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2 Principle ofHead andNeck Surgery andtheImportance ofAnatomical Characteristics
57
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Signicance ofAnatomical Versus
Surgical Landmarks inHead
andNeck Surgery
NorhazaMat Lazim , ZulIzharMohd Ismail,
MuhamadNorFirdausAb Rahman,
andBaharudinAbdullah
3
3.1 Introduction
Head and neck surgery entails multiple procedures involved with important structures of the
head and neck region. The organs for breathing,
hearing, taste, vision, and swallowing all reside
in the head region. In the neck, there are multiple
neural and vascular structures that are at signicant risk during surgery. This includes the lower
four cranial nerves, carotid artery, internal jugular vein, larynx, oesophagus, thyroid glands, and
so forth. In order to perform an effective and safe
surgery while minimizing the morbidity, an operating surgeon should have a sound anatomical
knowledge as well as rened surgical skills. In
addition, the availability of instruments and proactive communications with staffs would facilitate an efcient surgery (Fig. 3.1). Inadvertent
injury to aforementioned critical structures could
lead to serious and fatal complications. The availability of imaging tools like CT scan (Fig.3.2)
and other diagnostic optical endoscopy allows
N. Mat Lazim (*) · B. Abdullah
Department of Otorhinolaryngology-Head and Neck
Surgery, School of Medical Sciences, Universiti Sains
Malaysia, Health Campus,
Kubang Kerian, Kelantan, Malaysia
e-mail: norhaza@usm.my
Z. I. Mohd Ismail · M. N. F. Ab Rahman
Department of Anatomy, School of Medical Sciences,
Universiti Sains Malaysia, Health Campus,
Kubang Kerian, Kelantan, Malaysia
surgical mapping that would minimize surgeryrelated morbidity.
A variety of methods are available to enhance
the anatomical knowledge of young trainee and
junior surgeons practising in head and neck surgery. These range across cadaveric dissection,
simulation training, head and neck online courses,
and many more. An efcient way to consolidate
anatomical knowledge and to link this awareness
for better understanding of head and neck surgery
is the new interdisciplinary hands-on course [1].
The 3D simulation cadaveric dissection is probably the best way, as the head and neck’s detailed
anatomical structures could be mapped on virtual
reconstructive models. This will facilitate greater
understanding of relevant surgical landmarks
during the dissection process.
The neck region is a compartmental area with
supercial and deep layers of fasciae dividing the
region into many small spaces. All of these spaces
have clinical and surgical importance. The deep
space of the neck is crucial as multiple pathologies such as infection, tumour spread, neck node
metastasis, and spread of disease could occur
inside these spaces (Table3.1). For example, the
poststyloid compartment of the parapharyngeal
space is well known for the occurrence of pleomorphic adenoma of the deep lobe of parotid
glands and paragangliomas that originate from
the last four cranial nerves or those that arise
from sympathetic bre that overlies the carotid
wall. Surgical access to parapharyngeal space is
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022
N. Mat Lazim et al. (eds.), Head and Neck Surgery : Surgical Landmark and Dissection Guide,
https://doi.org/10.1007/978-981-19-3854-2_3
59
60
N. Mat Lazim et al.
Enhanced knowledge on
head & neck anatomy
Ability to identify surgical
landmarks during specific
surgical procedures
Fig. 3.1 Determining factors for a safe surgery
Well-equipped operating
theatre room with competent
assistant, paramedic & nurse
Effective communication with
anaesthetist, patient and
multidisciplinary team involvment
Requirements for a
safe and efficient head
& neck surgery
Nasal cavity
Nasopharynx
Maxillary sinus
Pterygoid muscle
Mastoid bone
Fig. 3.2 Identication of the structures visualized in the
CT scan images such as nasopharynx, pterygoid muscle,
maxillary sinus, nasal cavity, mastoid air cells, and adja-
cent critical structures is vital for preoperative surgical
mapping
3 Signicance ofAnatomical Versus Surgical Landmarks inHead andNeck Surgery
Table 3.1 Clinical importance of deep spaces of head
and neck region
Deep spaces of
head and neck
1. Parapharyngeal
space
2. Retropharyngeal
space
3. Danger space • Spaces posterior to
4. Prevertebral
space
5. Carotid space • Contains the neck nodes
6. Submandibular
space
7. Masticator space • Tumour spread
Clinical and surgical
importance
• Paraganglioma and deep
lobe pleomorphic
adenoma originate from
this space
• Abscess formation
• Collection of abscess and
infection
• Origin of deep neck
infection (DNI)
• Nodes of Rouviere/
retropharyngeal nodes
impact prognostication of
NPC
retropharyngeal space
• At risk of airway
obstruction in extensive
cases
• Indicative of inoperability
if tumour inltrated this
space
especially on the IJV wall,
at risk of neck metastasis
recurrence
• At risk of infection like
Ludwig’s angina, and in
severe cases can cause
airway obstruction
Fig. 3.3 Skin incision and landmarks have been drawn
for a bilateral selective neck dissection. The landmarks
include sternocleidomastoid muscle (scm), mandible (m),
external jugular vein (ejv), and outline of skin incision (sil)
during surgery and lacks the detailed knowledge
of anatomical structures of the related organs, the
vessels, nerves, muscles, and other organs might
be injured. Consequently, the risk of surgery will
be higher. Many critical tumours are located in
the head and neck and need to be addressed
according to the principle of oncologic surgery.
