This document describes the boundaries, contents, and structures of the anterior triangle of the neck. It is divided into four triangles based on boundaries: muscular, carotid, digastric, and submental. The carotid triangle contains the common carotid artery and its branches, the internal and external carotid arteries. It also contains the internal jugular vein and nerves like the vagus nerve. The main arteries discussed are the common, internal, and external carotid arteries and their branches. Veins and nerves of the region are also outlined.

1. ANTERIOR TRIANGLE
OF NECK – I
DR. SUNDIP CHARMODE
ASSOCIATE PROFESSOR
DEPARTMENT OF ANATOMY
AIIMS RAJKOT

3. BOUNDARIES
• In front: Anterior Median line from S. Mentis to
suprasternal notch
• Behind: Anterior border of the Sterno-cleido-mastoid
• Base: Lower border or Base of the Body of mandible
and a line extending from angle of mandible to
mastoid process
• Apex: Directed below and is formed by supra-sternal
notch

4. BOUNDARIES
• Roof:
1. Skin, Superficial Fascia,
2. Platysma
3. Investing layer of deep cervical fascia
4. Cervical branch of facial nerve
5. Ascending and descending branches of
Transverse cervical cutaneous nerve

6. SUB-DIVISIONS
• Each Anterior triangle is subdivided into :
1. Muscular triangle
2. Carotid triangle
3. Digastric triangle
4. Sub-mental – half triangle

7. MUSCULAR TRIANGLE
Boundaries
• In front: Anterior median line extending from
Hyoid bone to the supra-sternal notch.
• Behind and above: Superior belly of Omohyoid
• Behind and below: Anterior border of lower part
of sterno-cleido-mastoid
• Floor: Sterno-hyoid and Sterno-thyroid

9. CONTENTS
• No significant structures
• Beneath the floor, lies
1. Thyroid Gland,
2. Larynx,
3. Trachea,
4. Esophagus.

12. CAROTID TRIANGLE
Boundaries
• In front and above:
• Posterior belly of Digastric and Stylohyoid
• In front and below:
• Superior belly of Omohyoid
• Behind: Anterior border of sterno-cleido-
mastoid muscle.

15. CAROTID TRIANGLE
Boundaries
• Floor: Formed by parts of four muscles
1. Thyro-hyoid
2. Hyo-glossus
3. Inferior constrictor
4. Middle constrictor

16. FLOOR OF CAROTID TRIANGLE

18. CONTENTS
• Arteries
• Veins
• Nerves
• Other structures

19. ARTERIES
• Common Carotid artery and its two terminal
branches :
1. Internal carotid artery
2. External carotid artery

20. COMMON CAROTID ARTERY
• Origin
• Course

21. COMMON CAROTID ARTERY - RELATIONS
• In front and laterally:
– Skin
– Superficial fascia, Platysma, investing layer of deep
fascia
– Sterno-mastoid, Sternohyoid, Sternothyroid
– Descendens hypoglossi and ansa cervicalis
(embedded in the anterior wall of carotid sheath)

23. COMMON CAROTID ARTERY
• In behind:
– Transverse process of lower four cervical vertebrae
– Pre-vertebral muscles covered by pre-vertebral
fascia
– Sympathetic trunk
– Vertebral vessels below the carotid tubercle in
scaleno-vertebral triangle
– Carotid body at its bifurcation
• Laterally:
– Internal jugular vein with vagus nerve between and
behind them

25. COMMON CAROTID ARTERY
• Medially:
– Trachea, esophagus, recurrent laryngeal nerve
– Larynx and pharynx
– Thyroid gland
• Branches:

27. STRUCTURES BETWEEN ICA & ECA
1. A part of parotid gland
2. Styloid process of temporal bone
3. Styloglossus and stylopharyngeus muscles
4. Glossopharyngeal nerve
5. Pharyngeal branch of Vagus nerve

28. INTERNAL CAROTID ARTERY
• Supplies:
1. Cerebral hemispheres
2. Eyes
3. Contents of orbits
4. Forehead

29. EXTERNAL CAROTID ARTERY
• Origin :
• Course :

30. RELATIONS
• Superficial:
In Carotid Triangle-
• Overlapped by Sterno-cleido-mastoid
• Crossed by hypoglossal nerve, lingual and facial
veins
• Posterior belly of digastric, stylohyoid muscle
Within Parotid gland-
Overlapped by Retro-mandibular vein, facial nerve and
its branches

