Proposal to Replace the Terminology “Levator Claviculae Muscle” with “Cleidocervical Muscle” for Uniformity in the Anatomical Literature

Abstract

Several terminologies exist for a vestigial muscle connecting the clavicle to the cervical vertebrae; however, “levator claviculae muscle” and “cleidocervical muscle” are commonly found in the contemporary literature. The term “levator claviculae” does not determine the location of the superior insertion point, but rather describes a single function of the muscle. However, similar to the sternocleidomastoid muscle, the bilateral presence of this muscle could result not only in increased strength for elevating the clavicle, but also in enhanced neck flexion and greater neck stability. To provide anatomical precision, the muscle could be more accurately termed the cleidocervical muscle. This literature review was performed using “PubMed” as the search engine. Mesh terms such as levator AND claviculae, cleidocervicalis, cleidocervical, cleidoatlanticus, and cleidotrachelian were used. Our proposal for a precise methodology in addressing the terminology would be as follows: [Position 1: cleidocervical muscle] [Position 2: vertebra levels]. In this opinion paper, we advocate for the anatomical community to discontinue the use of the term “levator claviculae” and instead adopt the more appropriate “cleidocervical muscle” in academic discourse.

1. Introduction

The Latin term “levātor” means “the one that lifts or raises something”. The levator claviculae muscle (Latin: musculus levator claviculae) is a vestigial human muscle that connects the clavicle to the cervical vertebrae at various levels, traditionally known as the lifter muscle of the clavicle. However, the term “cleidocervical muscle” (Latin: musculus cleidocervicalis) has also been used interchangeably in the literature. This muscular variation in humans was first illustrated in a 1515 drawing by Leonardo da Vinci titled Anatomy of the Neck. Since the 19th century, multiple authors have described this muscle in the scientific literature [1,2]. For instance, Professor John Wood reported and illustrated the “levator claviculae” muscle to the Royal Society in 1864, and then published in 1870 [1]. In the year 1876, Professor Wenzel Gruber described the same muscle in a publication as cleidocervical sive (or) superior tracheloclavicular muscle in humans, which he cited as levator claviculae muscle found in monkeys [2]. In 1991, Newell et al. proposed the nomenclature “cleidotrachelian muscle”, which aligns with Gruber’s terminology [3]. It is obvious that the preferences of terminologies associated with the muscle vary in the literature. Therefore, we are interested in proposing a consistent use of terminology that enhances clarity, facilitates communication among researchers and clinicians, and reduces the risk of confusion or misinterpretation.

2. Materials and Methods

Our literature research was performed using the search engine “PubMed”. Mesh search terms such as “levator” AND “claviculae” using the filter “case reports” and “observational study” produced results with 23 references. Additionally, using the same filters, other keywords such as cleidocervical (4 references), cleidocervicalis (1 reference), cleidoatlanticus (3 references), and cleidotrachelian (1 reference) were used for the literature research. “Cleidoepistrophicus” as a search mesh term did not provide any results; therefore, this term was not used in Table 1. Out of a total of 32 publications initially found, 7 references were excluded because the studies were not case reports. One reference, O’Sullivan et al. 1998, was excluded because the cleidooccipital muscle was described as a variant of the levator claviculae, where the superior attachment of the muscle was to the trapezius muscle instead of the transverse processes of the cervical vertebrae [4]. Total exclusions included the following: “levator” AND “claviculae”—6 references, cleidocervical—1 reference, cleidocervicalis—0 reference, cleidoatlanticus—1 reference, cleidotrachelian—0 reference. Leon et al. 1995 [5] and Rosenheimer et al. 2000 [6] were common relevant results that were found under the mesh terms “levator” AND “claviculae” and cleidocervical. Therefore, altogether, 22 publications are included in Table 1.

3. Results and Discussion

While several terminologies exist for the muscle connecting the clavicle to the cervical vertebrae, only “levator claviculae muscle” and “cleidocervical muscle” are commonly found in the contemporary literature. Here are some examples related to our case.

(1)

Levator claviculae muscle [5,7];

(2)

Cleidocervical muscle [5,8,9];

(3)

(Superior) Tracheloclavicular muscle [2];

(4)

Cleidotrachelian muscle [3];

(5)

Cleidoatlanticus muscle [10,11];

(6)

Cleidoepistrophicus muscle [2].

