2. ANTERIOR TRIANGLE
CN XI (Levator Scapulae M)
Roots of Brachial Plexus
Exiting in the Scalene Gap
Omohyoid M
S
C
M
POSTERIOR
TRIANGLE
Infrahyoid
(Strap) MM
Facial V
Retromandibular V
Internal Jugular V
External Carotid A
3.
4. Anteriorly: by the
posterior border of
sternocleido mastoid
muscle
Posteriorly: by the antreior
border of trapezius muscle
Inferiorly: by the middle
third of the clavicle
Roof: by the investing
layer of deep fascia
5. Transverse Cervical N
Ansa Cervicalis
Ansa Cervicalis
Supraclavicular Nerves
Hypoglossal N
Nerve to geniohyoid
and thyrohyoid
C1
C2
C3
C4
C5
CN XI
Phrenic Nerve (C4,
with C3 and
C5),Motor, Sensory
and Sympathetic
Fibers
Great Auricular N
Lesser Occipital N
Nerve to Omohyoid
Nerve to omohyoid
Nerve to sternothyroid
Nerve to sternohyoid
(Medial) (Lateral)
6. On the lateral surface of the internal jugular vein,
the superior root of ansa cervicalis (C1) joins the
inferior root of ansa cervicalis (C2, C3) to form a
loop called ansa cervicalis.
Branches: to suprahyoid muscles –
1. Nerve to thyrohyoid muscle
2. Nerve to geniohyoid muscle
Branches : to infrahyoid muscles –
1. Nerve to sternohyoid
2. Nerve to sternothyroid
3. Nerve to omohyoid
Phrenic nerve– ventral rami of C3, C4, C5
7. The muscular floor of the
triangle is covered by
prevertebral layer of deep
fascia. It is formed from above
downwards by the
semispinalis capitis
splenius capitis
levator scapulae
scalenus posterior
scalenus medius
scalenus anterior
inferior belly of omohyoid
8. Structures near the root
of the neck:
Brachial plexus
Subclavian artery
Subclavian vein
The brachial plexus and
the subclavian artery
pass between the
scalenus anterior and
scalenus medius
muscles.
The subclavian vein
passes anterior to the
scalenus anterior muscle
9. Other structures in
posterior triangle:
• sa - spinal part of
accessory nerve
• bp - brachial plexus
• tc - transverse cervical
artery
• ss - suprascapular
artery
10. Sternomastoid:
Nerve supply: Spinal part of the accessory nerve.
Action: Rotates, extends the head, flexes the head.
Trapezius:
Nerve supply: Spinal part of the accessory nerve
Actions: Elevates the shoulder, rotates the scapula
laterally to help raise he shoulder retracts the scapula
Splenius capitis:
Nerve supply: Posterior ramus of spinal nerves C3 and C4
Action: extends and rotates head
11. Scalenus posterior:
Action: Raises the second rib; bends the neck to the side.
Scalenus medius:
Action: raises the 1st rib; bends neck to side
Scalenus anterior:
Action: raises the 1st rib; bends neck to side
Scalenus muscles receives the nerve supply from the
root of the brachial plexus
Levator scapulae:
Nerve supply: Dorsal scapular nerve
Action: Raises the scapula
12. Occipital triangle:
Boundaries – trapezius,
sternocleidomastoid muscle
and the inferior belly of
omohyoid.
Floor: semispinalis capitis,
splenius capitis, levator
scapulae, Scalenus posterior
and scalenus medius.
Contents: spinal accessory
nerve, lymph nodes, lesser
occipital nerve and external
jugular vein
13. Boundaries:
sternocleidomastoid muscle,
inferior belly of omohyoid and
the middle third of the clavicle.
Floor: scalenus medius and
scalenus anterior
Contents: subclavian artery,
subclavian vein, subclavian
lymph trunk, supraclavicular
lymph nodes, transverse
cervical artery and vein,
suprascapular artery and vein
and brachial plexus
15. ANTERIOR TRIANGLE
CN XI (Levator Scapulae M)
Roots of Brachial Plexus
Exiting in the Scalene Gap
Omohyoid M
Subclavian
artery
S
C
M
POSTERIOR
TRIANGLE
Infrahyoid
(Strap) MM
Facial V
Retromandibular V
Internal Jugular V
External Carotid A
17. Boundaries:
mid line of neck from chin
to manubrium
anterior border of
sternocleidomastoid
base or inferior border of
the mandible
The investing layer of cervical
fascia anteriorly covers the
anterior triangle of the neck
and fuses with the opposite
fascia in the midline
18. Muscles in the Anterior Triangle
D
D
A
C
E
F
G
H
Suprahyoid Muscles
mylohyoid (A)
geniohyoid
stylohyoid (C)
digastric (D)
Infrahyoid Muscles
sternohyoid (E)
omohyoid (F)
sternothyroid (G)
thyrohyoid (H)
Cervical
Plexus
Submental triangle
Carotid triangle
Muscular triangle
Digastric triangle
Midline of the neck
19. Situation: situated below
the chin.
Boundaries:
• Anteriorly by the midline
of the neck.
