{{Short description|Muscle between the clavicle and first rib}} {{Infobox muscle | Name = Subclavius muscle | Latin = musculus subclavius | Image = Subclavius muscle frontal2.png | Caption = Subclavius muscle (shown in red). | Image2 = Gray411subclavius.png | Caption2 = Deep muscles of the chest and front of the arm, with the boundaries of the axilla. (Subclavius visible at upper left, above first rib.) | Origin = First rib and cartilage | Insertion = Subclavian groove of clavicle (inferior surface of middle one third of the clavicle) | Action = Depression of clavicle<br />elevation of first rib | Blood = Thoracoacromial trunk, clavicular branch | Nerve = Subclavian nerve }}
The '''subclavius''' is a small triangular muscle, placed between the clavicle and the first rib.<ref name="Gray's-1918">{{cite book |url = http://education.yahoo.com/reference/gray/subjects/subject/122#p438 |title = Gray's Anatomy: The Muscles Connecting the Upper Extremity to the Anterior and Lateral Thoracic Walls |chapter = IV. Myology: 13 |year = 1918 |url-status = dead |archive-url = https://web.archive.org/web/20140308180931/http://education.yahoo.com/reference/gray/subjects/subject/122#p438 |archive-date = 2014-03-08 }}</ref> Along with the pectoralis major and pectoralis minor muscles, the subclavius muscle makes up the anterior axioappendicular muscles, also known as anterior wall of the axilla.<ref>Drake, Richard, et al. ''Gray's Anatomy For Students,'' Elsevier Inc., 2005</ref>
==Structure== It arises by a short, thick tendon from the first rib and its cartilage at their junction, in front of the costoclavicular ligament.<ref name="Gray's-1918" />
The fleshy fibers proceed obliquely superolaterally, to be inserted into the groove on the under surface of the clavicle.
===Innervation=== The nerve to subclavius (or subclavian nerve) innervates the muscle. This arises from the junction of the fifth and sixth cervical nerves, from the superior/upper trunk of the brachial plexus.
===Variation=== Insertion into coracoid process instead of clavicle or into both clavicle and coracoid process. Sternoscapular fasciculus to the upper border of scapula. Sternoclavicularis<ref>[http://www.pjsr.org/Jan13_pdf/8%20Yogesh%20Sontakke.pdf '''Sternoclavicularis '''is a rare muscle found in a large triangular gap between the sternocostal and clavicularheads of Pectoralis Major muscle on the right side during routine cadaveric dissection.]</ref> from manubrium to clavicle between pectoralis major and coracoclavicular fascia.<ref name="Gray's-1918" /> Rarely, the subclavius may be missing entirely.<ref>{{Cite journal|last1=Yun|first1=Sam|last2=Park|first2=Sekyoung|last3=Kim|first3=Chang Su|date=May 2018|title=Absence of the subclavius muscle with contralateral subclavius posticus muscle: first imaging report|url=https://doi.org/10.1016/j.clinimag.2017.10.008|journal=Clinical Imaging|volume=49|pages=54–57|doi=10.1016/j.clinimag.2017.10.008|pmid=29127878|issn=0899-7071|url-access=subscription}}</ref>
==Function== It depresses the lateral clavicle, acts to stabilize the clavicle while the shoulder moves the arm. It also raises the first rib while lowering the clavicle during breathing.
The subclavius protects the underlying brachial plexus and subclavian vessels from a broken clavicle—the most frequently broken long bone.
==Additional images== <gallery> File:Subclavius muscle animation2.gif|Subclavius muscle (shown in red). Humerus and scapula are shown in semi-transparent. Animation. File:Subclavius muscle frontal3.png|Subclavius muscle (shown in red). File:Gray115.png|Anterior surface of sternum and costal cartilages. File:Gray201.png|Left clavicle. Inferior surface. File:Gray523.png|The axillary artery and its branches. File:Gray809.png|The right brachial plexus (infraclavicular portion) in the axillary fossa; viewed from below and in front. File:Slide7b.JPG|Subclavius muscle - left view File:Slide10d.JPG|Subclavius muscle- right view File:1118 Muscles that Position the Pectoral Girdle anterior.png|Subclavius (labeled top left) — frontal view </gallery>
==References== {{Gray's}} {{Reflist}}
==External links== {{Commons category|Subclavius muscles}} * [https://web.archive.org/web/19991022040619/http://www.ptcentral.com/muscles/muscletrunk.html#subclavius PTCentral] * [http://www.massagetherapy.com/articles/index.php/article_id/414/Pivotal-Places%3A-Help-for-Problem-Shoulders Pivotal Places: help for problem shoulders]
{{Muscles of thorax and back}} {{Portal bar|Anatomy}} {{Authority control}}
Category:Muscles of the upper limb