Boundaries
 Superior － jugular notch, sternoclavicular joint, superior border of clavicle, acromion, spinous processes of C7
 Inferior － xiphoid process, costal arch, 12th and 11th ribs, vertebra T12
Regions
 Thoracic wall
 Thoracic cavity

 Thoracic cage is an osteo-cartilagenous conical cage which has a narrow inlet & a wide outlet …

Ant:
Sternum,
Costal cartilages and Ribs.
Thoracic vertebrae and ribs.
Lat:
Ribs.

 Ant :
Upper border of manubrium sterni .

: sup.sur.
st

:
st
st
 It is sloping downwards
& forward.

OUTLET OF THORAX
Def.-the broad lower end of thorax which is continuous with the abdominal cavity is called the outlet of thorax
BOUNDARIES :
In front-by : the xiphoid process & 7-10 th costal cartilage forming an intrasternal angle
Behind inf.surface of body of T12
On Sides - 11th & 12th ribs
Inferiorly : Diaphragm







 Thoracic vertebrae.
They are 12 vertebra.
From 2 to 8 they are called Typical.
 Character of typical thoracic vertebrae:
Body: Heart shape & carries 2 demi-facet at its side.
Transverse process: has a facet for rib tubercle of the same number.
Spine: Long, pointed & directed downward and backward.
Vertebral foramen:
Small & circular
.

.
 1 st , 10 th ,11 th and 12 th
 T1:
 Has a complete Superior costal facet.

 Spine nearly horizontal

One very small inferior demifacet.
Has costal facet in transverse process for the tubercle of first rib.
 It has a small body, looks like a cervical vertebra.



One complete facet tangential with the upper border
Small costal facet on transverse process.


One complete circular facet away from upper border.
No costal facet



Broad body & short, oblong spine.
One complete facet midway between upper & lower borders.
No costal facet


 Articulates with thoracic vertebrae.
- Number might ↑ or ↓ .
 Uppers ribs – oblique (max at 9 th ).
Lower ribs – less oblique.
 Length – maximum in 7 th and decreases towards both ends.

 Classification: True,false,typical and atypical ribs.


True and false ribs.
-True ribs – 1-7 as they are connected to the sternum through their respective cartilages .(vertebro sternal ribs).
False ribs – 8, 9, 10, 11, 12. Connected to next higher cartilages to reach sternum but 11, 12 are free in the anterior ends, called floating ribs.
Typical ribs: 3 – 9
 Atypical ribs: 1,2 & 10, 11, 12

Parts of typical rib:
Anterior,posterior ends & shaft.
-
Anterior end :
Oval, concave articulates with costal cartilage.
-Posterior end :
head with 2 facets articulating with the body of thoracic vertebra.
small neck .
tubercle : junction of neck & shaft; articulates with transverse process of thoracic vertebra .

Shaft: 2 surfaces
(outer and inner)& angle
- outer surface: convex
inner surface: concave, covered by pleura; & inner costal groove above the inferior border.

TYPICAL RIB

Atypical ribs
● 1st, 2nd, 10th, 11th, 12th ribs.
First rib
Shortest, flattest and most curved.
Articulate with T1 only.
2 groove:
-Anteriorsubclavian vein
-Posterior-lowest trunk of the brachial plexus and subclavian artery
1 tubercle (inner); attachment of scalenus anterior muscle.

Atypical ribs…
Second rib
-Less curved
-2x long as 1 st rib.
-tubercle (ext lower border)
Tenth rib
1 articular facet on its head.
Eleventh rib
-1 articular facet on its head.
- NO tubercle for articulation with the transverse process.
Twelfth rib
-1 articular facet on its head.
-NO tubercle and subcostal groove.

Forking or duplication of the ribs

Frontal chest radiograph shows a bone bridge joining the right anterior first and second ribs.
Pseudoarticulation is also present (arrows).
This finding is typical in pseudarthrosis and should not be mistaken for a fracture.

● Cervical ribs:
 Bony or fibrous bands between C7 and the 1st rib.


1-2% of subjects.
10% of these cause compressive symptoms, ranging from nerve compression or to subclavian artery post stenotic aneurysm. The remainder are asymptomatic.
 May be large or small, single or bilateral, and may articulate with the
1 st rib.
 If they consist only of a fibrous band they will not be visible on radiographs. They can be confused with hypoplastic first ribs.

*The 7th cervical transverse processes point downwards, 1st thoracic transverse processes are angled upwards.

Cervical ribs in an asymptomatic patient.
Frontal chest radiograph shows bilateral cervical ribs (arrowheads); the left one fuses anteriorly to the first rib (arrow).

● Lumbar ribs: transverse process
(costal element of the lumbar vertebra) may fail to fuse with the vertebral body and retain asynovial joint with the neural arch.
Asymptomatic.

● unossified anterior ends of the ribs.
● Slope upwards to the sternum 1 st – 7 th ribs articulate with sternum
(sternochondral joints)
● 8th – 10th ribs articulate with the costal cartilages of the ribs above.
● 11th and 12th costal cartilages have pointed ends and end in the muscles of the abdominal wall.

Sternum

Sternum
• Sternum is a flat bone, present in front of the thoracic cage.
• Parts:
Manubrium,
Body and
Xiphoid process.
• Manubrium is the
- upper part of the sternum.
- joins with medial end of clavicle and first costal cartilage.
- Jugular or interclavicular or suprasternal notch.

 Body :
- larger part of the sternum.
- on each side, it receives ribs through their costal cartilages
(3rd to 6th rib).
 Xiphoid process:
- the most variable part of the sternum.
- cartilaginous structure in adults.

● Manubrium
-opposite T3 and T4
-articulates with clavicle and with 1½ costal
-
Cartilages
● Sternal angle secondary cartilaginous joint,lies opposite T
4/5
● Body disc space
-opposite T
5
-T
9
, made up of four stenebrae which articulate with 5 ½ costal cartilages
● Xiphoid process
-remains cartilaginous into adult life.

Variation in
Sternal configuration:
Pectus excavatum, depression of the lower end.
Pectus carinatum, prominence of the midportion