6.💗SKELETON OF THE THORAX. JOINTS OF THE THORAX. THE THORAX AS A WHOLE. BIOMECHANICS💗

What are the functions of the thorax?**

- Place for muscle attachment of upper extremities
- Provides protection for the heart, lungs, and viscera

What structures are included in the thorax as a whole?**

- Sternum
- Ribs
- Costal cartilage
- Thoracic vertebrae
- Intervertebral (IV) disks

Describe the sternum and its components.**

- Flat bone in the middle of the thorax
- Composed of three fused bones: manubrium, body, and xiphoid process
- The body contains notches for the clavicle and jugular
- The body and manubrium meet at the sternal angle
- The body contains costal notches that articulate with the ribs
- The point of articulation between the body and xiphoid process is called the xiphisternal joint

How many thoracic vertebrae are there, and what is their function?**

- 12 thoracic vertebrae
- Part of the rib cage that protects the heart and lungs

How many pairs of ribs are there, and how are they categorized?**

- 12 pairs of ribs
- Categorized into:
- True ribs (1-7): attach directly to the sternum
- False ribs (8-10): do not join to the sternum directly; connected to the 7th rib by cartilage
- Floating ribs (11-12): do not reach the front of the body; about half the size of other ribs

What forms the thoracic cage, and what is its function?**

- Formed by bones and cartilage
- Designed to increase and decrease intrathoracic pressure
- Allows air to be sucked into the lungs during inspiration and expelled during expiration
- Facilitates the process of ventilation and gas exchange

Describe the types of joints associated with the thorax.**

- 2nd-7th costal cartilages articulate with the sternum by synovial joints
- Manubriosternal: slight movement of the sternum's body on the manubrium during respiration
- Costovertebral: connect the heads of ribs with bodies of thoracic vertebrae
- Costotransverse: tubercle of a typical rib articulates with the transverse process of the corresponding vertebra; forms a synovial joint
- Chondrosternal: cartilaginous joints that do not permit movement but help stabilize the shoulder girdle
- Costochondral: connect the sternal end of ribs with the lateral ends of costal cartilage
- Interchondral: 5th-9th cartilages articulate with one another via synovial joints; the 10th is united to the 9th by fibrous tissue

How is the movement of air in and out of the lungs changed?**

- By changes in the lung's volume

How do volume changes in the lungs enable inspiration and expiration?**

- Inspiration: air is taken in, oxygen enters the body, diaphragm and intercostal muscles contract (active process)
- Expiration: air is expelled, CO2 is removed from the body, diaphragm recoils, and intercostal muscles relax