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.

Additional examples in the hand include Flexor carpi radialis brevis which can compress the anterior interosseous nerve . Also see palmaris profundus muscle.

On the extensor side: extensor digitorum brevis manus, extensor carpi radialis intermedius, extensor medii proprius muscle

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

<span class="mw-page-title-main">Carpal bones</span> Eight small bones that make up the wrist (or carpus) that connects the hand to the forearm

The carpal bones are the eight small bones that make up the wrist (carpus) that connects the hand to the forearm. The term "carpus" and "carpal" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the carpal bones is to articulate with the radial and ulnar heads to form a highly mobile condyloid joint, to provide attachments for thenar and hypothenar muscles, and to form part of the rigid carpal tunnel which allows the median nerve and tendons of the anterior forearm muscles to be transmitted to the hand and fingers.

<span class="mw-page-title-main">Radial nerve</span> Nerve in the human body that supplies the posterior portion of the upper limb

The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial compartment of the forearm and the associated joints and overlying skin.

<span class="mw-page-title-main">Extensor carpi radialis longus muscle</span>

The extensor carpi radialis longus is one of the five main muscles that control movements at the wrist. This muscle is quite long, starting on the lateral side of the humerus, and attaching to the base of the second metacarpal bone.

<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 arm, forearm and hand, and is primarily used for climbing, lifting and manipulating objects.

<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">Serratus anterior muscle</span> Muscle on the surface of the ribs

The serratus anterior is a muscle of the chest. It originates at the side of the chest from the upper 8 or 9 ribs; it inserts along the entire length of the anterior aspect of the medial border of the scapula. It is innervated by the long thoracic nerve from the brachial plexus. The serratus anterior acts to pull the scapula forward around the thorax.

<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">Lateral epicondyle of the humerus</span> Structure of humerus

The lateral epicondyle of the humerus is a large, tuberculated eminence, curved a little forward, and giving attachment to the radial collateral ligament of the elbow joint, and to a tendon common to the origin of the supinator and some of the extensor muscles. Specifically, these extensor muscles include the anconeus muscle, the supinator, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris. In birds, where the arm is somewhat rotated compared to other tetrapods, it is termed dorsal epicondyle of the humerus. In comparative anatomy, the term ectepicondyle is sometimes used.

<span class="mw-page-title-main">Posterior interosseous nerve</span> Nerve of the forearm

The posterior interosseous nerve is a nerve in the forearm. It is the continuation of the deep branch of the radial nerve, after this has crossed the supinator muscle. It is considerably diminished in size compared to the deep branch of the radial nerve. The nerve fibers originate from cervical segments C7 and C8 in the spinal column.

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

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.

The posterior compartment of the forearm contains twelve muscles which primarily extend the wrist and digits. It is separated from the anterior compartment by the interosseous membrane between the radius and ulna.

<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">Outline of human anatomy</span> Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

<span class="mw-page-title-main">Cervical spinal nerve 6</span> Spinal nerve of the cervical segment

The cervical spinal nerve 6 (C6) is a spinal nerve of the cervical segment.

<span class="mw-page-title-main">Cervical spinal nerve 8</span> Spinal nerve of the cervical segment

The cervical spinal nerve 8 (C8) is a spinal nerve of the cervical segment.

Extensor digitorum brevis manus is an extra or accessory muscle on the backside (dorsum) of the hand. It was first described by Albinus in 1758. The muscles lies in the fourth extensor compartment of the wrist, and is relatively rare. It has a prevalence of 4% in the general population according to a meta-analysis. This muscle is commonly misdiagnosed as a ganglion cyst, synovial nodule or cyst.

<span class="mw-page-title-main">Extrinsic extensor muscles of the hand</span>

The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand. They include the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor digitorum (ED), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI).

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. 44 (2): 233–237. doi:10.1007/s00276-022-02887-x. PMC   8831266 . 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" (PDF). 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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