Axillary arch

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Axillary arch
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Axillary arch highlighted in red.
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Axillary arch labelled as 'achselbogen'.
Details
Origin Latissimus dorsi muscle
Insertion Humerus, Pectoralis major
Artery Lateral thoracic artery and subscapular artery
Nerve Lateral pectoral nerve
Identifiers
Latin arcus axillaris
Anatomical terms of muscle

The axillary arch is a variant of the latissimus dorsi muscle in humans. It is found as a slip of muscle or fascia extending between the latissimus dorsi muscle and the pectoralis major. There is considerable variation in the exact position of its origin and insertions as well as its blood and nerve supply. [1] The arch may occur on one or both sides of the body. [2] A meta-analysis revealed that the axillary arch had an overall prevalence of 5.3% of limbs. [3]

Contents

The arch is considered to have no functional significance, although this is challenged by some authors. [2] [4] It plays a role in entrapment of nearby structures and may alter local anatomy if a dissection of the local area is needed during surgery. The arch appears to arise from the panniculus carnosus, a structure found in most non-primate mammals, and has similarities with muscles found in many animals. The axillary arch has several other names including Langer's axillary arch, the muscle of Langer, axillopectoral muscle, Achselbogen and pectorodorsalis muscle. [5]

Structure

The axillary arch is an arch-shaped anatomical variant of the latissimus dorsi muscle of the human back. [6] [7] Its shape varies, but its defining characteristics are its origin from the latissimus dorsi muscle, its insertion close to or on the upper anterior part of the humerus, and that it crosses the neurovascular bundle associated with the axillary nerve from dorsomedial to ventrolateral. [6] Its size may vary from 7 to 10 cm (2.8 to 3.9 in) in length and 5–15 mm (0.2–0.6 in) in width. [7] The axillary arch may be seen when the arm is abducted and the palms put on the back of the head. An impression can be seen on the medial side of the axilla. [2] [4]

Nerve supply

Most commonly the lateral pectoral nerve innervates the axillary arch, although instances have been found where the intercostobrachial nerve, the medial pectoral nerve and the thoracodorsal nerve provide the nervous supply. [1]

Variation

The shape, size, insertion and origin of the arch can vary widely. [4] The arch usually occurs on both sides of the body; but may also occur only on one side. [4] The muscular component of the arch varies, with some arches seen to be purely fibrous. [8] The origin can be a direct continuation of the latissimus dorsi muscle fibres, originate with the tendinous element of the latissimus dorsi, or be a mixture of the two types originating from both the muscle and the tendon. [9]

The prevalence of the axillary arch in the European population is around 5.3%, [3] but this varies considerably among different genetic groups; lower in the Turkish population and more prevalent in the Chinese population. [10] [11]

The axillary arch may insert into the tendon of the pectoralis major muscle, the fascia of the coracobrachialis muscle, or the fascia covering the biceps brachii muscle. [7] Insertion into the pectoralis major muscle proper, the long head of the biceps brachii muscle, the coracoid process, the pectoralis minor muscle, the axillary fascia and to the bone at the crest of the greater tubercle of the humerus inserting distal to the insertion of the pectoralis major muscle have all been reported.[ citation needed ]

Function

The axillary arch is considered to have no functional significance, [4] although one small study of 22 participants has reported an increase in strength, endurance and motor control of the arm in women (but not men) with the arch as compared with those without; and an improvement in shoulder proprioception in both men and women. [2]

Clinical significance

There are several potential clinical consequences of the presence of an axillary arch including confusing the identification and palpation of enlarged or tumorous lymph nodes, the trapping of axillary structures including the axillary nerve and the axillary vein and causing potential problems in axillary surgery or breast reconstruction. [12] [13] There have also been reported instances of the axillary arch being involved in the development of deep vein thrombosis. [14]

History

The axillary arch muscle was first described by Bugnone in 1783 according to Pitzorno (1912) with Alexander Ramsay describing it as a novel variation during dissections performed in Edinburgh and London around 1793 by his own account of 1812. [6] [15] [16] In 1846 Karl Langer wrote up an account of the axillary arch, although he initially only described it as a fibrous arch, and termed it the Achselbogen (German : Axillary arch). [6] [8] Langer later described the presence of a muscular slip associated with the arch in certain cases. [17] Due to these publications Leo Testut used the term arc axillaire de Langer to refer to the muscular form of the arch, an association which has persisted. [18]