Therefore, surgeons should have a thorough
knowledge of this critical region’s surgical anatomy so that the tumour can be excised with free
surgical margins and without compromising the
adjacent structures. Of note, an inexperienced
junior surgeon with fear of causing damage to
important structures may lead to inadequate surtechnically challenging and requires a thorough
knowledge of the anatomical and surgical landmarks of these spaces. In addition, a meticulous
surgical technique is necessary during dissection
with regard to the preservation of the delicate
neurovascular structures and its relation to the
adjacent tissues, so that complications could be
avoided.
The surgical plane is a plane of dissection
which is used in relation to the tissues and organs,
so that the normal structures can be preserved. In
the surgery of malignant mass, the intention is to
excise a tumour, leaving the muscles and the neurovascular tissues that are not affected by the
tumour intact. In the majority of cases, if the dissection continues in a correct plane, severe tissue
damage is avoided, and bleeding can also be minimized. If the surgeon loses the surgical planes
gical treatment efcacy, with a consequent risk of
tumour persistence or recurrence [2].
During a neck surgical procedure, for instance
a bilateral selective neck dissection for a tongue
carcinoma, the surgeon should identify the landmarks of the neck structures which are ideally
marked with a marker pen, before starting a skin
incision (Fig. 3.3). This is a good practice in
order to orientate the structures or tumoural mass
dissection, so as to avoid the unnecessary bleeding or iatrogenic injury to neural structures.
In head and neck surgery, the subplatysmal
ap is the simplest ap that is ideal for an illustration for a teaching purpose, especially to the
junior trainees in head and neck surgical oncology practice for attaining a right plane of dissection during the surgery. In fact, it is a cornerstone
ap for access and removal of signicant neck
61
62
Fig. 3.4 A subplatysmal skin ap (ssf) is raised and
reected superiorly. The thicker the ap, the better it is for
ap vascularization in order to avoid ap necrosis. The
distal end of cut platysma is also shown (pm)
tumours such as thyroid tumour, laryngeal cancer, and neck node metastases; submandibulectomy; and most of the excision of the pathology
of neck region. All of these surgical procedures
require the elevation of subplatysmal ap.
Platysma is a supercial thin muscle that spans
from the inferior border of mandible to clavicle.
It criss-crosses the sternocleidomastoid muscle
(SCM) and is decient at the anterior and posterolateral parts of the neck (Fig.3.4). The vascular supply to the ap is through the submental
artery, a branch of facial artery, and suprascapular artery, a branch from thyrocervical trunk. The
thicker the ap, the better the vascular supply,
hence less risk of developing ap necrosis.
Further dissection and skeletonization of the
anterior border of SCM are required, so that it
can be retracted laterally, thus exposing the
carotid sheath. The dissection overlying the internal jugular vein (IJV) and carotid artery equates
level II, III, and IV neck dissection (Fig.3.5). The
assistant nurse or surgeon should retract the mandible superiorly with a cold instrument, while the
surgeon applies traction inferiorly on the dissected mass (Fig.3.6). This technique of countertraction and traction will facilitate neck dissection
effortlessly.
