Download Landmarks for the Identification of the Cutaneous Nerves of the

Clinical Anatomy 20:235–238 (2007)
ORIGINAL COMMUNICATION
Landmarks for the Identification of
the Cutaneous Nerves of the Occiput
and Nuchal Regions
R. SHANE TUBBS,* E. GEORGE SALTER, JOHN C. WELLONS III,
JEFFREY P. BLOUNT, AND W. JERRY OAKES
Pediatric Neurosurgery, Children’s Hospital, Birmingham, Alabama
Although surgical procedures are often performed over the posterior head and
neck, surgical landmarks for avoiding the cutaneous nerves in this region are
surprisingly lacking in the literature. Twelve adult cadaveric specimens underwent dissection of the cutaneous nerves overlying the posterior head and
neck, and mensuration was made between these structures and easily identifiable surrounding bony landmarks. All specimens were found to have a third
occipital nerve (TON), lesser occipital nerve (LON), and greater occipital nerve
(GON), and we found that the TON was, on average, 3 mm lateral to the
external occipital protuberance (EOP). Small branches were found to cross
the midline and communicate with the contralateral TON inferior to the EOP in
the majority of sides. The mean diameter of the main TON trunk was 1.3 mm.
This trunk became subcutaneous at a mean of 6 cm inferior to the EOP. The
GON was found to lie at a mean distance of 4 cm lateral to the EOP. On all but
three sides, a small medial branch was found that ran medially from the GON
to the TON *1 cm superior to a horizontal line drawn through the EOP. The
GON was found to pierce the semispinalis capitis muscle on average 2 cm
superior to the intermastoid line. The mean diameter of the GON was 3.5 mm.
The GON was found to branch into medial and lateral branches on average
0.5 cm superior to the EOP. The LON was found to branch into a medial and
lateral component at approximately the midpoint between a horizontal line
drawn through the EOP and the intermastoid line. The main LON trunk was
found on average 7 cm lateral to the EOP. In specimens with a mastoid branch
of the great auricular nerve (GAN), this branch was found at a mean of 9 cm
lateral to the EOP. The main trunk of this branch of the GAN was found to lie
on average 1 cm superior to the mastoid tip. Easily identifiable bony landmarks for identification of the cutaneous nerves over the posterior head and
neck can aid the surgeon in more precisely identifying these structures and
avoiding complications. Although the occipital nerves were found to freely communicate with one another, avoiding the main nerve trunks could lessen postoperative or postprocedural morbidity. Moreover, clinicians who need to localize
the occipital nerves for the treatment of occipital neuralgia could do so more reliably
with better external landmarks. Clin. Anat. 20:235–238, 2007. V 2006 Wiley-Liss, Inc.
C
Key words: neck; head; skin; iatrogenic; injury; anatomy
INTRODUCTION
The posterior head and neck is an area where neurosurgical intervention often occurs (e.g., approaches to the foramen magnum, cerebellopontine angle, and upper cervical
spine). In addition to these surgical approaches, procedures
C
V
2006 Wiley-Liss, Inc.
*Correspondence to: R. Shane Tubbs; Pediatric Neurosurgery,
Children’s Hospital, 1600 7th Avenue South ACC 400, Birmingham, AL 35233, USA. E-mail: [email protected]
Received 26 July 2005; Revised 22 November 2005; Accepted
29 November 2005
Published online 30 August 2006 in Wiley InterScience (www.
interscience.wiley.com). DOI 10.1002/ca.20297
236
Tubbs et al.
such as halo pin and Mayfield pin placement and nerve
blocks for occipital neuralgia necessitate a good working
knowledge of the cutaneous nerves in this region so as to
minimize complications such as severe dysesthesias following their injury (Sindou and Mertens, 1994). Bogduk (1982)
has pointed out the risk of inducing anesthesia dolorosa by
cutting these nerves with incisions over the posterior head
and neck. Likewise, Ebraheim et al. (1996) have stressed
complications of halo pin placement, such as traumatic neuroma formation. Additionally, locating the nerves over the
posterior head and neck for the surgical treatment of occipital neuralgia requires a thorough knowledge of their anatomy, which is not adequately addressed in standard anatomical textbooks. The nerves of this area from lateral to
medial are the lesser occipital nerve (LON), the greater occipital nerve (GON) (Arnold’s nerve), and the third occipital
nerve (TON) (least occipital nerve) (Barna and Hashmi,
2004). Most lateral, the great auricular nerve (GAN) may
have a mastoid branch (McKinney and Gottlieb, 1985).
