Exam 1, DLA 1210

1. Muscles of the Head
and Neck
Part I
MASTICATION, SUPRAHYOID, INFRAHYOID, TOUNGE

2. General Information
Muscles create movement via contraction
Suspended between origin, fixed structure or end, and
insertion, the movable end
Names of muscles may give information about their
origin and insertion.
Muscles move in direction of origin, which explains
motion
Muscles of the head and neck are divided into eight
groups

3. Muscles move in
the direction of
their ORIGIN

4. Muscle names are USUALLY a
combination of two bones..
The first part is the origin,
and the second part is the
insertion.

5. 8 Groups of Muscles of the Head and Neck
 Muscles of mastication
 Suprahyoid muscles
 Infrahyoid muscles
 Muscles of the tongue
Muscles of facial
expression
Muscles of the neck
Muscles of the soft palate
Muscles of the pharynx

6. Muscles of Mastication
Elevate, protrude, retrude, or cause lateral
movement of mandible
Work during chewing, hence name
Innervated by mandibular branch of
trigeminal nerve (V3)
Maxillary artery provides blood supply

7. Muscles of Mastication

8. Muscles of Mastication
 Temporalis muscles: elevate the jaw
 Fan shaped muscle starts from the temporal fossa of the
temporal bone
 Fibers form an anterior and posterior portion
 Anterior fibers are vertical; posterior fibers are somewhat
horizontal
 The muscle inserts onto the coronoid process of the mandible
and may also insert in the mandible distal to the mandibular
third molar.
 Elevation of the mandible is accomplished when the entire
muscle contracts
 The mandible is retruded if any of the posterior fibers contract
 It can be palpated above the zygomatic arch.

9. Muscles of Mastication
 Massetter: powerful muscle of mastication and
consisting of two parts:
 Superficial origin
 Fibers begin on the anterior two-thirds of the inferior
border of the zygomatic arch
 Insertion is in the outer surface of the angle of the
mandible
 Deep origin
 Fibers start from the posterior one-third of the zygomatic
arch.
 Insertion is at the outside surface of the mandible and
coronoid process of the mandible
 Contraction of this muscle causes the mandible to
elevate
 It is easily observed when the jaws are clenched.

10. Muscles of Mastication
 Medial Pterygoid has both superficial
and deep origins
Elevates the mandible
Superficial fibers originate at the
maxillary tuberosity
Deep fibers originate from the medial
side of the lateral pterygoid plate
The muscle inserts on the medial surface
of the angle of the mandible.

11. Muscles of Mastication
 Lateral Pterygoid
 The smaller, superior head originates from the infratemporal
surface of the sphenoid bone and inserts into the articular disc of
the temporomandibular joint.
 The larger, inferior head originates from the lateral surface of the
lateral pterygoid plate and inserts in the pterygoid fovea of the
mandible.
 Remember the origin of the medial pterygoid is the medial surface of
the lateral pterygoid plate.
 If both lateral pterygoid muscles contract, the jaw protrudes.
 If only one lateral pterygoid muscle contracts, there is a lateral
shift of the mandible to the opposite side.
 Lateral excursion

13. Suprahyoid Muscles
Located above hyoid bone
Found between mandible and hyoid bone and
function to lower mandible or raise hyoid bone
Digastric is a slinglike muscle
Mylohyoid creates the floor of the mouth
Geniohyoid innervated by the hypoglossal
Stylohyoid originates at the styloid process

14. Suprahyoid Muscles

15. Suprahyoid- Digastric
 Fibers on either end and is connected in the center
by an intermediate tendon or sling.
 The anterior belly begins (originates) on the
digastric fossa of the mandible (inferior surface of
the mandible at the midline) and inserts into the
intermediate tendon.
 The posterior belly originates from the intermediate
tendon and inserts on the digastric notch (medial to
the mastoid process).
 The anterior belly is innervated by the mandibular
branch of the trigeminal (V₃).
 The posterior belly is innervated by the facial nerve
(VII).

