Thyrocervical trunk

Arises from the subclavian artery usually near the medial border of the anterior scalenus muscle, more proximally than the costocervical trunk.

1. Ascending cervical artery
   • Ascends between the scalenus anterior and longus cervicis muscles, anterior to the transverse processes of the cervical vertebrae, medial to the phrenic nerve, posterior to the carotid artery and anterolateral to the vertebral artery
   • Anastomoses with the vertebral artery, the deep cervical artery and the occipital artery
   • Gives off branches to the cervical muscles, supplies small branches to the intervertebral foramina and may contribute small spinal branches

2. Inferior thyroid artery
   • Ascends anterior to the vertebral artery and longus colli muscle, courses superiorly and medially, behind the carotid sheath, toward the lower pole of the thyroid gland and loops medially and downward, often deep to the carotid sheath and sympathetic trunk, to reach the posteroinferior aspect of the thyroid gland
   • The ascending cervical artery may arise from the inferior thyroid artery
   • Supplies:
     • Thyroid branches to the inferior aspect of the thyroid. Anastomose with the superior thyroid artery
     • Inferior laryngeal artery
       • Accompanies the recurrent laryngeal nerve
       • Supplies the muscles and mucosa of the infraglottic portion of the larynx
     • Tracheal, esophageal and pharyngeal branches supply the respective structures

3. Transverse artery of the neck (transversallis colli)
   • Runs laterally across the anterior scalene muscle, phrenic nerve, and brachial plexus
   • Travels toward the posterior triangle of the neck with the accessory nerve and supplies the brachial plexus, trapezius muscle and overlying skin
   • The dorsal scapular artery sometimes arises as a deep branch of the transverse artery of the neck

4. Suprascapular artery
   • Runs inferolaterally posterior to the internal jugular vein and sternocleidomastoid muscle, reaches the superior border of the scapula
   • Supplies:
     • Parts of the sternocleidomastoid, subclavius, infraspinatus
     • Adjacent skin of the upper thoracic cage and shoulder

5. Dorsal scapular artery
   • Most often arises directly from the subclavian artery, less comonly from the thyrocervical trunk or the transverse artery of the neck
   • Passes posteriorly, often piercing the brachial plexus between middle and lower trunks
   • Travels along the medial border of the scapula, deep to the levator scapulae, rhomboid major, and rhomboid minor muscles
   • Runs with the dorsal scapular nerve (from the C5 root)
   • Supplies:
     • Levator scapulae
     • Rhomboid major and minor
     • Part of the trapezius
     • Scapular periosteum and associated fascia