The document provides a detailed overview of the anatomy of the neck, including its structure, boundaries, and key muscles such as the platysma, sternocleidomastoid, and trapezius. It also describes the various triangles of the neck—anterior and posterior—along with their contents, including important arteries, veins, and nerves. Clinical significance is noted, particularly regarding injuries and conditions related to the neck's musculature and vascular supply.

1. Dr. NDAYISABA CORNEILLE
CEO of CHG
MBChB,DCM,BCSIT,CCNA
TRIANGLE OF THE
NECK
Supported BY

2. objectives
• To define the neck
• To outline the structures found in the neck
• To describe the boundaries and contents of
the triangles of the neck.
• To describe the fasciae of the neck
DR NDAYISABA CORNEILLE

3. The neck
• Part of the body between the head and the
thorax
• Contains a number of vessels, nerves and
structures connecting the head to the trunk
and upper limbs
• These include the esophagus, trachea,
brachial plexus, carotid arteries, jugular veins,
vagus and accessory nerves, lymphatics
among others
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8. Superficial neck muscles
Three in number namely
• Platysma
• Sternocleidomastoid
• Trapezius
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9. Platysma
• A thin wide subcutaneous sheet of muscle
located in superficial fascia
• Upper attachment is to inferior border of the
mandible and skin of the face
• Lower attachment is to fascia over the
pectoralis major and deltoid muscles.
• Nerve supply: cervical branch of facial nerve
• Action: draws corners of the mouth inferiorly,
and depression of the mandible.
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11. Clinical importance of platysma
• Muscle of facial expression
• Can be used to express sadness, horror or
fright
• Can be paralysed in injuries of facial nerve.
Skin falls from the neck in slack folds
• Should be protected in dissections of the neck
to prevent gaping injuries
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13. Sternocleidomastoid
• A broad strap like muscle that is a key land mark
in the neck.
• Runs superolaterally from the clavicle and
sternum to the mastoid process
• Divides the neck into anterior and posterior
traingles
• It is crossed by platysma and the external jugular
vein.
• Covers and protects the great vessels of the neck
and the cervical plexus
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23. Clinical importance
• Can be injured during birth leading to
congenital torticollis
• Can follow breech presentation
• Trauma and heamorrhage leads to healing by
fibrosis hence shortening of the muscle
• Most are corrected in early child hood hence
not seen in adults
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24. Breech delivery
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26. Congenital torticolis
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27. • Sternocleidomastoid muscle also prevents
injury to blood vessels and nerves in deep
neck lacerations especially in people who
attempt suicide by cutting their necks.
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28. DR NDAYISABA CORNEILLE

