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Notoplatysma: an aberrant muscle in the parotid region
British Journal of Oral and Maxillofacial Surgery (2003) 41, 336–337 © 2003 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/S0266-4356(03)00130-X, available online at www.sciencedirect.com
SHORT COMMUNICATION Notoplatysma: an aberrant muscle in the parotid region M. Ethunandan, ∗ A. W. Wilson, † J. B. Murray ‡ ∗ Specialist
Registrar, South Coast Training Programme; †Consultant, Maxillofacial Unit; ‡Consultant Radiologist, St. Richards Hospital, Chichester, West Sussex, UK
INTRODUCTION
DISCUSSION
Access to the retromandibular region of the neck is often required for operations on the parotid and mandible and for face-lifts. In this region, awareness of the local anatomy is vital to gain appropriate access and to avoid damage to adjacent vital and important structures. We describe an aberrant muscle in the parotid area that was encountered during a parotidectomy. We are unaware of any reports of a similar muscle in a normal person. Knowledge of the aberrant muscle will help avoid confusion with other pathological conditions, and is relevant for both interpretations of radiological images and during operations in this area.
Access to the upper part of the neck is required for various operations, and it is known that there are variations in the suprahyoid and mid-facial muscles both in terms of their presence or absence and their insertions and origins.1 We are unaware of any report of the muscle, such as that encountered in this case in a normal adult. Development of the facial muscles is a complex process. A muscle similar to the one that we encountered is called Platysma occipitalis (Notoplatysma) and has been
CASE REPORT A 37-year-old man presented to the maxillofacial unit with a 2 × 3 cm, slowly enlarging swelling in the tail of the parotid that had been present for a year. On examination there was a firm, non-tender, mobile mass in the tail of the parotid, with no evidence of involvement of the facial nerve. A magnetic resonance (MR) scan showed a 1.5 cm mass in the superficial parotid. Fine needle aspiration biopsy suggested a pleomorphic adenoma, and the patient had a superficial parotidectomy. At operation, a standard ‘lazy S’ cervico-mastoid-facial flap was raised in the SMAS/preparotid fascia plane. There was a band of muscle 1 cm wide, lying in the subcutaneous plane, superficial to the sternocleidomastoid, and running from the skin overlying the angle of the mandible posteriorly to insert into the occiput and mastoid (Fig. 1). No other aberrant structures were encountered in the operative field. As this band of muscle prevented access to the parotid gland and identification of the trunk of the facial nerve, it was resected, followed by a superficial parotidectomy. The patient made an uneventful postoperative recovery, with no apparent functional or cosmetic deficit as a result of resection of the aberrant muscle.
Fig. 1 Operative site showing the aberrant muscle. SCM, sternocleidomastoid; GAN, great auricular nerve. 336
Notoplatysma: an aberrant muscle in the parotid region
described in primates, including wild spider monkeys (Ateles belzebuth), orangutans (Pongo abelii), Baboons (Papio anubis) and macaques.2 Anatomists who studied human embryos have described the Platysma occipitalis as appearing early in development (22.2 mm), but diminishing in size as development progresses and not seen in late fetuses.3 Huber described a similar muscle in a neonate as Transversus nuchae and suggested that it is the vestigial remains of the nuchal portion of the platysma, which is found commonly in lower primates.2 A similar muscle has also been described in neonates with chromosome 18 trisomy syndrome and chromosome 13 trisomy syndrome.4,5 Aziz described it as a narrow band (2 mm) extending from the trapezius (close to its origin) to the corner of the mouth, where it became confluent with the facial part of the platysma, located below the ear and crossed by the great auricular nerve. He suggested that it is an ‘atavistic’ structure. There was no clinical evidence to suggest chromosomal abnormalities in our case. The muscle seems to have been an aberrant platysma similar to those described in neonates and patients with chromosomal abnormalities, but occurring in a normal person. It is likely that this variation of the platysma or aberrant muscle may be encountered by other clinicians operating on or imaging this area. Awareness of the aberration may help to avoid confusion, possible damage to other structures, and an inappropriate operation as a result of misidentification during operation or imaging.
337
REFERENCES 1. Pessa JE et al. Variability of the midfacial muscles: analysis of 50 hemifacial cadaver dissections. Plast Reconstr Surg 1998; 102: 1888–1893. 2. Huber E. Evolution of facial musculature and cutaneous field of trigeminus. Part II. Rev Biol 1930; V: 389–437. 3. Gasser RF. The development of facial muscles in man. Am J Anat 1967; 120: 357–376. 4. Pettersen JC, Koltis CC, White MJ. An examination of the spectrum of anatomical defects and variations found in eight cases of trisomy 13. Am J Med Genet 1979; 3: 1833–1840. 5. Aziz MA. Possible “atavistic” structures in human aneuploids. Am J Phys Anthropol 1981; 54: 347–353.