Other animals

Possible homologous structures in other species have been identified as the dorsoepitrochlearis muscle, the pectoralis quartus muscle or the panniculus carnosus. [1] The dorsoepitrochlearis is an important climbing muscle in monkeys and apes where it has its origin in the tendinous region of the latissimus dorsi and extends down the arm as a superficial muscle. [19]

The panniculus carnosus is a layer of striated muscle deep to the panniculus adiposus. [20] Although absent in hominoids, the panniculus carnosus is common in non-hominoid primates and non-primate mammals. [21] In lower mammals the area of the panniculus carnosus can be extensive, almost covering the entire body in the case of the short-beaked echidna. [22] Several human muscles are considered discrete muscles originating from the panniculus carnosus, and some researchers classify the axillary arch as a sporadic vestigial muscle of this type. [23]

See also

List of anatomical variations

Related Research Articles

<span class="mw-page-title-main">Humerus</span> Long bone of the upper arm

The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.

<span class="mw-page-title-main">Latissimus dorsi muscle</span> Large, flat back muscle

The latissimus dorsi is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline.

<span class="mw-page-title-main">Deltoid muscle</span> Shoulder muscle

The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle is made up of three distinct sets of muscle fibers, namely the

  1. anterior or clavicular part
  2. posterior or scapular part
  3. intermediate or acromial part
<span class="mw-page-title-main">Upper limb</span> Consists of the arm, forearm, and hand

The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the shoulder, arm, elbow, forearm, wrist and hand, and is primarily used for climbing, lifting and manipulating objects. In anatomy, just as arm refers to the upper arm, leg refers to the lower leg.

<span class="mw-page-title-main">Pectoralis major</span> Main human chest muscle

The pectoralis major is a thick, fan-shaped or triangular convergent muscle of the human chest. It makes up the bulk of the chest muscles and lies under the breast. Beneath the pectoralis major is the pectoralis minor muscle.

<span class="mw-page-title-main">Pectoralis minor</span> Human chest muscle that protracts the shoulder

Pectoralis minor muscle is a thin, triangular muscle, situated at the upper part of the chest, beneath the pectoralis major in the human body. It arises from ribs III-V; it inserts onto the coracoid process of the scapula. It is innervated by the medial pectoral nerve. Its function is to stabilise the scapula by holding it fast in position against the chest wall.

<span class="mw-page-title-main">Axilla</span> Area of the human body beneath the joint between arm and torso

The axilla is the area on the human body directly under the shoulder joint. It includes the axillary space, an anatomical space within the shoulder girdle between the arm and the thoracic cage, bounded superiorly by the imaginary plane between the superior borders of the first rib, clavicle and scapula, medially by the serratus anterior muscle and thoracolumbar fascia, anteriorly by the pectoral muscles and posteriorly by the subscapularis, teres major and latissimus dorsi muscle.

<span class="mw-page-title-main">Aponeurosis</span> Tissue which connects muscles to other organs

An aponeurosis is a flattened tendon by which muscle attaches to bone or fascia. Aponeuroses exhibit an ordered arrangement of collagen fibres, thus attaining high tensile strength in a particular direction while being vulnerable to tensional or shear forces in other directions. They have a shiny, whitish-silvery color, are histologically similar to tendons, and are very sparingly supplied with blood vessels and nerves. When dissected, aponeuroses are papery and peel off by sections. The primary regions with thick aponeuroses are in the ventral abdominal region, the dorsal lumbar region, the ventriculus in birds, and the palmar (palms) and plantar (soles) regions.

<span class="mw-page-title-main">Triceps</span> Muscle on the back of the upper arm

The triceps, or triceps brachii, is a large muscle on the back of the upper limb of many vertebrates. It consists of 3 parts: the medial, lateral, and long head. It is the muscle principally responsible for extension of the elbow joint.

<span class="mw-page-title-main">Shoulder joint</span> Synovial ball and socket joint in the shoulder

The shoulder joint is structurally classified as a synovial ball-and-socket joint and functionally as a diarthrosis and multiaxial joint. It involves an articulation between the glenoid fossa of the scapula and the head of the humerus. Due to the very loose joint capsule ,that gives a limited interface of the humerus and scapula, it is the most mobile joint of the human body.

<span class="mw-page-title-main">Teres major muscle</span> Muscle of the upper limb

The teres major muscle is a muscle of the upper limb. It attaches to the scapula and the humerus and is one of the seven scapulohumeral muscles. It is a thick but somewhat flattened muscle.

