The sternocleidomastoid muscle divides the neck into anterior and posterior triangles. The anterior triangle contains several important structures and is further divided. The submental triangle contains lymph nodes and veins. The digastric triangle contains the submandibular gland, vessels, and nerves. The carotid triangle contains the common carotid artery and its branches, the internal and external carotid arteries. The external carotid artery gives off branches that supply the face and neck structures including the superior thyroid, lingual, and facial arteries.

1. 1

2.  The side of the neck is
roughly quadrilateral in
outline.
 It is bounded
 Anteriorly by –Anterior
Median Line
 Posteriorly- Anterior border of
Trapezius
 Superiorly- Base of the
Mandible, a line joining angle
of the mandible & mastoid
process, superior nuchal line.
 Inferiorly- Clavicle
 This quadrangular space is
divided obliquely by SCM
muscle into anterior and
2

3. STERNOCLEIDOMASTOID
 Origin:
a) Sternal head
b) Clavicular head
 Insertion:
a) Lateral process of mastoid process
b) Lateral half of the superior nuchal line of occipital bone
 Nerve Supply:
Spinal Accessory Nerve
 Blood Supply:
One br from sup thyroid A. and suprascapular A.
Two br from occipital A.
3

4. STERNOCLEIDOMASTOID
 One of the most important
landmark in neck.
 Actions-
 When one muscles
contracts-
 When both muscles
contracts
 To make scm taut on one
side, the pt is asked to turn
the head to opp. side
against resistance.
4

5. PLATYSMA
 It is a subcutaneous muscle
forming a wide, thin fleshy
sheet running upwards and
medially in the neck from
deltoid and pectoral fasciae
to the base of mandible.
 Supplied by cervical br. of
facial nerve.
5

6. ANTERIOR TRIANGLE OF
NECK
 Boundaries:
Medially: Ant median plane of neck
Laterally: SCM
Superiorly: Base of the mandible and a line joining the angle
of the mandible n mastoid process
 Subdivisions:
The ant triangle is subdivided by the digastric belly and sup
belly of omohyoid into:
a) Submental
b) Digastric
c) Carotid and
d) Muscular Triangles
6

7. ANTERIOR TRIANGLE -
SUBDIVISONS
7

8. 8

9. SUBMENTAL TRIANGLE
 This is a median triangle.
 Boundaries:
Either side- Anterior belly
of corresponding digastric
muscles
Base- Body of hyoid bone
Apex- at the chin
Floor- Rt and Lt
Mylohyoid muscle
9

10. CONTENTS OF SUBMENTAL
TRIANGLE
 It contains:
 one or two lymph glands, the
submental lymph nodes
 some small veins; the latter
unite to form the anterior
jugular vein
 The lymph nodes of the
submental triangle receive
lymph from the skin of the
chin, the lower lip, the floor of
the mouth, and the tip of the
tongue. They send lymph to
the submandibular and
jugular chains of nodes. They
belong to Level 1 gr of LNs
10

11. DIGASTRIC TRIANGLE
 The submandibular triangle
(or submaxillary or digastric
triangle) corresponds to the
region of the neck immediately
beneath the body of the
mandible.
 Boundaries:
Anteroinf: Ant belly of digastric
Posteroinf: Post belly of
digastric and stylohyoid.
Superiorly: Base of the
mandible.
Roof : Skin, superficial fascia
with platysma muscle, deep
fascia
Floor: Mylohyoid anteriorly and
hyoglossus posteriorly, part of
middle constrictor.
11

12. FLOOR OF DIGASTRIC
TRIANGLE
12

13. CONTENTS OF DIGASTRIC
TRIANGLE ANTERIOR PART OF
TRIANGLE
Strucures superficial to
mylohyoid are:
 Superficial part of
submandibular gland, Facial
vein , Subman. LN (belong to
Level 1 gr of LNs), Facial
A.,Submental A., Mylohyoid
nerve and vessels.
Structures superficial
to hyoglossus:
Subman.gland,Intermediate
tendon of digastric and
stylohyoid, Hypoglossal N.
13