32. RELATIONS
• Deep:
• Constrictor muscles of pharynx
• Superior laryngeal nerve and its branches:
• Internal laryngeal nerve
• External laryngeal nerve
• Internal carotid artery

34. BRANCHES
• Medial side (1) : Ascending pharyngeal
• Front (3) : Superior thyroid, Facial, Lingual
• Behind (2) : Occipital, Posterior auricular
• Terminal (2) : Superficial temporal, Maxillary

35. ASCENDING PHARYNGEAL ARTERY
• First and smallest branch
• Arises from medial side and ascends to the base of
skull
• Lies between the wall of pharynx and ICA
BRANCHES
1. Pharyngeal branches
2. Inferior Tympanic branches
3. Meningeal branches

36. ASCENDING PHARYNGEAL ARTERY -
DISTRIBUTION
1. Pharyngeal branches – wall of pharynx, tonsils, part
of auditory tube and soft palate
2. Inferior Tympanic branches – medial wall of
tympanic cavity
3. Meningeal branches – dura mater and adjacent
bones, enter cranium through foramen lacerum,
jugular foramen and hypoglossal canal.

39. SUPERIOR THYROID ARTERY
• Arises from front, below the tip of greater cornua of
hyoid bone
• Pass down and forwards
• Accompanied by External laryngeal nerve (postero-
medial to it)
• Lies on Inf. Constrictor. Deep to OH,SH,ST muscles.
• Reach upper pole of thyroid gland. Lie superficial to
gland and divide into terminal branches.

43. SUPERIOR THYROID ARTERY - BRANCHES
1. Infra-hyoid branch
2. Superior Laryngeal
3. Crico-thyroid branch
4. Sternomastoid branch
5. Glandular branches –
1. Anterior
2. Posterior
3. Lateral

44. SUPERIOR THYROID ARTERY - DISTRIBUTION
1. Infra-hyoid:
– Anastomose with opposite artery across median plane along
lower border of hyoid bone
2. Superior Laryngeal:
– Pierces thyro-hyoid membrane along with Internal laryngeal
nerve.
– Supply larynx
– Anastomose with Inferior laryngeal branch of Inferior thyroid
artery
3. Crico-thyroid:
– Pass across Crico-thyroid ligament
– Anastomose with fellow branch

45. SUPERIOR THYROID ARTERY - DISTRIBUTION
4. Sternomastoid branch:
– Pass down and back
– Supply SCM
5. Glandular branches:
1. Anterior
2. Posterior
3. Lateral

46. LINGUAL ARTERY
• Arises from front of ECA, opposite to tip of greater
cornua
• Course divided into 3 parts by Hyoglossus muscle
• First part –
– Lies in carotid triangle
– From the origin to posterior border of hyoglossus
– Rests on middle constrictor
– Crossed superficially by hypoglossal nerve

47. LINGUAL ARTERY
• Second part –
– Lies deep to hyoglossus
– Runs horizontally forwards along the upper border of hyoid
– Lies between hyoglossus laterally and middle constrictor and
stylohyoid medially
– Artery is separated from hypoglossal nerve and vena
comitantes by hyoglossus.

48. LINGUAL ARTERY
• Third part –
– Ascends along the anterior border of hyoglossus
– Runs forwards beneath the mucus membrane of
undersurface of tongue
– Lies between longitudinalis linguae laterally and
genioglossus medially
– Accompanied by lingual nerve
– At the tip of tongue it anastomoses with fellow branch.

51. LINGUAL ARTERY - BRANCHES
• First part – Suprahyoid artery:
– Pass forward, along upper border of hyoid
– Anastomose with fellow artery across middle line
• Second part – Dorsal lingual arteries (3-4 branches):
– Supplies mucous membrane of dorsal surface of
tongue, palatine tonsils, soft palate
• Third part/Arteria Profunda Linguae – Sub-lingual
artery:
– Supply sublingual gland
– Mucus membrane of floor of mouth and adjoining gums

55. FACIAL ARTERY
• Arises from front of ECA, just above the tip of greater
cornua
• Cervical part:
– Pass upward and forward deep to posterior belly of digastric &
stylohyoid
– Lodges in a groove at posterior end of submandibular gland
– Presents loop with upward convexity, rests on middle and
superior constrictor
– Pass down, forward between medial pterygoid and lateral surf.
SM gland
– Winds round the lower border of mandible at antero-inferior
angle of masseter by piercing investing layer.

