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Indian Journal for the Practising Doctor

Cleidohyoideus – A case report

Author(s): Srinivasa Rao Bolla, Satheesha Nayak, Venkata Ramana Vollala, Mohandas Rao, Vincent Rodrigues

Vol. 3, No. 6 (2007-01 - 2007-02)

Srinivasa Rao Bolla, Satheesha Nayak, Venkata Ramana Vollala, Mohandas Rao, Vincent Rodrigues

ISBN: 0973-516X

Drs Srinivasa Rao Bolla, Satheesha Nayak, Venkata Ramana Vollala, Mohandas Rao, Vincent Rodrigues are from the Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), International Centre for Health Sciences, Manipal – 576104, Karnataka, India.

Corresponding Author: Srinivasa Rao Bolla, Lecturer, Department of Anatomy, Melaka Manipal Medical College (Manipal Campus), International Centre for Health Sciences, Manipal – 576104, Karnataka, India.
E – mail: [email protected]
Phone Number: 0820 2922642
Fax: 0820 2571905

Abstract

Muscular variations are of importance not only to anatomists but also to the clinicians, because they can contribute to the errors in diagnosis and treatment. We present here a variation in the omohyoid muscle, in which the inferior belly was absent. The superior belly was originating from the clavicle and a portion of the muscle was attached to the middle third of the clavicle by thick fascia, the clinical implications of this variation are discussed.

Keywords: Omohyoid, Cleidohyoideus, Muscle, Clavicle, Variation

Case report

During the routine dissection of the triangles of the neck for undergraduate medical students, the inferior belly of omohyoid was found to be absent; the superior belly was attached to the middle third of the clavicle by thick fascia. On separation of the muscle from fascia, it was evident that the muscle originated from the posterior surface of the clavicle (Fig. 1). Thus, the omohyoid in this case was represented as a single belly connecting the clavicle to the hyoid bone.

Discussion

Omohyoid is one of the infrahyoid muscles. It consists of two bellies united by the intermediate tendon. Inferior belly arises from upper border of scapula near scapular notch. It then passes behind the sernocleidomastoid and ends there in intermediate tendon. The superior belly begins at the intermediate tendon, passes almost vertically upwards near the lateral border of the sternohyoid and is attached to the lower border of the hyoid bone. The actions of the muscle include depression of the hyoid bone after it has been elevated during movements like deglutition and tensing the lower part of deep cervical fascia in prolonged inspiratory efforts1. There are reports about unusual origin of omhyoid from transverse process of c62, double omohyoid3; and absence of superior belly4. According to Bergman et al (1988)5, the inferior belly may be doubled, with the second belly possibly arising from coracoid process. The inferior belly may attach along entire length of the clavicle. When inferior belly is absent, the superior belly arises from clavicle and the resulting muscle is termed cleidohyoideus5. It is essential to know these possible variations because the omohyoid muscle is a reliable landmark in the supraclavicular region, beneath which the suprascapular nerve can be found. Following the suprascapular nerve proximally leads to the plexus trunks6. There are reports of clinical cases due to abnormal omohyoid muscle, contracture of which causes congenital torticollis7,8. Hypertrophied omohyoid muscle can cause brachial plexus irritation9; omohyoid syndrome in which swelling appears when the throat ascends and subsides with its descent in unison with omohyoid prominence. The sternomastoid is passively tented up by an abnormal underlying omohyoid. The latter appears to have lost its restriction to bowstring by the retaining deep cervical fascia10 and compression of the internal jugular vein by the omohyoid muscle, leading to modifications in intracerebral venous hemodynamic, which can be affected in yawning11. The wide variability of the position of omohyoid muscle is likely to have implications for the surgical management of oral and oropharyngeal cancer12, which may also happen with short omohyoid muscle attached to the clavicle by thick fascia, as in our case. So we feel that the knowledge of this variation may be useful for surgeons and clinicians for proper diagnosis and treatment.

Dissection of the side of the neck

Fig. 1: Dissection of the side of the neck, showing the abnormal omohyoid muscle: SCM – sternocleidomastoid muscle, OM – omohyoid muscle, CO – clavicular origin

For larger image, please click here

References

  1. Susan Standring. (2005) Gray’s Anatomy, 39th edn, Churchil & Livingstone, 538-539.
  2. Tubbs RS, Salter EG, Oakes WJ Unusual origin of the omohyoid muscle. Clin Anat. 2004 Oct; 17(7):578-82.
  3. Miura M, Kato S, Itonaga I, Usui T.Okajimas. The double omohyoid muscle in humans: report of one case and review of the literature. Folia Anat Jpn. 1995 Aug; 72(2-3):81-97.
  4. Tamega OJ, Garcia PJ, Soares JC, Zorzetto NL. About a case of absence of the superior belly of the omohyoid muscle. Anat Anz. 1983; 154(1):39-42.
  5. Bergman RA, Thomson SA, Afifi AK, Saadesh FA (1988), Compendium of human anatomic variations, Urban & Schwarzenberg, Baltimore – Munich.
  6. Krishnan KG, Pinzer T, Reber F, Schackert G. Endoscopic exploration of the brachial plexus: technique and topographic anatomy - a study in fresh human cadavers. Neurosurgery. 2004 Feb; 54(2):401-8.
  7. Pirsig W. Congenital torticollis with dislocation of the larynx and trachea caused by contracture of one omohyoides muscle. Arch Otorhinolaryngol. 1977 May 31; 215 (3-4):335-7.
  8. Shih TY, Chuang JH. Fibrosis of the omohyoid muscle—an unusual cause of torticollis. J Pediatr Surg. 1998 May; 33(5):741-2.
  9. Fiske LG. Brachial plexus irritation due to hypertrophied omohyoid muscle; a case report. J Am Med Assoc. 1952 Jun 21; 149(8):758-9.
  10. Wong DS, Li JH. The omohyoid sling syndrome. Am J Otolaryngol. 2000 Sep- Oct;21(5):318-22
  11. Patra P, Gunness TK, Robert R, Rogez JM, Heloury Y, Le Hur PA, Leborgne J, Laude M, Barbin JY. Physiologic variations of the internal jugular vein surface, role of the omohyoid muscle, a preliminary echographic study. Surg Radiol Anat. 1988; 10(2):107-12.
  12. Mizen KD, Mitchell DA. Anatomical variability of omohyoid and its relevance in oropharyngeal cancer. Br J Oral Maxillofac Surg. 2005 Aug; 43(4):285-8.
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