The anterior triangle of the neck contains three smaller triangles - the submandibular, submental, and muscular triangles. The submandibular triangle contains the submandibular gland and associated nerves and vessels, including the lingual and hypoglossal nerves. The submental triangle drains lymph from the chin and lower lip. The muscular triangle contains the infrahyoid strap muscles that depress the hyoid bone during swallowing.

1. 

•Anterolaterally the neck
appears as a quadrilateral
area
This quadrilateral area is
divided into anterior and
posterior triangles by
sternocleidomastoid, whi
ch passes obliquely from
the sternum and clavicle
to the mastoid process
and occipital bone.

2. The ANTERIOR TRIANGLE lies
anterior to the sternocleidomastoid
muscle, while the POSTERIOR
TRIANGLE lies posterior to the
sternocleidomastoid muscle.

7. KIMAIGA H.O
1ST YEAR MBChB(UoN)

18. ANTERIOR TRIANGLE OF THE NECK
BOUNDARIES
Anteriorly- median line of the neck,
Posteriorly-anterior margin of sternocleidomastoid.
Base -inferior border of the mandible
•and its projection to the mastoid process,
•and its apexis at the manubrium sterni.
Made of suprahyoid and infrahyoid areas above and
below the hyoid bone,
TRIANGLES HERE ARE:
•Digastric/submandibular
•Submental
•Muscular
•Carotid triangles
By passage of digastric and omohyoid across the
anterior triangle

20. Table of Muscles
Muscle
Origin
Insertion
Action
Nerve Supply
Sternohyoid
sternum
hyoid
ansa
Omohyoid
Suprascapular
notch
hyoid
ansa
Sternothyroid
Below
sternohyoid on
manubrium
Thyroid
cartilage
oblique line
ansa
Thyrohyoid
Thyroid
cartilage
oblique line
hyoid
C1-C2 (ansa)
Anterior Belly
Digastric
----intermediate
tendon------
Inner surface of
mandile
Trigeminal
nerve
Posterior Belly
Digastric
Medial aspect
of the mastoid
process
-intermediate
tendon-
Facial nerve
Mylohyoid
Mylohyoid line
of mandible
Hyoid bone
Trigeminal
nerve
Hyoglossus
Hyoid bone
Lateral side of
tongue
hypoglossal
Stylohyoid
Styloid process
hyoid
Facial nerve

21. MUSCLE
ORIGIN
INSERTION
ACTION
INNERVATION
Digastric
•Digastric notch,
•medial surface of
base of mastoid
process
•Digastric fossa
•Depress the
mandible
•Posterior belly:
facial nerve
•Anterior
belly:nerve to
mylohyoid
Stylohyoid
•Back of styloid
process near the
base of skull
•By two slips into
the junction between
the greater horn and
body of hyoid bone
•ELevate hyoid bone
•Facial nerve
Mylohyoid
•Whole length of
mylohyoid line of its
own side on the
inner aspect of the
mandible from
medial to the third
molar tooth to
below the mental
spines
•Anterior ¾: into
each other
(interdigitation)
•Posterior ¼:
anterior surface of
the body of hyoid
bone
•Forms a mobile but
stable floor of the
mouth
•Mylohyoid nerve
Geniohyoid
•Inferior mental
spine
•Upper border of the
body of hyoid bone.
•Protracts and
elevates the hyoid
bone in swallowing
or if the hyoid is
fixed to depresses
the mandible.
•C1(superior root of
ansa cervicalis)

22. 




Platysma is a broad sheet of muscle of varying
prominence.
•arises from the fascia covering the upper parts of
pectoralis major and deltoid.
•Its fibres cross the clavicle and ascend medially in the
side of the neck.
•Anterior fibres interlace across the midline with the
fibres of the contralateral muscle, below and behind the
symphysis menti.
•Other fibres attach to the lower border of the
mandible or to the lower lip or cross the mandible to
attach to skin and subcutaneous tissue of the lower
face.

24. 

Origin – fascia overlying the pectoralis
major & deltoid muscle
Insertion




depression muscles of the corner of the mouth
the mandible
lower face
Function




wrinkles the neck
depresses the corner of the mouth
increases the diameter of the neck
assists in venous return

26. 





Vascular supply
•Platysma receives its blood supply from
–the submental branch of the facial artery
–and the suprascapular artery from the
thyrocervical trunk of the subclavian artery.
•Innervation
•Platysma is innervated by the cervical branch
of the facial nerve which descends on the
deep surface of the muscle close to the angle
of the mandible

27. 

Contraction diminishes the concavity
between the jaw and the side of the neck and
produces tense oblique ridges in the skin of
the neck.
•Platysma may assist in depressing the
mandible, and via its labial and modiolar
attachments it can draw down the lower lip
and corners of the mouth in expressions of
horror or surprise.

29. 
Origin



Insertion


mastoid process
Nerve supply


medial third of the clavicle (clavicular head)
manubrium (sternal head)
spinal accessory nerve (CNXI)
Blood supply



occipital a. or direct from ECA
superior thyroid a.
transverse cervical a.

30. 

Function – turns head toward opposite side &
tilts head toward the ipsilateral shoulder
Surgical considerations
Leave overlying fascia (superficial layer of deep
cervical fascia down)
 Lateral retraction exposes the submuscular recess


31. 
Origin


Insertion



via the intermediate tendon onto the clavicle and
first rib
hyoid bone lateral to the sternohyoid muscle
Blood supply


upper border of the scapula
Inferior thyroid a.
Function
depress the hyoid
 tense the deep cervical fascia


32. 
The INFERIOR
BELLY OF THE
OMOHYOID
MUSCLE crosses the
posterior triangle as it
spans from the hyoid
bone to the scapula.

33. 





Surgical considerations
Absent in 10% of individuals
Landmark demarcating level III from IV
Inferior belly lies superficial to the brachial
plexus
Phrenic nerve transverse cervical vessels
Superior belly lies superficial to IJV

34. 
Origin


digastric fossa of the mandible (at the symphyseal
border)
Insertion
hyoid bone via the intermediate tendon
 mastoid process


Function
elevate the hyoid bone
 depress the mandible (assists lateral pterygoid)


35. 