29. Trapezius
The muscle provides a direct attachment of the
pectoral girdle to the trunk. This large,
triangular muscle covers the posterior aspect
of the neck and the superior half of the trunk).
It was given its name because the muscles of
the two sides form a trapezium (G. irregular
four-sided figure).
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30. Attachments of Trapezius
Muscle origin insertion Nerve supply Action
Trapezius Medial third of
superior nuchal
line; external
occipital
protuberance;
nuchal ligament;
spinous processes
of C7 to T12
vertebrae
Lateral third of
clavicle;
acromion and
spine of scapula
Accessory
nerve (CN XI)
(motor fibers)
and C3, C4
spinal nerves
(pain and
proprioceptiv
e fibers)
Descending part
elevates;
ascending part
depresses; and
middle part (or all
parts together)
retracts scapula;
descending and
ascending parts
act together to
rotate glenoid
cavity superiorly
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32. Triangles of the neck
• Has 2 major triangles, the anterior & the
posterior.
• The anterior is further divided into 4, the
digastric(submandibular), submental, carotid,
mascular triangles
• The posterior has the supraclavicular, and
occipital triangles.
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35. The anterior cervical triangle
The boundaries are:
• Posteriorly: Anterior border of
Sternocleidomastoid muscle.
• Superiorly: Inferior border of the mandible.
• Anteriorly: midline of neck.
• Apex is by the jugular notch
This triangular region is the major surgical
approach to the trachea, esophagus, thyroid
gland among others.
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36. Contents of the anterior triangle
• Muscles: supra and infrahyoid muscles
Suprahyoid muscles: digastrics, mylohyoid,
genihyoid, stylohyoid
Infrahyoid muscles (strap muscles): omohyoid,
sternohyoid, sternothyroid, thyrohyoid
• Arteries: common carotid and its branches
• Veins: internal jugular vein and tributaries
• Viscera: trachea, esophagus, thyroid, parathyroid
glands
• lymphnodes
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37. Muscle Origin Insertin Nerve supply Action
mylohyoid Mylohoid line of
the mandible
Raphe and
body of hyoid
Nerve to
mylohoid(from
inferior
alveolar)
Elevation of
hyoid, floor of
the mouth and
tongue(swallo
wing)
Geniohyoi
d
Inferior mental
spines of mandible
Body of hyoid C1 via
hypoglossal
nerve
Pulls hyoid
anteroposterior
, shortens floor
of mouth,
widens
pharynx
Digastrics Ant belly: mandible
Post belly: mastiod
process
Btn body and
greater horn of
hyoid
Ant belly:
nerve to
mylohoid
Post belly:
cervical branch
of facial
Depression of
mandible,
elevation of
hyoid bone
Stylohoid Styloid process of
mandible
Body of hyoid Cervical branch
of facial
Elevation and
retraction of
hyoid
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38. Infrahyoid muscles
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39. Suprahyoid muscles
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40. Infrahyoid muscles
Muscle Origin Insertion Nerve supply Action
Sternohyoid Manubrium
sternum and
clavicle
Body of hyoid Ansa
cervicalis(C1,
C2 C3)
Depression of
hyoid bone
Sternothyroid Manubrium
sternum
Oblique line on
thyroid
cartilage
C1 via
hypoglossal
nerve
Depression of
hyoid bone and
larynx
thyrohyoid Thyroid
cartilage
Inferior border
of body and
greater horn of
hyoid bone
Ansa
cervicalis(C1,
C2 C3)
Depression of
hyoid bone and
elevation of
larynx
Omohyoid Superior
border of
scapular near
suprascapular
notch
Inferior border
of hyoid bone
Ansa
cervicalis(C1,
C2 C3)
Depression of
hyoid bone
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41. submandibular (Digastric) triangle
Borders
 Superior(above) : base of the mandible at its
projection to the mastoid process
 Posteriorly: post belly of the digastric & by
stylohyoid muscles
 Anteriorly: ant digastric belly
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43. submandibular (Digastric) triangle
• Roof : skin, superficial fascia, platysma & deep
fascia containing branches of the facial &
transverse cutaneous cervical nerves
• Floor: mylohyoid & hyoglossus.
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45. Contents
Anterior region
• Has the submandibular gland with the facial vein
superficial & the facial artery deep to it.
• Submental & mylohyoid arteries & nerves lie on
mylohyoid.
• Submandibular LNs receive afferent channels from
submental nodes, the oral cavity, and the anterior parts
of the face.
• Efferent channels drain primarily into the
jugulodigastric, jugulocarotid, and juguloomohyoid
nodes of the chain accompanying the internal jugular
vein (deep cervicalchain).
• A few channels pass by way of the sub parotid nodes to
the spinal accessory chain.
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46. Contents cont’d
Posterior region:
• Lower part of the parotid gland(tail)
• External carotid artery, deep to the stylohyoid
to curve above the muscle & overlap its
superficial surface & ascend deep to the
parotid gland later entering it.
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47. Contents cont’d
• Internal carotid artery, internal jugular vein &
vagus nerves are deeper & separated from the
external carotid artery by styloglossus,
stylopharygeous & the glossopharyngeal
nerves.
• Also contains the hypoglossal nerve
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49. Submental triangle
• Demarcated by the anterior bellies of both
digastric muscles.
• Base: body of hyoid bone
• Apex: at the chin
• Floor: both mylohyoid muscles
• Roof: skin & superficial fascia
• Medial: ant midline.
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50. contents:
• LNs & small vessels that unite to form the ant.
jugular vein.
• The submental lymphnodes receive efferents
from the tongue, floor of the mouth,
mandibular incisors and associated gingivae
and central part of lower lip and skin of chin.
• Efferents drain into the submandibular and
deep cervical nodes.
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52. Coronal section through the tongue, the mouth and the body of the mandible
opposite the first molar tooth (to illustrate contents of the submental triangle)
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53. Muscular triangle
Boundaries;
• Anterior: median line of the neck from the
hyoid bone to the sternum
 inferiorly: anterior margin of
sternocledomastoid
 superiorly: superior belly of the omohyoid

