THORACIC CAGETHORACIC CAGEand WALLand WALL

SURFACE LANDMARKSSURFACE LANDMARKS

Lines of OrientationLines of Orientation

Refer:Refer:Text:Text: pp 91-92 (91)pp 91-92 (91)

Syllabus: p 44Syllabus: p 44Midsternal lineMidsternal lineMidclavicular lineMidclavicular lineAnterior axillary lineAnterior axillary linePosterior axillary linePosterior axillary line

Lines of OrientationLines of Orientation

Midaxillary lineMidaxillary lineScapular lineScapular line

Surface LandmarksSurface Landmarks

Jugular notchJugular notchSternal angle:Sternal angle:

Marks rib 2Marks rib 2

Lies at level of T4-5 IV discLies at level of T4-5 IV discApex heart beat:Apex heart beat:

Left IC space 5; midclavicular lineLeft IC space 5; midclavicular lineAortic valve:Aortic valve:

Right IC space 2Right IC space 2

Surface LandmarksSurface Landmarks

Infrasternal angle:Infrasternal angle:Important in CPR.Important in CPR.

Depression between is the infrasternal Depression between is the infrasternal fossa.fossa.

Xiphisternal joint within the fossa is at the Xiphisternal joint within the fossa is at the level of the body of T9.level of the body of T9.

Surface LandmarksSurface Landmarks

Pulmonary valvePulmonary valveLeft IC space 2Left IC space 2

Tricuspid valveTricuspid valveRight IC space 5Right IC space 5

Bicuspid valveBicuspid valveLeft IC space 5Left IC space 5

Bifurcation of tracheaBifurcation of tracheaVertebral level T4-5Vertebral level T4-5

Surface LandmarksSurface Landmarks

Posterior thorax: scapula:Posterior thorax: scapula:Scapular spine is at level of 3Scapular spine is at level of 3rdrd rib and T2 rib and T2 vertebra.vertebra.

Inferior scapular angle is at the level of the Inferior scapular angle is at the level of the 77thth rib, the spine of T7 or the body of T9. rib, the spine of T7 or the body of T9.

Costal margin:Costal margin:Superior part is marked by the 7Superior part is marked by the 7 thth cartilage. cartilage.

Inferior part is marked by the 10Inferior part is marked by the 10 thth cartilage cartilage

Cutaneous innervationCutaneous innervation

Clavicular and scapular regions:Clavicular and scapular regions:C3-4C3-4

Region of xiphoid process:Region of xiphoid process:T6T6

Anterior thorax:Anterior thorax:T1-T6T1-T6

Upper extremity:Upper extremity:C5-T1C5-T1

Lower thorax and anterior abdomen:Lower thorax and anterior abdomen:T7-T12T7-T12

OSTEOLOGY OF THE OSTEOLOGY OF THE THORACIC CAGETHORACIC CAGE

Structure of the Thoracic CageStructure of the Thoracic Cage

Twelve thoracic vertebraeTwelve thoracic vertebraeTwelve pairs of ribs and their costal Twelve pairs of ribs and their costal

cartilagescartilagesSternum Sternum Intercostal musclesIntercostal muscles

Superior Boundary (outlet)Superior Boundary (outlet)

First thoracic vertebraFirst thoracic vertebraFirst pair of ribs and costal cartilagesFirst pair of ribs and costal cartilagesManubrium Manubrium Refer to Fig. 14, p. 53 in syllabusRefer to Fig. 14, p. 53 in syllabus

Inferior Boundary (outlet)Inferior Boundary (outlet)

Twelfth thoracic vertebraTwelfth thoracic vertebraTwelfth pair of ribs and costal cartilagesTwelfth pair of ribs and costal cartilagesXiphisternal joint Xiphisternal joint Refer to Fig. 14, p. 53 in syllabusRefer to Fig. 14, p. 53 in syllabus

Bones of the Thoracic CageBones of the Thoracic Cage

Manubrium Manubrium Body of sternum:Body of sternum:

Four sternebraeFour sternebraeXiphoid processXiphoid processManubriosternal joint:Manubriosternal joint:

Symphysis Symphysis

Synostosis after age 30 in someSynostosis after age 30 in some

RibsRibs

Costa:Costa:= Rib bone + its cartilage= Rib bone + its cartilage

Vertebrosternal ribs:Vertebrosternal ribs:1-71-7

Vertebrochondral ribs:Vertebrochondral ribs:8-108-10

Vertebral ribs (floating):Vertebral ribs (floating):

11-1211-12

Typical RibTypical Rib

Head:Head:Two articular facets for articulation with Two articular facets for articulation with

costal demifacets on adjacent thoracic costal demifacets on adjacent thoracic vertebrae.vertebrae.

Bony crest between facets for attachment Bony crest between facets for attachment to to intervertebral disc.intervertebral disc.

Typical RibTypical Rib

Neck:Neck:Narrow portion between head and Narrow portion between head and

tubercle.tubercle.Tubercle:Tubercle:

Articulates with transverse process of Articulates with transverse process of vertebra with same number.vertebra with same number.

Typical RibTypical Rib

ShaftShaft

Sternal extremitySternal extremity

Angle Angle

Typical RibTypical Rib

Costal groove:Costal groove:Contains superior to inferior:Contains superior to inferior:

Intercostal veinIntercostal vein

Intercostal arteryIntercostal artery

Intercostal nerveIntercostal nerve

Costal cartilageCostal cartilage

First RibFirst Rib

Flattened in a horizontal (transverse) Flattened in a horizontal (transverse) plane.plane.

Scalene tubercle:Scalene tubercle:For insertion of scalenus anterior muscle.For insertion of scalenus anterior muscle.

Shallow groove for subclavian vein:Shallow groove for subclavian vein:Anterior to tubercleAnterior to tubercle

Shallow groove for subclavian artery:Shallow groove for subclavian artery:Posterior to tuberclePosterior to tubercle

Thoracic VertebraThoracic Vertebra

Heart-shaped centrum (body)Heart-shaped centrum (body)Centrum notched on left side for Centrum notched on left side for

descending aortadescending aorta Intervertebral discs = ¼ of total length of Intervertebral discs = ¼ of total length of

thoracic vertebral regionthoracic vertebral regionSuperior and inferior costal demifacets:Superior and inferior costal demifacets:

(on typical vertebrae (T2 – T9)(on typical vertebrae (T2 – T9)

Thoracic VertebraThoracic Vertebra

Vertebra prominens (C7):Vertebra prominens (C7):First spinous process to be palpated.First spinous process to be palpated.

T1 spinous process most prominentT1 spinous process most prominent

Atypical Thoracic VertebraAtypical Thoracic Vertebra

T1:T1:Superior costal facet (not a demifacet).Superior costal facet (not a demifacet).

T10:T10:One pair of costal facets located partly on One pair of costal facets located partly on body and partly on pedicle.body and partly on pedicle.

T11 and T12:T11 and T12:One pair of costal facets located on One pair of costal facets located on

pedicles.pedicles.

Typical Rib ArticulationTypical Rib Articulation

Head articulates with demifacets of its own Head articulates with demifacets of its own number vertebra and the vertebra above number vertebra and the vertebra above as well as the intervertebral disc between:as well as the intervertebral disc between:

Tubercle articulates with transverse Tubercle articulates with transverse process process of same number vertebra.of same number vertebra.