14. CONTENTS OF DIGASTRIC
TRIANGLE POSTERIOR PART OF
TRIANGLE:
Superficial
Structures: Lower part of
parotid, ECA before it enters
parotid.
Deep structures:
Styloglossus,
stylopharyngeus,
glossopharyngeal N,
Pharyngeal br of vagus,
Styloid process, a part of
parotid
14

15. CONTENTS OF POSTERIOR PART
OF DIGASTRIC TRIANGLE
Deepest structures:
a) Internal carotid A.
b) Internal jugular vein
c) Vagus N.
• Submandibular LNs: Belong to Level 1 gr of LNs
• Clinically important because of their wide area of drainage. They are
very commonly enlarged.
• They drain: a) center of forehead
b) Nose with Max. Frontal & Ethmoid sinuses
c) Inner canthus of the eye
d) Upper lip and the ant part of cheek with adjoinin gums
e)Outer part of lower lip with gums and teeth excluding incisors
f)Ant 2/3rd of tongue and floor of mouth
15

16. CAROTID TRIANGLE
 Boundaries:
 Anterosup: Post belly of
digastric
 Anteroinf: Sup belly of
omohyoid
 Posteriorly: Ant border of SCM
 Roof: skin, superficial fascia,
investing layer of deep fascia
 Floor: Thyrohyoid M,
hyoglossus, Middle and Inf.
constrictors of pharynx
16

17. CONTENTS OF CAROTID
TRIANGLE
 ARTERIES:
 Common caortid A. with
carotid sinus and carotid
body at its termination
 Internal carotid A.
 External carotid A. with br.-
Ant br-sup thyroid, lingual
facial
Post br- Occipital , post.
Auricular
Medial- Asc. Pharyngeal
Terminal –Maxillary ,
Superficial Temporal.
17

19. CONTENTS OF CAROTID
TRIANGLE
 VEINS:
 Internal Jugular V.
 Common Facial V.
 Pharyngeal V
 Lingual V. all draining in to
internal jugular vein
directly or via facial vein
19

20. CONTENTS OF CAROTID
TRIANGLE
 NERVES:
 Vagus running vertically
downwards
 Sup L.N of vagus dividing
into ext n int L.N
 Spinal Accessory N
 Hypoglossal N
 Sympathetic chain
 Carotid sheath and its
contents
 Lymph Nodes: Jugulo-
digastric and jugulo-
omohyoid
20

21. CONTENTS OF CAROTID
TRIANGLE
ACCESSORY N.
HYPOGLOSSAL N.
21

22. COMMON CAROTID ARTERIES
 Right common carotid artery is a
branch of the brachiocephalic
artery.It begins in the neck behind
the right sternoclavicular joint.
 Left common carotid artery is a
branch of the arch of aorta.It
ascends to the back of the left
sternoclavicular joint and enters
the neck.
 In the neck,each artery runs
upwards within the carotid
sheath,under cover of the anterior
border of the sternocleidomastoid
muscle.

23. CAROTID SHEATH
 Carotid sheath is condensation
of the fibroareolar tissue around
the main vessels of the neck.
 CONTENTS:It contains the
common and internal carotid
arteries,internal jugular vein and
the vagus nerve.
 In the sheath,common carotid
artery is medially placed.Vagus
nerve lies in between.

24. RELATIONS
 The ansa cervicalis lies
embedded in the
anterior wall of the
carotid sheath.
 The cervical
sympathetic chain lies
behind the sheath.

25. BIFURCATION OF COMMON
CAROTID ARTERY
 Common carotid artery
bifurcates into external and
internal carotid arteries at the
level of upper border of the
thyroid cartilage.
 Two structures of importance
at the bifurcation are
Carotid sinus
Carotid body

26. CAROTID SINUS AND
BODY
26

27. CAROTID SINUS
 Carotid sinus is slight dilatation at the termination of the common
carotid artery or the beginning of the internal carotid artery.
 It receives a rich innervation from the glossopharyngeal and
sympathetic nerves.
FUNCTION:
Carotid sinus acts as a baroreceptor or pressure receptor and
regulates pressure.

