Strap muscle neurovascular supply

The previously undescribed variant of the thyrohyoid muscle and its potential impact on surgical procedures

The thyrohyoid muscle belongs to the infrahyoid group located in the carotid triangle. It normally originates from thyroid cartilage and inserts into hyoid bone. Quite often, it is continuous with the sternohyoid muscle. Furthermore, there are variants that have their origin in the cricoid cartilage only, however, this occurs very rarely. During anatomical dissection, a two-headed variant of this muscle was found. One head had its origin in the cricoid cartilage and the other in the thyroid cartilage. This variant of thyrohyoid had not been previously described in the available literature. Therefore, we believe that it may be referred to as the cricothyrohyoid muscle. As the thyrohyoideus is often used as a landmark during surgical procedures in the prelaryngeal area and as a muscle graft, a thorough knowledge of its anatomy and variation is extremely important. We speculate that the two-headed version of this muscle may be problematic during surgical procedures in this region, however, it may also provide more options as a muscular graft.

Anterolateral approach for thyroid swellings: impact on postoperative voice outcomes

Background

The sternothyroid muscle (ST) is routinely divided during grossly enlarged thyroid surgery to facilitate gland exposure. However, the ST is considered to play a role in controlling of pitch in the human voice. In this prospective cohort study, we described an anterolateral approach (AA) by which it was easy to expose the enlarged gland while preserving the ST, and evaluated the impact of this approach on vocal outcomes after total thyroidectomy.

Methods

The AA was performed on eligible patients from October 2018 to January 2020 in our department. Consecutive cases hospitalized from March 2020 and followed up to June 2021 who received total thyroidectomy via the midline approach (MA) served as controls. All participants underwent voice analysis before the operation and at 2 weeks and 3 months after the surgery. In 26 patients from AA group, strap muscles were mobilized along the anterior margin of both sternocleidomastoid muscles (SCMs) until 3 cm above the sternal notch followed by thyroidectomy, and their voice outcomes were compared to those of 36 patients from the MA group with a bilateral division of ST.

Results

Distribution of age, gender, specimen size, thyroid histopathology and laryngeal nerve identification rates did not differ significantly between groups. At 2 weeks post-surgery, objective assessment of voice change rate indicated no significant difference between groups, whereas the difference appeared to be partially manifest 3 months later. In the single-arm study, the AA group showed a decrease of maximum and fundamental pitch frequency 2 weeks after surgery but showed no difference in fundamental frequency after 3 months. The MA group continued to show a mild decrease in maximum and fundamental frequency at 3 months after surgery.

Conclusions

The AA affords sufficient visualization of the superior thyroid vessels and external branch of the superior laryngeal nerve (EBSLN) without sacrificing the integrity of the strap muscles. This approach is a feasible solution for selective difficult thyroid surgery and could reduce the postoperative changes in pitch of voice.

Unusual branch of the lingual artery supplies the infrahyoid muscles

Infrahyoid muscles are usually supplied by muscular arteries, originating from the superior and inferior thyroid artery and the internal thoracic artery. In this work, we reported a unilateral anatomical variation of the branching pattern of the lingual artery, which was observed during dissection studies at the University of Brescia. We found an accessory branch arising from the root of the lingual artery that run down medially and supplied the infrahyoid muscles. A similar case has not yet been reported in literature. Considering the current use of the infrahyoid muscles as pedicled myocutaneous flap for reconstructing surgical defects in the head and neck, this vascular variation appears interesting to be reported for appropriate clinical and surgical consideration.

