Slide 1

Thoracic wall

Skeleteon of thoracic wall

Ribs, costal cartilages and interocstal spaces

Thoracic vertebre

Sternum

Thoracic apertures

Superior thoracic aperture

Inferior thoracic aperture

Joints of thoraic wall

Costovertebral joints

Sternocostal joints

Movements of thoracic wall

Muscles of thoracic wall

Fascia of thoracic wall

Nerves of thoracic wall

Typical intercostal nerves

Atypical intercostal nerves

Vasculature of thoracic wall

Arteries of thoracic wall

Veins of thoracic wall

Breasts

Vasculator

Nerves of breast

Surface anatomy

Viscera of thoracic cavity

Pleurae, lungs and trahcobronchial tree

Pleurae

Lungs

Trachobronchial tree

Vasculator of lungs and pleura

Nerves of lungs and plearua

Mediastinum

Superior mediastnum

Inferior mediastnum

Posteiror mediastinum

Anteiror mediastnum

Thoracic wall

Structural function of thoracic cage. Because of its shape it allows us to: (protect, pressure, attachment)

Protect vital thoracic and abdominal organs form ext forces

Resist the negative sub atmospheric internal pressure generated by elastic recoil of lungs and inspiratory movements

Provide attachment for and support weight of upper limbs

Provide anchoring attachment of many of muscles for upper limb, muscles of abdomen, neck back and respiration

Flexibility of its joint + flexibility allow:

Absorb external blows and compression without fracture

Change shape for repsiraiton

Skeleton of thoracic walls

12 pairs of ribs + associated cartilages

12 thoracic vertebra + intervertebral disks in between

Sternum

Ribs, costal cartilages, intercostal spaces

Ribs:

Each rib has hematopoetic tissue. 3 types of ribs:

1-7 = true vertebrocostal ribs. Attach to sternum

8-10 = false vertebrochandral ribs. Connected to cartilage of rib above them. Connection to sternum is indirect

11,12 free verebral ribs

End in posterior abdominal musculature

Ribs:

Typical 3rd-9th

Atypical

Typical 3rd-9th

Head

Wedge shaped

2 facets sep by crest of head

1 facet for articulation with corrposneidng verbra

1 facet for vertebra superior to it

Neck

Connects the head of rib with body at level of tubercle

Tubercle

Located at junciton of neck and body.

2 articular parts:

Smooth articular part articulates with corresponding transverse process of vertebre

Rough non articular provides attachment for costotransevrse ligament

Body

Flat, curved, mostly markedly at costal angle

Demarcates the lateral limit of attachment for deep back mucles of ribs

Has the costal groove

Weakest part of rib is just anterior to its angle

Fractures of lower ribs may tear the diaphgram and reuslt in diaphragmatic hernia

Atypical ribs:

1st rib

a) broadest, shortest, most sharply curved of the seven true ribs

b) Single facet on head to articulate with T1 vertebra only

c) Two transversely directed grooves crossing its superior surface from subclavian vessels

d) Groovezs seperated by scalene tuercle and ridge, to which anterior scale muscles attach

Clinical:

Posterior inferior to clavicles

Rarely fracture because of protected position

You cannot palpate Rib 1

When broken structures crossting its superior aspect may be injured:

Brachial plexus of nerves

Subclavian vessels that serve uppe rlimb

Atypical ribs:

2nd rib

a)Thinner

b)less curved body

c)substantially longer than 1st rib

d)Head has two facets for articulation with bodies of T1 and T2 veretbrae

e)main atypical feature is a rought area on upper sraface, the tuberosity for serratus anterior, from which part the muscle originates

Atypical ribs:

10-12th ribs, like 1st rib, one fate on head. Articulate with single vertebra

11-12th ribs, short and have no neck or tubercle

Flail rib

Costal cartilages:

Function

1) length the ribs anteriorly

2) contribute to elasticity of thoracic walls

Costal cartilages 1-7:

Attach direct and independently to sternum

Costal cartilages 8,9,10th:

Articulate with costal cartilages superior to them- form a continuous articulate cartilaginous costal margin.

