Level IIa

Lymph nodes from level II (upper jugular nodes, deep cervical chain) extend from the skull base to the level of the bottom of the body of the hyoid bone. They are posterior to the back of the submandibular gland and anterior to the back of the sternocleidomastoid muscle.

• level IIa: anterior, lateral, or medial to the vein or posterior to the internal jugular vein and inseparable from it
• level IIb: posterior to the internal jugular vein and have a fat plane separating the nodes and the vein 

Nb: any nodes that lie medial to the internal carotid artery are retropharyngeal and not level II