16. Suprahyoid- Mylohyoid
 This muscle creates the floor of the mouth
 It begins on the Mylohyoid line of the mandible and inserts into a
raphe at its midline.
 It is innervated by the mandibular branch of the trigeminal nerve (V₃).

17. Suprahyoid- Geniohyoid
The muscle arises from the genial tubercles of the
mandible and inserts on the hyoid bone.
It is innervated by the hypoglossal nerve (XII)
Located above the Mylohyoid muscle

18. Suprahyoid- Stylohyoid
 The origin of this muscle is the styloid process
 Its insertion is the hyoid bone
 It lies near the posterior bely of the digastric
 It is innervated by the same branch of the facial nerve that supplies the posterior belly of the
digastric.

19. Suprahyoid Muscles

20. Suprahyoid Muscles

21. Infrahyoid Muscles
 Located below the hyoid bone, in front of the neck
Depresses the hyoid bone or fixes it in place so the surprahyoid
muscles can work.
Innervated by the first, second and third cranial nerves.
Omohyoid has two bellies joined by an intermediate tendon
Sternohyoid originates at the sternum
Sternothyroid arises from the sternum
Thyrohyoid originates on the thyroid cartilage

22. Infrahyoid Muscles

23. Infrahyoid- Omohyoid
 This muscle has two bellies that are joined by an intermediate tendon.
 The inferior belly comes from (originates) the scapula and ends (inserts) on the
intermediate tendon
 The superior belly originates on the intermediate tendon and inserts on the hyoid
bone.

24. Infrahyoid- Sternohyoid
 The origin of this muscle is the sternum (hence “sterno”) and
inserts into the hyoid bone.

25. Infrahyoid- Sterothyroid
This muscle originates from the sternum and inserts on
the thyroid cartilage.
It is located below the sternohyoid

26. Infrahyoid- Thyrohyoid
This muscle originates on the thyroid cartilage and
inserts into the hyoid bone

27. Infrahyoid Muscles

28. Muscles of the Tongue
Divided into two groups
Intrinsic and extrinsic
These muscles help the tongue change its shape and
position.
Tongue muscles are innervated by the hypoglossal
nerve (XII)
Glossal/glossus = tongue

29. Intrinsic Tongue Muscles
Lie in and are contained entirely within the tongue.
They are responsible for changes in the shape of the tongue and are
named for their direction in which they run.
These muscles are confluent (not viewed as individual muscles)
Superior and inferior longitudinal runs the length of the tongue assisting in
widening and moves the tip
Transverse are found on edges makes tongue narrow
Vertical runs from upper to lower widens the tongue tip

30. Intrinsic Tongue Muscles
 Superior longitudinal
 Runs the length of the tongue from anterior to posterior.
 Located near the top of the tongue
 Functions to widen the tongue and turn the tip up
 Inferior longitudinal
 This muscle also runs the length of the tongue from anterior to posterior, however, it lies near the bottom
of the tongue
 It also widens the tongue, but turns the tip DOWN.

31. Intrinsic Tongue Muscles
 Transverse
This muscle is found on the
lateral edges of the tongue
Function is to make the tongue
narrow
 Vertical
This muscle runs from the upper
surface to the lower surface of
the tongue
It aids in widening the tongue
tip.

32. Extrinsic Muscles of the Tongue
Originate from the close
structures and insert on or
intermingle with intrinsic
muscles
They aid in positioning the
tongue.

33. Extrinsic Muscles of the Tongue
Genioglossus
Origin is the genial tubercles and
insertion is on the tongue and
hyoid bone.
Anterior fibers retract the tongue,
posterior fibers push it forward.
does the majority of work for the
tongue

34. Extrinsic Muscles of the Tongue
Hyoglossus originates on the
hyoid bone and inserts on the
side of the tongue.
depresses the tongue and
draws the sides down

35. Extrinsic Muscles of the Tongue
 Styloglossus originates from the
styloid process and has two insertions
on the tongue.
 One head intermingles with the
inferior longitudinal and the other
joins with the hyoglossus.
 Draws the tongue up and backward

36. Suggested Homework
Complete pages 245-247 in the textbook