The knowledge of anatomy and function of the
nerves that innervate neck muscles may enable
surgeons to avoid inadvertent injury. For example,
N. Mat Lazim et al.
Fig. 3.5 A subplatysmal skin ap (ssf) is raised exposing
the sternocleidomastoid muscle (scm) and tissue at levels
I, II, III, and IV.This is the extent of exposure required in
selective neck dissection. The SCM is retracted laterally,
in order to dissect the brofatty tissue and fascia overlying
IJV (levels II, III, and IV). The distal end of cut platysma
is also shown (pm)
Fig. 3.6 Mandible is retracted with the assistance of a
nurse or surgeon to facilitate efcient dissection of brofatty tissues and neck node metastases. A good traction
and countertraction allow a quick dissection and will
shorten the operating time
ansa cervicalis is a loop of nerve that arises from
cervical plexus, which lies supercial to the internal jugular vein in the carotid triangle. It is the
nerve that innervates the sternohyoid, sternothyroid, and omohyoid muscles. Lesion to this nerve
would result in paralysis of these muscles. In
addition, the cervical plexus also gives rise to the
cutaneous nerves of the neck, which are located
supercially on the lateral neck muscles, namely
the great auricular, posterior auricular, transverse
cervical, and supraclavicular nerves. Lesion to
any of these would result in paraesthesia to the
skin areas supplied by the respective nerves.
Stemocleidomastoid muscle
Spinal accessory nerve
3 Signicance ofAnatomical Versus Surgical Landmarks inHead andNeck Surgery
Trapezius muscle
Clavicle
63
Stemum
Fig. 3.7 The course of the spinal accessory nerve (SAN)
in the posterior triangle or level V is critical for neck dissection. SAN exits at upper two-thirds at the posterior
Another important nerve in the posterior triangle which is of importance is the spinal accessory nerve (SAN). The SAN lies 1–2cm superior
to the exit point of cutaneous nerve branches
from cervical plexus at the posterior border of
SCM.This nerve runs in the posterior triangle of
the neck or level V crossing the carotid sheath,
SCM, and trapezius muscle in 45° angles
(Fig.3.7). Several landmarks are being used to
identify the SAN.These include
1. Erb’s point
2. SCM
3. Trapezius muscle
4. Transverse process of C2 vertebra
These landmarks allow the identication and
preservation of SAN during neck dissection at
level V region, as this nerve is located supercially (Table3.2). Injury and traction of the SAN
border of SCM and enters the anterior border of trapezius
at 5.0cm above the clavicle. The landmarks for identication of SAN are C2 vertebrae and Erb’s point
cause signicant morbidity like frozen shoulder
syndrome, which is characterized by limited arm
abduction, painful scapular region, and inability
to shrug the shoulder.
In the head and neck region, there is an extensive anastomotic network of the lower cranial
nerves. The understanding of the neural intercommunications of the skull base is vital in diagnosing and treating patients with pathology in this
critical area [3]. Facial nerve, hypoglossal nerve,
and vagus nerve are particularly important nerves
that need to be recognized and preserved during
the surgery. Injury to these nerves or inadvertent
denervation during aggressive dissection causes
signicant morbidity to patients as these nerves
are involved in many critical functions of the
facial-neck complex, such as mastication, swallowing, speech, and facial expression. Awareness
of the anatomy of these neural connections would
be especially useful in facial reconstructive sur-
64
N. Mat Lazim et al.
Table 3.2 Surgical landmarks of the spinal accessory
nerves, cranial nerve XI
Surgical landmarks for
SAN (CNXI) Description
1. Erb’s point The exit point of
cutaneous nerve
branches from cervical
plexus at the posterior
border of SCM.The
SAN lies 1–2cm above
this point
2. Transverse process of
cervical vertebra
3. Sternocleidomastoid
muscle
4. Trapezius muscle The SAN runs 5cm
5. Great auricular point The point of exit of
The SAN can be
palpated over the
transverse process, at
level IIB neck as the
nerve runs over this
vertebra
The SAN pierces
through this muscle at
its superior one-third. It
may also lie deep to this
muscle
above the clavicle at the
anterior border of
trapezius, before
piercing and supplying
the muscle
great auricular nerve at
the posterior border of
sternocleidomastoid
muscle. The SAN lies
1–2cm above this point
gery, neck dissection, and various nerve transfer
procedures as well as in understanding the pathophysiology of various cranial, skull foundation,
and neck disorders [4]. Hypoglossal nerve injury
leads to tongue atrophy, fasciculation, and deviation of the tip of the tongue. Vagus nerve injury
causes hoarseness of voice and aspiration,
whereas facial nerve injury causes facial asymmetry. All of these complications will indenitely
impair the patient’s quality of life.