Surgical considerations
Posterior belly is superficial to
ECA
Hypoglossal nerve
ICA
IJV
Anterior belly
Landmark for identification of mylohyoid for
dissection of the submandibular triangle

41. Origins and insertions on the mandible and hyoid

42. Origins and insertions on the mandible and hyoid

44. Omohyoid muscle (surgical landmark)

Junction with IJV

45. LEFT
ANTERIOR
TRIANGLE

46. Boundaries:
Inferomedially: Anterior
belly of digastric.
 Anterosuperiorly: Inferior
border of the mandible.
 Inferolaterally: Posterior
belly of digastric.
Floor;
 Mylohyoid (forms
diaphragm oris)
 hyoglossus
 middle constrictor muscle
of the pharynx


48. ROOF OF
SUBMANDIBULAR
TRIANGLE:
The skin.
Superficial fascia
Platysma
Deep fascia containing
branches of the facial
and transverse
cutaneous cervical
nerves e.g. cervical
branch of facial nerve

49. 
Removal of the superficial
structures displays the
submandibular salivary
gland itself.

50. CONTENTS OF SUBMANDIBULAR
TRIANGLE:

Submandibular gland

Hypoglossal nerve.XII

Mylohyoid nerve.

Facial artery and vein.

Submandibular lymph nodes





Lingual nerve and submandibular
ganglion (ln)
Submandibular duct (smd)
Lingual artery (la)
The lingual nerve and
submandibular duct pass through
a gap between the hypoglossal
(hg) and mylohyoid (mh) muscles
the lingual artery passes deep to
the hyoglossus muscle.

51. 




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

52. BOUNDARIES
 Apex –Inferior end of
symphysis menti
Laterally: Right and left
anterior bellies of digastric.

Base inferiorly -Body of the
hyoid bone

Floor - mylohyoid muscles.(mh)
Arise from the body of the hyoid
bone and insert into the
mylohyoid line of the inside of
the mandible.


Aids in swallowing and in
depressing the mandible.

54. CONTENTS OF SUBMENTAL
TRIANGLE
Submental lymph nodes.
These receive lymph from the
following areas:
•Tip of the tongue.
•Floor of the mouth.
•Mandibular incisor teeth and
associated gingivae
•Central part of the lower lip.
•Skin of the chin.
Lymph from here drains into
submandibular and deep cervical
lymph nodes.
Submental veins and arteries.
The submental veins unite to form
the anterior jugular vein.

55. 

In infections or cancer from any of the areas of
drainage of the submental nodes, especially the tip of
tongue and lip, the first nodes to be involved are
submental nodes. Subsequently, the submandibular
and deep cervical get involved.
A discharging sinus on the point of the chin often
results from an abscess of a mandibular incisor tooth.
The pus from the infected tooth passes from the apex
of the submental triangle located at the inferior end
of the symphysis menti where it forms a sinus from
which pus escapes.

56. BOUNDARIES
 Anteriorly -median line
of the neck from the
hyoid bone to the
sternum,
 Inferoposteriorly by the
anterior margin of
sternocleidomastoid,
 Posterosuperiorly by the
superior belly of
omohyoid.
 Apex-jugular notch
(3)

57. CONTENTS OF MUSCULAR TRIANGLE
1) Infrahyoid muscles (strap
muscles).
• Sternohyoid 1
• Sternothyroid
• Thyrohyoid
• Omohyoid* 2forming part of the
boundary.
NOTE: These muscles are
innervated by ansa cervicalis (c1-c3)
except thyrohyoid that is innervated
by C1 via Hypoglossal nerve. They
depress the hyoid bone and larynx
during swallowing and speaking,
anchoring it in position
2) The anterior jugular veins, run in
both sides of the midline. They are
joined by the jugular arch at the
suprasternal notch.
1-Sternohyoid
2-Omohyoid
3-Sternal head of
sternocleidomastoid

60. BOUNDARIES
Superomedially
 Posterior belly of the
digastric
Laterally:
 Anterior border of the
sternocleidomastoid
muscle
Inferomedially:
 superior belly of
omohyoid

62. 


Skin and superficial
fascia
Platysma
Deep fascia;
ramifying in which
are branches of the
facial and cutaneous
cervical nerves.

63. 

The muscles, at this level,
are Thyrohyoideus,
hyoglossus, the middle and
inferior pharyngeal
constrictors (mpc and ipc).
The structures seen passing
through this level are:
 superior laryngeal nerve,
a branch of the vagus its
2 terminal branches
 internal laryngeal (ilb)sensory to upper part of
the larynx
 external laryngeal (elb)motor to the Cricoid
muscle)

64. 

common facial vein (cf)
(within carotid triangle)
Other structures near by:





retromandibular vein (rm)
posterior auricular vein (pav)
facial vein (fv)
external jugular vein (ej)
anterior jugular vein (aj)

65. 
The nerves that enter
the carotid triangle and
that lie superficial to the
internal jugular vein,
internal and external
carotid arteries are:





hypoglossal (XII)
C1 root of ansa cervicalis
(C1)
C1 fibers running with
hypoglossal nerve (nerve
to thyrohyoid muscle
(nth)
C2-C3 root of ansa
cervicalis
ansa cervicalis (ac)

67. 





cca-common
carotid artery
eca-external carotid
artery
sta-supterior
thyroid artery
oa-occipital artery
la-lingual artery
fa-facial artery
ica-internal carotid
artery

69. 