The Authors M. Ethunandan BM, MDS FDSRCS, FFDRCS, MRCS Specialist Registrar South Coast Training Programme A. W. Wilson FDSRCS, FRCS Consultant Maxillofacial Unit J. B. Murray DA, FRCR Consultant Radiologist St. Richards Hospital Chichester, West Sussex, UK Correspondence and requests for offprints to: Mr A. W. Wilson FDSRCS, FRCS, Consultant, Maxillofacial Unit, St. Richards Hospital, Chichester, West Sussex PO19 4SE, UK. Tel: +44 (0) 1243 831531; Fax: +44 (0) 1243 831544; E-mail: [email protected] Accepted 20 June 2003
SHORT COMMUNICATION Notoplatysma: an aberrant muscle in the parotid region M. Ethunandan, ∗ A. W. Wilson, † J. B. Murray ‡ ∗ Specialist
Registrar, South Coast Training Programme; †Consultant, Maxillofacial Unit; ‡Consultant Radiologist, St. Richards Hospital, Chichester, West Sussex, UK
INTRODUCTION
DISCUSSION
Access to the retromandibular region of the neck is often required for operations on the parotid and mandible and for face-lifts. In this region, awareness of the local anatomy is vital to gain appropriate access and to avoid damage to adjacent vital and important structures. We describe an aberrant muscle in the parotid area that was encountered during a parotidectomy. We are unaware of any reports of a similar muscle in a normal person. Knowledge of the aberrant muscle will help avoid confusion with other pathological conditions, and is relevant for both interpretations of radiological images and during operations in this area.
Access to the upper part of the neck is required for various operations, and it is known that there are variations in the suprahyoid and mid-facial muscles both in terms of their presence or absence and their insertions and origins.1 We are unaware of any report of the muscle, such as that encountered in this case in a normal adult. Development of the facial muscles is a complex process. A muscle similar to the one that we encountered is called Platysma occipitalis (Notoplatysma) and has been
CASE REPORT A 37-year-old man presented to the maxillofacial unit with a 2 × 3 cm, slowly enlarging swelling in the tail of the parotid that had been present for a year. On examination there was a firm, non-tender, mobile mass in the tail of the parotid, with no evidence of involvement of the facial nerve. A magnetic resonance (MR) scan showed a 1.5 cm mass in the superficial parotid. Fine needle aspiration biopsy suggested a pleomorphic adenoma, and the patient had a superficial parotidectomy. At operation, a standard ‘lazy S’ cervico-mastoid-facial flap was raised in the SMAS/preparotid fascia plane. There was a band of muscle 1 cm wide, lying in the subcutaneous plane, superficial to the sternocleidomastoid, and running from the skin overlying the angle of the mandible posteriorly to insert into the occiput and mastoid (Fig. 1). No other aberrant structures were encountered in the operative field. As this band of muscle prevented access to the parotid gland and identification of the trunk of the facial nerve, it was resected, followed by a superficial parotidectomy. The patient made an uneventful postoperative recovery, with no apparent functional or cosmetic deficit as a result of resection of the aberrant muscle.
Fig. 1 Operative site showing the aberrant muscle. SCM, sternocleidomastoid; GAN, great auricular nerve. 336
Notoplatysma: an aberrant muscle in the parotid region
described in primates, including wild spider monkeys (Ateles belzebuth), orangutans (Pongo abelii), Baboons (Papio anubis) and macaques.2 Anatomists who studied human embryos have described the Platysma occipitalis as appearing early in development (22.2 mm), but diminishing in size as development progresses and not seen in late fetuses.3 Huber described a similar muscle in a neonate as Transversus nuchae and suggested that it is the vestigial remains of the nuchal portion of the platysma, which is found commonly in lower primates.2 A similar muscle has also been described in neonates with chromosome 18 trisomy syndrome and chromosome 13 trisomy syndrome.4,5 Aziz described it as a narrow band (2 mm) extending from the trapezius (close to its origin) to the corner of the mouth, where it became confluent with the facial part of the platysma, located below the ear and crossed by the great auricular nerve. He suggested that it is an ‘atavistic’ structure. There was no clinical evidence to suggest chromosomal abnormalities in our case. The muscle seems to have been an aberrant platysma similar to those described in neonates and patients with chromosomal abnormalities, but occurring in a normal person. It is likely that this variation of the platysma or aberrant muscle may be encountered by other clinicians operating on or imaging this area. Awareness of the aberration may help to avoid confusion, possible damage to other structures, and an inappropriate operation as a result of misidentification during operation or imaging.
337
REFERENCES 1. Pessa JE et al. Variability of the midfacial muscles: analysis of 50 hemifacial cadaver dissections. Plast Reconstr Surg 1998; 102: 1888–1893. 2. Huber E. Evolution of facial musculature and cutaneous field of trigeminus. Part II. Rev Biol 1930; V: 389–437. 3. Gasser RF. The development of facial muscles in man. Am J Anat 1967; 120: 357–376. 4. Pettersen JC, Koltis CC, White MJ. An examination of the spectrum of anatomical defects and variations found in eight cases of trisomy 13. Am J Med Genet 1979; 3: 1833–1840. 5. Aziz MA. Possible “atavistic” structures in human aneuploids. Am J Phys Anthropol 1981; 54: 347–353.
The Authors M. Ethunandan BM, MDS FDSRCS, FFDRCS, MRCS Specialist Registrar South Coast Training Programme A. W. Wilson FDSRCS, FRCS Consultant Maxillofacial Unit J. B. Murray DA, FRCR Consultant Radiologist St. Richards Hospital Chichester, West Sussex, UK Correspondence and requests for offprints to: Mr A. W. Wilson FDSRCS, FRCS, Consultant, Maxillofacial Unit, St. Richards Hospital, Chichester, West Sussex PO19 4SE, UK. Tel: +44 (0) 1243 831531; Fax: +44 (0) 1243 831544; E-mail: [email protected] Accepted 20 June 2003