the AV node-- would lead to chaos)

Front 77

The Venous Network

Back 77

each subclavian vein joins the internal jugular vein of the same side (behind the corresponding sternoclavicular joint) to form the left and the right brachiocephalic veins.

The brachiocephalic veins unite just to the right of the sternal angle forming the superior vena cava, which descends vertically beside the body of the sternum. It runs for a short while before it opens into the right atrium

The azygous vein runs from posterior to anterior over the hilum of the right lung to joint the superior vena cava just before it enters the heart.

The inferior vena cava runs a very short course to join the right atrium

Front 78

The Arterial System

Back 78

The aortic valve at the level T6 marks the commencement of the first part of the thoracic aorta: the ascending aorta, which ends at the level of T4 becoming the arch of the aorta, which curves up in an anteroposterior direction terminating at the level of T4 becoming the descending part of the thoracic aorta that leaves the thorax through the aortic opening between the crura of the diaphragm at T12

-arch of aorta reaches summit at T2.. gives off big arteries: brachiocephalic, right common carotid, and the right subclavian
-four arteries arise from the first part of the subclavian:
superior aspect: vertebral
inferior aspect: internal thoracic
anterior: thyrocervical trunk
posterior: costocervical trunk

*the internal thoracic divides into musculophrenic and superior epigastric

Front 79

The vagus nerve

Back 79

-arises from the brainstem
-leaves cranium through jugular foramen (posterior to internal jugular vein and internal carotid artery)
-in thorax it continues to descend posterior to hilum of lung, the runs with the esophagus, exiting the chest through the esophageal opening of the diaphragm
-each vagus gives off a recurrent (inferior) laryngeal nerve (the left in the chest and the right in the neck)

-superior laryngeal nerve gives motor supply to the pharynx
-vagus is responsible for all the parasympathetic supply in the thorax
-it controls the function of a vast area of the GIT proximal to the splenic flexure of the colon

Front 80

The phrenic nerve

Back 80

-arises in the neck from the cervical plexus (C 3, 4, and 5) and runs on the anterior surface of the anterior scalene
-in the thorax it runs anterior to the hilum of the lung, then it descens on the side of the heart to exit the thorax by piercing the diaphragm (the left close to the apex of the heart whereas the right to the inferior vena cava)

*both right and left phrenic nerves are mixed nerves that carry motor fibers to the thoracic diaphragm, and sensory to both sides of it, and to pericardium.