56. FACIAL ARTERY – BRANCHES
• Cervical part:
1. Ascending palatine artery:
– Arises from proximal loop, ascends along pharyngeal wall
– Winds round upper border of superior constrictor
– Supplies soft palate, tonsils, wall of pharynx and auditory
tube
2. Tonsillar artery:
– Arises close to Ascending palatine artery
– Reaches the gland by piercing superior constrictor
3. Glandular branches (3-4): Submandibular gland

57. FACIAL ARTERY – BRANCHES
4. Sub-mental artery:
– Winds round lower border of mandible
– Lies on mylohyoid muscle
– Supply adjoining structures
– Anastomose with mylohyoid branch of Inferior alveolar
artery
– Few branches anastomose with mental and inferior labial
arteries

59. FACIAL ARTERY - BRANCHES
• Facial part:
1. Inferior labial
2. Superior labial
3. Lateral nasal artery

60. OCCIPITAL ARTERY
• Arises from posterior aspect of ECA, opposite the
origin of Facial artery.
• Pass backwards and upwards
• Along and undercover of posterior belly of digastric
• Pass superficial to the contents of carotid sheath and
hypoglossal and accessory nerves.
• Pass deep to SCM, Splenius capitis, longissimus capitis
• Pierces trapezius and appears tortuously in posterior
part of scalp.

61. OCCIPITAL ARTERY
• Lodges in a groove on medial side of mastoid bone
• Pierces trapezius and appears tortuously in posterior
part of scalp.

62. OCCIPITAL ARTERY
1. Sterno-mastoid branches (2)- sterno-cleido-mastoid
2. Mastoid – enters cranial cavity, supply mastoid air
cells and duramater
3. Meningeal – enters skull and supplies duramater
4. Muscular- adjoining muscles
5. Occasional auricular – cranial surface of auricle

63. OCCIPITAL ARTERY
6. Descending branch -
– Superficial branch – anastomose with superficial branch of
transverse cervical artery
– Deep branch – anastomose with deep cervical artery
7. Occipital branches – scalp up to vertex

64. POSTERIOR AURICULAR ARTERY
• Arises from posterior aspect of ECA above the occipital
artery
• Pass back and upward along the upper border of
posterior belly of digastric
• Reach interval between auricle and mastoid process
and divide into terminal branches.

65. POSTERIOR AURICULAR ARTERY
1. Stylo-mastoid artery:
– Enters stylomastoid foramen
– Supply facial nerve, tympanic cavity, mastoid air cells,
semicircular canals
2. Auricular branch:
– Cranial and lateral surface of auricle
3. Occipital branch:
– scalp above and behind the auricle

66. SUPERFICIAL TEMPORAL ARTERY
• Smaller terminal branch
• Arises within the parotid gland behind neck of
mandible
• Lies superficial to temporal fascia
• About 5 cm above arch, divides into anterior and
posterior branches.

68. SUPERFICIAL TEMPORAL ARTERY - BRANCHES
1. Transverse facial artery:
– arises within parotid gland
– Pass forward across the masseter between the zygomatic
arch and parotid duct
– Supplies parotid gland and duct, TM joint, masseter muscle
– Anastomoses with branches of facial artery
2. Anterior auricular branch: Lateral surface of auricle
and external acoustic meatus
3. Zygomatico-orbital artery: Reach lateral angle of orbit

69. SUPERFICIAL TEMPORAL ARTERY - BRANCHES
4. Middle temporal artery:
– Supply temporalis
– Anastomose with middle temporal branch of maxillary
artery
5. Anterior/Frontal branch: Muscles and skin of
frontal region
6. Posterior/Parietal branch: Anastomose with
posterior auricular and occipital arteries

70. MAXILLARY ARTERY
• Largest terminal branch

71. VEINS
• Internal Jugular vein – Extends from Base of skull to the
root of neck.
• Collects blood from :
– Brain
– Superficial part of face and neck
• Lies lateral to the Internal and external carotid arteries
• Overlapped by Anterior border of sternocleidomastoid.

