The sternohyoid is a thin, flat, strap-shaped muscle running down the front of your neck from the hyoid bone to the back of your sternum and the inner end of the clavicle. Its primary job is pulling the hyoid bone downward after it rises during swallowing or speech, but that simple description barely hints at how much this muscle actually does. It plays roles in breathing, voice control, and airway stability during sleep, and it has become a surprisingly versatile tool in head and neck surgery.
Where It Sits and What It Connects
The sternohyoid belongs to a group of four muscles collectively called the infrahyoid or “strap” muscles, named for their flat ribbon-like shape draped over the front of the throat. The sternohyoid is the most superficial of the group, lying just beneath the skin and the thin sheet of platysma muscle. It originates from the posterior surface of the manubrium (the top portion of the breastbone) and the medial end of the clavicle, then travels upward to attach to the lower border of the hyoid bone. The left and right sternohyoid muscles run side by side, separated by a narrow midline gap.
The muscle is innervated by the ansa cervicalis, a loop of nerves formed by branches of the first three cervical spinal nerves (C1–C3). This nerve supply is shared with the other strap muscles, a detail that becomes important in surgical contexts involving nerve transfers. Blood supply comes primarily from branches of the superior thyroid artery.
Anatomical variation is uncommon but documented. A systematic review of infrahyoid muscle anomalies found cases where the sternohyoid was completely absent on one side, as well as instances of accessory sternohyoid muscles appearing on the opposite side.1PubMed Central. Anatomical variations of the infrahyoid muscles and ansa cervicalis: a systematic review and an updated classification system for the omohyoid muscle These variations rarely cause symptoms, but they matter for surgeons operating in the anterior neck who need to know what they are working around.
How It Contributes to Swallowing
Swallowing requires the hyoid bone to rise and then return to its resting position. The upward movement is driven by the suprahyoid muscles above the hyoid, while the return trip downward depends on the infrahyoid muscles, including the sternohyoid. This up-and-down cycle has to be precisely timed. If the hyoid does not elevate enough, the airway does not close properly and food or liquid can enter the trachea.
Research on what happens when anterior neck muscles carry too much tension showed that excessive tone in the sternohyoid region pulled the hyoid bone downward, working against the upward pull needed for a safe swallow. The study found increased muscle tone in both the suprahyoid muscles (which lift the hyoid) and the sternohyoid (which depresses it), creating a kind of tug-of-war that reduced the hyoid’s overall upward movement.2PubMed Central. Excessive anterior cervical muscle tone affects hyoid bone kinetics during swallowing in healthy individuals This finding is relevant for anyone dealing with chronic neck tension or age-related stiffness in the anterior throat muscles, where the balance between these opposing muscle groups can shift.
The mechanism behind the sternohyoid’s involvement in swallowing turns out to be more nuanced than simple motor commands from the brain. A study examining sternohyoid activity in rats found that when the muscle’s length was fixed in place, swallowing-related activity disappeared, even though inspiratory activity continued. The researchers concluded that the sternohyoid’s firing during swallowing is largely a stretch reflex rather than a direct command from the brain’s swallowing center.3PubMed. Functional involvement of the sternohyoid muscle during breathing and swallowing in rats In other words, when the suprahyoid muscles pull the hyoid upward and stretch the sternohyoid, that stretch itself triggers the sternohyoid to contract and pull the hyoid back down. It is a built-in recoil mechanism, not something your brainstem has to consciously orchestrate for each swallow.
Its Role in Voice Production
The hyoid bone does not only move during swallowing. It also shifts position during speech, and the larynx (voice box) is suspended from it. Moving the hyoid changes the tension and position of the laryngeal framework, which in turn affects vocal pitch. The sternohyoid participates in this system by pulling the hyoid and larynx downward, counterbalancing the muscles that elevate them.
Electromyographic recordings of the strap muscles during pitch changes revealed a pattern: at low pitches, the sternohyoid and its neighboring strap muscles are active, holding the larynx in a depressed position. As pitch rises, strap muscle activity decreases and the cricothyroid muscle (inside the larynx) takes over to stretch and thin the vocal folds.4PubMed. Electromyographic activity of strap and cricothyroid muscles in pitch change So the sternohyoid helps set the baseline position of the larynx for your lowest notes, while finer pitch control at higher frequencies shifts to intrinsic laryngeal muscles. Singers and voice professionals sometimes develop awareness of strap muscle tension for this reason, as excessive contraction can restrict upward laryngeal movement and limit the upper end of their range.
