Nech anatomy and surgical rationale for neck dissection. Classification methods , historical significance .

1. ANATOMY OF NECK
AASTHA MOZA
1stYR PG

2. Cervical fascia is divided into superficial and deep
layers.
The superficial fascia is immediately deep to the
dermis and it ensheathes the platysma as well as the
muscles of facial expression.
The superficial musculoaponuerotic system (SMAS).It
extends from the cranium down to the thorax and
axilla.
The deep layer is divided into superficial, middle, and
deep layers.
Fascial spaces of the neck

3. The neck is the area between the base of the skull and inferior border of the mandible and the
superior thoracic aperture.

4. The SLDCF: outer margin of odontogenic deep space neck infections
(DSNI).
SLDCF
Posteriorly at the nuchal ridge and spreads laterally& anteriorly splitting
to envelop the trapezius and sternocleidomastoid (SCM),attaches to the
hyoid bone anteriorly.
It envelops both the parotid and submandibular glands. It fuses with the
fascia, covering the anterior bellies of the digastric and mylohyoid
forming the inferior margin of the submandibular space.
At the mandible, the fascia splits and the internal layer covers the medial
surface of the pterygoid muscles up to the skull base . The external layer
covers the masseter muscle and inserts into the zygomatic arch. Inferiorly,
it inserts into the clavicles, sternum, and acromion of the scapula.

5. (MLDCF) is also known as the Pretracheal fascia
It often forms the base of deep space infections of the neck, thus creating a
barrier to the extension of infection into the pulmonary, tracheobronchial tree,
esophagus, and prevertebral space.
The muscular division surrounds the sternothyroid, sternohyoid, and thyrohyoid
muscles.
The visceral layer of the MLDCF envelops the thyroid, trachea, and
oesophagus. It extends inferiorly into the upper mediastinum and joins the
fibrous pericardium.
The middle layer also encloses the pharyngeal constrictors and the buccinator
muscles. The visceral layer of the MLDCF is the pathway to mediastinitis.

6. The deep layer of the deep cervical fascia (DLDCF) separates into a posterior prevertebral
division and an anterior alar division.
The prevertebral division is adherent to the anterior aspect of the vertebral bodies from the base
of the skull down the spine. It extends posteriorly around the spine and the muscles of the deep
neck, the vertebral muscles, muscles of the posterior triangle, and the scalene muscles. It
envelops the brachial plexus and subclavian vessels, extending laterally into the axillary sheath.
The alar division is located between the visceral division of the middle layer and the
prevertebral division of the deep layer. The deep layer corresponds to the posterior boundary of
the retropharyngeal space, extending down to the level of T2, where it fuses with the visceral
fascia. Thus the DLDCF is important in providing the posterior boundary for extension of
infection to the mediastinum.
The DLDCF is rarely perforated by infection, but when this occurs, it can result in cervical
spine osteomyelitis or epidural abscess following head and neck infection.

7. Monson and colleagues
Zone I extends from the level of the clavicles and sternal notch at
the thoracic inlet to the cricoid cartilage. Includes the arch of the
aorta, proximal carotid arteries, vertebral arteries, subclavian
vessels, innominate vessels, apices of the lungs, esophagus,
trachea, brachial plexus, and thoracic duct.
Zone II is the largest and most exposed area, and extends from the
level of the cricoid cartilage to the angle of the mandible .
Includes the common, internal, and external carotid arteries, the
jugular veins, various cranial nerves, the larynx, hypopharynx,
and proximal esophagus.
Zone III extends from the level of the angle of the mandible to the
base of the skull.

