CONCLUSIONS: This scoping review aims to summarize the technical strategies for obtaining trigeminocervical reflex (TCR) and trigeminospinal reflex (TSR) responses. Studies published on TCR or TSR elicitation in humans through electrical stimulation of trigeminal nerve branches were eligible for this scoping review. The data of interest included stimulation parameters, site of stimulation, recording parameters, and the feasibility of TCR and TSR elicitation, in healthy participants. Short-latency TCR responses were regularly obtained in both anterior and posterior neck muscles after electrical stimulation of the supraorbital and infraorbital nerves under voluntary muscle activation. However, without voluntary muscle activation, we found evidence of elicitation of short-latency TCR components only in the posterior neck muscles after supraorbital or infraorbital nerve stimulation. Long-latency TCR responses were regularly obtained in the anterior and posterior neck muscles in studies that evaluated this technique, regardless of the trigeminal branch stimulation or muscle activation status. Short-latency TSR components were not obtained in the included studies, whereas long-latency TSR responses were regularly recorded in proximal upper limb muscles. This scoping review revealed key heterogeneity in the techniques used for TCR and TSR elicitation. By summarizing all the methodological procedures used for TCR and TSR elicitation, this scoping review can guide researchers in defining optimized technical approaches for different research and clinical scenarios.

This study aimed to investigate the anatomy of the spinal accessory nerve (SAN) in the posterior cervical triangle, especially in relation to adjacent anatomical landmarks, along with a systematic review of the current literature with a meta-analysis of the data. Overall, 22 cadaveric and three prospective intraoperative studies, with a total of 1346 heminecks, were included in the analysis. The major landmarks relevant to the entry of the SAN at the posterior border of the SCM muscle (PBSCM) were found to be the mastoid apex, the great auricular point (GAP), the nerve point (NP), and the point where the PBSCM meets the upper border of the clavicle. The SAN was reported to enter the posterior cervical triangle above GAP in 100% of cases and above NP in most cases (97.5%). The mean length of the SAN along its course from the entry point to its exit point from the posterior triangle of the neck was 4.07 ± 1.13 cm. The SAN mainly gave off 1 or 2 branches (32.5% and 31%, respectively) and received either no branches or one branch in most cases (58% and 23%, respectively) from the cervical plexus during its course in the posterior cervical triangle. The major landmarks relevant to the entry of the SAN at the anterior border of the TPZ muscle (ABTPZ) were found to be the point where the ABTPZ meets the upper border of the clavicle and the midpoint of the clavicle, along with the mastoid apex, the acromion, and the transverse distance of the SAN exit point to the PBSCM. The results of the present meta-analysis will be helpful to surgeons operating in the posterior cervical triangle, aiding the avoidance of the iatrogenic injury of the SAN.

OBJECTIVE: This is a case series and a review of the literature of therapeutic outcomes of botulinum toxin (BT) injections for anterocollis.
METHODS: Data collected included gender, age, age at onset, muscles targeted, and doses injected. Routine forms were filled out during each visit: Patient Global Impression of Change, Clinician Global Impression of Severity, Tsui scale. The effect duration and side effects (SEs) of the previous treatment were noted.
RESULTS: We described 4 patients (3 men, 13 visits) with anterocollis, as primary postural abnormality of the neck, emphasizing the therapeutic response to BT injection. Mean age at onset was 75.3 ± 7.0 years, age at first injection was 80.7 ± 3.5 years. The mean total dose per treatment was 290.0 ± 95.6 units. Patient Global Impression of Change with any grade of favorable effect was reported in 27.3% of the treatments. In objective assessment, Global Impression of Severity and Tsui scores did not show a consistent tendency of improvement. Neck weakness was prevalent in 18.2% of the visits of the anterocollis group while no other SEs were noted. We found 15 articles describing experience with BT for anterocollis in 67 patients (19 in deep and 48 in superficial neck muscles).
CONCLUSIONS: This case series describes the poor outcome of BT treatment for anterocollis, with low efficacy and bothersome SE. Levator scapulae injection for anterocollis is not effective and is highly associated with head drop and should perhaps be abandoned. Injection to the longus colli might give some benefit in non-responders.

