THORACIC CAGE and WALL SURFACE LANDMARKS

Lines of Orientation Refer: Midsternal line Midclavicular line Text: pp 91-92 (91) Syllabus: p 44 Midsternal line Midclavicular line Anterior axillary line Posterior axillary line

Lines of Orientation Midaxillary line Scapular line

Surface Landmarks Jugular notch Sternal angle: Apex heart beat: Marks rib 2 Lies at level of T4-5 IV disc Apex heart beat: Left IC space 5; midclavicular line Aortic valve: Right IC space 2

Surface Landmarks Infrasternal angle: Important in CPR. Depression between is the infrasternal fossa. Xiphisternal joint within the fossa is at the level of the body of T9.

Surface Landmarks Pulmonary valve Tricuspid valve Bicuspid valve Left IC space 2 Tricuspid valve Right IC space 5 Bicuspid valve Left IC space 5 Bifurcation of trachea Vertebral level T4-5

Surface Landmarks Posterior thorax: scapula: Costal margin: Scapular spine is at level of 3rd rib and T2 vertebra. Inferior scapular angle is at the level of the 7th rib, the spine of T7 or the body of T9. Costal margin: Superior part is marked by the 7th cartilage. Inferior part is marked by the 10th cartilage

Cutaneous innervation Clavicular and scapular regions: C3-4 Region of xiphoid process: T6 Anterior thorax: T1-T6 Upper extremity: C5-T1 Lower thorax and anterior abdomen: T7-T12

OSTEOLOGY OF THE THORACIC CAGE

Structure of the Thoracic Cage Twelve thoracic vertebrae Twelve pairs of ribs and their costal cartilages Sternum Intercostal muscles

Superior Boundary (outlet) First thoracic vertebra First pair of ribs and costal cartilages Manubrium Refer to Fig. 14, p. 53 in syllabus

Inferior Boundary (outlet) Twelfth thoracic vertebra Twelfth pair of ribs and costal cartilages Xiphisternal joint Refer to Fig. 14, p. 53 in syllabus

Bones of the Thoracic Cage Manubrium Body of sternum: Four sternebrae Xiphoid process Manubriosternal joint: Symphysis Synostosis after age 30 in some

Ribs Costa: Vertebrosternal ribs: Vertebrochondral ribs: = Rib bone + its cartilage Vertebrosternal ribs: 1-7 Vertebrochondral ribs: 8-10 Vertebral ribs (floating): 11-12

Typical Rib Head: Two articular facets for articulation with costal demifacets on adjacent thoracic vertebrae. Bony crest between facets for attachment to intervertebral disc.

Typical Rib Neck: Tubercle: Narrow portion between head and tubercle. Articulates with transverse process of vertebra with same number.

Typical Rib Shaft Sternal extremity Angle

Typical Rib Costal groove: Costal cartilage Contains superior to inferior: Intercostal vein Intercostal artery Intercostal nerve Costal cartilage

First Rib Flattened in a horizontal (transverse) plane. Scalene tubercle: For insertion of scalenus anterior muscle. Shallow groove for subclavian vein: Anterior to tubercle Shallow groove for subclavian artery: Posterior to tubercle

Thoracic Vertebra Heart-shaped centrum (body) Centrum notched on left side for descending aorta Intervertebral discs = ¼ of total length of thoracic vertebral region Superior and inferior costal demifacets: (on typical vertebrae (T2 – T9)

Thoracic Vertebra Vertebra prominens (C7): First spinous process to be palpated. T1 spinous process most prominent

Atypical Thoracic Vertebra Superior costal facet (not a demifacet). T10: One pair of costal facets located partly on body and partly on pedicle. T11 and T12: One pair of costal facets located on pedicles.

Typical Rib Articulation Head articulates with demifacets of its own number vertebra and the vertebra above as well as the intervertebral disc between: Tubercle articulates with transverse process of same number vertebra.