Triangle anterior

2. Anterior Triangle of the Neck

3. Boundaries
 In front: Middle line of the
neck
 Behind: Anterior margin of the
sternocleidomastoid muscle
 Base, directed upward,
formed by the lower border of
the body of the mandible, and
a line extending from the
angle of the mandible to the
mastoid process
 Apex is below, at the sternum
 Roof: skin, investing layer of
cervical deep fascia,
platysma

4. Subdivisions
*

5. Digastric Triangle: Boundaries
 Anterior: Anterior belly
of digastric
 Posterior: Posterior
belly of digastric &
stylohoid
 Above: Lower border
of mandible
 Floor: Mylohyoid,
hyoglossus & superior
constrictor of pharynx

6. Digastric Triangle: Contents
Anterior part:
 Submandibular gland
 Facial artery
 Facial vein
 Submandibular lymph
nodes superficial to gland
 Hypoglossal nerve
 Nerve & vessels to
mylohyoid muscle

7. Digastric Triangle: Contents
Posterior part:
 Carotid sheath with its
contents
 Stylopharyngeus
muscle
 Glossopharyngeal
nerve
 Lower part of parotid
gland

8. Submental Triangle
 Lies below the chin
 Boundaries:
 Anterior: midline of the
neck
 Lateral: Anterior belly
of digastric
 Inferior: body of hyoid
 Floor: mylohyoid
 Contents: submental
lymph nodes; beginning
of the anterior jugular
vein

9. Carotid Triangle: Boundaries
 Superior: by the posterior
belly of digastric
 Inferior: by superior belly of
omohyoid
 Posterior: by anterior
border of sternomastoid
 Floor: formed by thyrohoid,
hyoglossus, middle &
inferior constrictors of
pharynx
 Roof: skin, superficial
fascia, platysma, investing
layer of deep fascia

10. Carotid Triangle: Contents
 Carotid sheath with CCA
dividing into EC & IC,
 Branches of EC, IJV and
its tributaries.
 Hypoglossal nerve & its
descending branch
 Internal & external
laryngeal nerves
 Vagus nerve
 Accessory nerve
 Part of chain of deep
cervical lymph nodes

11. Carotid Triangle: Contents

12. Carotid Sheath
 Condensation of deep
cervical fascia
 Extends from the base of
the skull to the root of the
neck
 Contains:
 Common & internal
carotid arteries medially
 Internal jugular vein
laterally
 Vagus nerve posteriorly
 Deep cervical lymph
nodes

13. Muscular Triangle: Boundaries
 Lies below the hyoid
bone
 Bounded:
 Anteriorly by the midline
of the neck
 Superiorly by superior
belly of omohyoid
 Inferiorly by the anterior
border of sternomastoid
 Floor: sternohyoid &
sternothyroid muscles
 Beneath the floor lies the
thyroid gland, larynx,
trachea

14. Infrahyoid Muscles
 Include:
 Sternohyoid
 Omohyoid
 Sternothyroid
 Thyrohyoid
 Stabilize hyoid bone
 Help in movements of
the larynx during
swallowing

15. Sternohyoid
 Origin: posterior
surface of manubrium
 Insertion: lower
border of body of
hyoid
 Nerve supply: ansa
cervicalis (C1, 2, 3)
 Action: Depresses the
hyoid bone

16. Sternothyroid
 Lies deep to the
sternohyoid
 Origin: posterior surface
of manubrium
 Insertion: Oblique line on
the lamina of thyroid
cartilage
 Nerve supply: ansa
cervicalis (C1, 2, 3)
 Action: Depresses the
larynx

17. Thyrohyoid
 Origin: Oblique line on
the lamina of thyroid
cartilage
 Insertion: lower border
of body of hyoid
 Nerve supply: C1 via a
branch of hypoglossal
nerve
 Action: Depresses the
hyoid bone or elevates
the larynx

18. Ansa Cevicalis
 A loop of nerves
 Embedded in the anterior wall
of the carotid sheath
 Formed by the union of
superior & inferior rami.
 Superior ramus (descendens
hypoglossi): composed of C1
fibers descends in front of IC &
CC arteries
 Inferior ramus (descendens
cervicalis) composed of C2 &
C3 fibers
 Branches: supply omohyoid,
sternohyoid & sternothyroid
muscles

19. Clinical Notes
 Arteriosclerosis of the internal carotid artery may cause visual
impairment or blindness on the side of lesion (central retinal
artery, branch of opthalmic artery)
 Penetrating wounds of the neck may causea large, slowly
expanding hematoma due to hemorrhage from IJV
 Air embolism is a serious complication of a lacerated wall of
IJV (due to large lumen, little smooth muscle in the wall &
attachment of its adventitia to the wall of the carotid sheath..
which hinder the collapse of vein). Blind clamping of vein is
not allowed because of close vicinity of hypoglossal & vgus
nerves
 IJV is remarkably constant in position and is used for venous
catheterization

20. Structures in the Midline of the
Neck
 Hyoid bone
 Thyrohyoid membrane
 Thyroid cartilage
 Cricothyroid membrane
 Isthmus of thyroid gland
& levator glandulae
thyroidae
 Trachea
 Jugular venous arch
 Inferior thyroid veins