This systematic review aims to summarise the evidence from studies that examined morphometric alterations of the deep neck muscles using diagnostic imaging (ultrasound imaging, magnetic resonance imaging, and computed tomography) in patients diagnosed with primary headache disorders (PHD). No previous reviews have focused on documenting morphometric changes in this population. We searched five databases (up to 12 November 2022) to identify the studies. The risk of bias (RoB) was assessed using the Quality in Prognostic Studies (QUIPS) tool and the overall quality of the evidence was assessed using The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. A total of 1246 studies were screened and five were finally included; most were at high RoB, and the overall level of confidence in results was very low. Only two studies showed a significant association between morphometric alterations of the deep neck muscles and PHD (p < 0.001); nevertheless, their RoB was high. Contradictory and mixed results were obtained. The overall evidence did not show a clear association between morphometric alterations of the deep neck muscles in patients diagnosed with PHD. However, due to the limited number of studies and low confidence in the evidence, it is necessary to carry out more studies, with higher methodological quality to better answer our question.

Congenital muscular torticollis is a problem that arises at birth or immediately after birth in which the sternocleidomastoid muscle is shortened on the afflicted side, leading to an ipsilateral rotated of the head and a contralateral rotation of the face and jaw. To determine the effectiveness of physical therapy treatment in infants treated for congenital muscular torticollis, relevant articles published between 2011 and 2020 were located using electronic databases. A total of 9 studies out of 24 potentially relevant articles were reviewed. All studies were randomised controlled trials with 6-8 score on the Physiotherapy Evidence Database scale (Pedro scale) which showed high quality of methodology. The studies typically found significant statistical effects in the management of congenital muscular torticollis. Additionally, most of the studies reported increased adherence to exercise as another essential advantage. Conservative physical therapy management showed positive outcomes, and early physiotherapy referral showed significant reduction in treatment duration.

The platysma muscle is a thin superficial muscle that covers the entire neck and lower part of the face. The platysma muscle is the primary target muscle for botulinum neurotoxin injection therapy aimed at treating platysmal band and lower facial lifting. In the procedure of botulinum neurotoxin injection therapy, a lack of knowledge of the anatomy of the platysma muscle and the properties of botulinum neurotoxin can lead to side effects such as dysphagia, dysphonia, and weakness of the neck muscles. Anatomically safe injection sites have been proposed for the platysma muscle, and the appropriate injection technique has been reviewed. We proposed optimal injection sites based on the external anatomical features of the mandible. The aim of these proposal was to standardize the procedure for the effective use of botulinum neurotoxin injections by minimizing the dose unit and injection points and thereby preventing adverse events.

BACKGROUND: Infrared thermography has the potential to help assess human head and neck muscles, as thermal variation measurements due to muscle imbalance can contribute to the evaluation and therapeutic follow-up of various clinical conditions in the field of health.
OBJECTIVE: This study investigated, with a scoping review, the use of infrared thermography in complementary assessments of human head and neck muscles to determine the extent of research on the topic, what methodologies are used in thermal assessment and thermographic analysis, what regions are assessed, and what results are expected in thermography.
METHODS: LILACS, MEDLINE, SciELO, and Web of Science were the databases searched to identify articles published on the topic, with no restriction of language or time of publication. Descriptive, analytical, and experimental observational studies on the assessment of the human head and neck muscle surface temperature with infrared thermography were included. Case studies, case series, methodological accuracy, literature review, animal studies, studies that assessed patients with head and neck cancer, and studies that did not assess head and neck muscle temperature with thermography were excluded. The articles were analysed with a protocol developed by the authors, with data on author, year, country, type of study, sample characterisation, muscles assessed, outcomes investigated, thermal assessment methodology, thermographic analysis methodology and thermography measurements.
RESULTS: This review identified and analysed 27 articles. The studies assessed thermal distribution in normal individuals and those with pathologies related to hyper- and hypofunctional head and neck muscle conditions for diagnosis or therapeutic follow-up. The masseter, temporal, digastric, anterior cervical region, orbicularis oris, frontalis, buccinator, suprahyoid, trapezius, sternocleidomastoid and levator scapulae muscles were assessed. Quantitative analyses with area selection tool predominated, considering absolute temperatures and temperature differences. The studies investigated temperature and its relationship with myogenic pain, quantitative assessment of muscle parameters and blood flow velocity. The mean temperature ranged from 32.97°C (±2.21) to 34.90°C, and hyper-radiant and/or asymmetric regions were observed in hyperfunctional conditions and normal subjects after muscle activation.
CONCLUSIONS: Thermography is used in complementary assessments of head and neck muscles, identifying hyper-radiant regions and thermal asymmetry related to muscle tension and activation state. Papers are limited to specific clinical conditions and few muscle groups, besides having great methodological variability.