Rarely, the suboccipital nerve (dorsal ramus of C1) which
normally innervates primarily the muscles of the suboccipital
triangle sends a small cutaneous filament to the occiput
(Bogduk, 1982). At a submuscular level, the suboccipital
nerve and branches of the second and third dorsal rami
intercommunicate to form the posterior cervical plexus of
Cruveilhier (Pick and Howden, 1974) (Fig. 1).
The LON is derived from the second and third cervical
ventral rami and ascends toward the occiput by running
parallel to the posterior border of the sternocleidomastoid
muscle. Near the cranium it perforates the deep fascia, and
is continued superiorly over the occiput where it supplies
the integument and communicates with the GON medially
(Lucas et al., 1994) (Fig. 1).
The medial branch of the dorsal ramus of the second
cervical nerve is referred to as the GON. Gawel and Rothbart (1992) have suggested that this nerve may also have
fibers derived from the dorsal ramus of C3. This nerve
passes between the inferior capitis oblique and semispinalis
capitis muscles and ascends to pierce this latter muscle and
the trapezius. At this point, it travels with the occipital
artery to supply the integument of the scalp as far anterior
as the vertex of the skull. Medially and over the occiput,
this nerve communicates with the TON and laterally with
the LON (Fig. 1).
The TON arises deep to the trapezius from the medial
branch of the dorsal ramus of the third cervical nerve. This
nerve ascends medial to the GON and is connected to it both
over the occiput and as the GON rounds the inferior edge of
the inferior capitis oblique (Bogduk, 1982). The medial terminal branch of the TON supplies the skin over the rostral
end of the neck and the occiput near the external occipital
protuberance (EOP). More lateral branches of this nerve are
directed toward the mastoid process.
The GAN arises from the ventral rami of cervical nerves
two and three, and ascends toward the posterior cranium
by curving from around the posterior border of the sternocleidomastoid. This nerve is mainly distributed to the auricle
and parotid regions but may have a mastoid branch that
communicates with the LON posteriorly (Fig. 1).
Fig. 1. Schematic drawing of the posterior view of
the head and neck. Horizontal lines are drawn through
the inion (superior line) and left (not seen) and right
mastoid tips (inferior line). The TON is shown at (a), the
left GON is shown at (b), the left LON is just inferior to
(c), and the mastoid branch of the GAN is seen just
superior to (d). Note the posterior arch of the atlas (e)
with the suboccipital nerve and vertebral artery superior
to this bony structure within the suboccipital triangle
(composed of the rectus capitis posterior major, superior
capitis oblique, and inferior capitis oblique). In addition,
observe the deep intercommunication between the TON,
suboccipital nerve, and GON.
of the cutaneous nerves (great auricular, lesser occipital,
greater occipital, and third occipital) of the posterior head
and neck, and measurements were made between these
nerves and surrounding superficial bony landmarks. Five
males and seven females were used in this study. All measurements were made with calipers. Measurements
included the diameters of the LON, GON, and TON as they
were found over the occiput and adjacent cranium. Measured distances were made from superior to the intermastoid
line (a line connecting the inferior tips of the mastoid processes) (Fig. 1) and distances superior to a horizontal line
drawn through the EOP and lateral to this bony landmark.
Statistical analysis was made between left and right sides
and genders using Student’s t-tests.
MATERIALS AND METHODS
RESULTS
In the prone position, 12 adult formalin-fixed cadavers
(aged 50–89 years, mean 75 years) underwent dissection
All specimens were found to have a LON, GON, and TON.
We were unable to locate a mastoid branch of the GAN on
Nerves of Occiput and Nuchal Regions
eight sides. A cutaneous branch of the suboccipital nerve
was not found in any specimen. No surgical scars were
found over the posterior head and neck in any specimen.