Treatment of Synchronous Traumatic Perforations of the Trachea and the Esophagus With Two Inferiorly Based Strap Muscle Interposition Flaps: An Innovative Approach

: Traumatic perforations of the esophagus and trachea are devastating injuries that necessitate prompt treatment. Large defects benefit from coverage with well vascularized tissue. Injuries at the level of the thoracic inlet are more challenging, as the options for local tissue coverage are limited.This report describes the case of a 24-year-old male who suffered gunshot wounds to his neck resulting in right posterolateral tracheal perforation as well as esophageal perforation at the level of the thoracic inlet. Bronchoscopy and esophagogastroduodenoscopy showed injury of the trachea at 19 cm from the incisors and 2 large defects of the anterior and posterior esophagus at 26 cm. The esophageal defects were temporized with a stent at a first stage. Plastic surgery team was then consulted for flap coverage of the defects.The thoracic team exposed the tracheal and esophageal perforations with a j-type incision of the neck, extending to the sternal notch, and the esophageal stent was removed. The 2 muscles, sternohyoid (SH) and sternothyroid (ST), were dissected free and were inferiorly rotated after they were disinserted superiorly. The SH was placed between the trachea and the esophagus, and the ST between the esophagus and the spine.Postoperative, the patient was receiving nutrition via a gastrostomy tube. An esophagogram was performed on postoperative day (POD) # 7, which showed no esophageal leak. Postoperative diet was started and the patient was discharged on POD# 10 in a good condition. Twelve months postoperative, his wounds were found to be intact, and had no trouble either with breathing or swallowing. LEVEL OF EVIDENCE:: V.

Surface Electromyographic Activity in Total Laryngectomy Patients following Laryngeal Nerve Transfer to Neck Strap Muscles

Hands-free triggering and pitch control would improve electrolarynx devices, which are inconvenient to use and sound unnatural. The present study tested the strategy of salvaging voice-related neural signals for hands-free electrolarynx control either by transferring cut recurrent laryngeal nerves (RLNs) to denervated neck strap muscles or by preserving strap muscles with their normal innervation. An RLN nerve transfer was performed at the time of total laryngectomy in 8 individuals, and in 5 of these subjects, strap muscles with intact ansa cervicalis innervation were also preserved for comparison. Neck surface electromyography performed over the strap muscles was used periodically for more than 1 year on phonatory and nonphonatory tasks. Signals were eventually obtained in all subjects from both RLN-innervated and ansa-innervated strap muscles that correlated with speech production. After 1 year, RLN-driven signals were larger than ansa-driven signals in magnitude, and their timing appeared better correlated with intended phonation. The results show that neck surface electromyography is an effective control source for hands-free electrolarynx activation, and that RLN transfer may provide the best approach for obtaining phonation-related activity.

Sternohyoid flap for facial reanimation: a comprehensive preclinical evaluation of a novel technique

IMPORTANCE

Neuromuscular reanimation of the face provides the correct specific neural functional input and thereby prevents synkinesis. Unfortunately, this ideal situation is rarely encountered in the clinical setting.

OBJECTIVES

To assess the technical feasibility of and define the surgical procedure for harvesting the sternohyoid muscle as a novel free flap for use in facial reanimation indications.

DESIGN, SETTING, AND PARTICIPANTS

Fresh, postmortem, nonfixed cadavers were used to define the anatomy and perform the flap harvest procedures. Twenty-four flap harvests were performed. Angiography was performed on the pedicle of the harvested flaps to assess potential flap perfusion. Adenosine triphosphatase staining was performed on the muscle specimens to establish fiber type.

MAIN OUTCOME MEASURES

The harvest technique, pedicle (arterial or venous), nerve length, and flap geometry parameters were characterized.

RESULTS

The sternohyoid muscle was found to be reliably vascularized by the superior thyroid artery in all cases with an appropriate arterial and venous pedicle for vascular anastomosis. The mean arterial (5.5 cm) and venous (5.9 cm) pedicle lengths are comparable with gracilis flaps. The mean motor nerve length was 10.7 cm. The inclusion of the hyoid bone allows rigid fixation, and the muscle size, fiber type, and volume profiles all compare favorably to the gracilis flap for use in the indication of facial reanimation. Mock surgical procedures were performed to define inset parameters. This flap potentially allows single-stage cross-facial neurorrhaphies to be performed.