Costal cartilges 11,12:

Caps on anterior ends of corresponding ribs and do not reach or attach any other bone or cartialge

Clinical pearls:

The very young

Very elastic injury to thorax can be prsesent even in asbence of rib fracture

The eldelry:

Costal cartilges lose elastaicity under go calcification making them radiopaque

Intercostal spaces

11 intercostal spaces

11 intercostal nerves

Intercostal spaces occoupied by inctercostal muscles and membranes and two sets (main and ocllateral) of intercostal blood vessels and nerves

Space below 12th rib = rubcostal sapce = anterior ramus branch of spinal nerve T12

ICS is widest anterolaterlaly and widen further with inspiration

Can also be widd by extension/and or lateral flexion of thoracic verebtral column of contra lateral side.

Thoracic Vertebrae

Typical vertebra:

Independent

Have bodies, vertebral arches and seven processes for muscles and articular connections

Characteristics:

Bilateral costal facets (demifacets) on vertebral bodies for articulation with heads of ribs

Can be divided into superior and inferior costal facets small demifacets. Will be covere din more detail next slide

Costal facets on trasverse processes for articulation with tubercles of ribs

Exception: inferior 2 or 3 thoracic vertebrae

Long inferiorly slating spinous processes

Facets of typical ribs

Superior and inferior costal facets:

Occur as bilaterally paired, planar surfaces on superior and inferior posterolateral margins of bodies of typical thoracic vertebrae (T2-T9)

Arranged in pairs on adjacent vertebra, flanking an interposed IV disc:

Typically two demifacets paired in this manner and the posterolateral marign of IV disc between them form a single psocket to receive head of rib of the same number as superior rib

e.g Head of rib 6 with superior costal facet of vertebra T6

Exceptions to facets

Vertebra T1

Superior costal facets of T 1 are not demifacet because there are no demifacets on C7 vertebra above

Rib 1 only articulates with vertebre T1

T1 has a typical inerior costal demi facet

T10

Only one bilateral pair of costal facets located parlty on its body and partily on pedicle

T11,T12:

Only a single pair of costal facets located on pedicles

Sternum:

Manubrium:

Thickest, widest

Easily palpated concave center of superior border of manubrium - jugular nothc

Inferolateral to calvicular notch, there is the synchondrosis of first rib

Manibrium and body of sternum not in same plane.

Sternal angle

Body:

Longer, narrower

Located level of T5-T9

Younger people: 4 sternebrae are obvious. Articulat with each other at primary cartiligouns joints (sternal synchondrosis)

These joints fuse and form from inferior end between buperty and age 25.

Nearly flat anterior surface of body of stenrum is marked in adults by 3 veriable transverse reiddgs.

Xyhpoid process

Inferior end lies at level of T10 vertebre

Can be blunt

Can be biifid

Can be cuved

can be deflected to onside or other

Impt landmark:

a) junction with sternal body indicates inferior limit of central part of thoracic cavity

b) midle marker for the superior limit of liver, the central tendon of diaphgragm, infeiror border of heart

Describing costoverebtral joint i.e ribs to thoracic spine. 2 parts:

Joints of head and ribs:

Head of rib articulates with the following:

superior costal facet of corrosponding vertebre

Infeiror costal facet of vertebre superior to it

Adjacent iv disc uniting the two vertebrae

Head of ribs crest attached to IV disc by an intraarticular ligameent of head of rib wihtin joint, this divides the enclosed space into two synovical caivities

Fibrous layer of joint capsule:

Strongest anteriorly where it forms the radiate ligament of head of rib that found out form anterior marign of head of rib to sides of bodies of two vertebre and IV disc between them.

Very tight connection

Almost no movement

Costotransverse joint

Describing costoverebtral joint i.e ribs to thoracic spine. 2 parts:

Joints of head and ribs:

Costotransverse joint

Tubercle of rib with transverse process of vertebre of same number

Very little movement at these joints and only have thin capsules

Few ligmaents:

Strengthening the anterior part: Costotransvgerse ligament passing from neck of rib to transverse process

Strengethinging the posterior part Lateral costotransverse liagment passing form tubercle of rib to tip of transverse process.