<span class="mw-page-title-main">Palmaris longus muscle</span> Muscle of the upper limb

The palmaris longus is a muscle visible as a small tendon located between the flexor carpi radialis and the flexor carpi ulnaris, although it is not always present. Reviews report rates of absence in the general population ranging from 10–20%; however, the rate varies in different ethnic groups. Absence of the palmaris longus does not have an effect on grip strength. The lack of palmaris longus muscle does result in decreased pinch strength in fourth and fifth fingers. The absence of palmaris longus muscle is more prevalent in females than males.

<span class="mw-page-title-main">Medial pectoral nerve</span>

The medial pectoral nerve is (typically) a branch of the medial cord of the brachial plexus and is derived from spinal nerve roots C8-T1. It provides motor innervation to the pectoralis minor muscle, and the lower half of the pectoralis major muscle. It runs along the inferior border of the pectoralis minor muscle.

<span class="mw-page-title-main">Lateral pectoral nerve</span>

The lateral pectoral nerve arises from the lateral cord of the brachial plexus, and through it from the C5-7.

<span class="mw-page-title-main">Sternalis muscle</span> Muscle seen in some humans

The rectus sternalis muscle is an anatomical variation that lies in front of the sternal end of the pectoralis major parallel to the margin of the sternum. The sternalis muscle may be a variation of the pectoralis major or of the rectus abdominis.

<span class="mw-page-title-main">Pectoral fascia</span>

The pectoral fascia is a thin lamina, covering the surface of the pectoralis major, and sending numerous prolongations between its fasciculi: it is attached, in the middle line, to the front of the sternum; above, to the clavicle; laterally and below it is continuous with the fascia of the shoulder, axilla, and thorax.

<span class="mw-page-title-main">Pterygomandibular raphe</span> Ligament formed from the buccopharyngeal fascia

The pterygomandibular raphe is a thin tendinous band of buccopharyngeal fascia. It is attached superiorly to the pterygoid hamulus of the medial pterygoid plate, and inferiorly to the posterior end of the mylohyoid line of the mandible. It gives attachment to the buccinator muscle, and the superior pharyngeal constrictor muscle (behind).

The brachial fascia is continuous with that covering the deltoideus and the pectoralis major muscle, by means of which it is attached, above, to the clavicle, acromion, and spine of the scapula; it forms a thin, loose, membranous sheath for the muscles of the arm, and sends septa between them; it is composed of fibers disposed in a circular or spiral direction, and connected together by vertical and oblique fibers.

The lumbar fascia is the lumbar portion of the thoracolumbar fascia. It consists of three fascial layers - posterior, middle, and anterior - that enclose two muscular compartments. The anterior and middle layers occur only in the lumbar region, whereas the posterior layer extends superiorly to the inferior part of the neck, and the inferiorly to the dorsal surface of the sacrum. The quadratus lumborum is contained in the anterior muscular compartment, and the erector spinae in the posterior compartment. Psoas major lies anterior to the anterior layer. Various superficial muscles of the posterior thorax and abdomen arise from the posterior layer - namely the latissimus dorsi, and serratus posterior inferior.

An accessory muscle is a relatively rare anatomical variation where duplication of a muscle may appear anywhere in the muscular system. Treatment is not indicated unless the accessory muscle interferes with normal function.

