Skull- mastoid process

Inferior view

The mastoid process is part of the temporal bone. It is the insertion for the sternocleidomastoid muscle. In fact it is this muscle that causes this landmark to develop. Several other muscles that you will not be responsible for also attach to this landmark. As a group these muscles are responsible for rotation or extension of the head. It gets its name from the similarity it has to the appearance of a breast. Dr. J did not name this landmark - he is just the messenger. The lateral side of the mastoid process of the temporal bone is of special functional importance because it is part of the insertion for:
1. the sternocleidomastoid muscle.
Lateral view of sternocleidomastoid insertion, right side
The above drawing of the insertion might help visualize this information (blue is the insertion).

Last Updated: 5/6/24