Definition
The auricle, also called auricula (lat. auris – ear), is the visible, shell-shaped and cartilaginous outer part of the outer ear and together with the external auditory canal forms the outer ear. Together with the middle ear, it forms the sound conducting apparatus of the human hearing organ. With its shell-like funnel shape and cartilaginous indentations, the pinna not only serves to capture the sound waves, but also to improve directional hearing.
Anatomy
The auricle gets its shape from a cartilaginous substructure, which determines the externally visible indentations and protuberances. At the same time, the cartilage provides attachment points for the muscles of the ear, which in humans have largely atrophied and become functionless, as the human no longer depends on being able to move the ears in certain directions. The cartilage of the ear gives the ear its typical shape, but is always malleable and flexible, as it is made of elastic cartilage.
Ears can be of different sizes, but they always have certain structures that any normally shaped ear presents. These structures were named by anatomists, so that an exact description of the ear is possible. These include the earlobe (Lobus auricularis), the wide arc of the ear (Helix) or the inner arc (Anthelix).
The blood supply to the ear is primarily provided by the external carotid artery, which supplies the ear from the front via the anterior auricular artery and from behind via the posterior auricular artery. These branches are connected by the rami perforantes, which run through the skin and subcutis of the auricle. The lymph of the outer ear, which consists of tissue fluid and immune cells, is drained via the lymph nodes and pathways that run along the internal jugular vein.
The ear is divided into three territories. The lower territory drains directly into the lymph nodes that run along the internal jugular vein. The lymph of the front territory flows first through the lymph nodes of the parotid gland, while the rear territory flows through the mastoid lymph node stations (lymph nodes near the mastoid process).
The sensitive innervation of the auricle is complex because the auricular region is the transition zone between the cranial nerves and the cervical plexus in terms of innervation. Of the cranial nerves, the facial nerve, trigeminal nerve, vagus nerve and glossopharyngeal nerve are involved. From the cervical plexus, the minor occipital nerve and the major auricular nerve are involved. It should be noted that the front half of the ear is primarily innervated by the trigeminal nerve and the rear half by the cervical plexus nerves. The entrance to the auditory canal, however, is primarily innervated by the vagus and glossopharyngeal nerves.