28. APPLIED ANATOMY
CAROTID SINUS SYNDROME
 Loss of consciousness due to simple head movements.
 Hypersensitivity of the carotid sinus due to an unknown etiology.
 Sudden slight pressure changes, such as that occasioned by
movement of the head, may result in stimulation of the carotid
sinus.
 Impulses transmitted by the sinus reduce blood pressure and slow
the pumping action of the heart.
Thus decreasing blood supply to the brain and resulting in sudden
loss of consciousness.
While supporting the mandible care should be taken not to apply
pressure on the carotid sinus.

29. CAROTID BODY
 Carotid body is a small,oval reddish-brown structure situated
behind the bifurcation.
 It receives nerve supply mainly from the glossopharyngeal nerve,
but also from the vagus and sympathetic nerves.
FUNCTION:
Carotid body acts as a chemoreceptor and responds to changes in
the oxygen and carbon dioxide and Ph content of the blood.

30. EXTERNAL CAROTID
ARTERY
 Generally,it lies anterior to the internal carotid artery.
 It is the chief artery of supply to structures in the front of the neck
and in the face.

31. COURSE
 ECA begins in the carotid
triangle at the level of upper
border of thyriod cartilage
opposite the disc between the
third and fourth cervical
vertibrae.
 In the carotid triangle,it lies
under cover of the anterior
border of the
sternocleidomastiod muscle
 As the artery ascends ,it passes
deep to the post. Belly of
digastric and stylohyoid muscle
and terminates behind the neck
of the mandible by dividing into
the maxillary and superficial
temporal arteries.

32. Has slightly curved course,so that it is anteromedial
to ICA in it lower part,and anterolateral to the ICA
in its upper part.

33. RELATIONSIN THE CAROTID TRIANGLE
Superficially—Cervical branch of facial nerve
Hypoglossal nerve
Facial,lingual,and superior
thyriod veins
Deep to the artery— Wall of pharynx
Superior laryngeal nerve
Ascending pharyngeal artery

34. ABOVE THE CAROTID TRIANGLE
Lies deep in the substance of the parotid
triangle.
Within the gland, it is related
Superficially—Retromandibular vein
Facial nerve
Deep to the artery—ICA
Structures passing between ECA and
ICA
Styloglossus
Stylopharyngeus
IXth nerve
Pharyngeal branch of
Xth nerve
Styloid process

35. BRANCHES OF EXT.CAROTID
ARTERY
35

36. ANTERIOR BRANCHES

37. SUPERIOR THYRIOD ARTERY
ORIGIN:Arises from the front of ECA
below the tip of greater cornua of hyoid
bone.
COURSE: Runs downwards and forwards
parallel and just superficial to the extenal
laryngeal nerve.
- It passes deep to omohyoid ,sternohyoid,
sternothyroid and reaches the upper pole of
lateral lobe of thyroid and divides into its
terminal branches.
 It is accompanied by same-named vein.

38. BRANCHES:
INFRAHYOID ARTERY
STERNOCLEIDOMASTOID ARTERY
SUPERIOR LARYNGEALARTERY
CRICOTHYROID ARTERY
GLANDULAR BRANCHES

39. APPLIED ANATOMY
 The arch of superior thyroid artery is characteristic – diagnostic landmark
 The artery and external laryngeal nerve are close to each other higher up,
but diverge slightly near the gland.
- So, ligature of superior thyroid artery in thyroid surgery should be made
close to the gland in order to avoid injury of the external laryngeal nerve.
-Damage to the external laryngeal nerve causes some weakness of
phonation due to loss of tightening effect of the cricothyriod on the vocal
cord.
 Intra-arterial infusion chemotherapy for laryngeal and hypopharyngeal
cancers.

40. LINGUAL ARTERY
ORIGIN:Arises from ECA opposite the
tip of the greater cornua of hyoid bone.
-It may arise in common with the facial
artery, then becoming the linguofacial
trunk.
COURSE:Divided into three parts by
hypoglossus muscle.
FIRST PART – In carotid triangle,
extends from origin to the posterior
border of hyoglossus.
- Rests on the middle constrictor,forms
a upward loop which is crossed by
hypoglossal nerve. This loop permits
the free movements of the hyiod bone.

