basically its surgical anatomy of the triangles of the neck

1. TRIANGLES OF NECK
Dr Tasnia Mahmud
Trainee in Otolaryngology
CMH, Dhaka

2. Quadrilateral outline of
the side of the neck

3. Above:
-lower border of the body of the
mandible
-an imaginary line extending from the angle
of the mandible to the mastiod process
Below: upper border of the clavicle
In front: middle line of the neck
Behind: by the anterior margin of the
trapezius.

5. Triangles within the Anterior
Triangle of the Neck

6. CAROTID TRIANGLE
BOUNDARIES:
• Superiorly:
posterior belly of
digastric
• Inferiorly: superior
belly of omohyoid
• Posteriorly:
sternomastoid
C

7. ROOF
• Skin
• Superficial fascia,
containing
-- the platysma
--cervical branch of
facial nerve
• Investing layer of
deep cervical fascia

8. FLOOR:
• Anteriorly:
hyoglossus &
thyrohoid
muscles
• Posteriorly:
middle &
inferior
constrictors
of pharynx

9. ARTERIES:
• Termination of
common carotid: at
level of disc between
C3 & C4 (level of upper
border of thyroid
cartilage)
• Proximal part of
external carotid
• Proximal part of
internal carotid
• Five branches of
external carotid:
superior thyroid,
ascending pharyngeal,
lingual, facial &
occipital
CONTENTS OF CAROTID
TRIANGLE

10. CAROTID SINUS
• Dilatation at the
beginning of the
internal carotid artery
• Tunica adventitia
thick
• Rich innervation from
glossopharyngeal
and
sympathetic nerves
• Baroreceptor or
pressure receptor

11. CAROTID BODY
• Small reddish brown
structure
• Behind the bifurcation
of common carotid
artery
• Nerve supply:
glossopharyngeal n.
vagus
sympathetic nerves
• Acts as chemoreceptor

12. • VEINS:
1. Internal jugular
vein
2. Five tributaries to
internal jugular
veins:
a. common facial,
b. lingual,
c. superior thyroid,
d. middle thyroid,
e. pharyngeal veins

13. CONTENTS OF CAROTID
TRIANGLE
CAROTID SHEATH:
• A condensation of deep fascia that
contains:
1. Common & internal carotid arteries:
(medially)
2. Internal jugular vein: (laterally)
3. Vagus nerve: between & a little
posterior to arteries & vein

14. CONTENTS OF CAROTID
TRIANGLE
FIVE NERVES:
• TWO NERVES
RELATED TO
CAROTID SHEATH:
1. Ansa cervicalis
(anterior rami of
C1,2,3): embedded in
the anterior wall of
sheath
2. Sympathetic trunk:
embedded in the
posterior wall of
sheath

16. 3 NERVES BETWEEN INTERNAL JUGULAR VEIN &
INTERNAL CAROTID ARTERY:
1. Vagus (10th
cranial) nerve:
superior
laryngeal br. Dividing into
ext and int laryngeal br
2. Spinal part of accessory
(11th
cranial) nerve:
crosses internal jugular
vein, passes deep to
sternomastoid to reach
posterior triangle
3. Hypoglossal (12th
cranial)
nerve: crosses internal &
external carotid arteries,
passes deep to posterior
belly of digastric to reach
digastric triangle

17. CONTENTS OF CAROTID
TRIANGLE
• DEEP
CERVICAL
LYMPH NODES:
• Jugulodigastric
jugulo-omohyoid
• Situated along the
internal jugular
vein

18. Surgical importance
• Care is taken during approaching to this
triangle to spare the sensory transverse
cervical nerve and its anastomosis with
the motor cervical br of facial nerve
• Known to be variations in the origin of
superior thyroid artery and its br superior
laryngeal artery.
• So chances of misidentification

19. MUSCULAR TRIANGLE
BOUNDARIES:
• Anteriorly:
midline of neck
• Superiorly:
superior belly
of omohyoid
• Inferiorly:
sternomastoid
M

20. FLOOR:
• PRETRACHEAL FASCIA
• STRUCTURES IN THE
INFRAHYOID PART OF
MEDIAN REGION OF FRONT
OF NECK:
1. Thyrohyoid membrane
2. Thyroid cartilage
3. Cricothyroid ligament
& muscle
1. Cricoid cartilage
2. Cricotracheal ligament
3. Trachea
4. Structures in front of
trachea: jugular arch,
inferior thyroid vein, isthmus of
thyroid gland

21. MUSCULAR TRIANGLE
CONTENTS:
THE INFRAHYOID
MUSCLES
• Superficial layer:
1. Sternohyoid:
medially
2. Omohyoid: laterally
• Deep layer:
1. Thyrohyoid: above
2. Sternothyroid:
below

