The Thoracic Wall (2):The Thoracic Wall (2):

MMuscles, nerves, vasculature & surface uscles, nerves, vasculature & surface anatomyanatomy

Thoracic Wall

• Structure:

skin fascia muscle bone

blood vessels & nerves

• Functions:

1. protection of thoracic

viscera

2. provides the mechanical

function of breathing

Muscles of Thoracic Wall:

Diaphragm, IM’s, Accessory muscles of respiration

DiaphragmDiaphragmA thin muscular & tendinous sheet that separates A thin muscular & tendinous sheet that separates

the thoracic cavity from the abdomenthe thoracic cavity from the abdomen

((primary muscle of respirationprimary muscle of respiration))

DiaphragmDiaphragm

• Origin:

Xiphoid process (sternal)lower 6 ribs & CC (7th-12th, costal)1st-3rd bodies of lumbar V & IV discs (as crura & ?, vertebral)

(see next slide)

• InsertionCentral Tendon

• InnervationMotor: Phrenic nerve (C3, 4 & 5)

Sensory: Central: phrenic Lateral: intercostal nerves (7-12)

• Action: ??

Vertebral Origin of DiaphragmVertebral Origin of Diaphragm

Crura:Crura:

vertical columns of muscle bundles vertical columns of muscle bundles

Rt:Rt: L1-L3 & IV discs L1-L3 & IV discs

Forms a sling around esophagusForms a sling around esophagus

Lf:Lf: L1-L2 & IV disc L1-L2 & IV disc

Arcuate Ligaments:Arcuate Ligaments:

Medial:Medial: L2 body L2 body L1 Trans. P. L1 Trans. P.

Lateral:Lateral: L1 TP L1 TP 12 12thth rib rib

Median:Median: medial borders of crura medial borders of crura

Shape of DiaphragmShape of Diaphragm

2 domes:2 domes:

Rt:Rt: upperupper border of 5 border of 5thth rib ( rib (why?why?))

Supports Rt. lungSupports Rt. lung

Lf:Lf: lowerlower border of 5 border of 5thth rib rib

Supports Lf. lungSupports Lf. lung

Central Tendon: Central Tendon:

3 leaves

At xiphisternal joint

Supports the heart

Merges with fibrous pericardium

Openings in The DiaphragmOpenings in The Diaphragm

3 main openings:

1. Aortic opening:

At T12, between crura

Aorta, azygos vein & thoracic duct

2. Esophageal opening:

At T10, in sling of right crus

Esophagus & vagus nerves

3. Caval opening:

At T8, in central tendon

IVC, & Rt phrenic nAny other openings?

Diaphragmatic HerniaDiaphragmatic Hernia

- Rupture in the diaphragm leading to - Rupture in the diaphragm leading to herniation of lumbar viscera into the thoraxherniation of lumbar viscera into the thorax

- most common in left side with stomach fundus - most common in left side with stomach fundus ((Sliding or paraesophagealSliding or paraesophageal))

HiccupHiccup

- Involuntary contractions of the - Involuntary contractions of the diaphragmdiaphragm

- After eating or drinking - After eating or drinking irritation of irritation of vagus n.vagus n.

Intercostal Muscles

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

spacesspaces

From outside to inside:From outside to inside:

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

runs toward sternum (runs toward sternum (your ant. your ant.

pocketspockets))

replaced replaced anteriorlyanteriorly by membrane by membrane

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

runs toward VC (runs toward VC (your post. pocketsyour post. pockets))

replaced replaced posteriorlyposteriorly by membrane by membrane

3. Innermost intercostal & Transversus 3. Innermost intercostal & Transversus ThoracicThoracic

IIm:IIm:

on lateral sides onlyon lateral sides only

TTm: TTm:

4-5 slips of muscles4-5 slips of muscles

From post. surface of sternumFrom post. surface of sternum

To 2To 2ndnd-6-6thth costal cartilages costal cartilages

Bld. Vessels & nerves run between:

Internal & innermost IMs

Intercostal MusclesIntercostal Muscles

Intercostal MusclesIntercostal MusclesLower broder of the rib above

Upper border of the rib below

External

Internal

Innermost

Intercostal neurovascular bundle runs between Internal & Innermost

Ex.

In.

Accessory MusclesAccessory Muscles

Levator CostarumLevator Costarum

Serratus Posterior Serratus Posterior SuperiorSuperior

Serratus Posterior Serratus Posterior InferiorInferior

Intercostal NeuroVascular BundleIntercostal NeuroVascular Bundle

Costal Costal Groove:Groove:

VVeinein

AArteryrtery

NNerveerve

Collateral neurovascular bundle: over Collateral neurovascular bundle: over upper upper bordersborders of the ribs of the ribs

Intercostal ArteriesIntercostal ArteriesEach intercostal space:Each intercostal space:

1 Large post. inter. 1 Large post. inter. arteryartery

2 small ant. inter. 2 small ant. inter. ArteriesArteries

Post.:Post.:

Descending aortaDescending aorta

& Costocervical trunk& Costocervical trunk

(sup. Inter. A.)(sup. Inter. A.)

Ant.:Ant.:

Internal Thoracic a.Internal Thoracic a.

& musculophrenic a.& musculophrenic a.

Intercostal VeinsIntercostal VeinsEach intercostal space:Each intercostal space:

Large post. inter. veinLarge post. inter. vein

2 small ant. inter. veins2 small ant. inter. veins

Post.:Post.:

Azygos VeinAzygos Vein

& hemiazygos& hemiazygos

Ant.:Ant.:

Internal Thoracic V.Internal Thoracic V.

& musculophrenic V.& musculophrenic V.

Intercostal NervesIntercostal Nerves

Surface Anatomy:

Surface markings & lines

Self Reading

Surface markings of Ant. Chest

ClavicleClavicle

Sternum:Sternum:

Jugular notchJugular notch

Sternal angleSternal angle

Body of sternumBody of sternum

Xiphoid processXiphoid process

Costal marginsCostal margins

Surface Anatomical Lines

Anterior:

1. Median sagittal line:

intersection of median plane with ant. chest wall

2. Midclavicular lines:

Midpoints of clavicles

to inguinal region

Lateral:Lateral:

1. Ant. axillary line:1. Ant. axillary line:

Along ant. axillary fold Along ant. axillary fold

(formed by border of Pec. Major (formed by border of Pec. Major m.)m.)

2. Post. axillary line:2. Post. axillary line:

Along post. axillary fold Along post. axillary fold

(formed by latissimus dorsi & (formed by latissimus dorsi & teres major M.)teres major M.)

3. Mid axillary line:3. Mid axillary line:

Runs from the apex of axillaRuns from the apex of axilla

Parallel to ant. & post. linesParallel to ant. & post. lines

Posterior:Posterior:

1. Post. median line:1. Post. median line:

Over the tips of spinous Over the tips of spinous processes of all vertebraeprocesses of all vertebrae

2. Scapular lines:2. Scapular lines:

Through Through sup. & inf. anglessup. & inf. angles of of the scapula when arms at the scapula when arms at anatomical positionanatomical position

Scapula (shoulder blade)

Triangular flat boneTriangular flat bone

Anterior (Anterior (costalcostal) surface) surface

22ndnd – 7 – 7thth ribs ribs

Posterior (Posterior (spinousspinous) surface) surface