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54. Contents
• omohyoid, sternohyoid, sternothyroid and
thyrohyoid (strap/infrahyoid).
• Thyroid & parathyroid glands, trachea,
oesophagus, sympathetic nerve trunk.
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56. Carotid triangle
Boundaries:
• Posterior: Sternocleidomastoid muscle.
• Anterior: Anterior belly of omohyoid muscle.
• Superior: Posterior belly of digastric muscle.
• Floor: Hyoglossus muscle, inferior constrictor
of pharynx, thyrohyoid muscle, longus capitis
muscle, and middle constrictor of pharynx.
• Roof: Investing layer of deep cervical fascia.
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57. contents
• Carotid artery bifurcation
• Int. carotid a( no neck branches)
• Ext. carotid a branches –sup. thyroid a,
superficial. temporal a, post. auricular a,
internal maxillary a, occipital a, ascending
pharyngeal a, scmd a, lingual a(occasional),
external maxillary (occasional)
• jugular vein tributaries- superior thyroid v,
occipital v, common facial v, the pharyngeal v;
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58. Contents cont’d
• Vagus nerve,
• spinal accessory nerve,
• hypoglossal nerve,
• Ansa hypoglossi, &sympathetic n.s (partially).
• Lymphatic drainage is by jugulodigastric
juguloomohyoid , & nodes along the int.
jugular v. from submandibular and submental
nodes, deep parotid nodes, and posterior deep
cervical nodes.
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59. Cervical LNs
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60. The branches of the external carotid artery.
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61. Common carotid artery
• Main blood supply to the head, neck, face and
brain
• The right arises from the brachiocephalic
artery while the left from arch of the aorta
• Ascends behind the sternoclavicular joint to
reach the thyroid cartilage and then divides
into external and internal carotid arteries
• Embedded in the carotid sheath with the
vagus nerve and internal jugular vein
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62. Common carotid artery
• Relations
• Anterolaterally: skin, fascia, SCM, sternoyhoid,
sternothyroid and superior belly of omohyoid
• Posteriorly: transverse processes of C1 to C4,
Prevertebral muscles and sympathetic trunk
• Medially: larynx, pharynx, trachea, esophagus
• Laterally: internal jugular vein, vagus nerve
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63. External carotid artery
• One of the terminal branches of CCA
• Supplies skin, face and scalp
• Starts at upper border of thyroid cartilage and
ends in parotid gland by dividing into maxillary
and superficial temporal arteries
Relations:
Anterolaterally: SCM, skin, fascia, hypoglossal
nerve, post belly of digastric, dtylohyoid, facial
nerve
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64. External carotid artery
• Medially: pharynx, ICA, stylopharyngeous,
glossopharyngeal nerve, vagus
nerve(pharyngeal branch)
• Branches
superior thyroid, acsending pahryngeal,
lingual, facial, occipital, posterior auricular,
superficial temporal, maxillary
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65. The posterior triangle;
The boundaries are:
• Anteriorly: posterior border of the
sternocleidomastoid
• Posteriorly: anterior border of the trapezius
• Inferiorly: middle 1/3rd clavicle
• Apex: scm & trapezius to the occiput
• Roof: deep cervical fascia(investing layer) ,
platysma, superficial veins, cutaneous nerves and
skin.
• Floor: prevertebral fascia overlying splenius
capitis, levator scapulae and the scalenus medius
and S. posterior muscles.
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66. Muscular floor of the posterior
triangle
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67. Contents
• Fat
• lymph nodes
• Nerves: spinal accessory nerve, cutaneous
branches of the cervical plexus,
• Arteries: occipital, transverse cervical and
suprascapular arteries, the third part of the
subclavian artery
• Veins: Subclavian and the external jugular vein.
• Muscles: splenius capitis, levator scapulae,
scalenus medius and scalenus posterior
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68. External jugular vein
• Drain most of the face and scalp on the same
side.
• Starts at the angle of the mandible as a union of
the posterior auricular vein and the posterior
division of the retromandibular vein
• Crosses the SCM in the superficial fascia and then
pierces deep fascia in the roof of the post
triangle, 5cm above the clavicle