41. SECOND PART – Deep to
hyoglossus, runs horizontally
forward along the upper border of
hyoid bone between hyoglossus
laterally and middle constrictor,
stylohyoid ligament medially.
THIRD PART [ ‘arteria profunda
linguae’ ]—Also called as deep
lingual artery.
-It runs upwards along the anterior
Border of hyoglossus, then
horizontally forwards on the
undersurface of tongue on each side
of frenum linguae.
-In vertical course,it lies b/t the
genioglossus medially & inferior
longitudinal muscle of tongue
laterally. Horizontal part is
accompanied by lingual nerve.

43. BRANCHES
 SUPRAHYOID ARTERY
 DORSAL LINGUALARTERY
 SUBLINGUALARTERY
 DEEP LINGUALARTERY

44. FACIAL ARTERY
ORIGIN: Arises from the ECA just above the tip of greater cornua
of hyoid bone.
COURSE: Runs upwards in -- neck as cervical part ; face -- facial
part.
Tortuous course—In neck allows free movements of pharynx
during deglutition,
on face -- free movements of mandible , lips, & cheek during
mastication & facial expressions, escapes traction & pressure
during movements.
.

45. Cervical part : Cervical part Runs
upwards on superior constrictor
of pharynx deep to the posterior
belly of digastric.
-It grooves the posterior border
of submandibular gland, makes
S-bend [2 loops] 1st winding
down over submandibular gland
& then up over the base of
mandible.

46. Facial part:The vessel enters the face by winding around the base of
the mandible, and by piercing the deep cervical fascia,at the
anteroinferior angle of the masseter muscle.
 It runs upwards and forwards deep to the risorus, to a point 1.25cm
lateral to the angle of the mouth.
 Then it ascends by the side of the nose upto the medial angle of the
eye where it terminates by anastomosing with the dorsal nasal
branch of the ophthalmic artery.

47. BRANCHES
CERVICAL PART:
ASCENDING PALATINE ARTERY
TONSILLAR A RTERY
GLANDULAR ARTERIES
SUBMENTALARTERY

48. FACIAL PART:
INFERIOR LABIALARTERY
SUPERIOR LABIALARTERY
LATERAL NASALARTERY
ANGULAR ARTERY

49. POSTERIOR BRANCHES

50. OCCIPITAL ARTERY
ORIGIN:Arises in carotid triangle
from posterior aspect of ECA
,opposite the origin of facial
artery.
-It is crossed at its origin by
hypoglossal nerve.
COURSE: Passes backwards and
upwards along & under cover of
lower border of post. Belly of
diagastric , crossing carotid sheath,
hypoglossal & accessory nerves.
Then it runs deep to the mastiod
process and muscles attached to it
i.e.,sternocleidomastiod,
digastric etc.

51. Then crosses the rectus capitus
lateralis,superior oblique,and
semispinalis capitus muscle at the
apex of the posterior triangle.
Finally it pierces the trapezius muscle
and ascends in a tortuous course in
the superficial fascia of the scalp.
Its terminal portion comes to lie along
the greater occipital nerve.

52. BRANCHES
 STERNOMASTOID BRANCHES
 AURICULAR BRANCH
 MASTOID BRANCH
 MENINGEAL BRANCH
 MUSCULAR BRANCH

53. POSTERIOR AURICULAR
ARTERYORIGIN: Arises from the posterior
aspect of the external carotid artery
just above the posterior belly of the
digastric.
COURSE:It runs upwards and
backwards deep to parotid gland,
but superficial to the styloid
process.It crosses the base of the
mastiod process and ascends behind
the auricle.

54. BRANCHES
Stylomastoid.
Auricular
Occipital.

55. MEDIAL BRANCH

56. ASCENDING PHARYNGEAL
ARTERY
ORIGIN:The smallest branch arising
from the medial side of the external
carotid artery, near its
commencement.
COURSE: Ascends vertically between
the internal carotid and the side of the
pharynx, to the under surface of the
base of the skull, lying on the Longus
capitis.

