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Home , Costal cartilage, Costochondral joint, Costotransverse ligament, Costovertebral joints, Intercostal space, Intervertebral disc

Anatomy – Thoracic cage

Sternum Manubrium+body+xiphisternum Manubrium and body connected by secondary cartilaginous

Manubrium Flat, 4 sided, broader above. Jugular notch (upper border of T3) Upper margin concave to form jugular notch, on which lies the interclavicular Two layed of deep cervical attached to anterior and posterior borders of the notch Upper angle Scooped out for the (atypical ) Lateral border Excavated for the first costal (primary ) Below this is the origin of the internal intercostal muscle Inferior angle (lower border of T4) Small facet for articulation of the upper part of the second (synovial joint) Anterior surface Attachments for and SCM Posterior surface Attachment for sternohyoid and sternothyroid

Body of (lower border is at lower border of T8) Lateral border Articular facets along lat border for lower part 2 nd costal cartilage and 3 rd to 7 th costal (synovial) Attachment for anterior intercostal membrane and internal intercostal muscle Anterior surface Attachment for pectoralis major Posterior surface Attachment for transversus thoracis; Sternopericardial ligament

Joints of thoracic cage Costovertebral Joints of costal heads Head of a typical has 2 facets sloping away from each other and separated by a ridge Lower rib facet articulates with of its own . Upper rib facet articulates with vertebra above Rib 1 articulates with T1 only 11 and 12 only articulate with their own vertebrae. Ridge is attached to the by the intra articular ligament Front of strengthened by radiate ligament Costotransverse joints 1 Tubercle of a typical rib has 2 facets Medial facet articulates with the tip of the transverse process. Lateral facet has no articulation and gives rise to the lateral Joint strengthened by costotransverse and superior costotransverse . Ribs 11 and 12 have no tubercles. Costal cartilage is unossified anterior rib Joint is primary cartilaginous 1st costal cartilage – primary cartilaginous joint 2nd -7th – synovial joints Manubriosternal joint Articulation manubrium/body sternum Secondary cartilaginous joint

First rib Head Small, single facet for joint with upper part body T1 (synovial) Sympathetic trunk lies in contact with anterior border of neck, alongside the head Lateral to this is the 1 st posterior intercostal Lateral to this is the superior intercostal Lateral to this is the 1 st thoracic Cervical dome and apex of hold these structures against the rib Tubercle Broad region at junction of neck and shaft Forms the most posterior convexity of the rib Cylindrical facet for articulation with the transverse process of T1 Lateral part of tubercle receives the lateral costotransverse ligament Shaft Under surface Crossed by small 1 st intercostal nerve and vessels External and internal intercostals attached to outer rim Outer border blunt for attachment of 1 st digitation of serratus anterior Upper surface Medial to lateral: Groove for subclavian artery Scalene tubercle and ridge Groove for subclavian vein. Anterior end Expands into a concavity for the 1 st costal cartilage Muscles attached Anterior scalene (tubercle) Middle scalene (medial to groove for artery) Longissimus portion erector spinae attaches tubercle - angle Intercostals Subclavius (at costocondral junction) Serratus anterior (lateral) Three layers Between middle and inner under the rib above lies Vein → Artery → Nerve Needle thoracostomy through lateral intercostal space: Skin → Subcut fat → external intercostal → internal intercostal → transversus → parietal pleura

2 Ribs Typical rib Head Bevelled by 2 articular facets separated by a crest Lower facet is vertical and articulates with own vertebra Upper facet articulates with vertebra above Each is a synovial joint. Ligament passes from crest to intervertebral disc Neck Passes backwards Two laminae for attachment superior costotransverse ligament Tubercle Two facets Medial facet (smooth) articulate transverse process own vert Lateral facet (rough) attachment to lat costotransverse ligament Shaft Slopes down and back to the angle, then curves forwards Head lies higher than anterior ends. Lower border of shaft is sharp and forms the costal groove External intercostal muscle arise from lower border Internal intercostal attached to costal groove Transversus group attached to inner surface of shaft Anterior end Concave fossa for costal cartilage (primary cartilaginous joint)

Intercostal space Skin Fascia External intercostal Internal intercostal Neurovascular bundle (under cover of rib above) - Superior to inferior Intercostal vein Each space has 1 posterior and 2 anterior that accompany . Posteriorly 1st – drains to vertebral or brachiocephalic 2nd and 3 rd – forms superior intercostal vein – right drains to azygous, left crosses arch of between vagus and phrenic to drain into left 4th -11 th space – drain to azygous system Intercostal artery Posteriorly 1st and 2 nd spaces – superior intercostal artery arises from the costocervical trunk from the 2 nd part of the subclavian artery Enters by passing in front of neck of 1 st rib (adjacent to stellate ganglion) 3rd -11 th spaces – posterior from the descending aorta. Each has small collateral branch that accompanies the collateral branch of intercostal nerve Anteriorly 1st -6th spaces – internal thoracic artery 7th -9th spaces – musculophrenic artery 10 th -11 th spaces – no anterior branch Intercostal nerve Mixed spinal nerve emerges from ; gives posterior ramus Passes between internal intercostal and transversus group Collateral branch – runs in inf border space, supplies muscles of space, parietal pleura, periosteum Lateral cutaneous branch – pierces and divides into /post branch to skin

Intercostal nerve ends as the anterior cutaneous nerve Anterior ramus of T1 gives 1 st intercostal nerve just before it crosses 1 st rib Lateral cutaneous branch 2 nd intercostal nerve crosses axilla, becomes intercostobrachial nerve Transversus group

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