1.masseter muscle
2.
5.parotid gland
8.facial artery
28.common carotid artery
29. internal carotid artery
30.external carotid artery
31. Superior thyroid artery
32. Ansa cervicalis

71. THE CAROTID SHEATH:
Location:
Longitudinal interval
between cervical viscera
(pharynx, esophagus,
larynx, trachea and thyroid
gland) medially, and
prevertebral muscles
posteriorly
Formation:
Prevertebral fascia behind
Pretracheal fascia medially

72. Mnemonics Of Carotid Sheath Contents
"I SEE(I.C)10 CC's IN THE IV"
I SEE (I.C) = Internal carotid artery
10 = 10 cranial nerve (vagus nerve)
CC = Common carotid artery
IV = Internal juglar vein

74. CONTENTS OF CAROTID SHEATH
1. Common and Internal Carotid arteries medially.
2. Internal jugular vein laterally.
3. Vagus nerve posteriorly and between the above two.
4. Ansa cervicalis embedded in the carotid sheath(anteriorly).
5. Deep cervical lymph nodes.
Note:
1) Common carotid artery divides at superior border of thyroid gland (C3,4).
2) The carotid sinus (the baroreceptor) is a slight dilatation at the proximal part
of the internal carotid artery. It is innervated by:
•Carotid sinus nerve, a branch of
glossopharyngeal.
•A branch of vagus nerve.
•Sympathetic division of ANS.
3) The carotid body, is a small reddish brown, ovoid mass of tissue located at
the carotid bifurcation. The same nerves that go to the carotid sinus innervate
it.

75. A-Vagus nerve
B-Comon carotid artery

76. COMMON CAROTID ARTERY
ORIGIN
Right:
Brachio cephalic trunk- behind right
sternoclavicular joint
Left:
Aortic arch – behind manubrium sterni
Course
Extends from sternoclavicular joint to upper
border of thyroid gland c3/ c4
Anterolateral neck in the carotid sheath lateral to
trachea/ esophagus and larynx/ pharynx
Palpable between sternocleidomastoid and angle
of the mandible
Divides in the carotid triangle into internal and
external carotid arteries
Innervation
Parasympathetic: Submandibular ganglion
Sympathetic: superior cervical ganglion

77. BRANCHES OF EXTERNAL CAROTID ARTERY
From the
ventral side:
From the
Terminates by
dorsal side: dividing into:
•Superior
•Occipital
thyroid artery. artery. [7]
[5]
•Lingual
artery. [4]
•Facial artery.
[3]
•Ascending
pharyngeal
(may form
from medial
side).
•Superficial temporal
artery [1]
•Posterior
•Maxillary artery. [2]
auricular. [6]

80. INTERNAL JUGULAR VEIN
Origin
Union of sigmoid and inferior petrosal sinuses
Extent
Base of skull to sternoclavicular joint
Landmark
Between sternal and clavicular heads of sterno cleido mastoid
muscles
Tributaries
Pharyngeal veins
Lingual
Common facial
Superior thyroid
Middle thyroid
Termination:
Joins subclavian vein to form brachio-cephalic vein

81. VAGUS NERVE
COURSE
1. Emerges through jugular foramen
2. Two ganglia- superior and inferior cervical ganglia
3. Runs straight down in the carotid sheath
4. Between and behind carotid artery and internal
jugular veins
5. At the root of the neck, it passes infront of the
subclavian artery to enter mediastinum

82. BRANCHES AND DISTRIBUTION
Branch
Meningeal
Auricular
Carotid body branch
Pharyngeal branch
Superior laryngeal
External Laryngeal
Internal Laryngeal
Recurrent Laryngeal
Cardiac branches
Distribution
•Dura of posterior cranial fossa
•Postero inferior quadrant of external surface of
tympanic membrane
•Floor of external auditory meatus
•Skin on the cranial auricular canal
•Carotid body
•Carotid sinus
•Muscles of pharynx except stylopharyngeus
•Muscles of soft palate except tensor palate
•
•Cricothyroid muscle
•Inferior pharyngeal constrictors
•Pharyngeal mucosa
•Laryngeal mucosa above vocal folds
•Trachea and Esophagus
•Cricopharyngeus
•Laryngeal muscles except cricothyroid
•Laryngeal mucosa below vocal folds
•
•Heart

84. The scalene triangle/ gap is
bounded by:
1. Posteriorly: Scaleneus
medius
2. Anteriorly: Scaleneus
anterior
3. Base: First rib
Through this gap, pass the
subclavian artery and the
brachial plexus.
Compression of these
structures causes the scalenus
anterior syndrome.

86. 
Posterior : anterior border of trapezius

Base : middle 3rd of clavicle

Apex : meeting point of sternocleidomastoid &
trapezius at superior nuchal line.

The inferior belly of omohyoid mscle, divides
the posterior triangle into two;
 Occipital triangle
 Supraclavicular/ omoclavicular triangle.

87. 
The floor of the posterior triangle consists of
four muscles, covered by the prevetebral layer
of the deep cervical fascia. The splenius
capitus, levator scapulae, ane the three scalenus
muscles.

88. 
The anterior free edge
of the TRAPEZIUS
MUSCLE forms the
posterior border of the
posterior triangle.

89. 
The LEVATOR
SCAPULAE MUSCLE
forms a portion of the
floor of the posterior
triangle.

90. 
The SCALENE
MEDIUS AND
POSTERIOR
MUSCLES complete
the floor of the
posterior triangle

91. 
The SCALENE
ANTERIOR MUSCLE
appears in the lower
anterior corner of the
triangle, often under
the cover of the
sternocleidomastoid
muscle.

92. 
The PHRENIC
NERVE can be
observed on the
anterior surface of the
scalene anterior
muscle.

93. 
The ROOTS AND
TRUNKS OF THE
BRACHIAL PLEXUS
emerge from the
interval between the
scalene anterior and
scalene medius &
posterior muscles.

94. 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

95. 1. external jugular vein (blue)
2. superficial cervical lymph nodes (green)
3. lesser occipital nerve (lc)
4. great auricular nerve (ga)
5. transverse cervical nerve (tc)
6. supraclavicular nerves (sc)
7. spinal accessory nerve (sa)

96. 
Mainly form by 2nd layer of muscle of neck
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.

100. 




This vein is formed near the angle of the mandible by the
union of the posterior branch of retromandibular and
posterior auricular veins .
• It crosses sternocleidomastoid muscle, runsover the roof of
the triangle and joins the subclavian veins
• The vein drains most of the scalp and face on the same side.
• This vein dilates and becomes visible in fluid overload, in
heart failure in SVC obstruction, prolonged raised
intrathoracic pressure, e.t.c.
• The walls of the vein are attached to the deep fascia. If the
vein is lacerated, the fascia pulls the vein open and blleding is
severe. Also, air embolism could follow.

