Download Thoracic cage

Thoracic cage
Thoracic inlet
Thoracic Cage
- The thoracic cage consists of the sternum, the ribs, and the
thoracic vertebrae.
- It has a narrow inlet and a wide outlet.
I. Thoracic inlet: (the upper opening of the thoracic cage)
Boundaries:
a. Anterior -------------- Supra-sternal notch of the
manubrium sterni.
b. On each side --------- First rib.
c. Posterior -------------- First thoracic vertebra.
II. Thoracic outlet
It is the lower opening of the thoracic cage.
Boundaries:
a. Anterior -------------- Xiphoid process.
b. On each side --------- Lower six costal cartilages +
Last two ribs.
c. Posterior -------------- Last thoracic vertebra.
- It is closed by the diaphragm which separates it from
the abdominal cavity.
Ribs
Classification of ribs according to their attachments to
the sternum:
- There are twelve ribs on each side classified as:
A: True ribs --------- Upper seven ribs (their anterior end is
attached to the sternum).
B: False ribs --------- Lower five ribs (they are not attached
anteriorly to the sternum).
- The lower two ribs are called the floating ribs because
they are free anteriorly.
Classification of ribs according to their structure:
A: Typical ----------- 3rd - 9th ribs.
B: Atypical ---------- 1st, 2nd, 10th, 11th, and 12th ribs. (first
two and last 3) ribs)
Typical rib
A: Posterior end, formed by:
1. Head, contains:
- Small upper demifacet for articulation with the small
lower demifacet on the side of the vertebra above it.
- Large lower demifacet for articulation with the large
upper demifacet on the side of the vertebra of the same
number.
- Between both demifacets there is the crest of the head.
2. Neck
- It is the flattened constriction next to the head.
3. Tubercle, formed by:
- Articular part (medial part), which articulates with the
circular facet on the tip of the transverse process of the
vertebra of the same number.
-Non articular part (lateral part), which is attached to the
lateral costo-transverse ligament .
Atypical ribs
First rib (general features)
First rib
Structures related
The neck of the first rib
The neck is related
anteriorly from medial to
lateral to:
a. Stellate ganglion.
b. Superior intercostal
artery.
c. Ventral ramus of the
1st thoracic nerve.
Second rib
Tenth rib
a. Single articular facet on
the head.
Eleventh rib
a. Single articular facet
on the head.
b. No tubercle.
Twelveth rib
a. Single articular facet on the head.
b. No tubercle.
c. No neck.
d. No costal groove.
e. Large head.
f. Tapering anterior end.
Sternum
(Parts)
Sternum
(General features)
Thoracic vertebrae
Classification of thoracic vertebrae:
- There are twelve thoracic vertebrae classified as:
A: Typical ------ 2nd – 8th vertebrae.
B: Atypical ----- 1st, 9th, 10th, 11th, and 12th vertebrae
(first one and last 4 vertebrae).
Characteristics of a typical thoracic
vertebra
1. The body is characterized by:
- Small in size and heart shaped.
- Its side contains two demifacets:
a. Large upper demifacet for articulation with the head of the rib
of the
corresponding number.
b. Small lower demifacet for articulation with the head of the rib
below it. 
2. The tip of the transverse process contains circular facet for
articulation with the
tubercle of the rib of the corresponding number. 
3. The spine is long, tapering, and directed downwards and
backwards.
4. The vertebral foramen is circular and small. 
5. The superior articular process faces backwards, while the inferior
articular
Typical thoracic vertebra
Lateral
surface
Superior
surface
First thoracic vertebra
1. The body is small .
2. The vertebral foramen is wide and triangular.
3. The body carries complete circular articular facet for
articulation with the head of the first rib.
4. The spine is horizontal.
The ninth& tenth thoracic
vertebrae
Ninth
vertebra
Tenth vertebra
The eleventh & twelveth thoracic
vertebrae
Eleventh vertebra
Twelveth vertebra
Thank You
Prof.: Dr. Wafaa Abdel-Rahman