topic 3: The bones and joints of the thorax. The movements of respiration.

Question 1

bones of thorax

Answer 1

Sternum: Also known as the breastbone, the sternum is a flat bone located in the anterior midline of the chest. It consists of three main parts: the manubrium, body, and xiphoid process.

Ribs: There are 12 pairs of ribs in the human body, which attach posteriorly to the thoracic vertebrae and anteriorly to the sternum via costal cartilages. Ribs are classified into three types:

True Ribs (1-7): Directly attach to the sternum via their own costal cartilages.
False Ribs (8-10): Indirectly attach to the sternum via the costal cartilage of the rib above.
Floating Ribs (11-12): Do not attach to the sternum and terminate anteriorly within the musculature of the abdominal wall.

Thoracic Vertebrae: The 12 thoracic vertebrae (T1-T12) form the posterior part of the thoracic cage, providing attachment sites for the ribs.

Question 2

joints

Answer 2

-Costovertebral articulations: costal head joint + costotransverse joint
-Sternocostal articulations: small sliding movements
-Synchondrosis of the first rib: no movement
-Costochondral articulations: no movement
-Interchondral articulations: small sliding movements
-Xiphisternal symphysis: ossification is frequent
-Manubriosternal symphysis: true symphysis

Question 3

1. Costovertebral Articulations

Answer 3

facets:Costal head joint: The head of the rib articulates with the vertebral bodies (two vertebrae and the intervertebral disc).
Costotransverse joint: The tubercle of the rib articulates with the transverse process of the vertebra.

Ligaments:

-Radiate ligament: Connects the rib head to the vertebral bodies and intervertebral disc.

-Costotransverse ligament: Connects the rib tubercle to the transverse process.

-Lateral costotransverse ligament: Reinforces the costotransverse joint.

Movements: Small sliding and gliding movements during breathing.

Question 4

2. Sternocostal Articulations

Answer 4

Type: Synovial plane joint (for ribs 2-7)

Facets:Articulation between the costal cartilage of the ribs (2-7) and the sternum (sternal notch, body of the sternum).

Ligaments:
Radiate ligament: Connects the costal cartilage to the sternum.

Movements: Small sliding movements for rib expansion during breathing.

Question 5

3. Synchondrosis of the First Rib

Answer 5

Type: Synchondrosis (cartilaginous joint)

Facets:The first rib cartilage articulates with the manubrium of the sternum.

Ligaments: None (cartilaginous connection).

Movements: No movement (immovable joint).

Question 6

4. Costochondral Articulations

Answer 6

Type: Primary cartilaginous joint (synchondrosis)

Facets:Costal cartilage of ribs 1-10 articulates with the sternal end of the ribs.

Ligaments: None (no synovial cavity).

Movements: No movement (immovable joint).

Question 7

5. Interchondral Articulations

Answer 7

Type: Synovial plane joints

Facets:Articulations between the costal cartilages of ribs 6-9.

Ligaments: None specific (usually reinforced by fibrous tissue).

Movements: Small sliding movements to allow rib movement during breathing.

Question 8

6. Xiphisternal Symphysis

Answer 8

Type: Symphysis (secondary cartilaginous joint)

Facets:The xiphoid process of the sternum articulates with the body of the sternum.

Ligaments: None specific.

Movements: Ossification occurs with age; minimal movement in early life.

Question 9

7. Manubriosternal Symphysis

Answer 9

Type: True symphysis (secondary cartilaginous joint)

Facets:The manubrium articulates with the body of the sternum.

Ligaments: Reinforced by the manubriosternal ligament.

Movements: Limited movement, but allows slight movement during deep breathing.

Question 10

insipiration

Answer 10

Inspiration: The process of inhalation involves the expansion of the thoracic cavity, which increases the volume of the lungs and allows air to flow in.

Key movements during inspiration include:

Elevation of the Ribs: Contraction of the external intercostal muscles lifts the ribs upward and outward.

Flattening of the Diaphragm:
Contraction of the diaphragm causes it to flatten, further increasing thoracic volume.

Question 11

expiration

Answer 11

Expiration: The process of exhalation involves the reduction of thoracic cavity volume, which compresses the lungs and expels air.

Key movements during expiration include:

Depression of the Ribs: Relaxation of the external intercostal muscles allows the ribs to return to their resting position.

Relaxation of the Diaphragm: Relaxation of the diaphragm causes it to return to its dome-shaped position, reducing thoracic volume.