103. 






External Jugular Vein is relatively superficial
therefore:
It can be easily lacerated
Can be used to draw blood, infuse drugs or
catheterize the heart
is visible when distended in heart failure
It pierces investing fascia therefore, when
lacerated
Can bleed profusely
Predispose to air embolism

104. The subclavian artery (third
part) -B
• Transverse cervical artery
from thyrocervical trunk to
supply muscles in scapular
region.
• Suprascapular artery from
the thyrocervical trunk.
• Occipital artery, from the
external carotid artery.
 Note the boundaries:
A: Anterior scalene muscle
B: Middle scalene muscle


105. 
The TRANSVERSE
CERVICAL ARTERY
crosses the posterior
triangle. It divides
into a deep branch
which enters the floor
of the triangle, and a
superficial branch
which passes laterally,
deep to the trapezius
muscle to travel with
the spinal acessory
nerve.

106. 
The
SUPRASCAPULAR
ARTERY AND VEIN
crosses the lower
portion of the
posterior triangle just
beneath the clavicle.

107. 

The spinal accessory nerve and the lymph nodes
are the true contents of the posterior triangle .
All others are behind or in front of the facial floor.
a. Muscle : inferior belly of omohyoid
b. Nerves :
1.
2.
Accessory nerves
Root, trunks of brachial plexus and their branches :
i.
ii.
iii.
iv.
Nerves to rhomboideus
Nerves tomserratus anterior
Nerves to subclavius
Suprascapular nerve

110. 3. Cervical nerves :
i.
ii.
iii.
iv.
v.

Greater occipital nerve emerges from the apex to pass on
the scalp.
Great auricle nerve
Lesser occipital nerve
Transverse cervical nerve of neck
Supraclavicular nerve
3rd and 4th cervical nerves supplying trapezius

111. Spinal accessory nerve to the
sternocleidomastoid muscle and
the trapezius muscle.

Cervical plexus and its cutaneous
branches from up downwards.
• Lesser occipital nerve (c2)
• Great auricular nerve (c2 c3)
• Transverse cervical nerve (c2 c3)

Suprascapular nerves (c3c4)

Supraclavicular part of the
brachial plexus


112. runs upward over
the
sternocleidomastoi
d muscle to supply
the skin of neck
and angle of the
mandible.

113. traverses across the sternocleidomastoid
muscle to supply the skin over the anterior
triangle.

114. 
LESSER OCCIPITAL
NERVE crosses the
upper posterior edge
of the
sternocleidomastoid
muscle to distribute to
the scalp posterior to
the ear.

115. 
The ANTERIOR and
INTERMEDIATE
SUPRACLAVICULA
R NERVES are
cutaneous branches of
the cervical plexus
over the anterior
border of the clavicle.

117. 
The SPINAL
ACCESSORY NERVE
(CRANIAL NERVE
IX) passes from
behind the
sternocleidomastoid
muscle from slightly
higher than the nerves
of the cervical plexus.
It innervates both the
sternocleidomastoid
and trapezius
muscles.

118. 
The spinal accessory nerve (Cranial Nerve XI)
pierces the anterior border of the sternomastoid
muscle nerar its upper attachment and leaves
the muscle at about the midpoint of its
posterior border. The nerve then passes
obliquely downward and laterally across the
posterior triangle, but within a sleeve of the
investing layer of deep cervical fascia. It enters
the trapezius muscle at the inferolateral corner
of the psoterior triangle.

119. 
The spinal accessory nerve runs in a very
superficial position within the deep cervical
fascai and may be injuried during surgical
procedures of the superficial neck. It is at risk
during surgery of the deep cervical lymph
nodes, particularly to those of the juguloomohyoid group. Damage to the nerve will
paralyze the trapezius muscle and cause severe
limitations of upward rotation of the scapula
such that the arm cannot be abducted beyond
90 degrees.

121. 



Originates in the spinal nucleus
Extend to the fifth cervical segment
Union of motor neurons
Passes through two foramen


Foramen Magnum – enters the skull posterior to the
vertebral artery
Jugular Foramen – exits the skull with CN IX,
X and the IJV

123. 


Crosses the IJV
Crosses lateral to the transverse process of the
atlas
Occipital artery crosses the nerve
Descends obliquely in level II (forms
and IIb
Level IIa

124. 4. Arteries
i.
Occipital artery emerges from apex
ii.
3rd part of subclavian artery and branches of subclavian artery
a.
Branches of thyrocervical trunk 1st part of subclavian-Transverse
cervical, Suprascapular
b.
Transverse cervical artery divides into acending and descending branch anterior
border of sternocleidomastoid.
5. Veins
External jugular veins and its tributaries.
Subclavian vein is lower down and not include in the triangle.
6. Lymph nodes :
a.
Supraclavicular lymph nodes along the posterior border of
sternomastoid.
b.
Occipital lymph nodes

125. 
The transverse cervical
and suprascapular arteries
arise medial to the
scalenus anterior muscle.
To reach the posterior
triangle they pass from
medial to lateral, anterior
to the scalenus anterior
muscle. They cross the
posterior triangle to reach
the trapezius and scapular
muscles respectively.

126. 
The dorsal scapular artery passes posteriorly
through the brachial plexus to supply the
posterior muscles of the back, specifically the
rhomboids. It is usaully present in approximately
75% of individuals. In the remaining 25%, the
dorsal scapular artery is absent. In these cases, the
transverse cervical artery, while in route to the
trapezius muscle, will give rise to a deep branch
which will pass posterior to the scapula to supply
the rhomboids. Once behind the scapula, the
terminology of dorsal scapular artery applies
regardless of its origin.

129. 




