Muscles of Mastication + Eustachian tube - Steph

Question 1

Describe the sphenoid bone and locations?

Answer 1

Central body (housing Stella Turcica + 4 clinoid processors) +
Lesser wings
Right Greater Wing + Pterygoid Plates
Left Greater Wing + Pterygoid Plates
Articulates with all bones in the cranium.

Question 2

What connects to the clinoid processors

Answer 2

Tentorium cerebelli

Question 3

Describe the eustachian tube pathway - (describe using a skull),

Answer 3

It is the canal passes from the middle ear to the nasopharynx enabling drainage of the middle ear to the back of the upper throat behind the nasal cavity.
Starts within the temporal bone btw the cartoid canal (posteriorly) and foramen ovale (anteriorly) > passes along inferior surface of the spheno-temporal suture at base of skull > terminates into nasopharynx close to pterygoid plate of sphenoid (see fig 35.8 pg 295)

Question 4

Describe the eustachian tube drainage and symptoms

Answer 4

Drains into the back of the upper throat.
When the eustachian tube will not open enough to equalize pressure, symptoms such as discomfort, dizziness, or ringing in the ear may be felt.
Nasal congestion, infection of the ear or sinus, or allergies can affect the eustachian tube
The eustachian tube opens during external rotation of the temporal bones and closes during internal rotation.

Question 5

What are the 4 muscles of mastication

Answer 5

Temporalis muscle
Masseter muscle
Medial pterygoid muscle
Lateral pterygoid muscle

Question 6

What bones does the Temporalis muscle attach to and which nerve innervates it .

Answer 6

Mandible at the medial side of coronoid process and ramus, 
Temporal bone, 
Parietal bones, 
Frontal bone and 
Greater wing sphenoid
Cr V3 Mandibular (Motor division)
(pg 117, fig 14.1)

Question 7

What bones does the Masseter muscle attach to and which nerve innervates it

Answer 7

Starts at zygomatic arch of the temporal bone
Attaches to lateral surface of the ramus of the mandible and extend down nearly to the angle of the jaw.
Cr V3 Mandibular (Motor division)
(pg 117, fig 14.2)

Question 8

What bones does the Medial pterygoid muscle attach to and which nerve innervates it

Answer 8

Medial pterygoid muscle has 2 heads. one large and one small
Large - Originates medial surface of the lateral pterygoid plates on sphenoid
Small - Originates palatine bone and maxilla
Both pass inferiorly and lateral to attach to the medial surface of the ramus of the mandible on each side. .
Extends from the angle of the jaw upwards along the ramus as far as the mandibular foramen.
Cr V3 Mandibular (Motor division)
(pg 118, fig 14.3, 14.5)

Question 9

What bones does the Lateral pterygoid muscle attach to

and which nerve innervates it

Answer 9

Lateral pterygoid muscle has 2 heads. one superior and one inferior
Superior head - originates from greater wing of sphenoid.
Inserts into temporo-mandibular joint and attaches to the articular disc in joint.
Inferior head - originates from lateral surface of the lateral pterygoid plates of sphenoid. Passes our laterally to neck of mandible just below condyle.
Cr V3 Mandibular (Motor division)
(pg 118, fig 14.4, 14.5)