8. MUSCLE ORIGIN INSERSION NERVE SUPPLY ACTION
Digastric
Anterior belly
Posterior belly
Diagastric fossa
Of mandible
Notch on medial
surface of mastoid
process of temporal
bone
Two bellies joined by
an intermediate
tendon held in a
fibrous sling attached
to hyoid bone at
junction of body and
greater cornu
Anterior belly
By mandibular nerve
Posterior belly
By facial nerve
Depression and
retraction of mandible
Elevation of hyoid
bone
Stylohyoid By tendinous fibers
from posterior side of
styloid process of the
temporal bone
Body of hyoid bone at
junction with greater
cornu
facial nerve Elevation and
retraction of hyoid
bone
Mylohyoid Entire length of
mylohyoid line of
mandible
Anterior and middle
fibers decussate in
median fibrous raphe
between symphysis
menti and midpoint on
body of hyoid bone
Mylohyoid branch
from inferior dental
branch of mandibular
division of trigeminal
nerve
Elevation of hyoid
bone and depression
of mandible
Geniohyoid Lower mental spine Anterior surface of
body of hyoid bone
Anterior ramus C1 Pulls mandible
downward, pulls hyoid
bone forward

9. MUSCLE ORIGIN INSERTION NERVE
MUSCLE ORIGIN INSERTION NERVE SUPPLY ACTION
Sternohyoid Posterior surface of
manubrium sterni
Medial portion of
lower border of body
of hyoid bone
Ansa cervicalis
Descendens
hypoglossi carrying C1
via XII nerve
Depression of hyoid
Omohyoid Superior belly with
intermediate tendon
of inferior belly of
omohyoid muscle
Into lateral portion of
inferior border of body
of hyoid bone
C1 – C3 Depression of hyoid
bone
Sternothyroid Posterior surface of
manubrium sterni
below attachment of
sternohyoid
Into oblique line on
external surface of
thyroid cartilage
C1-C3 Depression of hyoid
bone
and larynx
Thyrohyoid Oblique line on
external surface of
thyroid cartilage
Inferior border of the
body of hyoid bone
and greater cornu of
hyoid
C1 through XII nerve Elevation of larynx
and Depression of
hyoid bone

10. Posterior triangles of the neck
Boundaries:
Anterior: Posterior border of sternocleidomastoid muscle
Posterior: Anterior border of trapezius muscle
Inferior: Superior surface of the middle third of clavicle
Apex: at the point where SCM and trapezius muscles approximate towards each other
over the occipital bone
Floor:
Splenius capitis
Levator scapulae
Scalenus posterior
Scalenus medius
Scalenus anterior

11. Nerves:
Spinal accessory nerve
Branches of cervical plexus
Phrenic nerve C3-C5
Roots and trunks of brachial plexus
Vessels:
Subclavian artery
Transverse cervical artery
Suprascapular artery
External jugular vein

12. Lymph nodes:
Occipital
Supraclavicular
Muscles:
Inferior belly of omohyoid muscle
Anterior scalene , Middle , posterior scalene
Levator scapulae muscle
Subdivisions
Occipital triangle
Supraclavicular

13. Diagastric/ Submandibular triangle
Boundaries:
Superior: Base of mandible, line extending from mandible to mastoid process.
Posteroinferior: posterior belly of diagastric and stylohyoid muscles
Anteroinferior: Anterior belly of diagastric muscle
Roof: skin, superficial fascia, deep cervical fascia
Floor: mylohyoid and hyoglossus muscle
3 triangles within submandibular triangle:
Lesser’s triangle
Pirogoff’s triangle
Beclard’s triangle

14. Carotid triangle:
Boundaries:
Posterior: Anterior border of sternocleidomastoid muscle
Anteroinferior: Superior belly of omohyoid muscle
Superior:
Stylohyoid muscle
Posterior belly of digastric muscle
Floor:
Thyrohyoid
Hyoglossus
Middle constrictor
Roof: skin, superficial fascia, platysma , deep cervical fascia.
Anterior angle: level of hyoid bone

15. Muscular triangle :
Also called omotracheal
Boundaries:
• Anterior border of sternocleidomastoid
• Superior omohyoid
• Midline
Floor of the triangle is composed of :
Sternohyoid
Sternothyroid
Roof:
• Skin
• Superficial fascia
• Deep cervical fascia

16. Boundaries:
Submental triangle:
Anterior diagastric on right and left
Body of hyoid bone
Floor of the triangle:
Mylohyoid
Roof:
• Skin
• Superficial fascia with platysma
• Deep cervical fascia
Major contents are anterior jugular vein and submental lymph
nodes.

