Thorax

Question 1

Bones of the Thorax

Answer 1

1. Ribs (Costae):
   - True Ribs (1-7): These ribs attach directly to the sternum via their costal cartilages.
   - False Ribs (8-10): These ribs are indirectly attached to the sternum through the cartilage of the 7th rib.
   - Floating Ribs (11-12): These ribs do not attach to the sternum or the cartilage of other ribs and end between the abdominal muscles.
2. Sternum: Comprised of three parts – the manubrium, body, and xiphoid process. It serves as an attachment point for the true ribs.
3. Thoracic Vertebrae: The thoracic region consists of 12 thoracic vertebrae (T1-T12) that articulate with the ribs and provide structural support.

Question 2

Joints of the Thorax

Answer 2

1. Costovertebral Joints: These joints connect the heads of the ribs to the costal facets on the thoracic vertebrae. They allow for rotation and elevation of the ribs during respiration.
2. Costotransverse Joints: These joints connect the tubercle of the rib to the transverse process of the corresponding thoracic vertebra.
3. Sternocostal Joints: The first rib articulates with the sternum via a synchondrosis, while ribs 2-7 form plane-type joints with the sternum.
4. Manubriosternal Joint: A synchondrosis that may ossify with age.

Question 3

Muscles of the Thorax

Answer 3

1. Respiratory Muscles:
   - Diaphragm: The primary muscle of respiration, separating the thoracic and abdominal cavities. Innervated by the phrenic nerve.
   - Intercostal Muscles: External intercostal muscles assist in inhalation by elevating the ribs, while internal intercostal muscles aid in forced expiration.
   - Accessory Muscles of Respiration: Include the scalene muscles, pectoralis major and minor, sternocleidomastoid, and others that assist in breathing during exertion.

Question 4

Ligaments of the Thorax

Answer 4

1. Costotransverse Ligament: Connects the neck of the rib to the transverse process of the thoracic vertebra.
2. Lateral Costotransverse Ligament: Connects the tip of the transverse process to the roughened non-articular part of the rib tubercle.
3. Superior Costotransverse Ligament: Attaches the neck of the rib to the transverse process of the vertebra above.
4. Radiate Ligament: Reinforces the capsule of the joint of the head of the rib.

Question 5

Blood Vessels of the Thorax

Answer 5

1. Intercostal Arteries: Branches of the thoracic aorta that supply blood to the intercostal spaces.
2. Internal Thoracic Artery: A branch of the subclavian artery that supplies the anterior thoracic wall.
3. Subclavian Artery: Supplies blood to the upper limbs and parts of the thorax.
4. Pulmonary Arteries and Veins: Carry deoxygenated blood to the lungs and return oxygenated blood to the heart

Question 6

Nerves of the Thorax

Answer 6

1. Intercostal Nerves: These are the ventral rami of the thoracic spinal nerves (T1-T11) that innervate the intercostal muscles and provide sensory innervation to the skin over the thorax.
2. Phrenic Nerve: Arising from the cervical plexus (C3-C5), it innervates the diaphragm and is crucial for respiration.
3. Vagus Nerve: Provides parasympathetic innervation to the thoracic organs.