Download Sternum lecture outline

Sternum lecture outline
Location of Sternum
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17cm in length (less in females)
Lies in midline of anterior chest wall.
Shape of sternum
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Convex in front
Concave behind
Broadest at its upper border
Narrow at sternal angle
Parts of Sternum.
Flat bone divided into three parts:
1. Manubrium sterni.
2. Body (mesosternum)
3. Xiphoid process
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Manubrium
 Upper part of sternum.
 Has 2 surfaces and 4 borders
 Anterior surface
 Posterior surface
 Superior border (has a jugular notch, forms
sternoclavicular joint)
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Inferior border (forms manubriosternal joint)
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 2 lateral surfaces (facet for 1 costal cartilage
demifacet for 2nd costal cartilage)
 Articulates with:
 Body of sternum at manubriosternal joint.
 Clavicles
 First costal cartilage.
 Upper part of second costal cartilages on each side.
 Forms the anterior boundary of superior
mediastinum
 Extends from T3--T4
(Body) Mesosternum
Longer than manubrium
The body of sternum consists of four segments or
sternebrae.
There are three transverse processes
on anterior surface of body which
indicate the site of union of four
sternebrae
 Has 2 surfaces and 4 borders
Anterior surface (has 3 transverse ridges)
 Posterior surface (concave)
 Superior border (forms manubriosternal joint)
Inferior border (forms xiphisternal joint)
2 lateral surfaces (Demifacet for 2nd costal
cartilage
Facets for 3rd, 4th, 5th, 6th
Demifacet for 7th costal cartilage)
Extends from T5—T9
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Xiphoid process
Smallest and variable
Forms xiphisternal joint with body
th
 Has a demifacet for 7 costal cartilage superolaterally
Midline marker for:
 Superior level of liver
Central tendon of diaphragm
Inferior border of heart
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Xiphoid process is cartilaginous in youth
Muscle attachments
Manubrium
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Anterior surface
 Pectoralis major
 Sternocleidomastoid
Posterior surface
 Sternohyoid (on upper aspect)
 Sternothyroid (on lower aspect)
Jugular notch
 Interclavicular ligament
Mesosternum
 Anterior surface
Articular capsules of sterno-costal joint
 Sternal origin of pectoralis major
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Posterior surface
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Transversus thoracis
Xiphoid process
Anterior surface
 Rectus abdominis
Aponeurosis of ext. and int. oblique
Lower end
Linea Alba
 Borders
 Aponeurosis of int. oblique
 Transversus thoracis
Posterior
Slips of diaphragm
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RELATIONS
Manubrium
 Forms the anterior boundary of superior
mediastinum
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Posteriorly related to
Left common carotid artery
Brachiocephalic trunk
Left subclavian vein
Arch of aorta
Laterally lungs and pleura
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Mesosternum
Right to median plane
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Right lung and pleura
Left side related to
Upper sternebrae = left lung and pleura
Lower sternebrae = pericardium
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APPLIED ANATOMY OF STERNUM
STERNAL FRACTURES
 MEDIAN STERNOTOMY
To gain access to thoracic cavity for
surgeries e.g. heart surgery CABG
 STERNAL BIOPSY
Bone marrow needle biopsy because of
its subcutaneous position and breadth
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Congenital abnormalities of sternum
Pectus carinatum ,
Also called pigeon chest ,is a deformity of the
chest characterized by a protrusion of the sternum and
ribs .
Pectus excavatum(
A Latin term meaning hollowed chest
the most common congenital deformity of
the anterior wall of the chest, in which several ribs
and the sternum grow abnormally