Superior costcotransverse ligaement is a broad band that joins the crest of neck to rib to transverse process supieror to it:

Apertur ebetweeh this ligament and vrebtre permits passage of spinal nerve and posteiror branch of intercostal artery

Movement of thoracic wall

Changes from ribs 1-7 vs 8-10th

Upper ribs move in a pump handle movement

Lower ribs move in a buck handle movement

Pump handle:

Ribs 1-6

Very storng costcotransverse ligametns binding these joints and limiting their mogvements to slight gliding.

However, articualr surfaces on tubercles of superior 6 ribs are convex and fit into concatvities of the transverse process.

So rotaiton mostly at the transverse axis that transverses intrarticular ligamenet and head and neck of rib.

This results in elevation and depression movements of sternal ends of ribs and sternum in saggital plane

Bucket handle:

Ribs 7-10

Flat articular surfaces of tubercles and transverse processes of 7-10th ribs allow gliding allowing in elevation and dperssion of lateral most portions of these ribs

Sternal fractures

Not common any more thanks to airbags

Fracture of sternal body is usually a comminuted fracture (several pieces)

Displacement uncommon because :

Sternum invested by deep fascia (fibrous continuities of radiate sternocostal ligaments)

Sternal attachement of pectoralis major muscles.

Most common site of sternal fracture in eldelry people is at sternal angle i.e fusion of manubriosternal joint which results in dislocaiton of joint

Mortality 25-45% due to high likelhood of myocardial contusion, cardiac rupture, tamponade or lung injyr.

Even in cases of soft tissue sternal injjruy they should be eval for visceral injury.

Muscles of thoracic wall:

Axioappendicular muscles:

Pec major

Pec minor

Inferior part of serratus anterior

Scalene muscle

True muscles of thoracic wall:

Serratus posterior

Levatores costarum

Intercostal muscles

Subcostal muscles

Transverse muscles

Controversial role of serratous posterior

Perviously described as inspiratory muscles;

Serratous post sup was supposed to elevate the superior 4 ribs - thus increasing AP diamter of thorax and raising sternum

Serratous post inferior was supposed to depress the ifnerior irbs preventing from being pulled superiroly by diaphgram.

Recent studies show they do not have a primary motor function - important for prioperceptive fucniton -particualry serratus posterior sup has been implicated in chornic pain im yofascial pain syndrome

Some random points

External intecostal membranes are continous inferiorly with external oblique muscles in the anterolateral abdominal wall. More active during inspiration

Internal intercostal muscles most active during expiration

Innermost intercostal musces

Seperated from internal intercostals by intercostal nerves and vessel

External and internal intercostals

External active during inspiratoin

Internal expiration

Most activity is isometric increases tonus without producing movement mainly during forced respiration.

Main role is to support rigidity of intercostal space, resistent paradoxical movement espically during inspiration when intercostal thoracic pressures are lowst most negative

Clinical example:

High spinal cord injury initial flaccid paralysis of entire trunk but diaphgram remains active.

Here teh vatial capicty is markedly redcued by paraoxical incursion of thoracic wall during inspiration

When paralysis spastic thoracic wall stiffens and vital capicty rises

Nerves of thoracic wall

12 pairs of thoraic spinal nerves supply thoracic wal

Typical vs atypical intercostal nerves

As soon as they leave IV formina divided itno anterior and posterior rami or branches

Anterior

T1-T11 anterior rami forms the intercostal nerves which rund along extent of intercostal spaces

Anterior rami of Nerve T12 is the sucbostal nerve and is nefrior to 12th rib

Posterior:

Go lateral to the articular process of vertebre, to supply joints, deep back muscles and skin of back in thoracic region

Typical intercostal nerves:

Atypical intercostal nerves

Blood supply

Vertebre T6

gets tubercle of which rib?

Gets head of which rib

Tubercle of rib 6

Head of rib 6s inferior facet and rib 7s superior facet

33

Head of 6th rib articulates with?

Superior costal facet of body of T6 vertebrae

Inferio costalf acet of T6

IV disc between these verebtre

34

Very basic physiology

In healthy individuals, GFR remains stable despite changes in volume and blood pressure.

