Accessory muscle

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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. [1]

Contents

Examples

Examples are the accessory soleus muscle in the calf or ankle, the extensor digitorum brevis manus in the hand and epitrochleoanconeus muscle of the upper arm.

Accessory muscles of the anterior thoracic wall include the sternalis muscle, the axillary arch (Langer's), variations of pectoralis major such as the pectoralis minimus, pectoralis quartus, and pectoralis intermedius, the chondrocoracoideus and chondrofascialis. [2] The whole pectoral region is subject to a high degree of variability. The pectoralis major or pectoralis minor may be absent, or in some cases the pectoralis major may be doubled. Other variants noted in this region are the chondroepitrochleas originating in one or more ribs, or directly from the pectoralis major; the costocoracoideus from the 6th to 8th ribs, and a chondrocoracoideus and another variant of this waiting to be named. Most of these accessory muscles are implicated in neurovascular compression. Of clinical use the newly described chondrocoracoideus has potential for use in reconstructive surgery. [3]

Axillary accessory muscles may be encountered in axillary lymph node removal, the awareness of which could avoid complications. [4]

An accessory muscle can also refer to a muscle that is not primarily responsible for movement but does provide assistance. [1] Examples of such muscles are the accessory muscles of respiration where the sternocleidomastoid and the scalene muscles (anterior, middle and posterior scalene) are typically considered accessory muscles of respiration. [5]

See also

Related Research Articles

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

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<span class="mw-page-title-main">Rhomboid major muscle</span> Skeletal muscle in the human back

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

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<span class="mw-page-title-main">Rectus abdominis muscle</span> Paired straight muscle

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<span class="mw-page-title-main">Serratus anterior muscle</span> Muscle on the surface of the ribs

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<span class="mw-page-title-main">Lateral thoracic artery</span> Large blood vessel

In the human body, the lateral thoracic artery is a blood vessel that supplies oxygenated blood to approximately one-third of the lateral structures of the thorax and breast.

<span class="mw-page-title-main">Scalene muscles</span> Muscles on the sides of the neck

The scalene muscles are a group of three muscles on each side of the neck, identified as the anterior, the middle, and the posterior. They are innervated by the third to the eighth cervical spinal nerves (C3-C8).

<span class="mw-page-title-main">Intermammary cleft</span> Breast cleavage

The intermammary cleft, intermammary sulcus, or sulcus intermammarius is a surface feature of males and females that marks the division of the two breasts with the sternum (breastbone) in the middle. The International Federation of Associations of Anatomists (IFAA) uses the terms "sulcus intermammarius" or "intermammary cleft" when referring to the area between the breasts.

<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">Subclavius muscle</span> Muscle between the clavicle and first rib

The subclavius is a small triangular muscle, placed between the clavicle and the first rib. 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.

<span class="mw-page-title-main">Radical mastectomy</span> Removal of cancerous breast

Radical mastectomy is a surgical procedure that treats breast cancer by removing the breast and its underlying chest muscle, and lymph nodes of the axilla (armpit). Breast cancer is the most common cancer among women. During the early twentieth century it was primarily treated by surgery, when the mastectomy was developed. However, with the advancement of technology and surgical skills in recent years, mastectomies have become less invasive. As of 2016, a combination of radiotherapy and breast conserving mastectomy are considered optimal treatment.

<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>

The sternalismuscle 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">Winged scapula</span> Skeletal muscle condition around the shoulder blade

A winged scapula is a skeletal medical condition in which the shoulder blade protrudes from a person's back in an abnormal position.

<span class="mw-page-title-main">Muscles of respiration</span> Muscles involved in breathing

The muscles of respiration are the muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. The elasticity of these muscles is crucial to the health of the respiratory system and to maximize its functional capabilities.

<span class="mw-page-title-main">Axillary arch</span> Muscular slip associated with latissimus dorsi 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. The arch may occur on one or both sides of the body. A meta-analysis revealed that the axillary arch had an overall prevalence of 5.3% of limbs.

An anatomical variation, anatomical variant, or anatomical variability is a presentation of body structure with morphological features different from those that are typically described in the majority of individuals. Anatomical variations are categorized into three types including morphometric, consistency, and spatial.

References

  1. 1 2 "accessory muscle". Farlex. Retrieved June 6, 2013.
  2. ↑ Douvetzemis, S; Natsis, K; Piagkou, M; Kostares, M; Demesticha, T; Troupis, T (2019). "Accessory muscles of the anterior thoracic wall and axilla. Cadaveric, surgical and radiological incidence and clinical significance during breast and axillary surgery". Folia morphologica. 78 (3): 606–616. doi:10.5603/FM.a2019.0005. PMID   30664230.
  3. ↑ Zielinska, N; Ruzik, K; Georgiev, GP; Dimitrova, IN; Tubbs, RS; Olewnik, Ł (February 2022). "A new variety of chondrocoracoideus muscle, or an additional head of pectoralis major muscle". Surgical and radiologic anatomy : SRA. 44 (2): 233–237. doi:10.1007/s00276-022-02887-x. PMID   35064323.
  4. ↑ Natsis, K; Vlasis, K; Totlis, T; Paraskevas, G; Noussios, G; Skandalakis, P; Koebke, J (February 2010). "Abnormal muscles that may affect axillary lymphadenectomy: surgical anatomy". Breast cancer research and treatment. 120 (1): 77–82. doi:10.1007/s10549-009-0374-5. PMID   19306056.
  5. ↑ Netter FH. Atlas of Human Anatomy 3rd ed. Icon Learning Systems. Teterboro, New Jersey 2003 - plate 191
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