22. MUSCULAR TRIANGLE

23. INFRAHYOID MUSCLES
(SUPERFICIAL LAYER)
Sternohyoid:
• Origin: back of manubrium sterni
• Insertion: hyoid bone
• Action: depression of hyoid bone
Omohyoid:
• Superior belly: hyoid bone
• Inferior belly: upper border of scapula
• Insertion: intermediate tendon (deep to
sternomastoid) attached to clavicle
• Action: depression of hyoid bone

24. INFRAHYOID MUSCLES
(DEEP LAYER)
Thyrohyoid:
• Origin: oblique line of thryroid cartilage
• Insertion: hyoid bone
• Action: depression of hyoid bone,
elevation of larynx
Sternothyroid:
• Origin: back of manubrium sterni
• Insertion: oblique line of thryroid
cartilage
• Action: depression of larynx

25. INFRAHYOID MUSCLES
NERVE SUPPLY:
• All muscles are supplied by ansa
cervicalis (anterior rami of C1,2,3)
EXCEPT: thyrohyoid (by anterior ramus
of C1)

26. SURGICAL IMPORTANCE
• Chances of injury to superficial structures-
anterior jugular vein
jugular arch
ansa cervicalis and its branches
brachiocephalic trunk if situated at
high level

27. DIGASTRIC TRIANGLE
• Also called
submandibular triangle
• Superiorly:base of
mandible & line joining
the angle of mandible to
mastoid process
• Anteroinferiorly: anterior
belly of digastric m.
• Posteroinferiorly;posterio
r belly of digastric m. &
stylohyoid m.
Floor:mylohyoid &
hyoglossus

28. ROOF
the skin,
superficial fascia,
platysma and
deep fascia, which
contain branches
of the facial and
transverse
cutaneous
cervical nerves

29. CONTENT
Anterior part:
submandibular salivary
gland,
submental
artery,mylohyoid
vessels and facial
vein,lymph nodes
Posterior part :
external carotid a.
,parotid gland,styloid
process, styloglossus,
stylopharyngeus and
the glossopharyngeal
nerve & internal carotid
a.

30. APPLIED ANATOMY
• Infection in submandibular region is
limited to a triangular region.
• Posteriorly;hyoid bone and anterolaterally
on each side by halves of mandibular
base
• Because the layer of deep fascia is
attached to these bones.
• Triangular swelling= Ludwig’s Angina
• The swelling may push tongue upwards

31. SURGICAL IMPORTANCE
• To avoid injury to the marginal mandibular
br of facial nerve incision in this region is
given 3cm away from the lower border of
mandible.
• Other key concern for patient is lingual
nerve and hypoglossal nerve.
• Lingual nerve is seen when the gland is
retracted downwards and myelohyoid is
retracted anteriorly.

32. Continued
• Hypoglossal nerve runs parallel and
downwards to lingual artery and vein
• Renine veins (thin wall) runs close to
hypoglossal nerve and vulnerable for
bleeding
• Careful surgery done to avoid injury to
lingual artery,to avoid lingual atrophy

33. SUBMENTAL TRIANGLE
• Its apex is at the chin,
• Its base is the body of
the hyoid bone
• and its floor is formed
by both mylohyoid
muscles.
• It contains lymph
nodes and small veins
that unite to form the
anterior jugular vein

34. POSTERIOR TRIANGLE
• Posterior : anterior
border of trapezius
• Base : middle 3rd
of
clavicle
• Apex : meeting
point of
sternocleidomastoid
& trapezius at
superior nuchal line.

35. ROOF
a. Skin
b. Superficial facia
c. Investing layer of deep cervical facia
d. Roof is pierced by :
1. Nerves :
i. Lesser occipital
ii. Great auricle
iii. Transverse cutaneous nerves of
neck
iv. Supraclavicular nerves
2. Veins : external jugular veins and its
tributaries.
3. Lypmh vessels

36. FLOOR
1. Splenius capitis.
2. Levator scapulae.
3. Occasionally by
semispinalis capitis at
apex.
4. Scaleneus medius.
5. Scaleneus posterior.
6. Muscular floor is
carpeted by
preverterbral facia.

38. SURGICAL IMPORTANCE
• The retropharyngeal abscess maybe expressed in the
lower part of posterior triangle
• The Accessory Nerve may be damaged ,while taking lymph
node biopsy.
• The External Jugular Vein is present in a superficial
location here and this makes it vulnerable to injury.
• Left supraclavicular (Virchow’s) lymph nodes are enlarge
in malignancy of testis, stomach and other abdominal
organ

39. THANK YOU