The document describes the anatomy of the thorax, including the bones (thoracic vertebrae, ribs, sternum), joints (costovertebral, costotransverse, costochondral, chondrosternal), and movements (flexion, extension, lateral bending, rotation). It discusses the roles of the ribs, sternum, and associated ligaments in providing stability and allowing ventilation of the lungs during breathing.

1. thorax
BY: SYED MASOOD
MPT (ORTHO)

2. Introduction
The thorax, consisting of
1. the thoracic vertebrae, posteriorly
2. the ribs, laterally
3. and the sternum, anteriorly.
The thorax forms protection for the
heart, lungs, and viscera.
Therefore, there needs to be a certain
amount of inherent stability to the thorax.
The most important function of the chest
wall is its role in ventilation.
The process of ventilation depends on
the mobility of the bony rib thorax and
the ability of the muscles of ventilation to
move it.

3. The rib
cage is a
closed
chain that
involves
many
joints and
muscles.

5. Manubrium
 Jugular (suprasternal) notch
 Articulation with rib 1 & 2
 Clavicular Articular facets
 Sternal Angle – 2nd rib
Body of sternum
 Articulates w/ribs 2-7
 Xiphisternal joint
Xiphoid process
 Cartilage-calcifies through time.
 Partial attachment of many
muscles.

6. 12 pairs
• 7 True ribs-direct attachment to
sternum
• 5 False ribs-indirect or no attachment
to sternum
• Floating ribs- 11th and 12th no ventral
attachment.
Typical Ribs
• Ribs # 2-9
Atypical Ribs
• Ribs #1, 10,11,12
Ribs are placed obliquely, upper less
oblique than lower.
Length increases from Ist to 7th and
gradually decreases from 8th to 12th .
Reinforce thoracic cage

7. Neck

8. The articulations that join
the bones of the rib cage
are:
 Manubriosternal (MS),
 Xiphisternal (XS),
 Costovertebral (CV),
 Costotransverse (CT),
 Costochondral (CC),
 Chondrosternal (CS), and
the
 Interchondral.

9. The manubrium and the body of the
sternum articulate at MS joint. Also
known as the sternal angle or the
angle of Louis. Synchondrosis type
joint.
 Ossification of the MS joint occurs in
elderly persons.
The xiphoid process joins the inferior
aspect of the sternal body at the XS
joint.
 The XS joint is also a synchondrosis
that tends to ossify by 40 to 50 years
of age.

10. The typical CV joint is a synovial joint,
2 through 9.
Formed by head of the rib, two
adjacent vertebral bodies, and the
interposed intervertebral disk.
Ribs 2 to 9 have typical CV joints, as
heads of these ribs have 2 articular
facets, or so-called demifacets.
The demifacets r separated by ridge
called crest.
Small, oval, and slightly convex
demifacets of the ribs are called the
superior and inferior costovertebral
facets.
Adjacent thoracic vertebrae have
facets corresponding to those of the 9
ribs that articulates with them.
Typical cv joint

11.  Typical CV joint is divided into
two cavities by the
interosseous or intra-
articular ligament.
 The radiate ligament has three
bands:
 superior band, attached to the
superior vertebra
 intermediate band, attached to
the intervertebral disk; and the
 inferior band, attached to the
inferior vertebra.

12. The atypical CV joints of ribs 1 and
10,11 & 12 are more mobile because
the rib head articulates with only one
vertebra.
Interosseous ligament is absent in
these joints; therefore, have only one
cavity.
The radiate ligament is present in these
joints, with the superior band still
attaching to the superior vertebra.
Both rotation and gliding motions occur
at all of the CV joints
Atypical CV joints

13. The CT joint is a synovial joint. formed
by costal tubercle of rib with costal facet
on transverse process of the
corresponding vertebra.
10 pairs of CT joints articulates T1
through T10 with the rib of same
number.
CT joints on T1-T6 have slightly concave
costal facets on the transverse
processes and slightly convex costal
tubercles on the corresponding ribs. This
allows slight rotation movements.
At the CT joints of T7 through T10, both
articular surfaces are flat and gliding
motions predominate.
Ribs 11 and 12 do not articulate with
their respective transverse processes of
T11 or T12.

14. The CT joint is surrounded by a thin, fibrous
capsule.
Three major ligaments support the CT joint
capsule .
lateral costotransverse ligament, is a
short, stout band located between the lateral
portion of the costal tubercle and the tip of
the corresponding transverse process.
costotransverse ligament, is composed of
short fibers that run with in the
costotransverse foramen between the neck
of the rib posteriorly and the transverse
process at the same level.
superior costotransverse ligament The
superior costotransverse ligament runs from
the crest of the neck of the rib to the inferior
border of the cranial transverse process.