Overload

When overload of sodium and volume -> rise in atrial pressure -> release of natruietic peptides -> renal sodium secretion via direct ubular effects -> rise in GFR

RAAS is suppressed -> systemic vasodilatation and renal sodium excretion by inhibiting tubular effects of AGII and aldosterone

Volume depletion:

Increased RAAs -> systemic vasoconstrict and renal sodium absorption.

Angiotensin II induced renal effecert vasoconstriction, helping to maintain renal filling pressure and GFR despite decreased arterial pressure.

Interaction of cardiorenal system + osmoregulation

Normal physiological conditions-

High plasma osmolarity -> Release of arginine vasopresion (ADH) -> renal water retention -> Normal osmolarity

During pronounced water volume disturbances:

responses to volume depletion or overload can overcome osmotic triggers, contribute to restoration of volume status at expense of osmoregulation.

Basic mechanisms in play during AHF

Acute heart failure:

Decreased cardiac function -> Reduced CO + arterial underfilling -> decreased activation of arterial strech R -> compensatory systemic and intrarenal vasocnstriction

Decreased strech of glomeural afferent arteriole -> renin -> AGII

AGII -> afferent and efferent vasconstricion -> sodium retenion in proximal tuble + rls of aldosterone

Aldosterone -> increased sodium reabsorpiton in collecting duct -> ECF expansion and systemic congestion

Aldosterone escape mechanism

Protective effect of natruiretic peptides in AHF pt

Protective effect of natriuretic peptides is diminished in patients with AHF due to:

renal vasocontriction,

reduced sodium delivery,

fewer active formsof natriuretic peptides

and down reuglation of their receptors.

Decreased protective effect of natreretic peptides + adenisone

In addition, adenosine (which is released in reposnse to increased renal work load and high sodium concentration in distal tubule):

further reducedsrenal blood flow,

stimulates proximal sodium reabsorpaiton and through tubuloglomeural feedback futher decreased GFR via adenosine Areceptor.

In a typical heart failure patient kidneys get smashed

Pump failure

Neurohorminal activation

Usually on Ace I and ARB which overcome kideny`s capacity to comepnsate for reduced perfusion

Increased renal interstitium pressure + reduced transrenal perfusion

ANother hit to kindey:

increased vnous filling + abdo pressure ->

ascities -> increased renal afterload and intranreal pressure

reduce transrenal perfusion gardient

increased renal insteritum pressure (directly opposing pressure)

futher contirpute to renal insuff

Tx them with diuretics

Mechanisms of resistance

1) orally admin diuretics must be absorbed in gut - in presence of GI oedema or gut hypoperfusion, absorpiton of orally admin diuretics is impaired. IV admin can overcome impaired absorption.

2) Hypoalbuminemia:

Most diuretics are bound to plasma albumin:

thiazide diuretics

metolazone

acetazolamide

LOOP DIURETICS.

Hypoaluminemia common in ahf

Impairs uptake and secretionof active fursemide and enhances conversion to active form.

Coadmin of albumin and frusomide improved diuretic repsonse in patients with cirrhosis, nephrtic syndrome or chornic kindey disease but no date on hf.

3) Elevated BUN

reduces diuretic availaibility by competitively inhibiting the organic anion transporter

Furthermore, there is increased urea actively retains sodium itself.

This happens because RAAS and SNS lead to follow dependent passive resporation of urea in distal tubule; a concen trationg raident created by increasd sodium adn water resport in proximal tubule results in diminished distal aflow and increased reabsopriton.

How does it happen

1) Initially natriuretic effect results in intended negative sodium balance

2) Resulting decrease in ECF volume triggers a hoemostatic response (RAAS and SNS triggereD) increased sodium reteion at tubular sites

3) After several days, homeostatic resposne counterbalances diuretic effect fo drug creating a new steady state with lower Ecf

4) In patients with hyperaldosteronism, this phenomenon is pronouced cuasing rapid and abundand sodium reabsopriotn

5) Aslo you have hypertorphy of distal tubular cells due to rapid and abundant sodium reabsroption

Braking phenomenon appropriate homeostatic repsosne that prevents excessie volume depletion during continued diuretic therapy

Defn of diuretic resistance

Persistent congestion despite adequate adn eslcate doses of diuretics with > 80 mg lasix pre day

Amount of sodium excreted as a percentage of filtered load