STERNAL ANGLE:

It is a transverse ridge between the Manubrium sterni & body of the sternum
marking the menubrio-sternal joint.
Situation:
It lies at the level of the second costal cartilage anteriorly and the disc between
the 4th and 5th thoracic vertebrae posteriorly. It marks the upper limit of the
base of the heart. Line of junction between C4 & T2 dermatomes The upper
margin of superior venacava: It marks the plane which separates the superior
mediastinum from inferior mediastinum
Importance of Sternal angle (angle of Louis) *** RATPLANT
✓R- From this level, the ribs are counted (2nd rib)

✓A-The ascending aorta ends at this level. The arch of the aorta
begins and also ends. The descending thoracicaorta begins.
✓T- The trachea divides into two principal bronchi below this
level.(Level with the upper half of T6).
✓P- The pulmonary trunk divides into two pulmonary arteries
below this level, (level with the upper half of T6).
✓L- Left recurrent laryngeal nerve.

✓A-The azygos vein arches over the root of the right lung & open
into the superior venacava
✓N- The cardiac plexuses are situated at the same level.

✓T- The thoracic duct crosses from right to left behind

because it is subcutaneous and readily accessible. The bone

marrow sample is required for hematological examination. A thick

needle is inserted into the upper part of manubrium to avoid injury

to arch of aorta which lies behind the lower part. Sternal puncture

is not advisable in children because in them the plates of compact

bone of sternum are very thin and if needle passes through and

through the manubrium it will damage the arch of aorta and its

branches, leading to fatal hemorrhage.

Mid-sternotomy:

To gain access to the mediastinum for surgical operations on heart

and great blood vessels, the sternum is often divided in the median

plane called midsternotomy

Funnel chest (pectus excavatum)

It is an abnormal shape of thoracic cage in which chest is

compressed Anteroposteriorly and sternum is pushed backward by

the overgrowth of the ribs and may compress the heart

Pigeon chest (pectus carinatum)

It is an abnormal shape of thoracic cage in which chest is

compressed from side-to-side and sternum projects Forward and

downward like a keel of a boat.

Sternal fructure:

It is common in automobile accidents; e.g., when the driver's chest

is hit against the steering wheel, the sternum is often fractured at

the sternal angle.The backward displacement of fractured

fragments may damage aorta, heart, or liver and cause severe

bleeding which may prove fatal

This rib is usually represented by a fibrous band originating from

the seventh cervical vertebra and inserting on the first thoracic rib.

Arising from the anterior tubercle of the transverse process of C7.

Occasionally cervical may have free distal extremity or may be only

represented by a fibrous band, that is not visualized in X ray, it may

be asymptomatic, but because the subclavian artery and brachial

plexus course over it, a variety of symptoms may occur

The lower trunk of the plexus (mainly T1) is compressed, leading to

wasting of the interossei and altered sensation in the T1

distribution Compression of the subclavian artery may result in a

post-stenotic dilatation with thrombus and embolism formation.

The diagnosis, assessment and surgery are fraught with

uncertainties and are best left to those with a well-developed

interest in this problem. Plain radiograph demonstrates cervical rib

as small hom like structures.

• Incidence of 1:200. 0.5% (1%) of human

• May be bilateral in 1:500,

• Rib may be complete, articulates with transverse process of

seventh cervical vertebra behind and first rib in front.

Symptoms are less in complete rib than incomplete one.

❖Vascular consequences include post-stenotic dilatation of

subclavian artery,causing local turbulence thrombosis and

possibility of distal emboli. Subclavian aneurysm may also arise

❖Pressure on vein may result in subclavian vein thrombosis.

❖Can case pressure on lower trunk of brachial plexus → pain is

medial aspect of hand, forearms, result in paraesthesia.

Wasting of small muscle of hand.

Clinically ‘thoracic outlet syndrome' is used to describe symptoms

as it passes over the first rib and through the auxillary inlet into the

upper limb. ADSON TEST is performed to evaluate thoracic outlet

syndrome.

Rib fractures

The weakest part of the rib is the body anterior to the angle, and it

is here that most fractures occur after blunt trauma. Direct trauma

may produce fracture in any part of the rib. In both cases, the

fracture fragments may damage adjacent structures, such as

intercostal vessels, pleura, lung or spleen.

ADSON TEST

Full neck extension and head rotation toward the side being

examined, during deep inhalation, to detect a reduction in radial

pulse amplitude in thoracic outlet syndrome

Inlet of thorax

A tumor at the apex of the lung (Pan Coast tumor) may result in

thoracic inlet syndrome.

• Lumbar rib (Gorilla rib): It develops from the costal element of LI

vertebra. Its incidence is more common than the cervical rib, but

remains undiagnosed as it usually does not cause symptoms. It may

be confused with the fracture of transverse process of L1 vertebra,

•Fracture of rib: Usually the middle ribs are involved in the

fracture. The rib commonly fractures at its angle (posterior angle)

as it is the weakest point.

•Flail chest (stove-in-chest): When ribs are fractured at two sites

(c.g., anteriorly as well as at an angle), the flail chest occurs. The

flail segments of ribs are sucked in during inspiration and pushed

out during expiration leading to a clinical condition called

paradoxical respiration).
• Fracture of ribs is rare in children as the ribs are elastic in them.

• First two ribs (Ist and 2nd ribs) are protected by clavicle and last

two ribs (11th and 12th) are mobile (floating),hence they are rarely

injured.

Thoracic Vertebrae

There are 12 thoracic vertebrae. They are identified by the

presence of costal facet/facets on the sides of their bodies for

articulation with the heads of the ribs. These articulations are

characteristic of thoracic vertebrae as they are not found in the

cervical lumbar and sacral vertebrae. The size of thoracic vertebrae

increases gradually from above downwards.

The bodies of upper thoracic vertebrae is gradually changed from

cervical to thoracic type and those of lower from thoracic to lumbar

type. Thus the body of TI vertebra is typically cervical in type and

that of T12 vertebra is,typically lumbar in type,

★Presence of the articular facet(s) on the side of the body is the

cardinal feature of the thoracic vertebra

Classification

According to the features, the thoracic vertebrae are classified into

two types:

1. Typical: second to eighth

2. Atypical: first and ninth to twelfth