The question of what muscles allow ear movement points to a small, often overlooked group of muscles around the outer ear. While most people cannot actively control their ears, the underlying anatomy for this movement still exists in all humans. The ability to pivot the external ear, known as the auricle or pinna, relies on specific muscles that connect the ear cartilage to the surrounding skull and scalp. These structures represent an evolutionary remnant, hinting at a time when humans relied on their ears for sound localization.
The Three Auricular Muscles Responsible for Ear Movement
The movement of the human ear is controlled by three thin, sheet-like muscles collectively called the extrinsic auricular muscles. These muscles are named based on their position relative to the auricle, and they all receive their nerve signals from the facial nerve (Cranial Nerve VII).
The largest of the group is the Auricularis Superior, a fan-shaped muscle located above the ear. It originates from the temporal fascia of the head. Its primary function is to draw the ear upward, often slightly backward as well.
The Auricularis Anterior is situated in front of the ear. This muscle is responsible for pulling the ear forward and slightly upward. It arises from the lateral edge of the epicranial aponeurosis, a fibrous layer on the scalp, before inserting into the helix, the upper rim of the ear.
Finally, the Auricularis Posterior is located behind the ear, originating from the mastoid process of the temporal bone. This muscle’s action is to retract the ear, pulling it distinctly backward. The slight movement observed in many people is a subtle, involuntary response.
Why Human Ear Movement is Largely Vestigial
Despite the presence of these muscles, the ability to voluntarily move the ears is rare because the auricular muscles are considered vestigial structures in humans. A vestigial structure is an anatomical feature that has lost most of its original function through the course of evolution. For our distant ancestors, these muscles were fully functional, serving to orient the ear toward a sound source.
The muscles are present, yet the neurological pathways for conscious control have become weak or dormant in most people. Unlike the motor pathways that control facial expression, the neural connection allowing for purposeful ear wiggling is largely absent in the human brain. The decline in the use of these muscles began approximately 25 million years ago, coinciding with the development of alternative methods for sound localization, such as turning the head.
Even in people who cannot consciously move their ears, subtle activation of the auricular muscles can be detected during focused listening. Studies have shown that these muscles, particularly the Auricularis Superior, involuntarily contract when a person is straining to hear in a noisy environment. This residual activity suggests the muscles may still play a minor role in attentional effort.
Functional Ear Muscles in the Animal Kingdom
The human ear muscles stand in stark contrast to the robust and functional musculature found in many other mammals. Animals like cats, dogs, horses, and rabbits possess highly developed auricular muscles that allow for a wide range of motion. This ability is often referred to as “pinna steering,” where the external ear can swivel independently to pinpoint the direction of a sound.
This precise control offers an evolutionary advantage, allowing an animal to listen for the subtle sounds of predators or prey without needing to move its entire head. The well-developed muscles permit the ear to rotate up to 180 degrees, effectively funneling sound waves directly into the ear canal. For a solitary hunter or a grazing animal, this enhanced directional hearing can be the difference between survival and danger.
In these functional systems, the movement is a rapid, intentional adjustment that optimizes auditory input, not merely a reflex. The evolutionary loss of this system in humans is likely due to the shift toward binocular hearing, which uses the time difference between sound arriving at each ear, and the agility of the human neck. We rely on turning our whole head to localize sound, a strategy that rendered the complex ear muscles unnecessary.