72. VEINS
• Tributaries of Internal Jugular vein present in
carotid triangle are :
1. Superior thyroid vein
2. Lingual vein
3. Common facial vein
4. Pharyngeal vein
5. Occipital veins
• They follow the course of their corresponding
arteries

73. CAROTID SHEATH
• Tubular investment of deep cervical fascia extends
from base of skull to arch of aorta containing:
– Common carotid artery (medial)
– Internal carotid artery (medial)
– Internal jugular vein (lateral)
– Vagus nerve (in between)
• Feltwork of condensed areolar tissue

75. CAROTID SHEATH
• Thick: arteries, Thin/ill-defined: veins ?
• Anterior wall:
– Pre-tracheal fascia
– Ansa cervicalis embedded in it
– Attached to deep surface of SCM, fused with pre-tracheal
fascia
• Posterior wall:
– pre-vertebral fascia
– Separated from pre-vertebral fascia by loose areolar tissue
– Cervical part of sympathetic chain passes between PVF and
PWOCS

76. STRUCTURES PEIRCING CAROTID
SHEATH
• External carotid artery
• (Most of the tributaries) of Internal jugular
vein
• Glossopharyngeal, accessory, hypoglossal and
cervical branches of Vagus nerves

77. NERVES
• A portion of Spinal part of Accessory nerve:
• Crosses the upper angle of carotid triangle
• Pass either superficial or deep to the Internal jugular
vein
• Disappears beneath or through sternocleidomastoid

79. LOOP OF HYPOGLOSSAL NERVE
• Winds around lower sterno-cleido-mastoid branch of
occipital artery
• Crosses superficial to ICA and ECA and the loop of 1st
part of lingual artery.
• The nerve gives 2 branches from the convex side of
the loop.

81. ANSA CERVICALIS

82. ANSA CERVICALIS
• Descendens hypoglossi:
– pass down in front of carotid sheath
– carries fibers of C1
• Forms a loop called as Ansa Cervicalis after joining
with the Descendens Cervicalis from C2 and C3.

84. NERVES
3. Vagus nerve: gives many branches as :
– Pharyngeal
– Superior laryngeal nerve
– Branch to carotid sinus and carotid body
– Superior and inferior cervical cardiac branches
– Right recurrent laryngeal nerve
• Sup. Laryngeal nerve will divide into :
1. External laryngeal nerve-
2. Internal laryngeal nerve –
4. Cervical part of Sympathetic trunk

86. NERVES
• Internal laryngeal nerve:
– Essentially sensory
– Pierces thyro-hyoid membrane
– Supply laryngeal mucous membrane till vocal cords
• External laryngeal nerve:
– Slender motor, accompanies Sup. Thyroid artery
– Motor branch to cricothyroid muscle
– Motor branch to inferior constrictor

88. OTHER STRUCTURES
• Apex of Parotid gland: encroaches on upper
angle of triangle.
• A chain of Deep Cervical Lymph nodes along
Internal jugular vein namely:
– Jugulo-digastric group – below posterior belly of
digastric
– Jugulo-omohyoid group – above superior belly of
omohyoid

90. CLINICAL CORRELATION
• In case of ligation of CCA, collateral circulation may
be established at:
a. Occipital anastomoses
b. Anastomoses around thyroid gland
c. Anastomoses across the middle line
• Ligation of Sup. Thyroid artery should be done close
to the gland.

91. CAROTID SINUS
• Fusiform dilatation present at the bifurcation of CCA
and the beginning of ICA.
• Wall of sinus is thinner and more elastic than the
adjacent part of the artery.
• Acts as baroreceptors for controlling intracranial blood
pressure
• Stimulation leads to reflex fall in blood pressure,
slowing of heart.

92. CAROTID SINUS
• Receives:
– Sinus branch from the glossopharyngeal nerve
– Twigs from Vagus nerve
– Sympathetic trunk
• Carotid sinus syndrome -

93. CAROTID BODY
• Small, oval neurovascular structure situated close to
the posterior wall of carotid sinus.
• Receives supply from:
– Glossopharyngeal
– Vagus
– Sympathetic nerves
• Acts as chemoreceptor monitoring oxygen tension
within the artery.

94. CAROTID BODY
• Stimulation of the
body by anoxia
produces:
o Reflex rise in blood
pressure and heart rate
o Changes in the depth
and rate of respiration.

95. CLINICAL CORRELATION
• Wry neck – deformity of neck caused due to shortening
of sternocleidomastoid
• Torticollis - repeated painful contractions of SCM and
trapezius of one side.
• Posterior belly of digastric:
– Key muscle of neck
– Vagus, accessory and hypoglossal nerves pass under it
– ICA, IJV and ECA pass under it

96. THANKS