The term “levator claviculae” is most frequently used, implying a functional approach followed by the term “cleidocervical muscle” (Table 1). However, the term “levator claviculae” does not refer to a standardized superior insertion point, leading to potential misinterpretation. The term “cleidocervical muscle”, on the other hand, offers a purely anatomical description. Similar to other prevertebral muscles, such as the anterior scalene or longus colli muscles, cleidocervical muscles have a superior/distal attachment at the anterior tubercle of the cervical vertebrae and an inferior/proximal insertion on the clavicle. In our previous literature review paper, we showed that the inferior attachment was found slightly more frequently on the middle third of the clavicle, whereas the superior insertion was available more often on the superior cervical vertebrae than the lower ones (Figure 1) [9].

Table 1. A tabular illustration with examples of newly proposed terminologies in comparison to already existing ones in selected case reports. NP = not provided. This table has been derived and modified from the published literature by Silawal et al. 2022 [9].

Publications	Cervical Insertion	Terminology Used				Proposed Terminology
		Levator Claviculae	Cleidocervicalis	Cleidoatlanticus	Cleidotrachelian
Newell et al., 1991 [3]	C3–C4				+	cleidocervical muscle (C3–C4)
Fasel et al., 1994 [7]	NP	+				cleidocervical muscle
Tomo et al., 1994 [8]	C6		+			cleidocervical muscle (C6)
Leon et al., 1995 [5]	C2		+			cleidocervical muscle (C2)
Rüdisüli et al., 1995 [12]	C3	+				cleidocervical muscle (C3)
Rubinstein et al., 1999 [13]	C1–C3	+				cleidocervical muscle (C1–C3)
Ginsberg et al., 1999 [14]	C3	+				cleidocervical muscle (C3)
Rosenheimer et al., 2000 [6]	C6	+				cleidocervical muscle (C6)
Shaw et al., 2004 [15]	NP	+				cleidocervical muscle
Aydoğ et al., 2007 [16]	NP	+				cleidocervical muscle
Capo et al., 2007 [17]	C2	+				cleidocervical muscle (C2)
Loukas et al., 2008 [18]	C3–C4	+				cleidocervical muscle (C3–C4)
Natsis et al., 2009 [19]	C3–C5	+				cleidocervical muscle (C3–C5)
Rodríguez-Vázquez et al., 2009 [11]	C1			+		cleidocervical muscle (C1)
Feigl et al., 2011 [10]	C1			+		cleidocervical muscle (C1)
Odate et al., 2012 [20]	C4	+				cleidocervical muscle (C4)
Billings et al., 2014 [21]	C5		+			cleidocervical muscle (C5)
Bahls et al., 2016 [22]	NP	+				cleidocervical muscle
Schlarb et al., 2016 [23]	NP	+				cleidocervical muscle
Ferreli et al., 2019 [24]	C2–C3	+				cleidocervical muscle (C2–C3)
Costa González et al., 2020 [25]	NP	+				cleidocervical muscle
Ruiz Santiago et al., 2001 [26]	NP	+				cleidocervical muscle

Table 1. A tabular illustration with examples of newly proposed terminologies in comparison to already existing ones in selected case reports. NP = not provided. This table has been derived and modified from the published literature by Silawal et al. 2022 [9].