17. VASCULAR SUPLLY OF NECK

18. VASCULAR SUPPLY OF NECK

19. NERVE SUPPLY OF NECK

20. ANATOMY OF NECK II
Aastha Moza
1st year PG

21. Need for lymph node classification
• Lymph node status is the single most important prognostic factor in head and neck cancer
because lymph node involvement basically decreases overall survival by 50%.
Unfortunately, approximately 40% of patients with oral cancer will harbor cervical lymph
node metastasis at presentation.
• Removal of the atrisk lymphatic basins serves two important purposes.
• Allows the removal and identification of occult metastasis in patients in whom cervical
metastasis are a risk, which is referred to as an elective neck dissection.
• Secondly, it allows the removal of disease in patients in whom metastasis are highly
suspected based on imaging, clinical examination or fine needle aspiration, which is
referred to as a therapeutic neck dissection.

22. Classification by
the American Head
and Neck Society:

23. Level I Anatomic boundaries:
Level I a:
level I b:
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Symphysis of
mandible
Body of hyoid Anterior belly of
contralateral
diagastric
muscle
Anterior belly of
ipsilateral
diagastric
muscle
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Body of
mandible
Posterior belly
of diagastric
muscle
Anterior belly of
diagastric
muscle
Stylohyoid
muscle

24. Drainage
• Floor of the mouth
• Anterior oral tongue
• Lower lip and mandibular alveolar ridge.

25. Drainage
• oral cavity
• midface soft tissues
• submandibular gland
• Anterior nasal cavity.

26. Level II contains the upper jugular lymph nodes that surround the upper
third of the internal jugular vein and the spinal accessory nerve. It
includes the jugulodigastric node also known as the principle node of
Kuttner. Level II a:
Level II b:
Nodal tissue within level II receives efferent lymphatics : parotid,
submandibular, submental, and retropharyngeal nodal groups.
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Skull base Horizontal plane
defined by inferior
body of hyoid one
Stylohyoid muscle InVertical plane by
spinal accessory
nerve
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Skull base Horizontal plane
defined by inferior
body of hyoid one
InVertical plane by
spinal accessory
nerve
Lateral border of
sternocleidomast
oid muscle

27. Drainage
• oral cavity
• nasal cavity
• nasopharynx, oropharynx, hypopharynx,
larynx, and parotid gland.
• Subclassified into IIA and IIB by a vertical
plane created by the spinal accessory nerve.
Level IIA is anterior and level IIB is posterior
to the spinal accessory nerve.

28. Level III
Level III encompasses node-bearing tissue
surrounding the middle third of the internal jugular
vein.
Level III contains the dominant omohyoid node.
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Inferior border
of hyoid
Inferior border
of cricoid
Lateral border
of sternohyoid
muscle
Lateral border
of
sternocleidoma
stoid muscle

29. Drainage:
• oral cavity
• nasopharynx, oropharynx,
hypopharynx, larynx, and
parotid gland.

30. Level IV
Nodal tissue surrounding the inferior third of the
internal jugular vein. It extends from the inferior border
of level III to the clavicle.
The retropharyngeal, pretracheal, hypopharyngeal,
laryngeal and thyroid lymphatics also make a
contribution.
DRAINAGE:
Hypopharynx
Thyroid
Oesophagus, and larynx.
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Inferior border
of level III node
grp
Clavicle Lateral border
of sternohyoid
muscle
Lateral border
of
sternocleidom
astoid muscle

31. Level V makes up the posterior triangle.
Level V a:
Level V b:
Oropharyngeal cancers, however, such as tongue base
and tonsillar primaries can spread to level V nodes.
Drainage:
nasopharynx, oropharynx
cutaneous structures from
the neck and posterior
scalp.
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Apex of
convergence
of
sternocleido
mastoid and
trapezius
Horizontal
plane, lower
border of
cricoid
Posterior
border of
sternocleidom
astoid muscle
Anterior
border of
trapezius
SUPERIOR INFERIOR ANTERIOR POSTERIOR
Horizontal
plane, lower
border of
cricoid
Clavicle Posterior
border of
sternocleidom
astoid muscle
Anterior
border of
trapezius