Nerve point of the neck: is the region around the midpoint of the posterior border
of the sternocleidomastoid muscle. Several nerves lie superficially here, deep to the
platysma. This point is important because: Slash wounds of the neck may severe these relatively superficial nerves ,
resulting in loss of cutaneous sensation in the neck, and posterior part of the
scalp.
 Anaesthetic agent can be injected here.
Brachial plexus block . Local anaesthetic solution is injected around the brachial
plexus, superior to the midpoint of the clavicle. Be careful to locate the subclavian
artery by palpation so it is not damaged.
Subclavian artery, can be pressed in the suprascapular fossa, to control bleeding in
the upper limb.
Block dessection, is sometimes done in this region for the removal of lymph
nodes. The accessory and Phrenic nerves, together with the other structures should
be saved.
Safe/ danger sides. The accessory nerve may be used to divide the posterior
triangle into a carefree area superiorly and a danger area inferiorly, which has
major nerves and blood vessels

130. 
The scalene hiatus is
the trianglular gap in
which rami and
trunks of the brachial
plexus and the
subclavian artery pass
between the scalenus
anterior and medius
muscles. It is bounded
by the anterior and
medial scalene
muscles and the first
rib to which the

131. 1)
Left supracavicular (Virchow’s) lymph nodes are enlarge in
malignancy of testis, stomach and other abdominal organs.
2)
The pressure in the external jugular vein can be recorded in
the recumbent position. It is increased in right sided heart
failure and in the obstruction of the superior vena cava.
3)
The retropharyngeal abscess maybe expressed in the lower
part of posterior triangle.

133. CERVICAL PLEXUS

134. 




Results from damage to the cervical
sympathetic chain.
Therefore it presents with
Ptosis
Myosis
Facial flushing on the affected site

135. Prevertebral and lateral muscles

137. 
Fascial planes of the Neck
a) Investing layer
b) Pretracheal layer
c) Prevertebral

140. The fascia of the neck has a number of unique features.
•The superficial fasciain the neck contains a thin sheet of muscle (the platysma),
•Platysma begins in the superficial fascia of the thorax,
•runs upwards to attach to the mandible
•and blend with the muscles on the face,
•is innervated by the cervical branch of the facial nerve [VII], and is only found in
this location.
FUNCTIONS
1.Affords the slipperiness which enables structures to move and pass over one another ,
without difficulty, e.g. during swallowing.
2.Allows twisting of the neck without it creaking like a manilla rope.
3.It allows a looseness that provides the easiest pathways for vessels and nerves to reach
their destinations.

141. ATTACHMENTS
Proximal

External occipital protuberances

Superior nuchal line

Ligamentum nuchae

Spines of cervical vertabra

Mastoid process

Lower border of the mandible

Zygomatic arch

Styloid process

Hyoid bone
Distal

Acromion

Clavicle

Manubrium sterni

142. Encloses
 Sternomastoid muscle (1)
 Trapezius (2)
 Omohyoid muscle
 Parotid
 Submandibular gland
Roofs
 Posterior triangle of the neck
 Anterior triangle of the neck
 Covers
 Infrahyoid muscles

143. 

In the Suprasternal notch, the
investing fascia splits into two
layers:
 One attaches to the anterior
border of the manubrium
 The other to the posterior
border
This leaves a small suprasternal
space containing:
 A little fat
 A lymph node
 Lower sections of the anterior
jugular veins
 Jugular venous arch
 Sternal heads of sternomastoid

144. 


External jugular vein
Cervical plexus
Lymphatics

145. Attachments
 From hyoid bone to the
superior mediastinum.
 Oblique lines of thyroid
cartilage
 Cricoid cartilage
 The pericardium, and T.
adventitia of the bases of
great vessels.
 Becomes continous with
bucopharyngeal fascia
covering constrictor
muscles behind

146. 


Thyroid gland (1)
Infrahyoid muscles
Air and food passages

147. 

The fascia at the back of the thyroid lobe is thickened
to form a lateral ligament or “ligament of Berry”
which gains attachment to the cricoid cartilage.
At the level of the thyroid isthmus a looser
attachment of the pretracheal fascia occurs infront of
trachea.

148. Attachments
 Base of the skull
 Transverse process of
cervical vertebrae
 Extends further down
into the abdomen

149. 



Prevertebral muscles
Scalene muscles
Phrenic nerve
Thus, it covers the
floor of the posterior
triangle of the neck
Vertebral artery

150. 

In front of the subclavian artery, it is prolonged
laterally as the cervico-axillary(axillary) sheath which
invests the brachial pexus and the vessels.
The carotid sheath – said to be derived from fusion
or pretracheal and prevertebral fascia. Surrounds the
• Common and the internal carotid arteries.
• Internal jugular vein
• vagus nerve

151. Investing Fascia: Forms a tight sheath for the glands especially the parotid, restricting
swelling. Iinflammation of this glands causes pain due to high pressure.
Pretracheal Fascia:

The thyroid is completely enclosed in pretracheal fascia. The attachments to the
larynx and trachea result in movement of the thyroid gland with larynx during
swallowing. When a neck swelling moves in this way, it is almost certain to be
associated with the thyroid gland.

The Spaces around the pretracheal fascia provides for spread of infection. Thus
infections from the head and neck can spread infront of the trachea or behind the
esaophagus and reach the superior mediastinum .
Prevertebral Fascia:

The retropharyngeal space between pharynx and pre-vertebral fascia is clinically
important because it frequently becomes infected secondary to upper respiratory
tract infrections in childhood. The swelling appears on one side of the posterior
pharyngeal wall and may obstruct the airway. In adults such infections are usually
secondary to tuberculosis of the cervical vertebral column.

152. 




•the deep cervical fascia is organized into several
distinct layers
1.an investing layer, which surrounds all structures in
the neck;
2.the prevertebral layer, which surrounds the
vertebral column and the deep muscles associated
with the back;
3.the pretracheal layer, which encloses the viscera of
the neck;
4.the carotid sheaths, which receive a contribution
from the other three fascial layers and surround the
two major neurovascular bundles on either side of
the neck

153. 