3.2 Importance ofSurgical
Landmarks
The knowledge on the anatomical and surgical
landmarks will assist surgeons to perform the
surgery with most minimum complication as
possible. During the surgery, dissection is started
with the designing and drawing of the skin incision together with other landmarks. For instance,
during a tracheostomy, a skin incision drawing is
placed at 2.0cm above the sternal edge. In addition, the cricoid, thyroid, and hyoid cartilage
locations are also identied and drawn. This is to
ensure that tracheostomy is performed in the
midline, thus avoiding the crucial vascular structures such as the carotid artery and the laterally
positioned IJV in the carotid sheath. A correct
technique of tracheostomy would also prevent
the development of post-surgical stenosis, which
is due to the recurrence and would be very
debilitating.
During the skin incision, surgeons need to
anticipate the fascial layer of the neck that would
be encountered during the procedure. The supercial cervical fascia is encountered right after the
elevation of platysma muscle. The pretracheal fascia layer is the next layer to be incised, exposing
the strap muscles. Deep to the strap muscles is the
thyroid gland, which needs to be retracted superiorly. Once thyroid gland is retracted, the tracheal
ring could be easily palpated and visualized. So, in
essence, by knowing the order of the structures of
the neck from supercial to deep, it would facilitate a safe dissection and minimize complications
such as active bleeding, muscle injury, or nerve
transection. The ability to visualize the supercial
musculoaponeurotic system and its relationship to
crucial neurovascular structures allows surgeons
to plan the operation and minimize post-operative
complications [2]. As the surgical procedure is
performed, crucial neural structure injury should
be avoided as it can have a signicant impact on
patient’s functions like swallowing, speech,
breathing, and facial expression.
In addition, supercial skin lesion and its
related surgery should also be performed with a
sound knowledge of anatomical landmarks. Most
skin surgical procedures are performed in
sun- damaged areas of the face and head because
of the development of skin tumour like basal cell
carcinoma and malignant melanoma. Surgeons
or dermatologists should have a very good knowledge of the important layers of epidermis, dermis, and hypodermis in these areas so that they
3 Signicance ofAnatomical Versus Surgical Landmarks inHead andNeck Surgery
65
can perform an aesthetically safe skin surgical
procedure.
3.3 Thyroid Surgery andRelated
Surgical Landmarks
The thyroid mass surgery is one of the most common neck pathologies that are managed by the
ear, nose, and throat (ENT) surgeon in selected
centres. The surgical management of thyroid
tumour is critical as it is involved with the preservation of the recurrent laryngeal nerve (RLN),
which innervates the intrinsic muscles of the larynx (except the cricothyroid muscle). The mobility of vocal cord is crucial for the normal voice
production. Injury to the RLN will impair the
vocal cord mobility, hence resulting in hoarseness of voice. This impairs patient’s effective
communication and quality of life.
In the identication and safe dissection of the
RLN, sufcient knowledge of its surgical anatomy, clinical experience, and meticulous surgical
techniques are key factors. The RLN can be identied during a thyroidectomy using four different
approaches, depending on the type of thyroid
growth and the surgeon’s choice. These
approaches include the lateral, inferior, superior,
and medial approaches [5]. It depends on the surgeon’s preference and intraoperative ndings in
choosing the type of surgical approach. The surgical landmarks that are commonly used during
thyroid surgery include the laryngeal cartilages
such as the thyroid, cricoid, hyoid bone, and also
trachea. The easily palpable parts of laryngeal
cartilages are, for instance, the inferior cornua of
the thyroid cartilage, the thyroid cartilage inferior
tubercle, and the most anterior portion of the cricoid cartilage arch. These palpable landmarks
have been recognized as critical landmarks during thyroid surgery (Fig.3.8). Of note, the distances between these structures and the RLN
entry point on the medial aspect of the cricoid
cartilage arch have been recognized as a landmark for the identication and preservation of
recurrent laryngeal nerves [6].