• End by draining in the subclavian vein 2cm above
the clavicle
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70. External jugular vein
Tributaries of external jugular vein include
• Posterior auricular vein
• Posterior division of the retromandibular vein
• Posterior external jugular vein
• Transverse cervical vein
• Suprascapular vein
• Anterior jugular vein
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71. Subclavian vein
• Major venous channel draining the upper limb
• A continuation of the axillary vein above the
clavicle
• An occassional occurance in the posterior
triangle
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72. Subclavian artery
• Major blood supply to the upper limb
• Has three parts. Only 3rd part is found in post
triangle
• Begins about a finger breadth above the
clavicle and lies in contact with the first rib
posterior to scalenous anterior muscle
• Can be compressed to control heamorrhages
at this point
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74. Other arteries
• Transverse cervical: a branch of the thyrocervical
trunk(from subclavian). Lies superficial and lateral
across the post triangle, 2 cm above the clavicle
deep to omohyoid
• Suprascapular artery: another branch of
thyrocervical trunk. Lies in inferior part of the
triangle above the clavicle
• Occipital artery: a branch of external carotid.
Enters apex of the triangle and ends by supplying
the scalp
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75. Nerves in the posterior triangle
• Accessory nerve: enters triangle btn the superior
and middle 1/3 of SCM. Passes posteroinferiorly
and disappears deep to ant border of trapezius.
Supplies these two muscles
• Cervical plexus: gives off the lesser and greater
occipital, transverse cervical, phrenic and
supraclavicular nerves
• Brachial plexus: the three trunks are located in
this region
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76. Nerve of the posterior triangle
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77. Muscles in the posterior triangle
• Splenius capitis: occupies upper part of the triangle,
serves as a bandage that holds the deeper muscles of
the neck
• Levator scaplae: a strap like muscle partially covered by
SCM and Trapezius. Elevators the scapula
• Scalenus medius: longest and largest of the scalenus
muscles. Perforated by the dorsal scapular nerve and
the two superior roots of the long thoracic nerve. Lies
post. to the ant. roots of the brachial plexus and 3rd
part of subclavian artery
• Scalenous posterior: smallest and most deep of scalene
• muscles
• Partially fused to scalenus medius
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78. Muscular floor of the posterior
triangle
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79. Muscles in posterior triangle
Muscle origin Insertion Nerve supply Action
Splenius capitis Ligamentum
nuchae, spines
of C1 - C6
Mastoid process Dorsal rami of
middle cervical
spinal nerve
Lateral flexion
and rotation of
the head
Levator scapulae Transverse
processes of
C1 – C4
scapular Dorsal scapular
nerve and
cervical plexus
Elevation of the
scapular
Splenius medius Transverse
processes of
C4 – C6
External border of
second rib
Ventral rami of
cervical plexus(
C7 and C8)
Lateral flexion of
the neck,
elevation of 2nd
rib during
forcefull
insipiration
Scalenus
posterior
Transverse
processes of
C6 and C7
Superior surface
of 1st rib
Ventral rami of
cervical plexus(
C3 - C8)
Lateral flexion of
the neck,
elevation of 1st
rib during
forcefull
insipiration
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80. Splenius capitis
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81. Lymphnodes in the posterior triangle
• Superficial cervical nodes: lie along the
external jugular vein
• Deep cervical nodes: lie along internal jugular
vein
• The nodes receive efferents from the parortid,
occipital and mastoid lymphnodes, muscles
and skin
• Efferents pass to the supraclavicular nodes in
the subclavian triangle
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82. Lymphnode groups in the neck
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83. Subdivisions of the posterior triangle
• Divided by inferior belly of omohyoid into a
larger superior occipital and a smaller
supraclavicular triangle
• Occpital triangle: mainly contains the occpital
artery and the accessory nerve
• Supralavicular triangle: mainly has the
external jugular vein, the suprascapular artery
and subclavian artery(hence also called
subclavian triangle)
DR NDAYISABA CORNEILLE