The prevertebral layer is a cylindrical layer of
fascia that surrounds the vertebral column and
the muscles associated with it (Fig. 8.152).
Muscles in this group include the prevertebral
muscles, the anterior, middle, and posterior
scalene muscles, and the deep muscles of the
back.
•The prevertebral fascia is attached posteriorly
along the length of the ligamentumnuchae, and
superiorly forms a continuous circular line
attaching to the base of the skull. This circle
begins

154. 



anteriorly as the fascia attaches to the basilar part of the
occipital bone, the area of the jugular foramen, and the
carotid canal;
•continues laterally, attaching to the mastoid process;
•continues posteriorly along the superior nuchal line
ending at the external occipital protuberance, where it
associates with its partner from the opposite side.
•Anteriorly, the prevertebral column of fascia is
attached to the anterior surfaces of the transverse
processes and bodies of vertebrae CI to CVII.

155. 

The prevertebral fascia passing between the attachment
points on the transverse processes is unique. In this
location, it splits into two layers, creating a
longitudinal fascial space containing loose connective
tissue that extends from the base of the skull through
the thorax.
•There is one additional specialization of the
prevertebral fascia in the lower region of the neck. The
prevertebral fascia in an anterolateralposition extends
from the anterior and middle scalene muscles to
surround the brachial plexus and subclavian artery as
these structures pass into the axilla. This fascial
extension is the axillarysheath.

156. 


The pretracheal layerconsists of a collection of fascias that
surround the trachea, esophagus, and thyroid gland (Fig. 8.152).
Anteriorly, it consists of a pretracheal fascia that crosses the
neck, just posterior to the infrahyoid muscles, and covers the
trachea and the thyroid gland. The pretracheal fascia begins
superiorly at the hyoid bone and ends inferiorly in the upper
thoracic cavity. Laterally, this fascia continues and covers the
thyroid gland and the esophagus.
•posteriorly, the buccopharyngeal fascia forms the pretracheal
layer and separates the pharynx and the esophagus from the
prevertebral layer.
•The buccopharyngeal fascia begins superiorly at the base of the
skull and ends inferiorly in the thoracic cavity.

158. 




•The arrangement of the various layers of cervical fascia organizes the
neck into four longitudinal compartments:
•the first compartment is the largest, includes the other three, and
consists of the area surrounded by the investing layer;
•the second compartment consists of the vertebral column, the deep
muscles associated with this structure, and is the area contained
within the prevertebral layer;
•the third compartment (the visceral compartment) contains the
pharynx, the trachea, the esophagus, and the thyroid gland, which are
surrounded by the pretracheal layer;
•finally, there is a compartment (the carotid sheath) consisting of the
neurovascular structures that pass from the base of the skull to the
thoracic cavity, and the sheath enclosing these structures receives
contributions from the other cervical fascias

159. FASCIAL SPACES
•Between the fascial layers in the neck are spaces that may provide a conduit for the
spread of infections from the neck to the mediastinum.
•Three spaces could be involved in this process:
1.pretracheal space the first is the pretracheal spacebetween the investing layer of
cervical fascia (covering the posterior surface of the infrahyoid muscles) and the
pretracheal fascia (covering the anterior surface of the trachea and the thyroid
gland), which passes between the neck and the anterior part of the superior
mediastinum;
2.the second is the retropharyngeal spacebetween the buccopharyngeal fascia (on the
posterior surface of the pharynx and esophagus) and the prevertebral fascia (on the
anterior surface of the transverse processes and bodies of the cervical
vertebrae), which extends from the base of the skull to the upper part of the posterior
mediastinum
3.the third spaceis within the prevertebral layer covering the anterior surface of the
transverse processes and bodies of the cervical vertebrae. This layer splits into two
laminae to create a fascial space that begins at the base of the skull and extends
through the posterior mediastinum to the diaphragm

160. 1) Describe the boundaries, sub divisions and
their respective contents of the posterior
triangle of the neck
2) Write short notes on:



External jugular vein
Cervical plexus
Pretracheal fascia
3) Describe the attachments, extents, enclosures
and applied anatomy of the investing cervical
fascia

161. POSITION:





Antero- inferior part of the neck
Isthmus is midline between
second and fourth tracheal rings
The lobes are antero-lateral
between C4 and C6
Lobes are between trachea and
esophagus medially and carotid
sheath laterally.
Deep to platysma and strap
muscles.
1.
2.
3.
4.
5.
6.
7.
8.
Isthmus
Left lobe of thyroid gland
Right lobe of thyroid gland
Cricothyroid
Right common carotid artery
Vagus nerve
Thyroid cartilage
Cricoid cartilage

162. ISTHMUS





Anteriorly- Strap muscles, anterior jugular vein
Posterior -Second to fourth tracheal rings
Laterally -Continous with lobes
Superiorly -Anastomosis of superior thyroid artery
Inferiorly -Anastomosis of inferior thyroid artery

163. LOBES



Antero laterally -Strap
muscles, anterior jugular veins
Posterior -Parathyroid
glands, prevertebral muscles.
Postero-laterally Carotid sheath and
its contents





common carotid artery (4),
internal jugular vein (5) ,
vagus nerve (6). The sympathetic
chain is nearby.
Medially Larynx(1) pharynx and
external laryngeal nerve
above, trachea,
oesophagus(2) and recurrent
laryngeal nerve below.

164. Arterial
 • Inferior thyroid artery 2 from
the thyrocervical trunk
 • Superior thyroid artery 1from
the external carotid artery.
 • Occasional (unpaired)
thyroidea ima (middle thyroid)
from brachiocephalic trunk .
 • Several unnamed twigs from
pharyngeal and tracheal vessels.
 All these arteries anastomose with
each other.

165. 



• Superior thyroid vein (A) –
Internal jugular vein
• Middle thyroid vein (B) –
Internal jugular vein
• Inferior thyroid vein (C) –
Brachio cephalic vein.
The inferior thyroid veins
cover the trachea inferior to
the thymus. They constitute
potential sources of
haemorrhage in tracheostomy

166. 
Inferior deep cervical lymph
nodes [1].
Prelaryngeal lymph nodes[2]

Paratracheal lymph nodes[3].




Pretracheal lymph nodes.[4]
Parasternal lymph nodes.
Some may empty directly into
the thoracic duct.

167. 
Autonomic innervation from the cervical
sympathetic ganglia and vagus. This
innervation is vasomotor and affects the gland
indirectly through the action on blood vessels.

