The costocervical trunk is one of the branches of the second part of the subclavian artery. It arises from the posterior wall of the subclavian artery, posterior or medial to the anterior scalene muscle and courses posterosuperiorly across the suprapleural membrane where it divides into 2 branches:
- the superior (supreme) intercostal artery which supplies the first two intercostal spaces. It enters the thorax by passing across the neck of the first rib.
- the deep cervical artery which supplies the posterior deep cervical muscles and may anastomose with the occipital artery anterior to the semispinalis capitis muscle.