Publications	Cervical Insertion	Terminology Used				Proposed Terminology
		Levator Claviculae	Cleidocervicalis	Cleidoatlanticus	Cleidotrachelian
Newell et al., 1991 [3]	C3–C4				+	cleidocervical muscle (C3–C4)
Fasel et al., 1994 [7]	NP	+				cleidocervical muscle
Tomo et al., 1994 [8]	C6		+			cleidocervical muscle (C6)
Leon et al., 1995 [5]	C2		+			cleidocervical muscle (C2)
Rüdisüli et al., 1995 [12]	C3	+				cleidocervical muscle (C3)
Rubinstein et al., 1999 [13]	C1–C3	+				cleidocervical muscle (C1–C3)
Ginsberg et al., 1999 [14]	C3	+				cleidocervical muscle (C3)
Rosenheimer et al., 2000 [6]	C6	+				cleidocervical muscle (C6)
Shaw et al., 2004 [15]	NP	+				cleidocervical muscle
Aydoğ et al., 2007 [16]	NP	+				cleidocervical muscle
Capo et al., 2007 [17]	C2	+				cleidocervical muscle (C2)
Loukas et al., 2008 [18]	C3–C4	+				cleidocervical muscle (C3–C4)
Natsis et al., 2009 [19]	C3–C5	+				cleidocervical muscle (C3–C5)
Rodríguez-Vázquez et al., 2009 [11]	C1			+		cleidocervical muscle (C1)
Feigl et al., 2011 [10]	C1			+		cleidocervical muscle (C1)
Odate et al., 2012 [20]	C4	+				cleidocervical muscle (C4)
Billings et al., 2014 [21]	C5		+			cleidocervical muscle (C5)
Bahls et al., 2016 [22]	NP	+				cleidocervical muscle
Schlarb et al., 2016 [23]	NP	+				cleidocervical muscle
Ferreli et al., 2019 [24]	C2–C3	+				cleidocervical muscle (C2–C3)
Costa González et al., 2020 [25]	NP	+				cleidocervical muscle
Ruiz Santiago et al., 2001 [26]	NP	+				cleidocervical muscle

Similar to the sternocleidomastoid muscle, a bilateral presence of this muscle could result in greater neck stability, increased strength in elevating the clavicle, and enhanced neck flexion. A similar analogy can be found in the scalene muscles, where both elevation of the ribs and neck flexion are possible. The fixed point (punctum fixum) and mobile point (punctum mobile) can interchange depending on the muscle’s activity. This is how the function of the cleidocervical muscle is not limited to the elevation of the clavicle. The attachment points of this muscle, however, are constant, i.e., the transverse processes of the cervical vertebrae superiorly and the clavicle inferiorly. Therefore, we find it obvious to nomenclate the muscle accordingly. The biomechanical impact of this muscle can vary depending on its attachment at different cervical vertebrae levels superiorly or its insertion position on the clavicle. Since the attachment levels vary drastically among individuals [9], we find that mentioning the vertebral levels along with the nomenclature is an important addition. A similar argument can be made depending on the position of the inferior insertion point of this muscle. An attachment on the lateral part of the clavicle supports lateral flexion of the neck in addition to neck flexion, and allows for greater mobility of the clavicle in the sternoclavicular joint along the sagittal axis, compared to an attachment on the middle portion of the clavicle.

We propose a standardized nomenclature for the muscle based on anatomical precision. The suggested terminology would build on “cleidocervical muscle”, adding information regarding the cervical vertebrae involved. The proposed format is the following:

[Position 1: cleidocervical muscle] [Position 2: vertebra levels].

As an example, if a cleidocervical muscle attaches proximally on the clavicle and distally (superiorly) at the lateral processes of the third and the fourth cervical vertebrae, the suggested terminology would be “cleidocervical muscle (C3–C4)”. Table 1 demonstrates the proposed terminologies for this muscle as described in various publications.

Even though we have discarded the usage of the terms ‘middle’ or ‘lateral’ insertion of the muscle in the clavicle, we still encourage anatomists, clinicians, surgeons, and radiologists to be aware of the presence and exact course of the muscle when referring to it. Specifically, a unilateral presence of this muscle could be misinterpreted as a pathological entity, such as lymphadenopathy, metastatic lymph nodes, or neoplasms [6,14,15,25,27]. Anatomical variation is today an inherent part of academic and clinical daily practices [28,29]. Therefore, we find it essential that, beyond mere awareness of their existence, a structured use of appropriate terminology should be adopted. We encourage anatomists and all clinicians to engage in further discussion on this matter.

4. Conclusions

Our proposal seeks to encourage the adoption of a standardized term in forthcoming anatomical studies and the medical literature. In this opinion paper, we advocate for the anatomical community to discontinue the use of the term “levator claviculae” and instead adopt the more accurate “cleidocervical muscle” in academic discourse. To enhance precision in terminology, we recommend specifying the vertebral levels of the superior attachment alongside the term “cleidocervical muscle”, considering potential interindividual variations in attachment levels.