Joints of Thorax ,Respiratory Movements,Clinical Anatomy

Topic Overview

Joints of Thorax

1. Manubriosternal Joint

• Type – Secondary cartilaginous (symphysis).

• Permits slight gliding movement of the body of sternum on the manubrium during respiration.

• Forms the sternal angle (Angle of Louis), a major surface landmark at the level of the second costal cartilage and T4 vertebra.

2. Costovertebral Joints

• Each head of a typical rib articulates with the demifacets on its own vertebral body and that of the vertebra above.

• Type – Plane synovial joint with two cavities separated by an intra-articular ligament.

• Ligaments – Radiate and intra-articular ligaments.

• Movements – Rotation of rib necks during breathing.

3. Costotransverse Joints

• Between the tubercle of the rib and transverse process of the corresponding vertebra.

• Type – Plane synovial.

• Ligaments – Superior, lateral, and proper costotransverse ligaments.

• Movements – Gliding and rotation around the transverse axis.

4. Sternocostal Joints

• First → Primary cartilaginous (synchondrosis).

• 2nd to 7th → Plane synovial.

• Permit elevation and depression of the ribs during breathing.

5. Costochondral Joints

• Between ribs and their cartilages – Primary cartilaginous.

6. Interchondral Joints

• Between the cartilages of 6th–9th ribs – Small plane synovial joints; allow slight gliding.

7. Xiphisternal Joint

• Primary cartilaginous between the xiphoid process and the body of the sternum.

Respiratory Movements

Mechanism of Breathing

• Inspiration: Increase in thoracic cavity volume → negative pressure → air enters lungs.

• Expiration: Elastic recoil of lungs and chest wall → air expelled.

• Movements occur mainly at costovertebral and manubriosternal joints.

Types of Rib Movements

1. Pump-handle Movement:
    - Occurs in upper ribs (2nd–6th).
    - Axis passes through costovertebral and costotransverse joints.
    - Increases anteroposterior diameter of thorax.

2. Bucket-handle Movement:
    - Occurs in lower ribs (7th–10th).
    - Axis more oblique; increases transverse diameter.

3. Piston Movement of Diaphragm:
    - Descent of diaphragm increases vertical diameter.

Summary of Movements

Clinical Anatomy

• Fracture dislocation of ribs → Pain and restricted chest expansion.

• Costochondritis → Inflammation of costal cartilage causing localized tenderness (often mistaken for cardiac pain).

• Flail chest → Multiple rib fractures producing paradoxical chest movement.

• Sternal angle palpation → Used to locate 2nd rib for counting intercostal spaces.

• Thoracic outlet syndrome → Compression of subclavian vessels and brachial plexus by a cervical rib.

• Arthritis of costovertebral joints → Pain on deep breathing.

These points integrate all core anatomy, mechanisms, and applied correlations of thoracic joints and breathing movements—concise enough for exam and viva preparation