|Year : 2013 | Volume
| Issue : 3 | Page : 327-330
The axillary arch muscle (Langer's muscle): Clinical importance
Vaishaly K Bharambe, Vasanti Arole
Department of Anatomy, Padmashree, Dr D Y Patil Medical College, Hospital and Research Centre, Dr D Y Patil Vidyapeeth, Pune, India
|Date of Web Publication||5-Jul-2013|
Vaishaly K Bharambe
D-9 State Bank Nagar, Panchvati, Pashan Road, Opposite NCL, Pune - 411 008. Maharashtra
Source of Support: None, Conflict of Interest: None
This was a cadaveric study aimed at studying the incidence of axillary arch muscle and the extent of its different attachments, and discussing its clinical importance. Totally, 30 upper limbs were meticulously dissected to locate the axillary arch. Wherever found, the arch was dissected from its origin to insertion and its nerve supply and blood supply was noted. The dimensions of the arch were measured. Its relations to the structures in axilla were studied in detail. Any additional related variations were investigated. The axillary arch was present in one right upper limb i.e., an incidence of 3.33%. The muscle extended from the lateral border of latissimus dorsi muscle across the axillary vessels and nerves lying superficial to the coracobrachialis, short and long heads of biceps brachii muscles, finally dividing into multiple slips of insertions into fascia covering the deep surface of pectoralis major muscle, fascia covering the biceps brachii muscle, and some slips extending into the capsule of shoulder joint. Across the middle of the axillary arch, a tendinous intersection was observed. The muscle was supplied by a branch of the thoraco-dorsal nerve. The presence of the axillary arch must always be kept in mind due to the possibility of such a muscular arch causing axillary vein entrapment, lymphatic compression, and shoulder instability by neurovascular compression, impeding the access to axillary lymph nodes during breast cancer surgeries and in latissimus dorsi transplants. It may also restrict abduction at shoulder joint.
Keywords: Axillary arch, latissimus dorsi, pectoralis major, shoulder joint
|How to cite this article:|
Bharambe VK, Arole V. The axillary arch muscle (Langer's muscle): Clinical importance. Med J DY Patil Univ 2013;6:327-30
| Introduction|| |
Anatomic variations in the axilla have been described both in anatomic as well as surgical journals. Today, interest in such variations has been stimulated by their importance during axillary surgeries for breast cancer and other surgical procedures.
A muscular anatomic variation within the axilla is the axillary arch or the axillopectoral muscle. It has an incidence of about 7-8%.  The muscular axillary arch is a muscular band that crosses the edge of latissimus dorsi midway in the posterior fold of axilla, over the front of the axillary vessels and nerves to join the tendon of pectoralis major, coracobrachialis, or fascia over the biceps.  It receives nerve supply through thoraco-dorsal, medial pectoral, lateral pectoral or intercostobrachial nerves.  This muscle has been implicated in axillary vein compression, deep vein thrombosis of upper limb and neurovascular compression syndromes. ,, The axillary arch plays an important role in the management and kinesiology of the overhead shoulder mobility. 
The present study evaluated the incidence of axillary arch in 30 upper limbs in Indian population. Its anatomy, innervation, and detailed relation to neurovascular structures of axilla were studied. A thorough knowledge of this muscle may help reduce damage to the axillary neurovascular bundle during surgeries.
We studied 30 upper limbs in cadavers of adult age group, irrespective of sex. They were preserved in 10% formalin and were meticulously dissected to locate the axillary arch. Wherever found, the arch was dissected from its origin to insertion and its nerve supply and blood supply was noted. The dimensions of the arch were measured. Its relations to the structures in axilla, such as axillary artery, vein, and brachial plexus were studied in detail. Any additional related variations were also investigated.
| Case Report|| |
Of the 30 upper limbs the axillary arch was present in one right upper limb (of an adult male cadaver) i.e., an incidence of 3.33%. The fleshy belly was separated from the middle of the lateral border of latissimus dorsi muscle [Figure 1]. It extended upwards and laterally across the axillary vessels and nerves lying superficial to the coracobrachialis, short and long heads of biceps brachii muscles, the tendino-aponeurotic distal end forming multiple aponeurotic slips getting inserted into fascia covering the deep surface of pectoralis major muscle, fascia covering the biceps brachii muscle and some slips extending into the capsule of shoulder joint [Figure 2].
|Figure 1: The right pectoralis major muscle has been reflected to expose the anterior region of the Axilla showing, a - biceps brachii muscle, b - axillary Arch muscle, c - median nerve, d - tendinous intersection, e - coracobrachialis muscle, f - musculocutaneous nerve, g - axillary artery, h - lattisimus dorsi muscle|
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|Figure 2: Anterior view of right axilla showing, a - fascia covering deep surface of pectoralis major muscle, b - biceps brachii and giving multiple slips of attachment into, c - the axillary arch muscle crossing the, d - fascia covering biceps brachii muscle, e - capsule of shoulder joint|
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The muscle slip measured 14.5 cm in length and 6 mm in thickness. Its proximal portion at the latissimus dorsi muscle was wider, having a width of 2.5 cm and was muscular. Towards its distal end it became narrow with a width of 1 cm.
Across the middle of the axillary arch, a tendinous intersection was observed [Figure 1]. The muscle was supplied by a branch of the thoraco-dorsal nerve which supplied the latissimus dorsi muscle itself.
| Discussion|| |
The axillary arch was first identified in 1795.  In 1884 the muscle was described in further details and it thereafter became known as the Langer's arch.  Gray's Anatomy describes it as a muscular arch 7-10 cm in length and 5-15 mm in breadth, crossing from the edge of latissimus dorsi, midway in the posterior fold, over the front of the axillary vessels and nerves to join the tendon of pectoralis major, coracobrachialis or fascia over the biceps. 
