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Online Journal of Health and Allied Sciences
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Volume 14, Issue 4; Oct-Dec 2015
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Case Report:
Multiple Variations of the Nerves of Gluteal Region and their Clinical Implications
Authors
Prasad AM, Satheesha Nayak B, Deepthinath Reghunathan, Surekha D Shetty,
Melaka Manipal Medical College (Manipal Campus), Manipal University, Karnataka State, India.
Address for Correspondence
Satheesha Nayak B,
Professor of Anatomy
Melaka Manipal Medical College (Manipal Campus)
Manipal University
Madhav Nagar, Manipal-567104,
Karnataka State, India.
E-mail: [email protected]
Citation
Prasad AM, Nayak SB, Reghunathan D, Shetty SD. Multiple Variations of the Nerves of Gluteal Region and their Clinical
Implications. Online J Health Allied Scs. 2015;14(4):16. Available at URL: http://www.ojhas.org/issue56/2015-4-16.html
Open Access Archives
http://cogprints.org/view/subjects/OJHAS.html
http://openmed.nic.in/view/subjects/ojhas.html
Submitted: Dec 3, 2015; Accepted: Dec 21, 2015; Published: Jan 30, 2016
Abstract: Knowledge of variations of nerves of gluteal
region is important for clinicians administering intramuscular
injections, for orthopedic surgeons dealing with the hip
surgeries and possibly for physiotherapists managing the
painful conditions and paralysis of this region. We report
multiple variations of the nerves of gluteal region through
this article. In the current case, the sciatic nerve was absent.
The common peroneal and tibial nerves arose from sacral
plexus and reached the gluteal region through greater sciatic
foramen above and below piriformis respectively. The
common peroneal nerve gave a muscular branch to the
gluteus maximus. The inferior gluteal nerve and posterior
cutaneous nerve of the thigh arose from a common trunk. The
common trunk was formed by three roots. Upper and middle
roots arose from sacral plexus and entered gluteal region
through greater sciatic foramen respectively above and below
piriformis. The lower root arose from the pudendal nerve and
joined the common trunk. We discuss the clinical
implications of the variations.
Key Words: Sciatic nerve, Gluteal region, Tibial nerve,
Piriformis syndrome, Buttock, Peroneal nerve
Introduction:
Variations in the course and distribution of the nerves of
gluteal region are not uncommon. Knowledge of their variant
course and distribution can minimize their injuries during
various surgical procedures in this region. The sciatic nerve
is a branch of the sacral plexus. It leaves the pelvis through
greater sciatic foramen, below the piriformis muscle. In the
gluteal region, it runs under cover of gluteus maximus
muscle. It terminates by dividing into tibial and common
peroneal nerves at the upper angle of popliteal fossa. Some of
its reported variations include its early division either in the
pelvis itself, in the gluteal region or in the upper part of the
thigh.[1] The inferior gluteal, pudendal and posterior
cutaneous nerve of the thigh are also branches of the sacral
plexus. All the three nerves enter the gluteal region by
passing through the greater sciatic foramen below the
piriformis. Variations of these three nerves are rare compared
to the incidence of variations of the sciatic nerve. Inferior
gluteal nerve may pass through piriformis instead of passing
below it.[2] In some cases, the pudendal nerve pierces the
sacrotuberous ligament in its course.[3] Variations in the
course and distribution of posterior cutaneous nerve of the
thigh are very rare. We present some unique variations of
nerves of gluteal region and discuss about their clinical
importance in this article.
Case Report
During dissection classes for medical undergraduates, we
observed multiple variations of the nerves of right gluteal
region in an adult male cadaver aged approximately 70 years.
The following variations were noted.
1. Sciatic nerve was absent. The common peroneal nerve
came to the gluteal region through greater sciatic foramen
above the piriformis and the tibial nerve came to the gluteal
region through greater sciatic foramen below the piriformis.
2. The common peroneal nerve gave a muscular branch to the
gluteus maximus muscle. This branch arose from common
peroneal nerve at the greater sciatic foramen and entered the
deeper surface of the muscle.
3. The inferior gluteal nerve and the posterior cutaneous
nerve of the thigh arose from a common trunk.
4. The common trunk was formed by union of three roots.
Upper root of the common trunk arose from the sacral plexus
and passed through the greater sciatic foramen above the
piriformis to join the common trunk; the middle root arose
from the sacral plexus and passed out through the greater
sciatic foramen below piriformis to join the common trunk;
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the lower root arose from the pudendal nerve and joined the
common trunk. The common trunk was about 2 inches long
and was situated posterior to the tibial nerve. The distribution
of distal parts of tibial, common peroneal, posterior
cutaneous nerve and inferior gluteal nerves did not have any
variations. All the above said variations are show in in
figures 1, 2 and 3.