57. BRANCHES
 PHARYNGEAL BRANCHES
 PALATINE BRANCH
 PREVERTEBRAL BRANCHES
 INFERIOR TYMPANIC ARTERY
 MENINGEAL BRANCHES

58. TERMINAL BRANCHES

59. MAXILLARY ARTERY
ORIGIN:Large terminal branch given
off behind the neck of the mandible.
COURSE: Divided into three parts by
lateral pterygiod muscle.
 The first or mandibular portion
passes horizontally forward, between
the ramus of the mandible and the
sphenomandibular ligament, where it
lies parallel to and a little below the
auriculotemporal nerve; it crosses the
inferior alveolar nerve, and runs
along the lower border of the lateral
pterygiod.

60.  The second or pterygoid portion runs obliquely forward and
upward superficial to the lower head of the lateral pterygiod.
 The third or pterygopalatine portion passes between the two
heads of the lateral pterygiod and pterygomaxillary fissure,to enter
into the pterygopalatine fossa where it lies in front of the
sphenopalatine ganglion.

61. BRANCHES
First or Mandibular Portion
 Deep Auricular.
 Anterior Tympanic.
 Middle Meningeal
 Accessory Meningeal
 Inferior Alveolar.
Second or Pterygoid Portion
 Deep Temporal.
 Masseteric.
 Pterygoid.
 Buccinator.
Third or Pterygopalatine
Portion
•Posterior Superior
Alveolar.
•Infraorbital.
•Greater palatine artery
•Pharyngeal.
•Aretry of pterygiod canal
•Sphenopalatine.

62. SUPERFICIAL TEMPORAL
ARTERY
ORIGIN: The smaller of the two terminal branches of the external
carotid, appears, to be the continuation of ECA. It begins in the
substance of the parotid gland, behind the neck of the mandible.
COURSE: It runs vertically upwards crossing over the root of the
zygomatic process
-about 5 cm. above this process it divides into two branches, a
frontal and a parietal.

63.  Relations.—As it crosses
the zygomatic process, it
is covered by the
Auricularis anterior
muscle, and by a dense
fascia; it is crossed by the
temporal and zygomatic
branches of the facial
nerve and one or two
veins, and is accompanied
by the auriculotemporal
nerve, which lies
immediately behind it.

64. BRANCHES
Besides some twigs to the parotid gland, to the
temporomandibular joint, and to the Masseter muscle,
its branches are:
 Transverse Facial.
 Anterior Auricular.
 Middle Temporal.
 Frontal.
 Parietal

65. MUSCULAR TRIANGLE
Boundaries Anteriorly: midline of neck
 Superiorly: superior belly of
omohyoid.
 Inferiorly: anterior border of
sternomastoid .

66. Contents
Sternohyoid muscle
Sternothyroid
muscle
Thyrohyoid muscle

67. STERNOHYOID
 Origin :Back of
manubrium & medial end of
clavicle.
Insertion :Medial part
of the lower border of hyoid
bone.
 Nerve supply : Ansa
Cervicalis
 Action: Depression of
hyoid bone

68. STERNOTHYROID
Origin :Back of
manubrium sterni.
Insertion: Oblique line of
thyroid cartilage.
Nerve supply : Ansa
cervicalis.
Action :Depression of the
larynx.

69. THYROHYOID
Origin: Oblique line of
the thyroid cartilage.
Insertion :Lower border
of hyoid bone.
Nerve supply
:hypoglossal
nerve(C1fibers).
Action:Depression of
hyoid or elevation of larynx.

