| Mastoid lymph nodes | |
|---|---|
 Superficial lymph glands and lymphatic vessels of head and neck (mastoid lymph nodes are labeled as posterior auricular glands at center left) | |
 Lymph nodes at surface:
Facial lymph nodes:
| |
| Details | |
| System | Lymphatic system |
| Drains from | Scalp |
| Drains to | Superior deep cervical glands |
| Identifiers | |
| Latin | Nodi lymphoidei mastoidei |
| Anatomical terminology | |
The mastoid lymph nodes (retroauricular lymph nodes or posterior auricular glands) are a small group of lymph nodes, usually two in number, located just beneath the ear, on the mastoid insertion of the sternocleidomastoideus muscle, beneath the posterior auricular muscle.
A lymph node or lymph gland is an ovoid or kidney-shaped organ of the lymphatic system, and of the adaptive immune system, that is widely present throughout the body. They are linked by the lymphatic vessels as a part of the circulatory system. Lymph nodes are major sites of B and T lymphocytes, and other white blood cells. Lymph nodes are important for the proper functioning of the immune system, acting as filters for foreign particles and cancer cells. Lymph nodes do not have a detoxification function, which is primarily dealt with by the liver and kidneys.
The posterior auricular muscle consists of two or three fleshy fasciculi, which arise from the mastoid portion of the temporal bone by short aponeurotic fibers. They are inserted into the lower part of the cranial surface of the concha.
Contents
Their mastoid lymph nodes receives lymph from the posterior part of the temporoparietal region, the upper part of the cranial surface of the visible ear and the back of the ear canal. The lymph then passes to the superior deep cervical glands.
The ear is the organ of hearing and, in mammals, balance. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists of the pinna and the ear canal. Since the outer ear is the only visible portion of the ear in most animals, the word "ear" often refers to the external part alone. The middle ear includes the tympanic cavity and the three ossicles. The inner ear sits in the bony labyrinth, and contains structures which are key to several senses: the semicircular canals, which enable balance and eye tracking when moving; the utricle and saccule, which enable balance when stationary; and the cochlea, which enables hearing. The ears of vertebrates are placed somewhat symmetrically on either side of the head, an arrangement that aids sound localisation.
The ear canal is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the pinna to the eardrum and is about 2.5 centimetres (1 in) in length and 0.7 centimetres (0.3 in) in diameter.