Fig. 1. Dissection of the right gluteal region. Gluteus
maximus muscle (GM) has been reflected to show the
variations. GMD, gluteus medius; P, piriformis; STL,
sacrotuberous ligament; TN, tibial nerve; CPN, common
peroneal nerve; CT, common trunk for inferior gluteal
nerve (IGN) and posterior cutaneous nerve of the thigh
(PCN); NGM, nerve to gluteus maximus from common
peroneal nerve; M, medial; L, lateral; I, inferior; S,
superior.
Fig. 2. Closer view of variant nerves of gluteal region.
Gluteus maximus muscle (GM) has been reflected to show
the variations. GMD, gluteus medius; P, piriformis; TN,
tibial nerve; CPN, common peroneal nerve; CT, common
trunk for inferior gluteal nerve (IGN) and posterior
cutaneous nerve of the thigh (PCN); 3R, three roots of the
common trunk; PN, pudendal nerve; NGM, nerve to
gluteus maximus from common peroneal nerve; M,
medial; L, lateral; I, inferior; S, superior.
Fig. 3. Very close view of variant nerves of gluteal region.
Gluteus maximus muscle (GM) has been reflected to show
the variations. GMD, gluteus medius; P, piriformis; STL,
sacrotuberous ligament; TN, tibial nerve; CPN, common
peroneal nerve; CT, common trunk for inferior gluteal
nerve (IGN) and posterior cutaneous nerve of the thigh
(PCN); UR, upper root of common trunk; MR, middle
root of common trunk; LR, lower root of common
trunk; PN, pudendal nerve; NGM, nerve to gluteus
maximus from common peroneal nerve; M, medial; L,
lateral; I, inferior; S, superior.
Discussion:
Sciatic nerve is known to present variations in the level of its
termination. It might divide into tibial and common peroneal
nerves in the pelvis, in the gluteal region, in the upper part of
the thigh or at the upper part of the popliteal fossa. When it
divides in the pelvis, the common peroneal nerve passes
either above piriformis muscle or pierces it. Rarely the sciatic
nerve is formed by the union of three roots in the gluteal
region.[4] Sciatic nerve may terminate by giving three
branches instead of the normal two branches.[5] In the
present case, the sciatic nerve was totally absent. The tibial
and common peroneal nerves arose directly from the sacral
plexus and emerged out of the greater sciatic foramen. At its
exit from the greater sciatic foramen, the common peroneal
nerve gave a muscular branch to the gluteus maximus
muscle. In our literature survey, we could find only one
report where the common peroneal nerve gave a muscular
branch to gluteus maximus.[6] In that case, the common
peroneal nerve had medial and lateral trunks and they pierced
the piriformis muscle. The medial trunk supplied the gluteus
maximus; Inferior gluteal nerve was absent. In our case the
common peroneal nerve did not divide into two trunks and it
did not pierce the piriformis. Inferior gluteal nerve was
present and it supplied gluteus maximus. Thus gluteus
maximus had a duel innervation. Knowledge of the current
variation of the sciatic nerve is important in surgical
treatment of the piriformis syndrome.[7] Iatrogenic injuries
of the muscular branch of common peroneal nerve in our
case might lead to weakness of the gluteus maximus muscle.
Variations of inferior gluteal nerve and posterior cutaneous
nerve are extremely rare. Inferior gluteal nerve may be totally
absent in very rare cases. [6] A case of high division of
sciatic nerve with the formation of inferior gluteal nerve by
two roots has been reported.[7] Posterior cutaneous nerve has
a constant course and distribution pattern. There is one case
report on its communication with the sciatic nerve.[9] In the
current case, the posterior cutaneous nerve of thigh and
inferior gluteal nerve arose from a common trunk formed by
three roots. This is the first report on such a common trunk.
There is ample chance for the compression of the roots of this
common trunk when there is a hypertrophy of the piriformis.
Knowledge of the common trunk and origin of the two
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nerves from the common trunk is useful in posterior approach
to the hip joint.[10] While administering intramuscular
injections, if the common trunk is involved, there might be
altered or loss of sensation over the distribution of posterior
cutaneous nerve in addition to weakness of the gluteus
maximus muscle.
Conclusion:
The current case is unique in having a common trunk for
posterior cutaneous nerve of thigh and inferior gluteal nerve,
formed by three roots. Muscular branch from common
peroneal nerve to the gluteus maximus is also extremely rare.
Knowledge of these combined variations of the nerves may
be extremely useful for clinicians and orthopedic surgeons in
avoiding iatrogenic injuries to these nerves.
References
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