The superior root of the ansa cervicalis is formed by branches of spinal nerves [Cervical spinal nerve 1 (C1) and 2 (C2)].

These nerve fibers travel in the hypoglossal nerve

Hypoglossal nerve

The hypoglossal nerve is the twelfth cranial nerve , leading to the tongue. The nerve arises from the hypoglossal nucleus and emerges from the medulla oblongata in the preolivary sulcus separating the olive and the pyramid. It then passes through the hypoglossal canal...

 before separating in the carotid triangle to form the superior root.

The superior root goes around the occipital artery

Occipital artery

The occipital artery arises from the external carotid artery opposite the facial artery, its path is below the posterior belly of digastric to the occipital region. This artery supplies blood to the back of the scalp and sterno-mastoid muscles...

 and then descends on the carotid sheath

Carotid sheath

The carotid sheath is an anatomical term for the fibrous connective tissue that surrounds the vascular compartment of the neck. It is part of the deep cervical fascia of the neck, below the superficial cervical fascia meaning the subcutaneous adipose tissue immediately beneath the skin.The deep...

.

It sends off branches to the superior belly of the omohyoid muscle

Omohyoid muscle

The omohyoid muscle is a muscle at the front of the neck that consists of two bellies separated by an intermediate tendon. It belongs to the group of infrahyoid muscles...

, and the upper parts of the sternothyroid and sternohyoid muscles and is then joined by the inferior root.

External links

• Photo and description at Tufts University
  Tufts University
  Tufts University is a private research university located in Medford/Somerville, near Boston, Massachusetts. It is organized into ten schools, including two undergraduate programs and eight graduate divisions, on four campuses in Massachusetts and on the eastern border of France...
  
  
• http://www.med.mun.ca/anatomyts/nerve/cerplex.htm