Joll’s triangle
Trachea &
esophagus
Surgical
Inferior thyroid
artery
External laryngeal
nerve
Fig. 3.8 The critical structures encountered during a thyroid surgery
structures &
landmarks in
thyroid
surgery
Beahr’s triangle
Recurrent
laryngeal nerve
Parathyroid glands
Tracheoesophageal
groove
66
Left vagus nerve
Right vagus nerve
Right common
carotid artery
N. Mat Lazim et al.
Thyroid gland
Left common
carotid artery
Fig. 3.9 Anatomical relationship between vagus nerves, recurrent laryngeal nerves, arch of aorta, right subclavian
artery, common carotid arteries, and thyroid glands
between the right and the left sides of the neck.
At the point where the brachiocephalic artery is
divided into two branches, the right RLN, which
arises from the vagus nerve, rotates backwards
around the right subclavian artery and advances
towards the tracheoesophageal groove after passing the trachea at an angle of 15–45° posterior to
the carotid artery. While on the left neck, at the
level of the ligamentum arteriosum, the left RLN
branches out from the vagus nerve, turns posteriorly from the anterior aspect of the aortic arch,
and reaches the tracheoesophageal groove from
the medial side of the left common carotid artery
(Fig.3.9) [5].
important structures associated with the RLN.In
majority of the cases, the RLN is located anterior
or posterior to ITA, or passes within its branches.
After passing the ITA level, the RLN usually follows the same anatomical route on both sides, and
next runs close to the Zuckerkandl tubercle (ZT)
Right recurrent
laryngeal nerve
The anatomical course of the RLN is different
The inferior thyroid artery (ITA) is one of the
Trachea
Left recurrent
laryngeal nerve
Arch of aorta
and the Berry’s ligament. The Berry’s ligament is
encountered when the dissection is performed
posterior to the thyroid glands. The risk of RLN
injury in this area of Berry’s ligament is very high
[5]. The surgical procedure in thyroid surgery is
illustrated in Figs.3.10, 3.11, 3.12, and 3.13.
During the thyroid surgery, other important
neural structures are also at risk. In addition to
the recurrent laryngeal nerve (RLN), protection
must be provided to the external branch of the
superior laryngeal nerve (EBSLN) [7]. This
EBSLN supplies the cricothyroid muscle, which
tenses vocal cord. This is particularly crucial for
a professional voice user like singer, teacher, and
tutor. The entry point of the EBSLN into the muscle is usually 1.1mm from the insertion of the
sternothyroid into the oblique line of the thyroid
cartilage and 5–12mm from the muscle’s anterior border. There is a classication system by
Cernea etal., which highlights the course of the
external laryngeal nerve in relation to the upper
lobe of the thyroid glands. Ideally, the superior
3 Signicance ofAnatomical Versus Surgical Landmarks inHead andNeck Surgery
Fig. 3.13 Thyroid mass has been removed exposing the
Fig. 3.10 Important landmarks should be marked before
the rst skin incision in order to orientate the critical
structures that need to be addressed safely during the surgery. Outline of the mass is in dotted lines (big arrow),
skin incision (star), anterior border of SCM (small arrow),
and hyoid bone (hb)
trachea (T). The sternocleidomastoid muscle is visible on
either side of the neck, left SCM (L SCM) and right SCM
(R SCM)
67
Fig. 3.11 A midline thyroid mass is visualized on lateral
inspection
Fig. 3.12 A subplatysmal skin ap has been raised (black
arrow), and the strap muscle overlying the thyroid mass is
exposed. Classically, the skin ap can be retracted with a
Joules retractor (white arrow) or an assistant with a cold
retractor instrument
Fig. 3.14 Intraoperative neural monitoring in thyroid
gland surgery is vital for preservation of the recurrent
laryngeal nerve. The ground electrode (star) and the electric lead inserted to the intubation tube (arrow) are secured
thyroid artery should be ligated 1.0 cm away
from the upper pole of thyroid gland to avoid
injury to EBSLN. Before ligating the superior
thyroid vessels, these useful landmarks enable
the nerve to be consistently located, identied,
and preserved during thyroid surgery [8]. Thus, a
meticulous dissection needs to identify and preserve these nerves.
In addition to visual identication, the intraoperative neural monitoring (IONM) (Fig.3.14)
is able to assist surgeons to better identify the
nerves, both the RLN and ESBLN.The use of
IONM application can functionally locate the
EBSLN so that muscle twitch, i.e. the cricothyroid muscle, is a reliable evidence of the EBSLN’s
functional integrity. In the majority of patients,
activation of the EBSLN causes a recordable