70. INFRAHYOID / STRAP /
RIBBON MUSCLES
70

71. SUPRAHYOID
MUSCLESMUSCLE ORIGIN INSERTIO
N
NERVE
SUPPLY
DIGASTRIC Anterior belly from
digastric fossa
Post belly from
mastoid notch
Intermediate
tendon held by a
pulley to hyoid
bone
Ant belly by nerve
of mylohyoid
Post belly by facial
nerve
STYLOHYO
ID
Posterior surface
of styloid process
Junction of body
and greater
cornua of hyoid
bone
Facial nerve
MYLOHYOI
D
Mylohyoid line of
mandible
Body of hyoid
bone
Two m. muscle
of both side form
median raphe
Nerve to
mylohyoid
GENIOHYO
ID
Inferior mental
spine(Genial
tubercle)
Ant surface of
body of hyoid
bone
C1 thru
hypoglossal nerve71

72. INFRAHYOID
MUSCLESMuscle Origin Insertion Innervation
Sternohyoid Post surface
of manubrium
sterni
Medial part of
lower border of
hyoid bone
Ansa cervicalis
Sternothyr
oid
-Post surface
of manubrium
sterni
Oblique line on
lamina of
thyroid
cartilage
Ansa cervicalis
Thyrohyoid Oblique line
on lamina of
thyroid
cartilage
Body and greater
cornua of hyoid
bone
C1 thru
hypoglossal N
Omohyoid
Sup and inf
bellies
Upper border
of scapula
near
suprasternal
notch
Lower border of
body of hyoid
bone
Ansa cervicalis
72

73. SUPRAHYOID MUSCLES 73

74. 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

75. ANSA CERVICALIS
 Also known as Ansa
Hypoglossi.
 This is a thin nerve loop
that lies embedded in the
ant wall of carotid sheath.
 FORMATION:
Superior Root:continuation
of descending br of
hypoglossal N.
Inferior Root: 2nd and 3rd
cervical spinal N.
• Supplies Infrahyoid
muscles.
75

76. ANSA CERVICALIS
Def It is a loop of cervical nerves which lies on the surface
of carotid sheath.
It is formed by the union of:
 Descending hypoglossi :consist of fibers from C1.
 Descending cervicalis : consist of fibers from C2&C3
Branches:
• Sternohyoid
• Sternothyroid
• Omohyoid(both belies)

78. POSTERIOR
TRIANGLE The boundaries are:
 Anterior: Post. Border of
SCM
 Posterior: ant border of the
trapezius muscle (Fig. 1-21)
 Inferior or Base: Middle 1/3rd
of clavicle
 Apex: Lies on the sup nuchal
line where scm and trapezius
meet.
 Roof: Investing layer of the
deep cervical fascia, ext
jugular vein
78

79. ROOF OF POSTERIOR
TRIANGLE
79

80. FLOOR OF POSTERIOR
TRIANGLE
Floor: prevertebral layer
of deep cervical fascia,
covering following muscles
a) Splenius capitus muscle,
b) Levator scapulae
c) Scalenus medius
d) Occassionally scalenus
posterior
80

81. SUBDIVISIONS OF
POSTERIOR TRIANGLE OF
NECK Subdivided by inf. belly of
the omohyoid into
a) Larger upper triangle-
Occipital triangle
b) Smaller lower triangle-
Supraclavicular or
Subclavian triangle
81

82. CONTENTS OF POSTERIOR
TRIANGLE Nerves
• Accessory nerve
• Root, trunks of brachial plexus and their branches :
Nerves to rhomboideus(dorsal scapular n)
Nerves to serratus anterior(long thoracic n)
Nerves to subclavius
Suprascapular nerve
 Cervical nerves
Greater occipital nerve
Great auriclular nerve
Lesser occipital nerve
Transverse cervical nerve of neck
Supraclavicular nerve 82

83. NERVES OF POSTERIOR 83

84. ARTERIES OF POSTERIOR
TRIANGLE
 Arteries
 Occipital artery
 Third part of
subclavianartery &
branches of
subclavianartery
 Suprascapular
 Transverse cervical
84

85. VEINS IN POSTERIOR
TRIANGLE
 Lower part of
External
jugular vein &
its tributaries
 Superficial
cervical vein
 Subclavianvein
is lower down
and not in the
triangle
85

86. LYMPH NODES OF POSTERIOR
TRIANGLE
 Supraclavicularlymp
h nodes are present
on posteriorborder of
sternocleidomastoid
 Occipital nodes
 The nodes of
posterior triangle
belong to 5th level of
cervical LNs
86