References

  1. 1 2 3 Wilson JT, The Innervation of the Achselbogen Muscle, J Anat Physiol. 1912 Oct; 47(Pt 1): 8–17.
  2. 1 2 3 4 Clarys, J. P.; Provyn, S.; Cattrysse, E.; Snoeck, T. H.; Van Roy, P. (1 December 2008). "The role of the axillary arch (of Langer) in the management and the kinesiology of the overhead shoulder mobility". The Journal of Sports Medicine and Physical Fitness. 48 (4): 455–465. ISSN   0022-4707. PMID   18997648.
  3. 1 2 Taterra, Dominik; Henry, Brandon Michael; Zarzecki, Michał P.; Sanna, Beatrice; Pękala, Przemysław A.; Cirocchi, Roberto; Walocha, Jerzy A.; Tubbs, R. Shane; Tomaszewski, Krzysztof A. (2019). "Prevalence and anatomy of the axillary arch and its implications in surgical practice: A meta-analysis". The Surgeon: Journal of the Royal Colleges of Surgeons of Edinburgh and Ireland. 17 (1): 43–51. doi:10.1016/j.surge.2018.04.003. ISSN   1479-666X. PMID   29801707. S2CID   44092725.
  4. 1 2 3 4 5 Besana-Ciani, I.; Greenall, M. J. (1 October 2005). "Langer's axillary arch: anatomy, embryological features and surgical implications". The Surgeon. 3 (5): 325–327. doi:10.1016/s1479-666x(05)80111-8. ISSN   1479-666X. PMID   16245651.
  5. ↑ Bergman R. "Axillary Arch". Anatomy Atlases. Retrieved 28 September 2015.
  6. 1 2 3 4 Jelev, L; Georgiev, GP; Surchev, L (2007). "Axillary arch in human: common morphology and variety. Definition of "clinical" axillary arch and its classification". Annals of Anatomy - Anatomischer Anzeiger. 189 (5): 473–481. doi:10.1016/j.aanat.2006.11.011. PMID   17910401.
  7. 1 2 3 Susan Standring; Neil R. Borley; et al., eds. (2008). Gray's anatomy : the anatomical basis of clinical practice (40th ed.). London: Churchill Livingstone. p. 811. ISBN   978-0-8089-2371-8.
  8. 1 2 Langer C., Zur Anatomie des Musculus latissimus dorsi., Österr Med Wochenschrift., 1846, 15: 454–458.
  9. ↑ Dharap, A (June 1994). "An unusually medial axillary arch muscle". Journal of Anatomy. 184 (3): 639–41. PMC   1259973 . PMID   7928652.
  10. ↑ Kalaycioglu, A; Gümüsalan, Y; Ozan, H (1998). "Anomalous insertional slip of latissimus dorsi muscle: arcus axillaris". Surgical and Radiologic Anatomy. 20 (1): 73–75. doi:10.1007/s00276-998-0073-7. PMID   9574494. S2CID   24102742.
  11. ↑ Wagenseil F., Muskelbefunde bei Chinesen., Verh. Ges. Phys. Anthrop., Stuttgart, 1927, 2:42–50.
  12. ↑ Rizk, E; Harbaugh, K (October 2008). "The muscular axillary arch: an anatomic study and clinical considerations". Neurosurgery. 63 (4 Suppl 2): 316–9, discussion 319–20. doi:10.1227/01.neu.0000327033.22068.74. PMID   18981837. S2CID   21188499.
  13. ↑ Bharambe VK, Arole V, The axillary arch muscle (Langer's muscle): Clinical importance, Med J DY Patil Univ, 2013, 6:327–30.
  14. ↑ Magee, Claire; Jones, Claire; McIntosh, Stuart; Harkin, Denis W. (January 2012). "Upper limb deep vein thrombosis due to Langer's axillary arch". Journal of Vascular Surgery. 55 (1): 234–236. doi: 10.1016/j.jvs.2011.07.002 . PMID   21924577.
  15. ↑ Pitzorno H., Contributo alla morfologia dell'arco ascellare musculare di Langer., Arch Ital Anat Embryol., 1911, 10: 129–144.
  16. ↑ Ramsay A., An account of unusual conformation of some muscles and vessels., Edinburgh Med. Surg. J., 1812, 8:281–283.
  17. ↑ Langer C., Zur Anatomie des Musculus latissimus dorsi (Schluss). Österr Med Wochenschrift., 1846, 16: 486–492.
  18. ↑ Testut L., Les Anomalies Musculaires chez l'Homme Expliquées par l'Anatomie Comparée et leur Importance en Anthropologie., Paris: Masson, 1884.
  19. ↑ Edwards WE, The Musculoskeletal Anatomy of the Thorax and Brachium of an Adult Female Chimpanzee,6571st Aeromedical Research Laboratory, New Mexico, 1965.
  20. ↑ McGrath, J.A.; Eady, R.A.; Pope, F.M. (2004). Rook's Textbook of Dermatology (Seventh Edition). Blackwell Publishing. Page 3.1. ISBN   978-0-632-06429-8.
  21. ↑ Diogo R, Wood BA, Comparative Anatomy and Phylogeny of Primate Muscles and Human Evolution, CRC Press, 2012. ISBN   978-1-57808-767-9
  22. ↑ Griffiths M, Walton DW (Editor), Richardson BJ (Editor), Fauna of Australia Volume 1B 15. Tachyglossidae, AGPS Canberra, 1989.
  23. ↑ Bonastre, V; Rodríguez-Niedenführ, M; Choi, D; Sañudo, JR (August 2002). "Coexistence of a pectoralis quartus muscle and an unusual axillary arch: case report and review". Clinical Anatomy. 15 (5): 366–70. doi:10.1002/ca.10053. PMID   12203382. S2CID   27677770.

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