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.

RibsClassification 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 ribsFirst 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 riba. Single articular facet on the head.

Eleventh riba. 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 vertebraeClassification 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

Superior surface

Lateral 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

Prof.: Dr. Wafaa Abdel-Rahman