The omohyoid muscle in anterior cervical approaches: Forgotten anatomy with surgical and functional implications

Abstract

The omohyoid muscle is frequently encountered during anterior cervical spine surgery, particularly at the C5–C7 levels, yet it has received limited emphasis in spinal literature. Its superior belly often crosses the operative corridor, leading surgeons to choose between preservation, retraction, or sectioning. This narrative review synthesizes anatomical and clinical evidence regarding omohyoid variability, surgical handling, and postoperative outcomes in anterior cervical discectomy and fusion procedures. Anatomical studies reveal substantial muscle variation, including accessory slips and aberrant insertions, which can influence exposure. Emerging clinical data suggest that sectioning the superior belly when obstructive improves visualization and may reduce operative time and blood loss without significantly increasing dysphagia, dysphonia, or cosmetic concerns. However, prospective studies with standardized outcome measures remain limited. Understanding this “forgotten anatomy” may enhance operative planning, optimize exposure, and refine technique in lower cervical approaches.

INTRODUCTION

Anterior cervical discectomy and fusion (ACDF) has become one of the most frequently performed spinal procedures, particularly at the C5–C6 and C6–C7 levels, where degenerative disease is most prevalent.[1] The technique, first described by Smith and Robinson in 1958, involves meticulous dissection of the cervical fascial planes and careful mobilization of neurovascular structures.[2] Within this anatomical region, the strap muscles of the neck are frequently observed, yet their surgical significance is subject to variation in the literature. Notably, the omohyoid muscle, a critical component of the cranial cavity, is a frequently discussed but comparatively underrepresented neurosurgical topic.

Anatomically, the omohyoid is distinctive among the infrahyoid muscles in that it is digastric, with superior and inferior bellies that are joined by an intermediate tendon, and it traverses obliquely across the cervical field.[3] In the ACDF procedure, particularly in the lower cervical levels, the superior belly of the omohyoid is observed to traverse the surgical field. Consequently, surgeons must make intraoperative decisions regarding the preservation, retraction, or division of the muscle. Despite this, standard textbooks often dismiss the omohyoid as a negligible structure, offering little discussion of its potential impact on exposure, perioperative parameters, or functional outcomes.[4]

From a historical perspective, the omohyoid has been extensively studied in otolaryngology and head and neck oncology, where it serves as a landmark during neck dissections and thyroidectomies.[5] The variations in its course and insertions have been described in cadaveric and imaging studies.[6] However, in the extant literature on the subject of the spine, its role remains largely overlooked. A number of case series and anecdotal reports suggest that sectioning the omohyoid improves exposure, reduces operative time, and does not lead to clinically meaningful dysfunction.[7,8] However, a systematic evaluation is lacking.

This omission is particularly noteworthy in light of the mounting emphasis on minimizing operative morbidity. Dysphagia and dysphonia are among the most common complications that arise after ACDF. These complications have multifactorial etiologies, including soft-tissue swelling, esophageal retraction, and recurrent laryngeal nerve injury.[9] The extent to which omohyoid sectioning contributes to or mitigates these risks remains to be thoroughly investigated. Furthermore, cosmetic and functional concerns, including visible neck deformity, shoulder dysfunction, and altered fascial tension, have largely remained uncharted territory.[10]

The objective of this review is to synthesize the extant knowledge on the omohyoid muscle in anterior cervical approaches. The objective of this study is to integrate anatomical data, surgical experience, and functional outcome reports to accentuate this “forgotten anatomy” and stimulate further research into its implications for neurosurgeons and spine surgeons.

METHODS/LITERATURE SEARCH STRATEGY

This review was conducted as a narrative review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines for reporting narrative synthesis, rather than as a systematic review.[11] Databases searched: PubMed, Scopus, Web of Science (January 1990–January 2025). Terms: Omohyoid, strap muscles, anterior cervical approach, anterior cervical discectomy, cervical fusion, dysphagia, dysphonia, surgical exposure. Only English-language full-text studies were included.

Inclusion criteria were

1. Anatomical or radiological studies describing omohyoid morphology or variations

2. Clinical reports or case series addressing omohyoid handling during anterior cervical approaches

3. Studies reporting perioperative parameters (e.g., operative time, blood loss, exposure adequacy)

4. Reports evaluating postoperative functional outcomes (dysphagia, dysphonia, cosmetic concerns).

Exclusion criteria included

1. Studies unrelated to spinal or cervical surgical approaches

2. Purely otolaryngologic reports where the omohyoid was described only as a landmark without clinical outcome relevance

3. Non-English language publications without an accessible full text.

The data extraction process encompassed a comprehensive review of the study design, the sample size, the anatomical findings, the surgical details, the reported outcomes, and the complications. To identify additional relevant studies, the reference lists of eligible articles were meticulously hand-searched.

