The thyrocervical trunk is a branch of the subclavian artery

Subclavian artery

In human anatomy, the subclavian arteries are two major arteries of the upper thorax , below the clavicle . They receive blood from the top of the aorta...

 arising from the first portion of this vessel, i.e. between the origin of the subclavian artery and the inner border of the scalenus anterior

Scalenus anterior

The Scalenus anterior , also known as anterior scalene muscle, lies deeply at the side of the neck, behind the Sternocleidomastoideus.-Anatomy:...

 muscle. It is located distally to the vertebral artery

Vertebral artery

The vertebral arteries are major arteries of the neck. They branch from the subclavian arteries and merge to form the single midline basilar artery in a complex called the vertebrobasilar system, which supplies blood to the posterior part of the circle of Willis and thus significant portions of the...

 and proximally to the costocervical trunk

Costocervical trunk

The costocervical trunk arises from the upper and back part of the subclavian artery, behind the scalenus anterior on the right side, and medial to that muscle on the left side....

.

Branches

It is a short and thick vessel and it divides soon after its origin in three branches:

• inferior thyroid artery
  Inferior thyroid artery
  The inferior thyroid artery arrises from the thyrocervical trunk and passes upward, in front of the vertebral artery and Longus colli, then turns medially behind the carotid sheath and its contents, and also behind the sympathetic trunk, the middle cervical ganglion resting upon the...
  
  
• suprascapular artery
  Suprascapular artery
  The suprascapular artery is a branch of the thyrocervical trunk.-Course:At first, it passes downward and laterally across the scalenus anterior and phrenic nerve, being covered by the sternocleidomastoid muscle; it then crosses the subclavian artery and the brachial plexus, running behind and...
  
  
• transversalis artery colli or transverse cervical artery
  Transverse cervical artery
  The transverse cervical artery is a branch of the thyrocervical trunk, running at a higher level than the suprascapular artery.-Path:...
  
  

The suprascapular artery

Suprascapular artery

The suprascapular artery is a branch of the thyrocervical trunk.-Course:At first, it passes downward and laterally across the scalenus anterior and phrenic nerve, being covered by the sternocleidomastoid muscle; it then crosses the subclavian artery and the brachial plexus, running behind and...

 and transverse cervical artery

Transverse cervical artery

The transverse cervical artery is a branch of the thyrocervical trunk, running at a higher level than the suprascapular artery.-Path:...

 both head laterally and cross in front of (anterior to) the scalenus anterior muscle and the phrenic nerve

Phrenic nerve

The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 5th and 3rd cervical nerves in humans....

. The inferior thyroid artery runs superiorly from the thyrocervical trunk to the inferior portion of the thyroid gland.