CONCLUSIONS AND RELEVANCE

This is the first article, to our knowledge, of the sternohyoid muscle as a potential donor site for free-tissue transfer. This muscle has a predictable vascular pedicle and neural innervation along with size and fiber type parameters that make it an ideal potential free flap for facial reanimation.

LEVEL OF EVIDENCE

NA.

Thyroid surgery

Diseases of the thyroid are common and surgical treatment is often the preferred option. Thyroid surgery is becoming subspecialised and falls within the repertoire of maxillofacial, and head and neck surgeons. Multidisciplinary management of most patients with diseases of the thyroid is key to providing the best care particularly for those with malignancies and retrosternal extension. To reduce postoperative complications a meticulous search for, and protection of the recurrent laryngeal nerve and parathyroid glands, with an incision along the skin crease in the lower neck, which can be extended for neck dissection, are paramount. Recent advances in thyroid surgery include ultrasound-guided cervical plexus block, use of the Harmonic Scalpel(®) (Ethicon Endo-Surgery, Inc., USA), intraoperative nerve stimulation to monitor the recurrent laryngeal nerve, use of TissuePatch™ 3 (Tissuemed Ltd., Leeds, UK) adhesive sealant, and minimal access surgery.

The combined use of hyoid bone flap and radial forearm free flap for reconstruction following partial laryngopharyngectomy

In hypopharyngeal carcinoma, even partial laryngopharyngectomy, results in functional disorders involving swallowing and speaking. We reconstructed partial defects following partial laryngopharyngectomy using a combined flap of a hyoid bone flap and radial forearm free flap. Before ablative surgery, we prepared an ipsilateral hyoid bone as a bone flap with sternohyoidal muscle. Then a radial forearm free flap was prepared simultaneously with tumor surgery. Thereafter, we reconstructed the epiglottis and pyriform recess using the combined flap. We successfully reconstructed 7 patients suffering from squamous cell carcinoma of the hypopharynx. The tracheostoma in all patients could be closed. Six patients could swallow without dysphagia within 48 days. This is the first report of the successful combined use of a hyoid bone flap and radial forearm free flap for hypopharyngeal carcinoma.

Repair with sternohyoid muscle fascia after subtotal laryngectomy

Background:

The subtotal laryngectomy procedure enables the patient to avoid some of the serious consequences of total laryngectomy without having to relinquish oncological effectiveness. However, the important complication of aspiration may still seriously affect some patients. Many methods of reconstruction have been described in an attempt to avoid or minimise this complication.

Methods:

Thirty-nine patients (15 with supraglottic laryngeal cancer and 24 with hypopharyngeal cancer) who had undergone subtotal laryngectomy between 2000 and 2006 were included in this study. In all patients, a sternohyoid muscle flap has been used for primary, one-stage reconstruction of laryngopharyngeal defects, following resection of advanced stage lesions. Patients' times to oral intake and decannulation, their speech function and their post-operative complications were reviewed.

Results:

The patients' three-year overall survival rate was 46.1 per cent. Their mean time to oral intake was 14 days. Twenty-six patients were decannulated (66.7 per cent). Almost all patients regained their speech function post-operatively, although their voice quality was not as good as before surgery.

Conclusions:

Sternohyoid muscle fascia reconstruction leads to optimal repair of subtotal laryngectomy defects and restored laryngeal function.

Observation of the relationship between the shape of skeletal muscles and their nerve distribution patterns: a transparent and microanatomic study

BACKGROUND

There are many gaps in the understanding of the neuroanatomy of skeletal muscles with regards to the nerve distribution pattern and shape of the muscles. This study was designed to examine the entire intramuscular nerve-distribution patterns of various human skeletal muscles.

METHODS

The relationships among nine skeletal muscles with various architecture (rhomboid major, biceps brachii, flexor pollicis longus, rectus femoris, sternohyoid, trapezius, masseter, digastric muscles) and their nerve-distribution patterns were investigated in four fetal cadavers using the Sihler staining method. The diameter and number of extramuscular (main) and major nerve branches, the number of minor nerve branches, and anastomoses were examined and evaluated statistically.