Keeping the Airway Open During Sleep
This is where the sternohyoid’s story gets particularly interesting. During sleep, the muscles that hold the upper airway open tend to relax, which is why snoring and obstructive sleep apnea occur. Most research on airway-dilating muscles during sleep has focused on the genioglossus (the main tongue muscle), but the sternohyoid plays a role too, and an unusual one.
Animal studies found that during REM sleep, two key upper airway muscles (the genioglossus and the sternothyroid) lost their inspiratory activity. The sternohyoid, however, kept firing. The researchers concluded that the sternohyoid serves a dual purpose during sleep: it helps maintain airway patency by pulling the hyoid bone forward and downward (stiffening the pharyngeal wall), and it stabilizes the rib cage to optimize the diaphragm’s action.5Experimental Neurology. Respiratory roles of genioglossus, sternothyroid, and sternohyoid muscles during sleep A follow-up study confirmed that the sternohyoid retained its inspiratory activity across both non-REM and REM sleep, making it one of the more resilient airway-protecting muscles during the vulnerable hours of rest.6Experimental Neurology. Respiratory functions of the inferior pharyngeal constrictor and sternohyoid muscles during sleep
In humans, a study comparing people with obstructive sleep apnea to healthy sleepers found a more troubling picture. While the genioglossus ramped up its activity during sleep to compensate for airway narrowing (reaching more than double its waking level), other peripharyngeal muscles including the sternohyoid did not keep pace. On average, the non-genioglossus muscles reached only about two-thirds of their wakefulness activity levels during sleep, even as the airway was collapsing.7PubMed Central. Alteration in upper airway dilator muscle coactivation during sleep: comparison of patients with obstructive sleep apnea and healthy subjects The researchers speculated that this mismatch, where one airway muscle works overtime while others slack off, could explain why airway collapse continues even when the genioglossus is contracting hard. The airway needs coordinated support from multiple muscles, and the sternohyoid’s failure to coactivate during sleep may be part of the problem in obstructive sleep apnea.
Behavior Under Respiratory Stress
When breathing becomes obstructed, the sternohyoid does not just passively sit there. Studies using tracheal airway occlusion in anesthetized animals showed that the sternohyoid increased its electrical activity in response to the obstruction, trying to stabilize the hyoid bone and keep the airway open. However, something counterintuitive happened simultaneously: even as the muscle contracted harder, it lengthened during inspiration in most animals, and this lengthening was actually greater during obstruction than during normal breathing.8Journal of Applied Physiology. Effects of tracheal airway occlusion on hyoid muscle length and upper airway volume The muscle was fighting against the negative pressures generated by a blocked airway and losing the battle, getting stretched out even while contracting. This is the mechanical reality of airway obstruction: the suction forces generated by trying to inhale through a collapsed passage can overpower the muscles trying to hold things open.
The Sternohyoid as a Surgical Tool
Because the sternohyoid is thin, well-vascularized, and conveniently located in the anterior neck, surgeons have found it valuable as a local muscle flap for reconstructing nearby structures after cancer surgery. The muscle can be detached from one of its bony anchors, rotated on its blood supply, and used to fill defects or reinforce closures.
One of the most studied applications is in supracricoid laryngectomy, a partial removal of the larynx for cancer. A study comparing patients who received a sternohyoid muscle flap during reconstruction to those who did not found striking differences in recovery. The flap group was able to have their breathing tubes removed in roughly a month on average, compared to about four months in the group without flaps. Feeding tube removal was also faster, and swallowing function at six months was significantly better in the flap group, with roughly 96% achieving decannulation compared to about two-thirds without the flap.9PubMed. Laryngeal reconstruction with a sternohyoid muscle flap after supracricoid laryngectomy: postoperative respiratory and swallowing evaluation
The sternohyoid flap has also been used to close tracheoesophageal puncture sites that fail to heal on their own. These punctures are intentionally created during voice restoration after total laryngectomy, but sometimes they need to be closed, especially in patients who have had radiation therapy and struggle with wound healing. A case series described the sternohyoid flap as a low-morbidity option for closing small to moderately sized fistulas in this setting.10PubMed. Sternohyoid or sternocleidomastoid muscle flap for tracheoesophageal puncture closure in irradiated patients: A CARE case series For larger reconstructions involving both the throat and voice box, the sternohyoid has been combined with other flaps. A series of patients who received a combination of a sternohyoid muscle flap and a supraclavicular artery island flap for hypopharyngeal and laryngeal reconstruction achieved normal swallowing and voice in all cases.11PubMed Central. Successful management of the supraclavicular artery island flap combined with a sternohyoid muscle flap for hypopharyngeal and laryngeal reconstruction
Cutting the Strap Muscles During Thyroid Surgery
Thyroid operations sometimes require dividing the strap muscles to get adequate exposure of a large goiter. This worries patients and sometimes surgeons, since the strap muscles contribute to voice and swallowing. A study that directly compared patients whose strap muscles were cut during thyroidectomy to those whose muscles were left intact found reassuring results. Both groups experienced some voice and swallowing complaints in the first week after surgery, but by six months, scores in both groups had returned to preoperative levels with no significant difference between them.12PubMed Central. The effect of strap muscle transection on voice and swallowing changes after thyroidectomy in patients without laryngeal nerve injury The early complaints appear to be caused by the surgery itself and the swelling that follows, not by damage to the strap muscles specifically. For patients facing thyroidectomy for a large goiter, this is useful information: if your surgeon says the strap muscles need to be divided, that step by itself is unlikely to cause lasting voice or swallowing problems.
