The Thoracic wall(Bones)

By Dr. Noura El Tahawy

MD. Ph. D

Axial vs. Appendicular Skeleton

• Axial Skeleton– Skull = Cranium + Facial bones– Vertebral Column– Ribs– Sternum

• Appendicular Skeleton– Bones of upper/lower limbs– Limb Girdles

The Bony Thorax

The Bony Thorax

• Sternum– Manubrium, Body

(Gladiolus), Xiphoid Process

• Ribs– 7 True Ribs– 5 False Ribs

• Clavicle• Scapula• Vertebrae

– Cervicle,Thoracic, Lumbar, Sacral (Sacrum), Coccygeal (Coccyx)

The Bony Thorax

The Sternum (Composed of fused sternebrae)

• Manubrium

– Jugular (sternal) notch

– Articulation with rib No.1 & 2

– Clavicular Articular facets

– Sternal Angle – 2nd rib

• Body

– Articulates with ribs 2-7

– Xiphosternal joint

• Xiphoid process

– Cartilage-calcifies through time

– Partial attachment of many muscles

Sternum.

Sternocostal joints.

Clinical Notes

Sternum and Marrow Biopsy

Since the sternum possesses red hematopoietic marrow throughout life, it is a common site for marrow biopsy.

Under a local anesthetic, a wide-bore needle is introduced into the marrow cavity through the anterior surface of the bone. The sternum may also be split at

operation to allow the surgeon to gain easy access to the heart, great vessels, and thymus.

Rib Anatomy

• Typical Ribs– Head– Neck– Tubercle– Angle– Shaft– Subcostal

Groove

•Atypical Ribs

• No.1-short, flat (S-I), wide, Supports Subclavian vessels

• No.1, 10-12 articulate with only = No. vertebra

• No.11, 12 don’t articulate with transverse processes, or anteriorly at all

The Ribs• Typical Ribs

– Ribs No. 2-9• Atypical Ribs

– Ribs No.1, 10, 11, 12 • Reinforce thoracic cage

Anatomy of the ribs

• True ribs: The upper seven pairs are attached anteriorly to the sternum by their costal cartilages

• False ribs: The 8th, 9th, and 10th pairs of ribs are attached anteriorly to each other and to the 7th rib by means of their costal cartilages and small synovial joints.

• Floating ribs: The 11th and 12th pairs have no anterior attachment.

• Long, twisted, flat bone having a rounded, smooth superior border and a sharp, thin inferior border. The inferior border overhangs and forms the costal groove, which accommodates the intercostal vessels and nerve. The anterior end of each rib is attached to the corresponding costal cartilage • A rib has a head, neck, tubercle, shaft, and angle .

• The head has two facets for articulation with the numerically corresponding vertebral body and that of the vertebra immediately above.

• The neck is a constricted portion situated between the head and the tubercle.

• The tubercle is a prominence on the outer surface of the rib at the junction of the neck with the shaft. It has a facet for articulation with the transverse process of the numerically corresponding vertebra.

• The shaft is thin and flattened and twisted on its long axis. Its inferior border has the costal groove. The angle is where the shaft of the rib bends sharply forward.

Typical rib

Fifth right rib, as seen from the posterior aspect.

A typical rib. A. Anterior view. B. Posterior view of proximal end of rib.

Atypical Ribs

• The first rib is important clinically because of its close relationship to the lower nerves of the brachial plexus and the main vessels to the arm, namely, the subclavian artery and vein .This rib is small and flattened from above downward. The scalenus anterior muscle is attached to its upper surface and inner border. Anterior to the scalenus anterior, the subclavian vein crosses the rib; posterior to the muscle attachment, the subclavian artery and the lower trunk of the brachial plexus cross the rib and lie in contact with the bone.

Atypical ribs.

Thoracic vertebrae

Dr, Noura El Tahawy

Typical thoracic vertebra.

Atypical thoracic vertebrae.

Thoracic vertebra. A. Superior surface. B. Lateral surface.

Typical Rib Articulation

• Dorsal (P) Attachment Thoracic Vertebrae

– Head of Rib 2 Demifacets

» Superior demifacet

» Inferior demifacet of vertebra above it

» Intervertebral disc

– Tubercle of Rib Transverse Costal Facet

– e.g. Rib No. 4 articulates with Superior Demifacet and Transverse Costal Facet of T4 & Inferior demifacet of T3

• Ventral (A) Attachment to Sternum

– Via costal cartilage

Fifth right rib as it articulates with the vertebral column posteriorly and the sternum anteriorly. Note that the rib head articulates with the vertebral body of its own number and that of the vertebra immediately above. Note also the presence of the costal groove along the inferior border of the rib.

alsoalso

Joints of the Chest Wall

Dr. Noura El Tahawy

Joints of the Chest Wall

• Joints of the Sternum

• The manubriosternal joint is a cartilaginous joint between the manubrium and the body of the sternum. A small amount of angular movement is possible during respiration. The xiphisternal joint is a cartilaginous joint between the xiphoid process (cartilage) and the body of the sternum. The xiphoid process usually fuses with the body of the sternum during middle age.