We found that the TON was 0–4 mm (mean 3 mm) lateral
to the EOP and that in all but two sides (one left and one
right in separate specimens) that this nerve had a lateral
small communicating branch to the GON that branched just
inferior to the EOP. Additionally, very small branches were
found to cross the midline and communicate with the contralateral TON inferior to the EOP in the majority of sides (n
= 7). These branches were always less than 0.5 mm in diameter. The mean diameter of the main TON trunk was 1.3
mm (range 0.5–2 mm). This trunk became subcutaneous
at a mean of 6 cm inferior to the plane of the EOP (range
4–7.5 cm) (mean of 3 cm inferior to the intermastoid line)
and this most often occurred in the lateral aspect of the
nuchal ligament. The GON was found to lie at a mean distance of 4 cm lateral to the EOP (range 3.5–6.5 cm). On all
but three sides, a small medial branch was found that ran
medially from the GON to the TON *1 cm superior to a horizontal line drawn through the EOP (Fig. 1). These medial
branches when present coursed at approximately 308 toward the midline. The GON was found to pierce the semispinalis capitis muscle on average 2 cm (range 1.5–3.3 cm)
superior to the intermastoid line (Fig. 1). One right side
demonstrated two branches of the GON as it pierced the
semispinalis capitis muscle that reunited into a single trunk
2 cm inferior to the EOP. The mean diameter of the GON
was 3.5 mm (range 2.8–4.1 mm). The GON was found to
branch into medial and lateral branches on average 0.5 cm
superior to the EOP (range 0–2.5 cm). The LON was found
to branch into a medial and lateral component at approximately the midpoint between a horizontal line drawn
through the EOP and the intermastoid line.
The main LON trunk was found on average 7 cm lateral
to the EOP (range 6–9 cm) and this nerve was found to lie
at a mean of 3 cm medial to the tip of the mastoid process.
In specimens with a mastoid branch of the GAN, this branch
was found at a mean of 9 cm lateral to the EOP (range 8–
11 cm). The main trunk of this branch of the GAN was
found on average to lie 1 cm superior to the mastoid tip.
Overall, we found that the areas of the posterior head
and neck that were less concentrated with these nerve
trunks were the midline and a midpoint between a line
drawn between the EOP and mastoid tip. No significant differences were found between left or right sides or genders
(Student’s t-test; P > 0.05).
DISCUSSION
Greater occipital neuralgia (Arnold’s neuralgia) is characterized by a lancinating pain extending from the suboccipital region up to the cranial vertex. This pathology may be
idiopathic or may appear following a history of cervical
trauma (e.g., whiplash injury) (Stechison and Mullin,
1994), osteophyte formation on the C2 vertebrae (Clavel
and Clavel, 1996), arthritis of the C2 vertebrae (Ward,
2003), cervical cord tumors (Clavel and Clavel, 1996),
Chiari I malformation (cerebellar tonsillar ectopia inferior to
the foramen magnum) (Gille et al., 2004), or muscle
entrapment (Magnusson et al., 1996; Mosser et al., 2004)
(e.g., inferior capitis oblique, semispinalis capitis, or trapezius muscles). Invasive treatments for this disorder include
nerve blocks, neurolytic injections, C2 dorsal rhizotomy,
237
neurectomy, decompression of the C2 dorsal root ganglion,
ganglionectomy, occipital nerve stimulator placement, and
radiofrequency lesions of the C2 dorsal root (Stechison and
Mullin, 1994; Barna and Hashmi, 2004).
The GON was found to lie at a mean distance of 4 cm lateral to the EOP and this nerve was found to pierce the
semispinalis capitis muscle on average 2 cm superior to the
intermastoid line (Fig. 1). Stechison and Mullin (1994) have
found that the dorsal root ganglion of C2 is located approximately 2 mm from the inferior aspect of the posterior arch
of C1 and that this ganglion was 15 mm from the midline.
Mosser et al. (2004) have found that the GON emerges
from the semispinalis capitis muscle *14 mm from the midline and that this site was roughly 30 mm inferior to the
EOP. However, Bovim et al. (1991) have written that in routine clinical work, they have had success in blocking this
nerve 2 cm inferior to the EOP and 2 cm lateral to the midline.
