Lectures in head and neck anatomy

1. The anterior triangle
Boundaries:
- Superiorly: body of the
mandible
- Posteriorly:
sternocleidomastoid
muscle
- Anteriorly: midline
Subdivisions:
- Carotid triangle
- Digastric triangle
- Submental triangle
- Muscular triangle

2. Submandibular
(Digastric) triangle
Boundaries:
- Superiorly:
inferior border
of the mandible
- Inferiorly:
anterior and
posterior bellies
of the digastric
muscle
Contents: Submandibular gland; submandibular lymph nodes; hypoglossal
nerve [XII]; mylohyoid nerve; facial artery and vein
Floor: formed by the mylohyoid and hyoglossus muscles and the middle
pharyngeal constrictor

3. Submental triangle
Boundaries:
Inferiorly: the
hyoid bone
Laterally: the
anterior belly of
the digastric
muscle
The midline
Contents:
Submental lymph
nodes; tributaries
forming the
anterior jugular
vein
Floor: formed by
the two
mylohyoid
muscles

4. Muscular triangle
Boundaries:
Superiorly: the
hyoid bone,
Laterally: the
superior belly of the
omohyoid muscle,
and the anterior
border of the
sternocleidomastoid
muscle
The midline
Contents:
Sternohyoid,
omohyoid,
sternohyoid, and
thyrohyoid muscles;
thyroid and
parathyroid glands;
pharynx
Floor: formed by the sternohyoid, sternothyroid,
muscles

5. Carotid triangle
Boundaries:
Anteroinferiorly:
the superior belly of
the omohyoid
muscle
Superiorly: the
stylohyoid muscle
and posterior belly
of the digastric,
Posteriorly:
anterior border of
the
sternocleidomastoid
muscle.
Floor: thyrohyoid, hypoglossus, middle and inferior constrictors of pharynx
Contents:
Tributaries to common facial vein; cervical branch of facial nerve [VII]; common
carotid artery; external and internal carotid arteries; superior thyroid; ascending
pharyngeal; lingual, facial, and occipital arteries; internal jugular vein; vagus [X],
accessory [XI], and hypoglossal [XII] nerves; superior and inferior roots of ansa
cervicalis; transverse cervical nerve

6. Digastric:
Origin
(Posterior belly):
Mastoid process
(Anterior belly):
Digastric fossa on
lower inside of
mandible
Insertion: Intermediate
tendon is held to hyoid
by fascial sling
NS:
Anterior : Nerve to
mylohyoid
Posterior: Facial nerve
Action: Depresses
mandible or elevates
hyoid bone
Muscles in the anterior triangle

7. Stylohyoid:
Origin: Styloid
process
Insertion: Lateral
area of body of
hyoid bone
NS: Facial nerve
Action: Elevates
hyoid bone
Muscles in the anterior triangle

8. Mylohyoid:
Origin: Mylohyoid line of body of mandible
Insertion: Body of hyoid bone
NS: Inferior alveolar nerve
Action: Elevates floor of mouth and hyoid bone or depresses
mandible
Muscles in the anterior triangle

9. Geniohyoid
Origin: Inferior mental spine of mandible
Insertion: Body of hyoid bone
NS: 1st cervical nerve
Action: Elevates hyoid bone or depresses mandible
Muscles in the anterior triangle

11. Sternohyoid
Origin: Manubrium sterni and clavicle
Insertion: Body of hyoid bone
NS: Ansa cervicalis; C1, 2, and 3
Action: Depresses hyoid bone
Muscles in the anterior triangle

12. Sternothyroid
Origin: Manubrium sterni
Insertion: Oblique line on lamina of thyroid cartilage
NS: Ansa cervicalis; C1, 2, and 3
Action: Depresses larynx
Muscles in the anterior triangle

13. Thyrohyoid
Origin: Oblique line on lamina of thyroid cartilage
Insertion: Lower border of body of hyoid bone
NS: 1st cervical nerve
Action: Depresses hyoid bone or elevates larynx
Muscles in the anterior triangle

14. common carotid artery
The right common carotid artery arises from the brachiocephalic
artery
The left artery arises from the arch of the aorta
Runs under cover of the anterior border of the sternocleidomastoid
muscle
Begins: sternoclavicular joint
Ends: upper border of the thyroid cartilage.
Divisions: external and internal carotid arteries

15. common carotid artery
The carotid sinus: localized
dilatation in the terminal part
of the common carotid artery
Contains numerous nerve
endings derived from the
glossopharyngeal nerve.
serves as a reflex
pressoreceptor mechanism
The carotid body: is a small
structure that lies posterior to
the point of bifurcation of the
common carotid artery
Innervated by the
glossopharyngeal nerve.
The carotid body is a
chemoreceptor, being
sensitive to excess carbon
dioxide and reduced oxygen
tension in the blood.

16. Anterolaterally:
skin, fascia,
sternocleidomast
oid, sternohyoid,
sternothyroid, and
the superior belly
of the omohyoid
Posteriorly: The
transverse
processes of the
lower four
cervical
vertebrae, the
prevertebral
muscles, and the
sympathetic trunk
(In the lower part
of the neck are
the vertebral
vessels.
Relations of common carotid artery

17. Organized into several distinct layers:
Investing layer: which surrounds all structures in the neck
Prevertebral layer: surrounds the vertebral column and the deep muscles
associated with the back
Pretracheal layer: encloses the viscera of the neck
Carotid sheath: vascular
Deep cervical fascia

18. Medially: The larynx
and pharynx and,
below these, the
trachea and
esophagus The lobe
of the thyroid gland
Laterally: The
internal jugular vein
and,
posterolaterally,the
vagus nerve
Relations of common
carotid artery

19. Begins: at the level of the
upper border of the thyroid
cartilage
Terminates: in the
substance of the parotid
gland behind the neck of
the mandible by dividing
into the superficial temporal
and maxillary arteries.
Medial to the internal
carotid artery, then passes
backward and lateral to it.
Crossed by the posterior
belly of the digastric and
the stylohyoid
The external carotid artery

20. Relations of the
External
Carotid Artery
Anterolaterally:
- Beginning: anterior
border of the
sternocleidomastoi
d
- Crossed by: the
hypoglossal nerve
the posterior belly
of the digastric
muscle, and the
stylohyoid muscles.
Within the parotid
gland, facial nerve
- The internal
jugular vein first
lies lateral to the
artery and then
posterior to it.
Medially: The wall of the pharynx and the internal
carotid artery. The stylopharyngeus muscle, the
glossopharyngeal nerve, and the pharyngeal branch of
the vagus pass between the external and internal
carotid arteries

21. Branches of the External Carotid Artery
Superior Thyroid
Artery: curves
downward to the
upper pole of the
thyroid gland, It is
accompanied by
external laryngeal
nerve, which
supplies the
cricothyroid muscle.
Ascending
Pharyngeal Artery:
ascends along and
supplies the
pharyngeal wall.
Lingual Artery:
loops upward and
forward and
supplies the tongue

22. Facial Artery
Occipital Artery
Posterior Auricular
Artery
Superficial Temporal
Artery
Maxillary Artery
Branches of the External Carotid Artery