• Joints of the Ribs

• Joints of the Heads of the Ribs

• The first rib and the three lowest ribs have a single synovial joint with their corresponding vertebral body. For the second to the ninth ribs, the head articulates by means of a synovial joint with the corresponding vertebral body and that of the vertebra above it. There is a strong intraarticular ligament that connects the head to the intervertebral disc.

• Joints of the Tubercles of the Ribs

• The tubercle of a rib articulates by means of a synovial joint with the transverse process of the corresponding vertebra. (This joint is absent on the 11th and 12th ribs

• Joints of the Ribs and Costal Cartilages

• These joints are cartilaginous joints. No movement is possible

• Joints of the Costal Cartilages with the Sternum

• The first costal cartilages articulate with the manubrium, by cartilaginous joints that permit no movement. The 2nd to the 7th costal cartilages articulate with the lateral border of the sternum by synovial joints. In addition, the 6th, 7th, 8th, 9th, and 10th costal cartilages articulate with one another along their borders by small synovial joints. The cartilages of the 11th and 12th ribs are embedded in the abdominal musculature.

Sternocostal joints.

Joints between ribs and vertebreae

Costovertebral joints.

Chest radiographs. A. Standard posterior-

anterior view of the chest. B.

Standard lateral view of

the heart.

Openings of the Thorax

Dr. Noura El Tahawy

• The chest cavity communicates with the root of the neck through an opening called the thoracic outlet. It is called an outlet because important vessels and nerves emerge from the thorax here to enter the neck and upper limbs.

• The opening is bounded posteriorly by the first thoracic vertebra, laterally by the medial borders of the first ribs and their costal cartilages, and anteriorly by the superior border of the manubrium sterni. The opening is obliquely placed facing upward and forward.

• Through this small opening pass the esophagus and trachea and many vessels and nerves. Because of the obliquity of the opening, the apices of the lung and pleurae project upward into the neck.

• The thoracic cavity communicates with the abdomen through a large opening. • The opening is bounded posteriorly by the 12th thoracic vertebra, laterally by the curving costal margin, and anteriorly by the xiphisternal joint.

• 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.

Openings of the Thorax

Thoracic outlet showing the cervical dome of pleura on the left side of the body and its relationship to the inner border of the first rib. Note also the presence of brachial plexus and subclavian vessels. (Anatomists often refer to the thoracic outlet as the thoracic inlet.

Superior thoracic aperture.

components, contents, passages and relationshipsSuperior thoracic aperture: vertebra TI, rib I, costal cartilage I, manubrium of sternumContents: Apices of right and left lung; brachiocephalic, subclavian arteries and veins;

trachea, esaphagus; vagus nerves; sympathetic trunc; phrenic nerves

Contents: Apices of right and leftlung; brachiocephalic,subclavian arteries and veins;trachea, esaphagus; vagusnerves; sympathetic trunc;phrenic nerves

The Thoracic Outlet Syndrome

The brachial plexus of nerves (C5, 6, 7, and 8 and

T1) and the subclavian artery and vein are closely

related to the upper surface of the first rib and the clavicle as they enter the upper limb. It is here that the nerves or blood

vessels may be compressed between the

bones. Most of the symptoms are caused by

pressure on the lower trunk of the plexus

producing pain down the medial side of the forearm and hand and wasting of the small muscles of the

hand. Pressure on the blood vessels may compromise the

circulation of the upper limb.

• A cervical rib (i.e., a rib arising from the anterior tubercle of the transverse

process of the seventh cervical vertebra) occurs in about 0.5% of humans.

It may have a free anterior end, may be connected to the first rib by a

fibrous band, or may articulate with the first rib. The importance of a

cervical rib is that it can cause pressure on the lower trunk of the brachial

plexus in some patients, producing pain down the medial side of the

forearm and hand and wasting of the small muscles of the hand. It can also

exert pressure on the overlying subclavian artery and interfere with the

circulation of the upper limb see the figure in the previous slide.

Cervical Rib

Thoracic outlet as seen from above. Note the presence of the cervical ribs (black) on both sides. On the right side of the thorax, the rib is almost complete and articulates anteriorly

with the first rib. On the left side of the thorax, the rib is rudimentary but is continued forward as a fibrous band that is attached to the first costal cartilage. Note that the cervical

rib may exert pressure on the lower trunk of the brachial plexus and may kink the subclavian artery.

A. Inferior thoracic aperture. B. Diaphragm.

Flexible thoracic wall and inferior thoracic aperture.

Major structures passing between abdomen and thorax.

 Diaphragm as seen from below. The anterior portion of the right side has been removed. Note the sternal, costal, and vertebral origins of the muscle and the important structures that pass through it.

References

1- Richard Snell; Clinical Anatomy by regions; Eighth Edition; 2008

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