168. 
When the strap
muscles are
reflected, you can
see the thyroid
gland (tg) with its
arteries (superior
thyroid artery from
the external carotid
(sta) and the inferior
thyroid artery from
the thyrohyoid
trunk from the
subclavian (ita).

169. 
If the thyroid gland is
reflected laterally, the
structures making up
the larynx and trachea
are seen:


Cartilages and membranes



thyrohyoid membrane
(thm)
thyroid cartilage (Adam's
apple)(tc)
cricothyroid membrane
and ligament (ctm)
cricoid cartilage (cc)
tracheal rings (tr)

174. 


The thyroid gland is
hidden under the
sternohyoid and
sternothyroid muscles
and consists of two
lobes and an isthmus.
An occasional
pyramidal lobe extends
upward near the mid
line.
The inferior thyroid
artery is closely
associated with the
recurrent laryngeal
nerve (rln).

175. 


Four small reddishbrown pea-sized glands
may be seen on the
deep surface of the
thyroid gland.
These are the superior
and inferior parathyroid
glands (ptg).
Also note the close
relationship of the
recurrent laryngeal
nerves to the thyroid
gland and inferior
thyroid artery (rln, ita).

176. • Thyroglossal duct cysts (TDC): May develop from a
persistent thyroglossal duct anywhere along the
course of the duct. The cysts may be in the tongue in
the midline of the neck or retrosternal. TDC move up
with protrusion of the tongue
• Thyroglossal duct sinuses: Are openings into the
skin from a patent part of the thyroglossal duct. They
usually open in the neck and could be due to
perforation of the cyst following infection.
• Ectopic thryoid gland: Could be in the tongue,
larynx, retrosternal or hyoid region.

177. • Goitre:
This is an enlargement of the thyroid gland. It could
be due to iodine deficiency, hormone or enzyme
defect, infection or tumor. May be associated with
hyperfunction or hypofunction .
(What are the features of each?)
 Besides, goitre causes compression of the following:
 Trachea: affecting breathing.
 Oesophagus: affecting swallowing.
 Recurrent laryngeal nerve: affecting voice.
 A retrosternal goitre is worse for there is no space for
expansion.

178. 

Thyroid gland in its capsule is enclosed by
pretracheal fascia, which attaches inter alia to the
hyoid bone. Thus, the thyroid gland moves upwards
with swallowing and speech. This is a good test for
masses in the neck.
Thyroglossal cysts move when the tongue is
protuded due to the attachment of the thyroglossal
duct to the tongue.
• The inferior thyroid artery runs close to the
recurrent laryngeal nerve near the gland. Thus, the
artery should be ligated further laterally to avoid
injury to the nerve.

179. 


The superior thyroid artery is closer to the external
laryngeal nerves superiorly than near the gland. Thus,
this artery can be ligated as close to the gland as
possible without danger of injury to the nerve.
• In thyrodectomy, the recurrent laryngeal nerve
must be preserved. The parathyroids must be
identified and at least one spared.
• Since colossal sizes of goitre may damage the
recurrent laryngeal nerve, it is good habit to do
laryngoscopy before thyroidectomy, so that preoperative damage can be distinguished from postoperative damage.

180. 

The cricothyroid ligament and membrane are
frequently pierced in emergency situations to
open the airway.
It has been known that an empty ball-point pen
or a hollow stem has been used in the field to
save lives, where an air passage has been
closed above this region.

181. STRUCTURES AT THE ROOT OF THE NECK
 Brachio cephalic trunk
 Subclavian artery and its branches
 Subclavian vein
 Termination of internal jugular vein
 Thoracic duct
 Apex of lung
 Phrenic nerve
 Vagus nerve

182. 



•
•
•
•
The brachiocephalic trunk.
Right common carotid.
Right subclavian.
May also give thyroidea ima.

183. Divided into 3 parts by scalenus anterior muscle.

Part 1:
Medial to the muscle and gives 3 branches:
• Vertebral artery : Enters foramen transversarium at C6
• Thyrocervical trunk : Inferior thyroid artery, transverse cervical artery and
suprascapular artery.
• Internal thoracic artery.

Part 2:
Posterior to the muscle and gives 1 branch, the costocervical trunk which
gives superior intercostal and deep cervical arteries.

Part 3:
Lateral to the muscle, usually giving one branch (dorsal scapula). It may also
occasionally give the suprascapular artery.

184. 1.
2.
3.
4.
5.
6.
7.
8.
Vertebral
Transverse
cervical
Inferior thyroid
Transverse
cervical
Costocervical
Suprascapular
Deep cervical
Highets
intercostal

185. Branch
Distribution relevant to respiration
Vertebral
•Respiratory center in the midbrain
•Cervical cord segments that give phrenic
nerve
Internal thoracic
•Intercostal muscles
•Ribs and sternum
•Thoracic diaphragm
•Phrenic nerve
•Abdominal wall
Supreme Intercostal
•1st two ribs
Inferior thyroid
•Trachea
•Larynx
•Cervical portion of spinal cord
Transverse Cervical
•Trapezium and Scapula muscles
Suprascapular artery
•Clavicle and scapula to which accessory
muscles are attached

187. 



• External jugular veins.
• Anterior jugular veins: These either drain
into the external jugular or subclavian vein.
The two veins are joined by the jugular venous
arch, but could unite to form a single trunk in
the midline of the neck. These veins have no
valves.
• The subclavian vein: A continuation of the
axillary vein. This vein usually has only one
named tributary, the external jugular vein. The
veins that correspond to the arterial branches

188. The Vagus Nerve:

This is cranial nerve 10. Located between
common carotid and the internal jugular
vein. This nerve gives the following branches
in the neck:
1.
Meningeal nerve: Recurrent to the dura.
2.
Auricular nerve: Anastomoses with similar
branches from the glossopharyngeal and
facial nerves and supplies the pinnae and
external auditory meatus.
3.
Pharyngeal nerves: Join the pharyngeal
plexus.
4.
Superior laryngeal nerve: Divides into
internal laryngeal and external laryngeal.
5.
Recurrent laryngeal nerve:
6.
Cardiac branches: Cardiac plexus.