Vital et al. (1989) have cited measured distances of this nerve
as dichotomous as 3 cm lateral to and superior to the EOP to
6 cm lateral to and 3 cm superior to this bony landmark. The
mean diameter of the GON at this point was 3.5 mm.
The GON was found to branch into medial and lateral
branches on average 0.5 cm superior to the EOP. Bogduk
(1982) has stated that the GON divides into its terminal
branches just inferior to the superior nuchal line. In contrast, Ebraheim et al. (1996) have described this nerve as
dividing into medial, middle, and lateral branches 1 cm inferior to the EOP with the lateral branch ascending at a mean
angle of 388. These authors also found that the lateral
branch is most often found *5 cm lateral to the midline.
We did not appreciate three such distinct branches but
rather a medial and lateral branch with the medial branch
often providing a sizable lateral branch. Sindou and Mertens
(1994) have found the portion of the GON adjacent to the
EOP between the medial and middle one thirds of a line
connecting this bony process to the mastoid tip. Incidentally, the occipital artery is normally found just lateral to
the GON in the proximity of the EOP. Schmidt and Adelmann (2001) have noted that the occipital artery travels at
a mean distance of 3.92 cm on the right side and 4.4 cm on
the left side from the midline.
Pain in the region of the LON is a frequent component of
cervicogenic headache often brought about by physical
exertion (Okuda et al., 2001). Raffaelli et al. (1987) have
stated that injection of the LON can be performed inferior
to the medial groove of the mastoid tip and 1 cm superior
to its tip. Becser et al. (1998) reported that this nerve most
frequently first branched inferior to the superior nuchal line
in their specimens. However, this line is often difficult to
palpate and thus is not as useful a landmark as the EOP or
mastoid process. Barna and Hashmi (2004) have stated
that the LON is about 2.5 cm lateral to the occipital artery
over the occiput. We found that the LON branched into a
medial and lateral component at approximately the midpoint between a horizontal line drawn through the EOP and
the intermastoid line. The main LON trunk was found on average 7 cm lateral to the EOP, and this nerve was found to lie
at a mean of 3 cm medial to the tip of the mastoid process.
Lord et al. (1994) have reported a 27% (95% confidence
interval) incidence of TON headache in post whiplash
patients. Third occipital neurotomy has been performed for
patients with this neuralgia (Govind et al., 2003). Lang
(1993) has reported that this nerve becomes subcutaneous
*5 cm inferior to the EOP and *7 mm lateral to the midline. We found the TON was 0–4 mm lateral to the EOP.
238
Tubbs et al.
The mean diameter of the main TON trunk was 1.3 mm.
This trunk became subcutaneous at a mean of 6 cm inferior
to the EOP and a mean of 3 cm inferior to the intermastoid
line and this most often occurred in the lateral aspect of the
nuchal ligament.
Although we were unable to find reports of injury to the
mastoid branch of the GAN it is possible that this nerve
injury occurs especially with procedures such as retromastoid approaches to the posterior cranial fossa. This nerve
may be duplicated (Pantaloni and Sullivan, 2000). Although
of an unclear etiology, some have found that the GAN may
be involved in some cases of tic douloureux (WyburnMason, 1953; Pantaloni and Sullivan, 2000). This branch
was not found in the majority of our specimens.
CONCLUSIONS
Our study has documented potentially useful superficial
bony landmarks for the identification of the cutaneous
nerves of the posterior head and neck. We found that the
areas of the posterior head and neck that were less concentrated with these nerve trunks were the midline and a midpoint between a line drawn between the EOP and mastoid
tip. It is our hope that these data will aid the surgeon and
clinician in avoiding complications in this region.
REFERENCES
Barna S, Hashmi M. 2004. Occipital neuralgia. Pain Manage Rounds
1:1–4.
Becser N, Bovim G, Sjaastad O. 1998. Extracranial nerves in the
posterior part of the head. Anatomic variations and their possible clinical significance. Spine 23:1435–1441.