RESULTS

With regards to the number of extramuscular (main) nerve branches, the rhomboid major muscle resembled the flexor pollicis longus, trapezius, masseter, and sternohyoid muscles, and the anterior belly of the digastricus muscle (p > 0.05), whereas it was significantly different from the rectus femoris, the posterior belly of digastricus, and the long and short heads of the biceps brachii (p < 0.05). Trapezius and masseter muscles were different from all of the skeletal muscles that were studied with regards to the diameter of main branches (p < 0.05). The masseter muscle had the largest diameter (p < 0.05). With regards to the number of minor nerve branches, the sternohyoid muscle was significantly different from all the skeletal muscles that were studied (p < 0.05) except the short head of the biceps brachii, rectus femoris, and the posterior belly of digastricus (p > 0.05). As for the number of neural anastomoses, the sternohyoid muscle was statistically different from all skeletal muscles that were studied (p < 0.05) except the masseter and trapezius muscles (p > 0.005).

CONCLUSIONS

A surgeon's thorough knowledge of the relationship between the shape and nerve distribution pattern of skeletal muscles is important in successful reinnervation and regeneration of these muscles. It might also be useful in the field of muscle transplantation.

Vascular pedicles of infrahyoid muscles: An anatomical study

This study was designed to determine the entering sites of vascular pedicles of the infrahyoid muscles. The neck regions of 12 cadavers were investigated bilaterally. The vascular pedicles of the infrahyoid muscles (except the thyrohyoid and inferior belly of the omohyoid muscle) were dissected and measurements taken with a caliper in reference to the attachments of the muscles. For the sternothyroid muscle, two vascular pedicles were found bilaterally in all cadavers. Two vascular pedicles were found bilaterally for the sternohyoid muscle in 11 cadavers; in one cadaver the inferior vascular pedicle was absent bilaterally. One vascular pedicle was found bilaterally for the superior belly of the omohyoid muscle in all cadavers. These data regarding the vascular pedicles of the infrahyoid muscles might be useful for preserving the vascular supply of the infrahyoid muscles during flap preparation.

The angiosomes of the head and neck: anatomic study and clinical applications

The angiosome concept was introduced over a decade ago by Taylor and Palmer, whereby the body was considered to be composed anatomically of multiple three-dimensional composite blocks of tissue supplied by particular source arteries. Since then, detailed studies of the forearm and leg have been examined by Taylor and his coworkers. This study focuses on another region--the head and neck. Six fresh head and neck cadaver specimens were examined after infusion with a radio-opaque lead oxide mixture and correlated with over 24 previous body studies. The vascular anatomy of the skin, superficial musculoaponeurotic system (SMAS), muscles, brain, dura, and bone was examined. Each layer was painstakingly removed, photographed, labeled, and mapped to the respective arteries and veins. A radiologic subtraction technique was used to allow successive layers to be compared. This information was then scanned into a computer, analyzed, color coded, and labeled, thereby producing a three-dimensional study of the head and neck region to identify the respective angiosomes. As in previous detailed examinations of the leg and forearm, the angiosomes were found to be connected usually within tissues, such as muscle, skin, specialized organs or glands, rather than between the tissues. The muscles usually had vessels of two or more angiosomes supplying them and fell into three major groups based on the similarity of their arterial supply. In some areas, the midline anastomoses were rich, especially in the integument of the scalp, forehead, and lips. In other regions, the midline vascular connections were poor, especially in the tongue and palate. No fewer than 13 angiosomes of the head and neck, supplied by the branches of the external carotid, internal carotid, and subclavian arteries, have been defined, mapping their three-dimensional territories in the skin, the deep soft tissues, and the bones. Although most angiosomes spanned between skin and bone, three territories, those of the vertebral, lingual, and ascending pharyngeal vessels, were confined to the deep tissues without cutaneous representation. Finally, this study provides additional data for the surgeon to help plan safer incisions and better reconstructive flap procedures. It also gives information that may help explain the etiology and treatment of head and neck arteriovenous vascular malformations.