• Laterally by the anterior
belly of digastric muscle
• Inferiorly by the body of
the hyoid bone
• Floor: by the mylohyoid
muscle
Content: submental lymph
nodes & anterior jugular
vein
20. Anteriorly: by the anterior belly of
digastric
Posteriorly: by the posterior belly of
digastric and stylohyoid muscle
Above : by the lower border of the
body of the mandible
Floor: is formed by the mylohyoid
and the hyoglossus muscle
Contents: The anterior part of the
triangle contains the
submandibular gland.
21. The facial artery lies deep to the gland, & the facial vein and
the submandibular lymph nodes lies superficial to the gland.
Deep to the gland the hypoglossal nerve lies on the
hyoglossus muscle
The nerve and vessels to the mylohyoid are also seen
In the posterior part of the triangle –
lies the carotid sheath with:
o the carotid arteries
o internal jugular vein
o the vagus nerve
The lower part of the parotid gland project into this triangle
22. Nerve to mylohyoid, and
submental vessels in the
digastric triangle
Parotid gland
Submandibular gland
Facial artery and vein
23. Situation: lies behind the hyoid
bone.
Boundaries:
Superiorly: by the posterior belly
of digastric
Inferiorly : by the superior belly
of omohyoid
Posteriorly : by the anterior
border of the sternocleidomastoid
muscle.
Floor:
◦ portion of the thyrohyoid
muscle
◦ hyoglossus muscle
◦ middle constrictor and
inferior constrictor muscles of
the pharynx
24. Contains carotid sheath, with the common carotid
artery dividing within the sheath into internal and
external carotid artery at the upper border of the
thyroid cartilage.
The internal jugular vein and its tributaries
The hypoglossal nerve with its descending branch
The internal and external laryngeal nerves
The accessory and vagus nerve.
Part of the chain of deep cervical lymph nodes
25. External carotid branches
i. superior thyroid artery
ii. ascending pharyngeal
artery
iii. lingual artery.
iv. facial artery
v. occipital artery
Facial vein
Lingual vein
Superior thyroid vein.
27. Greater horn of hyoid bone
Body of the hyoid bone
Lesser horn of hyoid bone
28. Muscles in the Anterior Triangle
D
D
A
C
E
F
G
H
Suprahyoid Muscles
mylohyoid (A)
geniohyoid
stylohyoid (C)
digastric (D)
Infrahyoid Muscles
sternohyoid (E)
omohyoid (F)
sternothyroid (G)
thyrohyoid (H)
Cervical
Plexus
Submental triangle
Carotid triangle
Muscular triangle
Carotid triangle
Midline of the neck
29. Situation: lies below the hyoid
bone.
Boundaries:
Anteriorly: by the mid line of the
neck
Superiorly: by the superior belly of
omohyoid muscle.
Inferiorly: by the anterior border of
the sternocleidomastoid muscle.
Floor: is formed by the sternohyoid
and sternothyroid muscles
beneath the floor lies the thyroid
gland, the larynx, trachea and the
oesophagus.
Contents : infrahyoid muscles
(sternohyoid, sternothyroid,
mylohyoid and thyrohyoid muscles)
Also includes the recurrent
laryngeal nerve, inferior laryngeal
artery and external laryngeal nerve.
30. Number of important
structures in the midline
1. median thyrohyoid
ligament
2.Laryngeal prominence
3. Cricothyroid ligament
4. isthmus of the thyroid
gland
( 2 to 4th tracheal ring)
Pyramidal lobe of thyroid
gland
Below the isthmus – the
inferior thyroid veins lie
anterior to the trachea
31. Hyoid bone
Anterior jugular vein
Thyroid cartilage
Thyrohyoid membra
Isthmus of the thyroid gla
Jugular arch
Inferior thyroid vein
Structures in the midline of the neck
32.
33.
34. An endocrine gland, situated in front of the neck.
The thyroid gland is a butterfly-shaped organ
Right and left lobes – joined by isthmus.
Pyramidal lobe – project upwards from the isthmus.
Accessory thyroid gland – small detached masses of
thyroid tissue found above the isthmus.
35.
36.
37. Corresponds to vertebrae C5, C6, C7, and T1.
Each lobe extends from middle of the thyroid
cartilage to the fourth or fifth tracheal ring.
Isthmus extends from second to the fourth tracheal
ring.
Reaches posteriorly the oesophagus and carotid
sheath.
38. Thyroid
The thyroid gland is composed of two lobes
connected by an isthmus that lies on the trachea
approximately at the level of the second tracheal
ring.
The gland is enveloped by the deep cervical fascia
and is attached firmly to the trachea by the
ligament of Berry.
Between the two layers of the capsule and on the
posterior side of the lobes, there are on each side
two parathyroid glands.
39. Thyroid
Each lobe resides in a bed between the trachea
and larynx medially and the carotid sheath and
sternocleidomastoid muscles laterally.
The strap muscles are anterior to the thyroid
lobes, and the parathyroid glands and recurrent
laryngeal nerves are associated within the
posterior surface of each lobe.