16. CC joints are formed by articulation of the
1st through 10th ribs anterolaterally with the
costal cartilages.
Synchondroses type.
The CC joints have no ligamentous support.
CS joints are formed by the articulation of
costal cartilages of ribs 1 to 7 anteriorly with
the sternum.
Rib 1 attaches to the lateral facet of the
manubrium.
Rib 2 is attached via two demifacets at the
manubriosternal junction,
Ribs 3 through 7 articulate with the lateral
facets of the sternal body. The CS joints of
the 1st, 6th, and 7th ribs are
synchondroses.
The CS joints of ribs 2 to 5 are synovial
joints.

17. Ligamentous support for the capsule
includes
anterior and posterior radiate
costosternal ligaments.
The sternocostal ligament is an intra-
articular ligament, that divides the two
demifacets of the 2nd CS joint.
The CS joints may ossify with aging.
The costoxiphoid ligament connects
the anterior and posterior surfaces of the
seventh costal cartilage to the front and
back of the xiphoid process.

18. The 7th to 10th costal cartilages
articulate with cartilage above
them.
For 8th through 10th ribs,
articulation is indirectly with
sternum .
Interchondral joints are synovial
joints and are supported by a
capsule and interchondral
ligaments.
The interchondral articulations,
tend to become fibrous and fuse
with age.

19. There is a single axis of motion for the 1st to 10th ribs through the center of the CV and CT
joints.
For upper ribs axis lies close to frontal plane(frontal axis) allowing motion predominantly in
sagittal plane.
For lower ribs axis is nearly in sagittal plane(sagittal axis) allowing motion predominantly in
the frontal plane.
The axis of motion for the 11th and 12th ribs lies close to frontal plane.

20. During inspiration, the ribs elevate.
In upper ribs, most of movement
occurs at anterior aspect of the rib,
nearly frontal axis at the vertebrae.
The movement of ribs pushes the
sternum ventrally and superiorly.
Less movement occurs at manubrium
becoz first rib is short this causes
movement at the MS joint.
The motion of upper ribs and sternum
has greatest effect by increasing
anteroposterior (A-P) diameter of
thorax.
This combined rib and sternal motion
has been termed as “pumphandle”
motion.

21. Elevation of the lower ribs occurs nearly at
sagittal axis.
Lower ribs have more angled shape and an
indirect attachment anteriorly to sternum.
These factors allow the lower ribs more motion
at the lateral aspect of the rib cage.
Elevation of the lower ribs has greater effect to
increase the transverse diameter of the lower
thorax.
This motion has been termed the “bucket-
handle” motion of the thorax.
The orientation of the axes of motion from
cephalad to caudal is shifting gradually
therefore, the intermediate ribs perform both
types of motion.
The 11th and 12th ribs do not participate in
closed-chain motion of the thorax.

23. Movements




FLEXION

24. EXTENSION
During extension of the mobile thorax,
extension of the superior vertebra
occurs.
The ribs posteriorly rotate about a
paracoronal axis along the line of the
neck of the rib such that the anterior
aspect travels superiorly while the
posterior aspect travels inferiorly.
At the limit of backward bending, the
vertebrae stop and the ribs continue to
posteriorly rotate relative to the
vertebrae.
The posterior rotation of the neck of the
rib results in an inrerior glide coupled
with a posterior roll of the tubercle al the
costotransverse joint.

25. LATERAL BENDING
Lateral bending towards right, a left convex curve is produced.
The thoracic vertebrae side flex to the right and the ribs on the right approximate while the
ribs on the left separate at their lateral margins.
Since the tubercle of the rib is convex, as the thoracic vertebra sideflexes to the right it has
to move posterior and inferior on the right and anterior and superior on the left.
The ribs appear to stop moving before the thoracic vertebrae. The thoracic vertebrae then
continue to sideflex to the right. This motion can be palpated at the costotransverse joint.
This slight increase in right sideflexion of the thoracic vertebrae against the fixed ribs- cause
the following arthrokinematic motion.
Ct joint is concavoconvex, a relative superior glide of the right rib occurs, it produces a
relative anterior roll of the neck of the rib with respect to the transverse process.
The inferior glide of the left rib occurs at Ct joint, it produces a posterior roll of the neck of
the rib relative to the transverse process.
It is important to note that the moving bone is the thoracic vertebra, not the rib.
Osteokinematically, this produces a right rotation of the thoracic vertebra relative to its
starting position.

27. ROTATION
During right rotation of the trunk the superior vertebra (eg. T5) rotates to
the right and translates to the left.
The left (6th) rib anteriorly rotates and translates posterolateral relative to
the ipsilateral transverse process of the inferior vertebra (T6).
The right (6th) rib posteriorly rotates and translates anteromedial relative
to the ipsilateral transverse process of the inferior vertebra (T6).
When the limit of this horizontal translation is reached, both the
costovertebral and the costotransverse ligaments are tensed. Stability of
the ribs both anteriorly and posteriorly is required for the following motion
to occur.
Further right rotation of the superior vertebra (T5) occurs as the superior
vertebral body tilts to the right. This tilt causes right side flexion of the
superior vertebra (T5-6 ) during right rotation of the thoracic segment.