189. Root value :

C3, C4, C5
Course

Descends obliquely on the anterior surface of scalenus anterior muscle

Crosses first part of sub clavian artery on the left

Crosses posterior to sub clavian vein on both sides

Lies anterior to the internal thoraci artery

Goes through thoracic inlet
Distribution

Parietal pericardium

Parietal pleura

Thoracic diaphragm

Biliary apparatus

190. 




From T1 to T4. There are 3 ganglia, lies on pre-vertebral fascia behind carotid
sheath
Inferior cervical ganglion: At the level of the superior border of the neck of the
first rib. It is commonly fused with the first thoracic ganglion to form
cervicothoracic ganglion (Stellate ganglion).
Middle cervical ganglion: On the anterior aspect of the inferior thyroid artery , at
the level of cricoid cartilage pm the posterior aspect of inferior thyroid.
Superior cervical ganglion: Located at the level of the axis and atlas / (C1/ C2) /
angle of mandible.
From these ganglia, postganglionic fibres reach their targets in four principal ways:





Joining spinal nerves.
Joining cranial nerves.
Forming plexuses on blood vessels
Directly.
Provides secretomotor innervation to blood vessels and glands of the head and neck

191. 

There are lymph nodes within the carotid
sheath, along the internal jugular vein. Another
group runs along the transverse cervical artery.
These, deep cervical lymph nodes are divided into
superior and inferior, relative to the omohyoid
muscle.
The efferents drain into the jugular lymph
trunk, which drains into the right lymphatic duct, or
the thoracic duct. Both of these ducts enter the
venous system, at the junction of the subclavian and
the internal jugular veins.

192. 




They are small, yellowishbrown endocrine glands
Located posterior to the
thyroid, in their own capsule,
but sharing the same fascial
investment.
The superior are thought to
originate in the 4 th
pharyngeal pouch.
The superior ones are
consistent in position.
The inferior are inconsistent
and could be found in the
anterior mediastinum.

193. Blood supply
 Usually by the inferior thyroid arteries but may be supplied
by the superior thyroid arteries or from longitudinal
anastomosis between superior and inferior thyroid arteries.
 The veins drain into the thyroid plexus of the veins on the
anterior surface of the thyroid.
Lymphatics of the Parathyroid glands
• Inferior deep cervical lymph nodes.
• Paratracheal lymph nodes.
 The lymph vessels from here end in the thoracic duct.
Innervation of the parathyroid glands
Autonomic from the cervical sympathetic chain (and vagus).
These are vasomotor.

194. 


The parathyroid glands are essential for
regulation of blood calcium.
(What are the functions of calcium in the
body?)
They are in danger of being destroyed or
removed during thyroidectomy. Surgeons
usually leave bits of the thyroid posteriorly or
identify and preserve at least one of them.

195. 










Hyoid bone
Thyrohyoid membrane
Thyroid cartilage
Cricothyroid membrane
Cricoid cartilage 2
Crico-tracheal ligament
Thyroid gland isthmus
Tracheal rings
Jugular venous arch.
It is important to identify these
important midline structures.
(When and where is tracheotomy and
laryngectomy done? What structures
may be injured?)

196. Position
 Continuous with
laryngopharynx at
pharyngo esophageal
junction
 Starts at lower border of
cricoid cartilage (C6
vertebrae) and ends at
thoracic inlet
 In the median plane
 Inclines slightly to the left

197. Anterior
Posterior
•Trachea
•Longus coli
•Recurrent
•Body of C7
laryngeal nerve in
tracheoesophagea
l groove
Right
•Right lobe of
thyroid
•Right carotid
sheath
•Apex of right
pleura
Left
•Left lobe of
thyroid
•Left carotid
sheath
•Left subclavian
artery
•Apex of left
pleura
•Thoracic duct

198. Musculature
•Voluntary muscle
•Outer longitudinal and inner muscle
•Cricopharyngeal fibres of inferior constrictor act as a sphincter
Blood supply
•Segmental anastomosing esophageal branches of inferior thyroid
artery
•Veins drain into inferior thyroid vein
Lymphatic drainage
•Para tracheal nodes
•Inferior deep cervical lymph nodes
Innervation
•Somatic motor and sensory: Recurrent laryngeal nerve
•Vasomotor: Inferior cervical sympathetic ganglion through plexus
on inferior thyroid artery

199. Position
 Found in the midline of the
lower neck
 Continues from larynx into
thoracic trachea
 Extends from lower edge of
cricoid cartilage (C6) to
thoracic inlet at T1
 Inclines backwards as it
descends

200. Relations
Anterior
Posterior
•Isthmus of thyroid gland occassionaly pyramidal
lobe and thyroidea ima if present
•Inferior thyroid vein
•Jugular venous arch
•Sternohyoid and sternothyroid muscles
•In babies left brachiocephalic vein and pleurae
•Esophagus
•Recurrent laryngeal nerve and inferior thyroid
artery
•Lateral
•Lobes of thyroid gland
•Carotid sheath and its contents
•Brachiocephalic trunk on the right side

201. Blood supply
•Inferior thyroid artery
•Inferior thyroid vein
Lymphatic drainage
•Pre tracheal nodes
•Paratracheal nodes
•Inferior deep cervical nodes
Innervation
Sensory - Recurrent laryngeal nerve
Sympathetic- Inferior cervical ganglion

202. Diagnosis (metastatic lymph node)
Lymph node groups with the most
likely sites of the primary lesion.

204. 1.
2.
3.
4.
5.
6.
Give an account of the boundaries , contents and applied anatomy of the
various subdivisions of the anterior triangle of the neck
Describe the location , extents , relations , blood supply and lymphatic
drainage of the thyroid gland. Add notes on the clinical importance of
the topographic relations of the arteries and nerves of the thyroid
State the boundaries , contents and clinical relevance of the scalene
triangle and the triangle of the vertebral artery
Give an account of the course ,origin,relations and distribution of the
vagus nerve in the neck
Describe the origin , course and distributions of the vertebral artery .
Add a note on the clinical importance.
Discuss the distribution of the first part of the subclavian artery