The thoracic inlet Flashcards
What is the thoracic inlet formed from?
The first thoracic vertebrae, the first ribs and their costal cartilages and the manubrium
What does the first rib articulate with?
The head articulates with its own first thoracic vertebra
The neck articulates with the transverse process of T1
In what direction do the bodies of the ribs travel?
Downwards and forwards towards their costal cartilages
What does a chrondrosternal joint connect?
The lateral border of the sternum and the costal cartilages
What is the classification of a chondrosternal joint?
A primary cartilaginous, immobile joint
In what direction does the thoracic inlet slope?
Downwards and forwards
What is the mediastinum?
The space between the pleural cavities which occupies the centre of the thoracic cavity
What are the borders of the superior mediastinum?
It is limited superiorly by the thoracic inlet and inferiorly by a transverse plane that passes backwards from the manubriosternal joint to the T4/5 intervertebral disc.
How are the brachiocephalic veins formed?
The union of the internal jugular vein with the subclavian vein, posterior to the sternoclavicular joint
What are the subclavian veins?
The continuations of the axillary veins and arch over the first rib, anterior to scalenus anterior
What path is taken by the internal jugular veins and what do they supply?
They start in the jugular foramina in the skull, from the sigmoid sinuses.
They descend in the neck lateral to the internal and common carotid arteries, and receive much of the deep venous drainage from the head and neck
What happens to the brachiocephalic veins?
They unite to form the superior vena cava behind the lower border of the first right costal cartilage
What are the major veins in the thoracic inlet?
Brachiocephalic
Subclavian
Internal jugular
Where does the arch of the aorta travel after leaving the heart?
Passes mainly anteroposteriorly from the manubrium, beginning and ending at the T4/5 level. It runs beside the trachea and arches over the left main bronchus
What are the 3 main branches from the aorta?
- Brachiocephalic
- Left common carotid
- Left subclavian
Where is the brachiocephalic artery and what does it divide into?
Lies to the right of the trachea and ascends to divide into the right subclavian and right common carotid arteries
Where does the subclavian artery lie?
Behind scalenus anterior and is described as having three parts in relation to that muscle
What are the main branches of the subclavian artery?
- Internal thoracic artery
- Vertebral artery
- Thyrocervical trunk
- Costocervical trunk
Where does the internal thoracic artery run and what does it supply?
Down the inner aspect of the thoracic wall behind the costal cartilages just lateral to the sternum, sending anterior intercostal branches into the appropriate spaces and perforating branches to supply the breast.
Its terminal branches are the musculophrenic and superior epigastric arteries
What is the path of the vertebral artery?
Ascends and enters the transverse foramen of C6, where it ascends in these foramina, finally entering the foramen magnum. It unites with its partner to form the basilar artery, supplying cerebellum and occipital lobe. During its course it also sends spinal branches to the vertebrae and spinal cord.
What arteries are given off by the thyrocervical trunk and what do they supply?
Gives the inferior thyroid artery supplying the lower poles of the thyroid gland, and the ascending cervical, suprascapular, and transverse cervical arteries. These arteries lie in the posterior triangle of neck, supplying adjacent muscles.
The suprascapular artery provides important branches to the scapular anastomosis which is completed by branches from the axillary artery in the upper limb
What does the costocervical trunk supply?
Posterior intercostal arteries to the upper intercostal spaces, and the deep cervical artery to deep structures in the neck