84. DR NDAYISABA CORNEILLE

85. Occipital triangle
Boundaries;
• Ant: post belly of sternocleidomastoid
• post: ant border of trapezius,
• inferiorly by the inferior belly of the omohyoid
muscle.
• Floor: splenius capitis, levator scapulae, and
scaleni medius and posterior; semispinalis capitis
occasionally appears at the apex.
• Roof: skin, superficial & deep fasciae & inferiorly
by the platysma .
DR NDAYISABA CORNEILLE

86. Contents
• The spinal accessory nerve pierces sternocleidomastoid
and crosses levator scapulae obliquely downwards and
backwards to reach the deep surface of trapezius.
(surface marking: jxn of sup 1/3rd & inf 2/3rds of the
scmd to the jxn of inf 1/3rd & sup 2/3rds of trapezius )
• Cutaneous & muscular branches of the cervical plexus
emerge at the posterior border of scmd.
• Inferiorly; supraclavicular nerves ,cervical vessels &
uppermost part of the brachial plexus cross the
triangle.
• Lymphnodes
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87. Supraclavicular triangle
boundaries;
• Superior: inf belly of omohyoid
• Anterior : post. border of the SCM
• Inferior: sup middle 1/3rd boarder of the clavicle.
• & communicates with the greater supraclavicular
fossa
• Floor; 1st rib, scalenus medius, 1st slip of serratus
anterior.
• Roof; skin, superficial & deep fasciae & platysma
crossed by the supraclavicular nerves.
DR NDAYISABA CORNEILLE

88. Contents
• 3rd part of subclavian artery, vein.. Usually not
but may rise as high as the artery. ,
• brachial plexus partly sup & post to the artery.
• Suprascapular vessels pass tranversely behind
the clavicle, below the transverse cervical
artery and vein.
• The ext. jugular vein drains into the subclavian
vein following the post boarder of the scmd.
DR NDAYISABA CORNEILLE

89. Contents cont’d
• It receives the transverse cervical & supra
scapular veins to later form a plexus anterior
to the 3rd part of the subclavian artery.
Occasionally, a small branch from the cephalic
vein is received.
• Nerve to the subclavius
• Lymphnodes
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90. Illustration (posterior triangle)
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91. Clinical significance
• Brachial plexus trunk palpation
• Arterial flow control of the subclavian artery
by retroclavicular compression.
• Communication with the greater
supraclavicular fossa……..
• Lymphnodes
DR NDAYISABA CORNEILLE

92. END
Dr Ndayisaba Corneille
THANKS FOR LISTENING
By
DR NDAYISABA CORNEILLE
MBChB,DCM,BCSIT,CCNA
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