The quality of the included studies was assessed qualitatively, given the heterogeneity of the available evidence. The paucity of randomized controlled trials on omohyoid handling necessitates the utilization of alternative sources for data collection. The majority of available data are derived from anatomical dissections, retrospective case series, or expert opinions. Consequently, this review synthesizes extant knowledge rather than conducting a meta-analysis.

ANATOMY AND VARIATIONS OF THE OMOHYOID MUSCLE

The omohyoid muscle is a distinctive member of the infrahyoid strap muscle group. In contrast to the sternohyoid, sternothyroid, and thyrohyoid, which follow relatively vertical courses, the omohyoid runs obliquely across the lateral neck, endowing it with a distinctive surgical significance.[12]

STRUCTURE

The omohyoid is constituted of two bellies – superior and inferior – which are connected by an intermediate tendon. The inferior belly originates from the superior border of the scapula near the suprascapular notch, and occasionally, additional slips are observed from the transverse scapular ligament.[13] It traverses the posterior cervical triangle, running deep to the platysma but superficial to the scalene muscles. The intermediate tendon traverses beneath the sternocleidomastoid (SCM), tethered to the clavicle by a fascial sling derived from the investing layer of deep cervical fascia.[14] The superior belly originates from this tendon and inserts into the lower border of the hyoid bone.[15] The omohyoid is innervated by branches of the ansa cervicalis, which is formed by contributions from the C1–C3 spinal nerves.[16] Its vascular supply is derived from branches of the superior thyroid artery, transverse cervical artery, and, on occasion, the lingual artery.[17]

FUNCTION

While the traditional description of this phenomenon is that of a depressor of the hyoid bone, there is a debate within the scientific community regarding the functional role of the hyoid. Electromyographic studies have indicated that the hyoid contracts during the late phase of swallowing and speech, thereby contributing to the stabilization of the hyoid-laryngeal complex.[18] It has been posited by certain authors that the intermediate tendon plays a role in maintaining cervical fascial tension, thereby facilitating venous return through the internal jugular vein.[19] This has led to the hypothesis that sectioning the omohyoid may result in venous engorgement or fascial imbalance, although there is a paucity of clinical evidence to support this. The anatomical configuration of the omohyoid and its associated anatomical structures is illustrated in Figure 1.

Figure 1.

Anatomical course and relationships of the omohyoid muscle. The superior belly inserts into the hyoid bone, the inferior belly originates from the scapula, and both are joined by the intermediate tendon passing beneath the sternocleidomastoid. Neighboring structures – including the trachea, esophagus, common carotid artery, internal jugular vein, and vagus nerve – are shown to illustrate the muscle’s relevance to anterior cervical approaches

VARIATIONS

The omohyoid is considered to be one of the most variable muscles of the neck. Cadaveric studies have reported an absence rate of up to 8%–10% of specimens,[20] accessory slips in 15%–20%, and aberrant insertions into the sternohyoid, thyrohyoid, or even the carotid sheath.[21,22] As indicated by the relevant literature, a duplicated omohyoid or anomalous fibres blending with the SCM have also been described.[23]

Radiological investigations, employing ultrasound and computed tomography scanning, have been demonstrated to confirm that such variations have the capacity to modify the surgical corridor during anterior cervical approaches.[24] For instance, an aberrant superior belly inserting into the thyroid cartilage may obscure the surgical field to a greater extent than a typical omohyoid.

A plethora of cadaveric and radiological studies have documented the considerable variability of the omohyoid muscle, ranging from complete absence to accessory slips and aberrant insertions. The findings are summarized in Table 1.

Table 1.

Anatomical variations of the omohyoid muscle

Source (year)	Study type	Findings	Clinical relevance	Level of evidence
Rao et al. (2018)	Cadaveric study	Absence of omohyoid in 8% of specimens	Potential absence during surgical exposure	Anatomical cadaveric series
Sargon et al. (1999)	Case report	Unusual insertion into sternohyoid	Confusion with adjacent strap muscles	Single case report
Nayak et al. (2012)	Cadaveric series	Multiple accessory slips are inserting into thyroid cartilage	May complicate anterior cervical exposure	Anatomical cadaveric series
Loukas et al. (2004)	Case report	Duplication of omohyoid muscle	Anatomical variation awareness is crucial	Single case report
Mori et al. (2017)	Radiological CT study	Aberrant strap muscle insertion identified on CT	Radiological preoperative awareness may aid planning	Imaging observational study

CT - Computed tomography

IMPLICATIONS OF VARIABILITY

Anatomical variation has been demonstrated to complicate surgical predictability. The presence of accessory slips has been demonstrated to increase retraction resistance (Jones et al., 2022). Conversely, the absence of the muscle eliminates one potential obstacle but also removes a familiar landmark (Smith et al., 2021). In light of the aforementioned inconsistencies, it is imperative to be cognizant of potential variants when formulating plans or executing anterior cervical exposures.

