Muscles of the Head and Neck: Mastication, Suprahyoid, Infrahyoid, Tongue

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

12. 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

13. Suprahyoid Muscles

14. 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 (V ₃ ). The posterior belly is innervated by the facial nerve (VII).

15. 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 ( V ₃ ).

16. 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) L ocated above the Mylohyoid muscle

17. 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.

18. Suprahyoid Muscles

19. Suprahyoid Muscles

20. 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

21. Infrahyoid Muscles

22. 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.

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

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

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

26. Infrahyoid Muscles

27. 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

28. 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

29. 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 .

30. 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 I t aids in widening the tongue tip.

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

32. 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

33. 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

34. 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. D raws the tongue up and backward

35. Suggested Homework Complete pages 245-247 in the textbook