Crying is a complex physiological response combining emotional signaling, fluid secretion, and involuntary muscular actions. Though often associated with the face, the act of crying involves a coordinated effort from muscles across the head, chest, and throat. Understanding the muscles required to cry means looking beyond the visible facial expression to the hidden biological systems at work.
The Facial Muscles That Create the Crying Expression
The recognizable look of distress is created by the simultaneous contraction of a core group of facial muscles, primarily around the eyes and mouth. While the specific number varies with intensity, about 10 to 12 muscles form the basis of the expression. These muscles pull the features into the configuration associated with sadness or pain.
Furrowing the brow is a characteristic movement achieved by the corrugator supercilii muscle. This muscle draws the eyebrows together and downward, creating the vertical wrinkles above the nose. Simultaneously, the depressor anguli oris muscle pulls the corners of the mouth downward and laterally. This muscle’s action is so closely linked to sadness that its underdevelopment can cause an asymmetric crying face in infants.
The orbicularis oculi muscle, which encircles the orbit, shapes the eyes. Tightening this muscle contributes to the characteristic, often involuntary, squeezing of the eyelids. Smaller muscles, such as the depressor labii inferioris and the mentalis, contribute to the quivering of the lower lip and chin. This combined muscular activity transforms the neutral face into the expressive signal of emotional crying.
The Mechanics of Tear Generation and Drainage
Tears are produced by the lacrimal glands, located in the upper outer area of the eye socket. These glands secrete a watery solution distributed across the eye’s surface for lubrication, protection, and in response to emotional signals. The tears then travel into the lacrimal drainage system for management.
Muscular action moves tears out of the eye and into the nose, which often causes a runny nose during intense crying. The orbicularis oculi muscle plays a distinct role here, separate from its function in facial expression. Specific portions of this muscle act as a lacrimal pump during each blink.
When the eye closes, muscle contraction squeezes the lacrimal sac, creating negative pressure that draws tears through small openings called puncta. When the muscle relaxes upon eye opening, the lacrimal sac collapses, pushing the tears down the nasolacrimal duct and into the nasal cavity. This tear-pumping mechanism is an involuntary muscular process that manages fluid continuously.
Respiratory Muscles and the Physical Act of Sobbing
Sobbing, the most intense form of crying, extends muscular involvement beyond the face and eyes to include the entire respiratory system. Sobbing is characterized by irregular, labored breathing caused by the spasmodic action of the primary muscles of respiration. The dome-shaped diaphragm muscle, the main muscle responsible for breathing, begins to pulse or spasm erratically.
This diaphragmatic spasm, combined with the action of the intercostal muscles between the ribs, disrupts the normal rhythm of inhalation and exhalation. This irregular breathing pattern leads to the gasping and erratic inhalations accompanying a strenuous cry. The glottis, the opening between the vocal folds, may narrow or close abruptly, creating the characteristic choking or stuttering sound of a sob.
The physical sound of crying, from whimpering to wailing, is produced by the laryngeal muscles that control the vocal cords. These muscles regulate the tension and position of the vocal folds, shaping the airflow into the unsteady vocalization of distress. The full act of crying engages a wide range of muscle groups, from delicate facial muscles to powerful respiratory muscles.