The document summarizes the anatomy of the thoracic cavity. It describes that the thoracic cavity is bounded by the chest wall superiorly and the diaphragm inferiorly. It has two openings: the thoracic inlet superiorly and the thoracic outlet inferiorly. The thoracic outlet communicates with the neck and has boundaries of the first rib, sterna, and vertebrae. The lower opening communicates with the abdomen through the diaphragm. Intercostal spaces contain muscles that aid in respiration. The anterior and posterior chest walls contain identifiable anatomical landmarks.

1. THORACIC CAVITY
By DR. Aliza Moin

2. Studying objectives
• To learn chest cavity
• Thoracic outlet
• Lower thoracic opening
• Intercostal space and muscles
• Anterior and posterior chest walls

3. Chest Cavity
• The chest cavity is bounded by
the chest wall and below by
the diaphragm
Extent
• Superiorly – root of neck
• Inferiorly – diaphragm

4. Openings of the Thorax
• Thorax has two openings
1. Thoracic inlet
2. Thoracic outlet

5. Thoracic outlet
• The chest cavity
communicates with the root
of the neck through an
opening called the thoracic
outlet
• The opening is obliquely
placed facing upward and
forward

6. Boundaries of thoracic outlet
posteriorly -- the 1st thoracic
Vertebra
laterally -- medial borders of the
1st ribs and their costal cartilages
anteriorly -- superior border of
the manubrium sterni

7. Contents of thoracic outlet
1. Esophagus
2. Trachea
3. Vessels and nerves

9. Lower thoracic opening
• The thoracic cavity
communicates with the
abdomen through a large
opening
• Through this large opening,
which is closed by the
diaphragm, pass the esophagus
and many large vessels and
nerves, all of which pierce the
diaphragm

10. Boundaries of Opening
• Posteriorly -- the 12th thoracic
vertebra
• Laterally -- the curving costal
margin
• anteriorly -- the xiphisternal
joint

11. Intercostal spaces and muscles

12. Intercostal Spaces
• The spaces between the ribs are
called inter costal spaces.
• contain three muscles of
respiration:
1. the external intercostal
2. the internal intercostal
3. the innermost intercostal
muscle

14. endothoracic fascia
• The innermost intercostal
• muscle is lined internally by the
endothoracic fascia, which
• is lined internally by the parietal
pleura

16. external intercostal muscle
• forms the most superficial layer
• Runs from from the inferior border
of the rib above to the superior
border of the rib below
• The muscle extends forward to the
costal cartilage where it is replaced
by an aponeurosis, the anterior
(external) intercostal membrane

17. internal intercostal muscle
• forms the intermediate
• Runs from the subcostal groove of
the rib above to the upper border
of the rib below
• The muscle extends backward from
the sternum in front to the angles
of the ribs behind, where the
muscle is replaced by an
aponeurosis,the posterior
(internal) intercostal membrane

18. innermost intercostal muscle
• forms the deepest layer
• crosses more than one
intercostal space within the ribs
• It is related internally to fascia
(endothoracic fascia) and
parietal pleura and externally to
the intercostal nerves and
vessels

19. Action
• Pull the ribs up ward in
inspiration
• Pull the ribs downward in
expiration

20. Levatores costarum
• Origin
Tip of transverse
process of C7 and
T1–11 vertebrae
• Insertion
Rib below
• Nerve supply
• Posterior rami of thoracic spinal
nerves
• Action
• Raises ribs and therefore inspiratory
muscles

21. Serratus posterior superior
• Origin
• Lower cervical and upper thoracic
spines
• Insertion
Upper ribs
• Nerve supply
Intercostal nerves
• Action
Raises ribs and therefore
inspiratory muscles

22. Serratus posterior inferior
• Origin
• Upper lumbar and lower thoracic
spines
• Insertion
Lower ribs
• Nerve supply
Intercostal nerves
• Action
• Depresses ribs and therefore
expiratory muscles

23. Intercostal nerve and blood vessels
• The intercostal nerves and blood
vessels run between the
intermediate and deepest layers
of muscles.
• Order
Vein  artery  Nerve

24. Chest walls

25. Anterior chest wall
• suprasternal notch
• sternal angle (angle of Louis)
• xiphisternal joint
• subcostal angle
• costal margin
• Clivicle
• Nipple

26. Posterior chest wall
• spinous processes
• The first spinous process to be
felt is that of the seventh
cervical vertebrae
• Scapula
1. Superior angle
2. Spine
3. Inferior angle