The Thoracic Wall:

Bony Thoracic Cage

Thoracic Wall

• Structure:skin fascia muscle boneblood vessels & nerves

• Functions:1. protection of thoracicviscera

2. provides the mechanical function of breathing

Thoracic Cage

The bony part of thoracic The bony part of thoracic wallwall

- 12 pairs of ribs & CC- 12 pairs of ribs & CC- 12 thoracic vertebrae- 12 thoracic vertebrae- Sternum- Sternum

Ribs- Flat curved bones with high - Flat curved bones with high resilienceresilience

- Form most of the thoracic cage- Form most of the thoracic cage

-3 types:3 types: 1. True (11. True (1stst – 7 – 7thth))

2. False (82. False (8thth – 10 – 10thth))

3. Floating (113. Floating (11thth & 12 & 12thth))

Features of Typical Ribs

1. Head: wedge-shaped with 2 articular facets

2. Neck: connects the head with the body

3. Tubercle: articular & non-articular parts

4. Shaft (Body): angle & costal groove

Typical Ribs

33rdrd – 9 – 9thth ribs are considered ribs are considered typicaltypical

1.1. Articular facets Articular facets 2.2. Crest of HeadCrest of Head3.3. NeckNeck4+5. Tubercle4+5. Tubercle6. Angle6. Angle7. Costal groove7. Costal groove8. shaft8. shaft

Atypical Ribs

• 1st ribFlat, scalene tubercle & grooves for subclavian v.

• 2nd ribrough tuberosity for serratus anterior m.

• 10th ribone facet on the head

• 11th & 12th one facet on the head & no neck or tubercle

1st Rib

1.1.Flat ribFlat rib

2. Scalene Tubercle2. Scalene Tubercle

3. Grooves for 3. Grooves for subclavian vesselssubclavian vessels

4. One Facet on the 4. One Facet on the headhead

Clinical: Cervical Rib

• Extra rib arise from C7 vertebra

• Present in 1% of people

• Complications:

Causes pressure on nerves & arteries supplying the

upper limb

Tingling & numbness Partial paralysis

Cervical Rib

Rib Fractures

• Common chest injuries (middle ribs, 5-10)

• Mostly in weakest part (the angle)

• Present as a sever localized pain

• Complications: inj. to underlying structurespneumothorax (air in pleural cavity)

Structure of VertebraeBodyBody

Vertebral archVertebral arch(P & L)(P & L)

7 processes 7 processes

Distinguishing Features of Thoracic Vertebrae

Sternum

((G, Sternon: chest boneG, Sternon: chest bone))

Flat, vertically elongated Flat, vertically elongated bone that forms the middle bone that forms the middle anterior part of the thoracic anterior part of the thoracic cagecage

3 parts:3 parts:ManubriumManubrium

BodyBody

Xiphoid processXiphoid process

ManubriumShapedShaped

(L, Handle)(L, Handle)

* Several notches:* Several notches:Jugular Jugular Clavicular Clavicular Costal Costal

* Manubriosternal Joint:* Manubriosternal Joint:22oo fibrocartilaginous fibrocartilaginousSternal angleSternal angle

Sternal Angle

Angle of louisAngle of louisManubriosternal Manubriosternal

jointjoint

Easily palpatedEasily palpated

Opposite to T4-Opposite to T4-T5 discT5 disc

2nd costal cartilage:2nd costal cartilage:Counting the ribs & intercostal Counting the ribs & intercostal

spacesspaces

Body:Body: T5 – T9, costal notches 3 T5 – T9, costal notches 3rdrd – 7 – 7thth

Xiphoid process:Xiphoid process: T10, hyaline cartilage T10, hyaline cartilage ossifiedossified

Openings of Thoracic Wall•Boundaries of superior Boundaries of superior thoracic opening:thoracic opening:•Post: T1, Post: T1, •On each side: 1On each side: 1stst rib, rib,• Ant: manubriumAnt: manubrium•Contents of InletContents of Inlet• Viscera : Tachea, oesophagusViscera : Tachea, oesophagus• Large Vessels: Brachiocphalic Large Vessels: Brachiocphalic arteryartery

Lf common caotid artLf common caotid art•Small Vessels:Small Vessels:

Rt&Lt Int thorasic artRt&Lt Int thorasic artRt&Lt superior Intercosatal Rt&Lt superior Intercosatal

artart• Nerves& muslesNerves& musles

Boundaries of inferior Boundaries of inferior thoracic openingthoracic opening/outlet/outlet::

• Posteriorly: T12, Posteriorly: T12, • On each side: 7-10 CC, On each side: 7-10 CC,

• Anteriorly: xiphisternal jointAnteriorly: xiphisternal joint

Thoracic Outlet Syndrome

• On the superior thoracic opening (anatomical inlet) • Compression of subclavian art. between the clavicle & 1st rib

(Costoclavicular syndrome)

• Pale color & coldness on the skin of upper limb

• Diminished radial pulse

Joints of Thoracic CagePosteriorly:Posteriorly:

1.1. Intervertebral joints Intervertebral joints (2(2oo cartilaginous) cartilaginous)

2. Costovertebral joints2. Costovertebral joints(synovial plane)(synovial plane)

3. Costotransverse joints 3. Costotransverse joints (synovial plane)(synovial plane)

1

2

3

Joints of Thoracic CageAnteriorly:Anteriorly:

1.1. Costochondral joints Costochondral joints (1(1oo cartilaginous) cartilaginous)

2. Sternocostal joints2. Sternocostal joints(synovial plane, (synovial plane, except 1except 1stst CC CC))

3. Manubriosternal joint 3. Manubriosternal joint (2(2oo cartilaginous) cartilaginous)

4. Xiphisternal joint4. Xiphisternal joint(1(1oo cartilaginous) cartilaginous)

Intercostal Muscles

3 layers3 layers of m. that cover intercostal spaces of m. that cover intercostal spaces

From outside to inside:From outside to inside:

1. External intercostal m.:1. External intercostal m.:

runs downward toward sternum (runs downward toward sternum (your ant. your ant. pocketspockets))

replaced replaced anteriorly anteriorly by membraneby membrane

2. Internal intercostal m.:2. Internal intercostal m.:

runs downward toward VC (runs downward toward VC (your post. your post. pocketspockets))

replaced replaced posteriorlyposteriorly by membrane by membrane

3. Innermost intercostal & Transversus 3. Innermost intercostal & Transversus ThoracicThoracicIIm:IIm: on lateral sides onlyon lateral sides only

TTm:TTm: 4-5 slips of muscles4-5 slips of musclesFrom post. surface of sternumFrom post. surface of sternumTo 2To 2ndnd-6-6thth costal cartilages costal cartilages

Bld. Vessels & nerves run between:

Internal & innermost IMs