Authors have described findings of axillary arch muscles along with their attachments and nerve supply. Some of the described axillary arches are as follows.
In a study of 26 cadavers, axillopectoral muscle was found in one right axillary fossa. The muscle was originating from coracoid process, passing over the distal part of latissimus dorsi tendon, and finally blending into the fibers of long head of triceps brachii muscle. 
A muscular slip originating from the medial part of the coracoid process inserting into the superior and medial region of the tendon of latissimus dorsi has been reported. It was considered to be an elevator of latissimus dorsi muscle. 
A study carried out on 68 upper limbs, 1.47% incidence of axillary arch was observed. Here the axillary arch was found to take origin from latissimus dorsi muscle and inserted into fascia covering the short head of biceps brachii muscle. The muscular slip was supplied by a separate branch from the lateral cord of brachial plexus. The author went on to state that a simple excision of this muscle was curative to relieve the compression over the neurovascular bundle in the axilla. 
A variation of the axillary arch muscle was reported in 2009 where the muscular slip was originating from the medial border of left latissimus dorsi muscle and was inserted into the pectoralis major, pectoralis minor, and coracoid process. It received innervation from the medial pectoral nerve. 
After studying the above reports it is clear that axillary arch is a variable structure. Most authors have described it as a muscular slip attached at one end to the latissimus dorsi muscle, but the attachment at the other end shows variations. Commonly, the muscle slip gets attached to fascia covering pectoralis major, pectoralis minor, triceps brachii, and biceps brachii muscle. It has also been described as taking origin from coracoid process. In the present study we did not find any attachment of the axillary arch to either coracoid process or to triceps brachii.
The present study reports the attachment of the axillary arch muscle to the capsule of shoulder joint. During rotator cuff tears it is necessary sometimes to transfer the tendon of latissimus dorsi muscle to greater tubercle of humerus to stabilize the shoulder joint.  Attachment of part of a slip of axillary arch muscle to the capsule of shoulder joint could be a natural attempt to further strengthen the shoulder joint capsule.
Variations in the axillary arch muscle appearance and attachments, led to the classification as complete and incomplete, where the "complete muscle" would extend from latissimus dorsi to the tendon of pectoralis majorly close to its attachment on the humerus but the "incomplete" form would extend till axillary fascia, biceps brachii muscle, coracobrachialis muscle, distal end of bicipital groove, and inferior edge of pectoralis minor muscle or the coracoid process.  As per this classification the axillary arch being reported in the present study by virtue of "the axillary arch muscle giving slips of attachment to the capsule of shoulder joint" is a complete muscle.
The finding of 14.5 cm length and 2.5 cm width seen in the present study, are exceeding the maximum dimensions of 10 cm and 15 mm respectively as described by Gray's Anatomy. 
Present article also reports a tendinous intersection in the axillary arch muscle. There is no documentation of tendinous intersection in the axillary arch muscle in literature.
Gray's Anatomy  states that
- Tendinous aponeuroses increase the area available for attachment of the muscle fibers, the given muscle can then be employed as a large number of short fibers, increasing the cross-sectional area and hence the force available for action.
- The intersections may occur secondarily during development and may enhance the force and contraction of a muscle.
- They may represent myosepta delineating the myotomes that form the muscle.
Considering the above statements it is possible that the tendinous intersection across the middle of the axillary arch could have evolved to increase the force of action of the axillary arch muscle fibers thus further strengthening the functional importance of these muscle fibers. Can the tendinous intersections be showing the segmental origin of latissimus dorsi muscle?
Clinical and Surgical Importance
The Langer's arch is in direct relation to the axillary structures. Pressure by the muscle during contraction can cause axillary vein entrapment, lymphatic compression with subsequent venous thrombosis or lymphoedema. On palpation the Langer's arch can be confused with enlarged axillary lymph nodes or soft tissue swellings in the axilla.
Due to its close proximity to the neurovascular structures it can cause shoulder instability by neurovascular compression. Gradual contracture of the axillary arch muscle resulting in the patient being unable to abduct the shoulder joint beyond 95° has been described in 1988. 
The axillary arch muscle fibers can impede adequate exposure of the axilla limiting the access to the lower lateral group of axillary lymph nodes during surgery for breast cancer. Access for bypass surgery using axillary vessels may be compromised if there is a failure to identify the Langer's arch. Therefore the possible presence of the axillary arch should be searched during axillary surgeries to avoid any intra-opertive or post-operative complications.
The Latissimus dorsi muscle is used widely as a flap in reconstructive surgeries. The muscle is tunneled from the back to the mastectomy area to create a reconstructed breast following mastectomy.  A myocutaneous flap of latissimus dorsi is used to cover large soft tissue defects in head and neck region as well. Therefore knowing the exact extent, attachment and innervation of this muscle becomes mandatory.
Further, the possibility of attachment of a slip of the axillary arch to the capsule of shoulder joint should be kept in mind during shoulder joint surgeries.
Clinical detection of this muscle is difficult; however, it is possible to detect the presence of the axillary arch on performing computed tomography scan or magnetic resonance imaging of the axillary region.
Regarding the possible genesis of this muscular arch, various theories are proposed. In lower mammals the panniculus carnosus is very well developed to form the pectoral group of muscles. With evolution these muscles have regressed due to reduced functional importance. Langer's arch could be an embryological remnant of the panniculus carnosus in the axillary region.  In 1980 bilateral axillary arch muscle was reported in a case of Trisomy 13 indicating a possible genetic basis. 
- The axillary arch muscle may be a remnant of Panniculus carnosus. or
- Is it showing alterations in attachments of latissimus dorsi in an ever evolving human species?
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[Figure 1], [Figure 2]