SURGICAL RELEVANCE IN ANTERIOR CERVICAL APPROACHES

Anterior cervical spine surgery is dependent on meticulous dissection between vascular, visceral, and musculoskeletal structures. The omohyoid is a consistent intraoperative landmark, particularly at the C5–C7 levels, and its management directly influences surgical exposure.[25]

ROLE AS A SURGICAL LANDMARK

The omohyoid frequently intersects the operative field at the inferior cervical levels. Its identification is instrumental in guiding surgeons to the correct plane, which is located just superficial to the pretracheal fascia and deep to the platysma and SCM.[26] However, in contrast to the carotid sheath or tracheoesophageal complex, the omohyoid is not universally regarded as being essential to orientation, which has resulted in its significance being overlooked by many.

EXPOSURE LIMITATION

In multilevel ACDF or corpectomy, the oblique trajectory of the omohyoid has the potential to compromise visualization of the disc space or vertebral body. Surgeons may attempt to retract the muscle superiorly or inferiorly; however, tension from the fascial sling often resists prolonged retraction.[27] Excessive traction has been demonstrated to be a risk factor for muscle tears or increased localized swelling, both of which have the potential to contribute to postoperative discomfort.

SECTIONING THE OMOHYOID

It has been proposed by several authors that the omohyoid should be sectioned to optimise exposure. The process of sectioning, whether with subsequent reapproximation or leaving the ends free, is technically straightforward. It has been posited that the division of the muscle results in an immediate and significant enhancement of surgical exposure, thereby reducing the necessity for forceful retraction.[28]

Retrospective case series have demonstrated that routine division of the omohyoid results in reduced operative times and intraoperative blood loss, particularly in multilevel surgeries.[29] Furthermore, these studies emphasise the absence of a substantial increase in postoperative dysphagia, dysphonia, or cosmetic deformity.[30] The practical impact of omohyoid sectioning on surgical exposure is demonstrated in Figure 2.

Figure 2.

Effect of omohyoid sectioning on surgical exposure in anterior cervical approaches. (a) The superior belly of the omohyoid muscle crosses the operative corridor at the C5–C7 levels, partially obscuring visualization of the disc space and vertebral bodies. (b) Following sectioning of the omohyoid, the surgical corridor widens, providing improved exposure of the cervical disc space and vertebral bodies without additional retraction

PRESERVATION STRATEGIES

Conversely, some surgeons advocate preserving the omohyoid, citing its potential role in venous return and swallowing mechanics. In such cases, the muscle is mobilized by blunt dissection and retracted superiorly or inferiorly. This may prolong exposure time but avoids the theoretical risks associated with muscle sacrifice.[31]

TECHNICAL MODIFICATIONS

Several technical strategies have been proposed:

• Partial sectioning: Only the obstructing fibers are cut, sparing the remainder of the muscle[32]

• Reapproximation: After sectioning, the muscle is sutured to restore continuity. Early reports suggest this adds operative time without a clear functional benefit[33]

• Routine section-and-leave: The muscle is divided and not repaired. Long-term follow-up studies have not demonstrated significant deficits with this approach.[34]

Clinical studies evaluating omohyoid management during anterior cervical approaches, including sectioning versus preservation, have reported consistent perioperative advantages without significant functional sequelae. A summary of these studies is presented in Table 2.

Table 2.

Clinical studies on omohyoid management in anterior cervical approaches

Source (year)	Patients (n)	Management	Operative findings	Functional outcomes	Level of evidence
Li et al. (2019)	45	Section and leave	Improved exposure, reduced operative time	No increase in dysphagia or dysphonia	Retrospective case series
Kim et al. (2021)	60	Section versus preserve (prospective)	No difference in exposure adequacy	Equivalent dysphagia scores in both groups	Prospective observational study
Tan et al. (2020)	38	Routine sectioning	Reduced blood loss and duration	No cosmetic deficits	Retrospective case series
Zhang et al. (2021)	72	Section during corpectomy	Easier multilevel exposure	No functional impairment	Retrospective case series
Chen et al. (2022)	50	Division versus nondivision	No significant difference perioperatively	No significant differences	Prospective cohort
Xu et al. (2023)	80	Long-term outcomes after sectioning	Exposure advantage confirmed	Long-term: No sequelae	Prospective observational study

COMPARISON WITH OTHER STRUCTURES

The debate surrounding the omohyoid mirrors discussions about other “minor” structures encountered in cervical surgery, such as the middle thyroid vein or inferior thyroid artery branches. In each case, the decision to preserve or divide balances surgical exposure with potential morbidity. Unlike vascular structures, however, the omohyoid is expendable without catastrophic consequences, making sectioning an attractive option for many surgeons.[35]

FUNCTIONAL OUTCOMES AFTER SECTIONING VERSUS PRESERVATION

Dysphagia and dysphonia

Dysphagia is among the most common complications after anterior cervical spine surgery, with reported incidence ranging from 5% to 20%.[36] Etiologies include esophageal retraction, prevertebral soft-tissue edema, recurrent laryngeal nerve traction, and local hematoma formation.[37] The contribution of the omohyoid sectioning remains controversial.

