Anat Cell Biol.  2012 Mar;45(1):66-69. 10.5115/acb.2012.45.1.66.

Bipartite clavicular attachment of the sternocleidomastoid muscle: a case report

• Mehta V
• Arora J
• Kumar A
• Nayar AK
• Ioh HK
• Gupta V
• Suri RK
• Rath G

• KMID: 1447456
• DOI: http://doi.org/10.5115/acb.2012.45.1.66

Abstract

Morphological variations of the sternocleidomastoid (SCM) muscle assume relevance during attempted surgical interventions in the cervical region. The present study reports bipartite clavicular attachment of the SCM in the neck of an adult male cadaver during performance of a routine anatomy demonstration. The anomaly was unilaterally observed on the left side of the neck. The clavicular head of the muscle exhibited two bellies, one medial and one lateral. While the medial belly was fused with the sternal head, the lateral belly appeared to blend with the medial. Cranially, the SCM attached to the mastoid process and superior nuchal line. We have attempted to elucidate the embryological basis of the above muscular variant. Additionally, we discuss its clinical relevance, highlighting the utility of the SCM in various reconstructive procedures. We assert that detailed anatomical knowledge of such SCM variants is of utility not only to the gross anatomist, but also for neck and orthopaedic surgeons and anaesthetists. Moreover, radiologists require familiarity with such aberrations to decipher magnetic resonance imaging scans of the cervical region.

Keyword

Sternocleidomastoid; Variation; Clavicular head; Additional head

MeSH Terms

Adult
Anatomists
Cadaver
Head
Humans
Magnetic Resonance Imaging
Male
Mastoid
Muscles
Neck
Recognition (Psychology)

Figure

• 

  Fig. 1 Dissection of the left lateral cervical region showing. BP, brachial plexus; CL, clavicle; O, inferior belly of omohyoid; SCM, sternocleidomastoid musle; T, trapezius muscle; I, sternal head; II, medial clavicular belly; III, lateral clavicular belly; *1, lesser occipital nerve; *2, transverse cutaneous nerve; *3, spinal accessory nerve.

Reference

1. Ramesh RT, Vishnumaya G, Prakashchandra SK, Suresh R. Variation in the origin of sternocleidomastoid muscle: a case report. Int J Morphol. 2007. 25:621–623.

2. Bergman RA, Thompson SA, Afifi AK. Compendium of human anatomic variation: text, atlas, and world literature. 1988. Baltimore: Urban & Schwarzenberg;32–33.

3. Casler JD, Conley J. Sternocleidomastoid muscle transfer and superficial musculoaponeurotic system plication in the prevention of Frey's syndrome. Laryngoscope. 1991. 101(1 Pt 1):95–100.

4. Nayak SR, Krishnamurthy A, Sj MK, Pai MM, Prabhu LV, Jetti R. A rare case of bilateral sternocleidomastoid muscle variation. Morphologie. 2006. 90:203–204.

5. Coskun N, Yildirim FB, Ozkan O. Multiple muscular variations in the neck region: case study. Folia Morphol (Warsz). 2002. 61:317–319.

6. Mustafa MA. Neuroanatomy. In : 10th National Congress of Anatomy; 2006 Sep 6-10; Bordum, Turkey. 6–10.

7. Cherian SB, Nayak S. A rare case of unilateral third head of sternocleidomastoid muscle. Int J Morphol. 2008. 26:99–101.

8. Conley J, Gullane PJ. The sternocleidomastoid muscle flap. Head Neck Surg. 1980. 2:308–311.

9. Timoşca GC. Sternocleidomastoid muscle flaps following parotidectomy. Br J Oral Maxillofac Surg. 1994. 32:262.

10. Natsis K, Asouchidou I, Vasileiou M, Papathanasiou E, Noussios G, Paraskevas G. A rare case of bilateral supernumerary heads of sternocleidomastoid muscle and its clinical impact. Folia Morphol (Warsz). 2009. 68:52–54.

11. Fazliogullari Z, Cicekcibasi AE, Dogan NU, Yilmaz MT, Buyukmumcu M, Ziylan T. The levator claviculae muscle and unilateral third head of the sternocleidomastoıd muscle: case report. Int J Morphol. 2010. 28:929–932.

12. Sarikcioglu L, Donmez BO, Ozkan O. Cleidooccipital muscle: an anomalous muscle in the neck region. Folia Morphol (Warsz). 2001. 60:347–349.

13. Kumar MS, Sundaram SM, Fenn A, Nayak SR, Krishnamurthy A. Cleido-occipital platysma muscle: a rare variant of sternocleidomastoid muscle. Int J Anat Var. 2009. 2:9–10.

14. Kent GC, Carr RK. Comparative anatomy of the vertebrates. 1987. Dubuque: Wm. C. Brown Publishers;352–369.

15. Boaro SN, Fragoso Neto RA. Topographic variation of the sternocleidomastoid muscle in a just been born children. Int J Morphol. 2003. 21:261–264.

16. Costa D, Vitti M, de Oliveira Tosello D, Costa RP. Participation of the sternocleidomastoid muscle on deep inspiration in man. An electromyographic study. Electromyogr Clin Neurophysiol. 1994. 34:315–320.