Nerve Transfers for Vocal Cord Paralysis
When the recurrent laryngeal nerve is damaged (from surgery, tumors, or trauma), the vocal cord on the affected side becomes paralyzed, causing a breathy, weak voice and sometimes aspiration of food into the airway. One way to restore some tone to the paralyzed vocal cord is to borrow a nerve from a nearby muscle and connect it to the damaged nerve. The ansa cervicalis, the same nerve loop that supplies the sternohyoid, is the most common donor for this procedure.13PubMed. Surgical anatomy of the ansa cervicalis nerve: which branch to use for laryngeal reinnervation in humans?
Specifically, surgeons identify the branch of the ansa cervicalis that runs to the sternohyoid (and often the sternothyroid as well) and connect it directly to the severed end of the recurrent laryngeal nerve.14JAMA Otolaryngology–Head & Neck Surgery. Vocal Outcome After Arytenoid Adduction and Ansa Cervicalis Transfer Over months, nerve fibers grow from the ansa cervicalis branch into the denervated laryngeal muscles, restoring enough bulk and tone to the vocal cord to improve voice quality and airway protection. The common trunk supplying both the sternohyoid and the sternothyroid has been identified as the preferred donor because of its caliber and accessibility.15Neurology India. Laryngeal Reinnervation in Recurrent Laryngeal Neuropathy with Ansa Cervicalis – RLN End-to-End Neurorrhaphy Sacrificing this nerve branch does mean the sternohyoid loses its motor supply on that side, but the functional consequences are minimal. With the other strap muscles intact and the opposite sternohyoid still working, patients do not typically notice any deficit in swallowing or voice from losing one sternohyoid’s innervation.
Forensic Significance in Strangulation Cases
The sternohyoid occupies a vulnerable position in the front of the neck, and damage to it can become evidence in forensic investigations of death by strangulation or hanging. Pathologists examining suspected strangulation victims look for hemorrhages in the anterior neck muscles as signs of compression. In manual and ligature strangulation cases, hemorrhages in the nearby sternocleidomastoid muscles were found within the muscle tissue itself rather than at the periosteal attachment.16PubMed Central. Diagnostic Value of Sternocleidomastoid Muscle Hemorrhage on Clavicular Periosteum in Hanging Deaths The sternohyoid presents its own forensic challenge: small intramuscular hemorrhages within the sternohyoid muscle, along with hemorrhage of the vocal cords, can be missed even on MRI imaging.17Journal of Forensic Sciences & Criminal Investigation. Fatal Manual Strangulation: A Brief Overview This means autopsy with direct visual inspection of the strap muscles remains important in these cases, as imaging alone may not reveal the full extent of neck trauma.
Evolutionary Origins
The sternohyoid has a deep evolutionary pedigree. It is a hypobranchial muscle, part of a group that migrated ventrally from the body-wall musculature early in vertebrate evolution. These muscles originally served to open the mouth and expand the gill chamber in aquatic vertebrates, operating the bony apparatus of the throat to generate suction during feeding. As vertebrates transitioned from water to land, the gill-related functions became obsolete, but the muscles themselves were repurposed. Research tracking muscle precursor cells in zebrafish confirmed that the sternohyoid develops from the same migratory population of hypaxial muscle cells that give rise to the pectoral fin muscles and ventral body-wall muscles.18Nature Communications. Co-option of neck muscles supported the vertebrate water-to-land transition In modern land-dwelling vertebrates, the sternohyoid’s attachment shifted from the gill skeleton to the hyoid bone and sternum, and its function shifted from gill ventilation to the constellation of roles described throughout this article: depressing the hyoid during swallowing, stabilizing the larynx for speech, and helping to keep the airway open during breathing. It is a muscle that has been reinvented several times over hundreds of millions of years, each time adapted to whatever the throat needed to do next.