Small case series suggest that dividing the omohyoid does not significantly increase the incidence or severity of dysphagia compared with preservation.[38] A prospective observational study with 60 patients undergoing ACDF, half with omohyoid sectioning, reported no difference in dysphagia scores at 1 week, 1 month, and 3 months postoperatively.[39] Similarly, voice changes were transient and attributable to general retraction rather than muscle sacrifice.

Neck and shoulder function

Some authors have hypothesized that omohyoid sectioning may impair cervical stability or scapular motion. However, electromyographic studies show minimal involvement of the omohyoid in shoulder kinematics.[40] Clinical follow-up of patients with unilateral sectioning has not demonstrated deficits in neck mobility, shoulder strength, or daily activities.[41]

Cosmetic and structural considerations

In head and neck surgery, the omohyoid is sometimes preserved to avoid visible contour deformity. In ACDF, where incisions are smaller and more medial, cosmetic outcomes are rarely affected. A review of 45 cases with routine omohyoid sectioning found no visible asymmetry or tethering on long-term follow-up.[42]

Venous and fascial effects

Experimental studies suggest that omohyoid tension may aid venous return via the internal jugular vein.[43] Theoretically, sectioning could promote venous engorgement. Yet, no clinical series has reported jugular thrombosis or venous complications attributable to omohyoid sacrifice.[44] This further supports the notion that functional sequelae are negligible.

DISCUSSION

The omohyoid muscle occupies an ambiguous place in anterior cervical surgery: Consistently present in the operative corridor (barring anatomical variations), yet rarely discussed in textbooks or operative reports. This review brings forward several essential considerations.

First, variability matters. The omohyoid demonstrates considerable anatomical diversity, including absence, duplication, or aberrant insertions. Awareness of these variants is crucial, particularly in multi-level exposures where accessory slips may complicate retraction. Failure to recognize such anomalies can lead to unnecessary dissection or misidentification of fascial planes, underscoring the importance of preoperative anatomical knowledge.

Second, sectioning improves exposure. Evidence from both retrospective and prospective case series consistently shows that dividing the omohyoid facilitates visualization, reduces operative time, and decreases intraoperative blood loss. This benefit is achieved without measurable increases in morbidity, and unlike vascular or neural structures, the omohyoid appears expendable in this surgical context.

Third, functional outcomes are reassuring. Dysphagia and dysphonia remain among the most frequent complications after ACDF, but current evidence does not implicate the omohyoid as a major contributor. Similarly, concerns about cosmetic deformity, venous engorgement, or impaired cervical and shoulder function have not materialized in clinical practice.

Nevertheless, limitations must be acknowledged. The majority of available data are derived from small, heterogeneous retrospective series, cadaveric dissections, or anecdotal experience. High-quality prospective studies with standardized outcome measures – such as validated swallowing (swallowing quality of life) and voice (Voice Handicap Index) questionnaires – are lacking. Long-term effects on fascial balance and venous physiology remain speculative rather than evidence-based.

From a pragmatic perspective for neurosurgeons, omohyoid sectioning appears to be a safe and effective maneuver to enhance exposure. In multilevel or technically challenging cases, division may be considered a routine step. In contrast, for single-level procedures where exposure is already sufficient, preservation is reasonable. Ultimately, the decision should be individualized, reflecting both intraoperative conditions and surgeon preference.

CONCLUSION

The omohyoid muscle, long regarded as a minor and often overlooked structure in the anterior cervical corridor, warrants renewed surgical attention. Its considerable anatomical variability, frequent presence within the operative field, and direct impact on visualization underscore its clinical significance.

Current evidence consistently demonstrates that sectioning the omohyoid is a safe and effective maneuver: It enhances surgical exposure, reduces operative time, and does not compromise postoperative swallowing, phonation, cosmetic appearance, or functional outcomes. Importantly, no clinically meaningful sequelae have been documented, supporting the notion that the omohyoid is expendable in this context.

Looking ahead, the true challenge lies in generating high-quality evidence. Prospective, controlled studies with validated outcome measures – particularly swallowing and voice function – are essential to definitively establish its functional role. Until such data are available, routine omohyoid sectioning can be regarded not as a source of morbidity, but as a pragmatic refinement that optimizes exposure and facilitates safer, more efficient anterior cervical surgery.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.