In the neck, the accessory nerve crosses the internal jugular vein around the level of the posterior belly of digastric muscle.

The feathers of the posterior belly, flanks and vent are white with grey-black bases.

The posterior belly, flanks and vent are off-white.

The posterior belly is supplied by the digastric branch of facial nerve.

Ib is the triangle formed by the anterior and posterior bellies of the digastric and body of mandible.

It also innervates the posterior belly of the digastric muscle, the stylohyoid muscle, and the stapedius muscle of the middle ear.

The stylohyoid muscle is a slender muscle, lying anterior, and superior of the posterior belly of the digastric muscle.

Tensing the stylohyoid muscles and posterior bellies of the pair of digastric muscles also helps.

These muscles include the muscles of facial expression, the posterior belly of the digastric, stylohyoid muscle, and the stapedius muscle of the middle ear.

It is the posterior belly of the occipitofrontalis muscle, and functions to move the scalp.