32. Level VI The anterior compartment lymph node
group.
It is made up of the lymph node bearing tissue
occupying the visceral space. Prelaryngeal
prethyroid, and pretracheal and paratracheal nodal
groups.
It begins at the hyoid bone, extends inferior to the
suprasternal notch, and laterally is bound by the
common carotid arteries.
Drainage:
Thyroid gland,
Larynx
Piriform sinus
Oesophagus

33. INCISIONS FOR NECK DESSECTION
McFee incision Martin incision Three-quarter H incision
De Quervain incision Lahey incision Modified hockey-stick

35. Classifications of neck dissection
ACADEMY’S CLASSIFICATION
Radical neck dissection (RND)
Modified radical neck dissection
(MRND)
Selective neck dissection (SND)
Extended neck dissection
AAO- HNS CLASSIFICATION
1991 2001
Radical neck dissection (RND) Radical neck dissection (RND)
Modified radical neck dissection
(MRND)
Modified radical neck dissection
(MRND)
Selective neck dissection (SND)
Divided into anterior/
posterolateral/lateral/
supraomohyoid
Selective neck dissection (SND)
( each variation is denoted by SND,
sublevels of lymph nodes removed)
Extended neck dissection Extended neck dissection

36. MEDINA CLASSIFICATION 1989
Comprehensive neck dissection
Radical neck dissection
Modified Radical neck dissection
MRND I - Preserve spinal accessory
MRND II – Preserve spinal accessory and sternocleidomastoid but sacrifice
internal jugular vein.
MRND III- Preservation of all the structures.
Selective neck dissection
Supraomohyoid neck dissection
Jugular neck dissection
Anterior triangle neck dissection
Central compartment neck dissection
Posterolateral neck dissection

37. RADICAL NECK DESSECTION
Refers to the removal of all ipsilateral
cervical lymph node groups extending
from the inferior border of the mandible
to the clavicle, from the lateral border of
the sternohyoid muscle, hyoid bone, and
contralateral anterior belly of the digastric
muscle medially, to the anterior border of
the trapezius.
Included are levels I– V. This entails the
removal of three important, non-
lymphatic structures: the internal jugular
vein, the sternocleidomastoid muscle, and
the spinal accessory nerve.

38. MODIFIED RADICAL NECK DESSECTION
Modified radical neck
dissection (MRND):
Refers to removal of the
same lymph node levels
(I–V) as the radical
neck dissection, but
with preservation of the
spinal accessory nerve,
the internal jugular vein,
or the
sternocleidomastoid
muscle.

39. MODIFIED RADICAL NECK DESSECTION
Oblique incision extending from the mastoid
inferiorly and crossing the sternocleidomastoid
muscle then extending across the neck in a natural
neck crease at approximately the level of the
cricoid cartilage allows adequate access in most
cases.
HOCKEY STICK INCISION

40. SELECTIVE NECK DESSECTION
Selective neck dissection (SND)
Refers to the preservation of one or more
lymph node groups normally removed in
a radical neck dissection.

41. CAROTID BODY TUMOR
It is a small, reddish-brown, oval structure, located in the
posteromedial aspect of the carotid artery bifurcation.
The gland is highly vascular and receives its blood
supply from feeder vessels running through external
carotid artery, typically the ascending pharyngeal artery.
It is innervated by the Hering nerve, originating from the
glossopharyngeal nerve about 1.5 cm distal to the
jugular foramen.
Shamblin describes 3 different types or stages of
carotid body tumors.
1. Type I consists of a small tumor that is easily
dissected from the adjacent vessels in a
periadventitial plane.
2. Type II tumors are larger and more adherent and
partially surround the vessel.
3. Type III tumors are large and completely surround
the carotid bifurcation.