Chronic neck pain is a common musculoskeletal disorder. Previous studies have found that chronic neck pain is associated with changes in neck muscle morphology and fat infiltration (FI). This systematic review summarizes and analyzes all studies on neck muscle morphology in patients with chronic nonspecific neck pain (CNNP). The main objective of this study was to review and analyze measurements of neck muscles in all patients with CNNP, including morphologic changes in the multifidus muscle (MF), longus colli muscle (LC), and semis-spinalis capitis muscle (SCa) in patients with CNNP compared with controls.
This was a systematic review with meta-analysis A comprehensive search of online databases, including PubMed, Web of Sciences, Embase, and Medline was conducted to identify relevant studies reporting changes in neck muscle morphology in patients with chronic neck pain versus healthy controls. Search scope was from inception to June 30, 2022, with no language restrictions. Two reviewers participated in the screening process independently. Due to the lack of relevant data from other studies, only studies that reported morphologic changes of MF, LC, and SCa in patients with CNNP, including muscle cross-sectional area (CSA), lateral diameter (LD), and anteroposterior diameter (APD), were selected. A modified Newcastle-Ottawa scale was used to assess study quality and risk of bias. A total of 11 studies were included based on inclusion and exclusion criteria, of which 8 were included in the meta-analysis.
The results showed that the CSA of LC was slightly smaller in patients with CNNP (mean difference-0.23, 95% confidence interval -0.37 to -0.08), and the multiplied linear dimensions (multiplied linear dimensions: lateral diameter × anteroposterior diameter) of SCa was slightly smaller (mean difference -0.19, 95% confidence interval -0.34 to -0.03). There was no difference in MF muscle size between Patients with CNNP and healthy controls.
LC and SCa sizes were slightly smaller in patients with CNNP; there was no difference in MF muscle size between the 2 groups. In addition, no conclusions could be drawn in fat infiltration due to insufficient evidence. In summary, CNNP has influence on neck muscle morphology but the evidence is limited.

From a topographical standpoint, the digastric muscle is key to the formation of several triangles of the neck, which are of the utmost clinical significance. Herein, we present a previously unrecognised variation of the digastric muscle: a quadrigastric muscle with two accessory bellies originating from the body and angle of the mandible and inserting to the intermediate tendon. Three new triangles are demarcated between the four bellies of the aberrant muscle. Detailed knowledge of variations of the digastric muscle, changing the borders and relationships of the topographic triangles, is paramount for radiologists and surgeons operating on the anterior region of the neck.

The sternocleidomastoid muscles (SCM) are prominent paired muscles of the neck connecting proximally the manubrium sterni and the clavicle to the mastoid process and the occipital bone distally. Following their points of attachment sternomastoid, sternooccipital, cleidomastoid and cleidooccipital portions of this muscle have been described. Altogether 23 case reports from year 2000 till 2020 with 29 subjects related to the SCM supernumerary variations were searched and analysed where parameters such as supernumerary proximal variation types (sternal vs. clavicular), insertional variation, unilaterality/bilaterality of the variation, study type, reported gender of the subjects and the country of research were extracted. The research shows that 48.3% of the subjects had bilateral presentation of SCM variations. If present unilaterally, three quarters of the cases were on the left side. The most frequent variation is located at the clavicular side of the proximal SCM head whereas isolated sternal sided proximal head variation or an insertional variation alone are very rare. Interestingly, with 96.6%, most of cases in the literature were discovered in cadavers during anatomical dissections. Male gender represented with 82.8% higher prevalence than females. The higher male prevalence in the body donor system, predominantly in the Asian continent could play a decisive role in the outcome as more than half of the reported cases stemmed from India in this period. Importantly, the knowledge of different anatomical variations of the SCM is highly relevant for surgical, clinical or radiological approaches in the neck.