Muscles of mastication

Question 1

Muscles of mastication

Answer 1

Four paired muscles: 
Masseter
 Temporalis
 Medial pterygoid
 Lateral pterygoid
ORIGIN & INSERTION: varies
ACTION: responsible for moving the jaw; depression, elevation, protrusion, retraction, lateral deviation
INNERVATION: trigeminal (V) mandibular division

Question 2

Masseter muscle

Answer 2

Most superficial, largest, strongest of 4 muscles of mastication.
Originates from two heads superficial and deep. Both originate on the zygomatic arch.
nsert on the external surface of mandible
Superficial head on lateral surface of the angle
Deep head on the ramus superior to the angle

Question 3

Masseter action

Answer 3

elevates the mandible (Closes mouth)

Question 4

Masseter pathology

Answer 4

Habitual clenching or bruxism can lead to masseteric hypertrophy
Can be confused with parotid gland pathology, dental infection, maxillofacial cancer

Question 5

Temporalis muscle (origin and insertion)

Answer 5

ORIGIN & INSERTION
Originates on temporal fossa of temporal bone
Inserts on coronoid process of mandible

Question 6

Temporalis muscle Action

Answer 6

When the entire muscle contracts, it elevates the mandible-closing the jaw
Contraction of ONLY the posterior portion causes retraction of the mandible

Question 7

Medial Pterygoid muscle (Origin and insertion)

Answer 7

Origin- Deep head: lateral pterygoid plate of sphenoid bone
Superficial head: process of the palatine bone & maxillary tuberosity
INSERTION
Both heads: medial surface of ramus and angle of the mandible

Question 8

Medial Pterygoid muscle Action

Answer 8

elevates (closes) the mandible

Question 9

Lateral Pterygoid Muscle (Origin and insertion)

Answer 9

Entire muscle lies within infratemporal fossa
ORIGIN & INSERTION:
Two heads of separate origin: superior & inferior
Superior head originates from greater wing of sphenoid
Inserts with the articular disc of TMJ & anterior condyle
Inferior head originates from the lateral pterygoid plate of sphenoid
Inserts on the anterior condyle of mandible

Question 10

Lateral Pterygoid Muscle Action

Answer 10

Only muscle of mastication that assists in depressing mandible, opening jaw
When both muscles contract, brings lower jaw forward (protrusion)
When only one side contracts, jaw shifts to opposite side (lateral deviation of mandible)

Question 11

Hyoid muscles

Answer 11

Grouped as suprahyoid or infrahyoid muscle
Aid in mastication & swallowing
Most muscles are in a superficial position in the neck tissue

Question 12

Suprahyoid Muscle group

Answer 12

Located superior to the hyoid; act to raise the hyoid & larynx
 Digastric
 Mylohyoid
 Stylohyoid,
 Geniohyoid

Question 13

Digastric Muscle (Origin and insertion)

Answer 13

ORIGIN & INSERTION:
Anterior belly originates from tendon on hyoid bone; inserts near the symphysis of mandible
Posterior belly originates from mastoid notch; inserts on intermediate tendon of hyoid

Question 14

Digastric Muscle action

Answer 14

Pulls back the jaw

Question 15

Mylohyoid muscle (Origin and Insertion)

Answer 15

ORIGIN & INSERTION:
Originates from the mylohyoid line on medial surface of mandible
Inserts on body of hyoid

Question 16

Mylohyoid muscle action

Answer 16

Forms floor of the mouth
Elevates the tongue
Assists in elevating mandible
Elevates the hyoid bone

Question 17

Stylohyoid muscle (Origin and Insertion)

Answer 17

ORIGIN & INSERTION
Originates from stylohyoid process of temporal bone
Inserts on body of hyoid

Question 18

Stylohyoid muscle action

Answer 18

Elevates the hyoid bone

Question 19

Geniohyoid Muscle (Origin and Insertion)

Answer 19

Originates from the genial tubercles on the mandible

Inserts into the body of the hyoid

Question 20

Geniohyoid Muscle Action

Answer 20

Elevates hyoid bone

Question 21

Infrahyoid muscle group

Answer 21

Inferior to hyoid bone
Include:
 sternothyroid
 sternohyoid
omohyoid
 thyrohyoid
Most infrahyoid muscles act to depress the hyoid bone

Question 22

Sternothyroid Muscle (Origin and Insertion)

Answer 22

Originates on sternum; inserts on thyroid cartilage

Superficial to thyroid gland

Question 23

Sternothyroid Muscle action

Answer 23

Depresses the thyroid cartilage and the larynx (NOT the hyoid)

Question 24

Sternohyoid muscle (Origin and insertion)

Answer 24

Originates on the sternum
Inserts on body of the hyoid
Superficial to sternothyroid, thyroid cartilage & gland

Question 25

Omohyoid muscle (Origin and insertion)

Answer 25

Lateral to sternothroid & thyrohyoid
Two bellies: superior & inferior
ORIGIN & INSERTION
Inferior belly originates from scapula & attaches to tendon of superior belly, which is then the origin of the superior belly that inserts on the body of the hyoid

Question 26

Thyrohyoid muscle (Origin and insertion)

Answer 26

Located deep to omohyoid & sternohyoid
ORIGIN & INSERTION:
Originates on the thyroid cartilage
Inserts on body and greater cornu of the hyoid bone
In addition to depressing the hyoid, it raises the thyroid cartilage and larynx

Question 27

Muscles of the tongue

Answer 27

Aid in speech, mastication, swallowing
All are innervated by hypoglossal nerve (XII)
Grouped into intrinsic and extrinsic muscles

Question 28

Intrinsic tongue muscles

Answer 28

Located entirely within the tongue
Includes the superior longitudinal, inferior longitudinal, transverse, vertical muscles
Superior & inferior longitudinal muscles change the shape of tongue, shortening & thickening, act singly to curl tongue in various directions
Transverse & vertical muscles act together to lengthen and narrow the tongue

Question 29

Extrinsic tongue muscles

Answer 29

All insert inside the tongue; their names indicate their origin
Genioglossus 
protrudes the tongue
Styloglossus
retracts the tongue
Hyoglossus
depresses the tongue

Question 30

pharynx

Answer 30

Pharynx consists of three parts:
nasopharynx
oropharynx
laryngopharynx

Question 31

Muscles of the pharynx

Answer 31

The muscles of the pharynx include:
Stylopharyngeus
Pharyngeal constrictor
Soft palate muscles

Question 32

Muscles of the soft palate (five paired muscles)

Answer 32

Palatoglossus
Palatopharyngeus,
Levator veli palatini 
Tensor veli palatini, 
Muscle of the uvula