Bogduk N. 1982. The clinical anatomy of the cervical dorsal rami.
Spine 7:319–330.
Bovim G, Bonamico L, Fredriksen TA, Lindboe CF, Stolt-Nielsen A,
Sjaastad O. 1991. Topographic variations in the peripheral
course of the greater occipital nerve: Autopsy study with clinical
correlations. Spine 16:475–478.
Clavel M, Clavel P. 1996. Occipital neuralgia secondary to exuberant
callus formation: Case report. J Neurosurg 85:1170–1171.
Ebraheim NA, Lu J, Biyani A, Brown JA. 1996. Anatomic considerations of halo pin placement. Am J Orthop 25:754–756.
Gawel MJ, Rothbart PJ. 1992. Occipital nerve block in the management of headache and cervical pain. Cephalalgia 12:9–13.
Gille O, Lavignolle B, Vital JM. 2004. Surgical treatment of greater
occipital neuralgia by neurolysis of the greater occipital nerve
and sectioning of the inferior oblique muscle. Spine 29:828–832.
Govind J, King W, Bailey B, Bogduk N. 2003. Radiofrequency
neurotomy for the treatment of third occipital headache. J
Neurol Neurosurg Psychiatry 74:88–93.
Lang J. 1993. Clinical Anatomy of the Cervical Spine. New York:
Thieme.
Lord SM, Barnsley L, Wallis BJ, Bogduk N. 1994. Third occipital
nerve headache: A prevalence study. J Neurol Neurosurg Psychiatry 57:1187–1190.
Lucas GDA, Laudanna A, Chopard RP, Raffaelli E Jr. 1994. Anatomy
of the lesser occipital nerve in relation to cervicogenic headache.
Clin Anat 7:90–96.
Magnússon T, Ragnarsson T, Björnsson A. 1996. Occipital nerve
release in patients with whiplash trauma and occipital neuralgia.
Headache 36:32–36.
McKinney P, Gottlieb J. 1985. The relationship of the great auricular
nerve to the superficial musculoaponeurotic system. Ann Plast
Surg 14:310–314.
Mosser SW, Guyuron B, Janis JE, Rohrich RJ. 2004. The anatomy of
the greater occipital nerve: Implications for the etiology of migraine headaches. Plast Reconstr Surg 113:693–697.
Okuda Y, Matsumoto T, Shinohara M, Kitajima T, Kim P. 2001. Sudden
unconsciousness during a lesser occipital nerve block in a patient
with the occipital bone defect. Eur J Anaesthesiol 18:829–832.
Pantaloni M, Sullivan P. 2000. Relevance of the lesser occipital nerve
in facial rejuvenation surgery. Plast Reconstr Surg 105:2594–
2599.
Pick TP, Howden R. 1974. Gray’s Anatomy Descriptive and Surgical.
Philadelphia: Running Press.
Raffaelli E Jr., Martins OJ, dos Santos A, Filho PD. 1987. Minor occipital neuralgia. Cephalalgia 7:173–174.
Schmidt D, Adelmann G. 2001. The course of the occipital artery—
An anatomical investigation for biopsy in suspected vasculitis.
Eur J Med Res 6:235–241.
Sindou M, Mertens P. 1994. Posterior fossa approaches with preservation of the sensory occipital nerves: Microsurgical anatomy
and surgical implications. In: Samii M, editor. Skull Base Surgery. Basel: Karger. p 719–722.
Stechison MT, Mullin BB. 1994. Surgical treatment of greater occipital
neuralgia: An appraisal of strategies. Acta Neurochir 131:236–
240.
Vital JM, Grenier F, Dautheribes M, Baspeyre H, Lavignolle B, Sénégas
J. 1989. An anatomic and dynamic study of the greater occipital
nerve (n. of Arnold). Applications to the treatment of Arnold’s neuralgia. Surg Radiol Anat 11:205–210.
Ward JB. 2003. Greater occipital nerve block. Semin Neurol 23:59–62.
Wyburn-Mason R. 1953. The nature of tic douloureux: Treatment by
alcohol block or section of the great auricular nerve. Brit Med J
2:119–122.