Muscles of facial expression

Question 1

Muscles of facial expression

Answer 1

• Innervated by the facial nerve
• Not covered by fascia, except the buccinator
• Includes:

1. Forehead muscles (2)
2. Muscles of the palpebral fissure (3)
3. Muscles of the mouth (11)
4. Muscles of the nose (1)

Question 2

Gala aponeurotica

Answer 2

• The forehead muscles converge onto it from the front, back and sides
• It grows together with head skin
• Through a layer of porous smooth subgaleal CT it connects witht he skull periosteum of the cranial vault
• Removed during scalping

Question 3

Occipitofrontalis

Answer 3

• Has two bellies

1. Occipital - originates on linea nuchae suprema ossis occipitalis, runs cranially and inserts onto galea aponeurotica
2. Frontal - originates from the anterior margin of the galea aponeurotic, radiates frontally and caudally, and inserts into the skin of the upper eyelid and forehead

• Function: Occipital - traction of skin dorsally (erases wrinkles), Frontal - transverse forehead wrinkles and elevation of the superior palpebra

Question 4

Temporoparietalis

Answer 4

• Rudimentary muscle
• Origin: superior border of the cartilaginous auricula
• Insertion: lateral border of galea aponeurotica
• Function: Pulls auricula superiorly

Question 5

Orbicularis oculi

Answer 5

• Three parts:

1. Pars palpebralis
2. Pars Orbitalis
3. Pars lacrimalis (Horner muscle) - originates on crista lactimalis posterior and on the dorsal side of saccus lacrimalis, and inserts into the margins of the eyelids

• The palpebral and orbital parts originate from the medial palpebral ligament and then encircle the eyelids and aditus orbitae, with the orbital part being more peripheral
• Function: forms the basis of eye-lids, its contraction causes contraction of the lids and winking, the lacrimal part enlarges the saccus lacrimalis and so helps suction tears from the conjunctival sac

Question 6

Corrugator supercili

Answer 6

• Origin: frontal bone, above sutura nasofrontalis
• Runs laterocranially
• Insertion: skin over the middle and lateral parts of the eyebrows
• Function: shifts eyebrow skin to the middle plane, causing vertical furrowint over radix nasi

Question 7

Procerus

Answer 7

• Origin: radix nasi
• Diverges in a fan like shape cranially
• Insertion: skin in the glabellar area
• Function: contraction causes transverse skin foldes above radix nasi
• It is an antagonist to the frontal belly of the orbitofrontalis muscle

Question 8

Nasalis

Answer 8

• Origin: juga alveolaria of the upper lateral incisor and canine teeth
• Divides into two parts:

1. Alar part - inserts into ala nasi
2. Transverse part - inserts into dorsum nasi

• Function: narrowing of nostril

Question 9

Orbicularis oris

Answer 9

• Circular shape
• Encircles oral fissure
• Starts on juga alveolaria of upper and lower incisors, and contiguous inferior part of apertura piriformis
• Firmly connected to labial skin
• Connection with oral vestibule mucosa is looser
• Part of its fibres run towards the nasal septum and become the m. depressor septi
• Function: mouth closing, labial constriction, labial puckering, and the m. depressor septi pulls cuadally the cutaneous part of the nasal septum

Question 10

Depressor anguli oris

Answer 10

• Triangular shape
• Origin: Basis mandibulae
• Insertion: skin of angulus oris
• Function: traction of angulus oris caudally

Question 11

Depressor labi inferioris

Answer 11

• Plane quadrangular muscle
• Origin: basis mandibulae
• Ascends cranially
• Insertion: skin of labium inferioris
• Partly overlapped by depressor anguli oris
• Function: traction of lower lip caudally

Question 12

Risorius

Answer 12

• Thin longitudinal muscle
• Origin: fascia masseterica
• Runs ventrocaudally
• Insertion: skin of angulus oris
• Function: traction of oral angle laterocranially, causes cheek dimples in some people

Question 13

Levator labii superioris alaeque nasi

Answer 13

• Origin: processus frontalis of maxilla and dorsum nasi
• Insertion: skin in the nasolabial sulcus and skin of ala nasi
• Function: elevation of upper lip and enlargement of nostrils

Question 14

Zygomaticus minor

Answer 14

• Origin: inferior edge of aditus orbitae (more cranially than zygomaticus major)
• Insertion: labium superius in the area of the nasolabial sulcus (more medially than zygomaticus major)
• Function: pulls angulus oris laterocranially

Question 15

Zygomaticus major

Answer 15

• Origin: anterior surface of the zygomatic body (caudally to zygomaticus minor)
• Insertion: skin of sulcus nasolabialis (laterally to zygomaticus minor)
• Function: pulls angulus oris laterocranially

Question 16

Levator anguli oris

Answer 16

• Origin: facies anterior corporis maxillae and fossa canina (below foramen infraorbitale)
• Descends to angulus oris
• Insertion: fibres intertwine with orbicularis oris and depressor anguli oris
• Function: elevates angulus oris

Question 17

Mentalis

Answer 17

• Origin: juga alveolaria of lower incisors
• Runs mediocaudally
• Insertion: chin skin
• Funtion: pulls chin skin cranially creating a chin dimple and elevates lower lip cranially

Question 18

Buccinator

Answer 18

• Strong flat muscle
• Origin: processus alveolaris maxillae (till last molars), tuber maxillae and raphe buccopharyngea and processus alveolaris mandibulae (till last molars)
• Insertion: angulus oris
• Functon: facial compression to processus alveolares of both jaws during filling of vestibulum oris, it enlarges the oral slit during laughing or weeping, muscle contraction diminishes size of vestibulum oris, and during UC pulls angulus oris to HLS - enlargement of oral slit
• Separated from oral vestible by mucous membrane
• Penetrated by parotid duct
• Compact adipose body adjoins the dorsal part of the muscle, and dorsally reaches to fossa infratemporalis
• Covered by thin fascia buccopharyngea

Question 19

Raphe buccopharyngea

Answer 19

• a ligamentous band running from hamulus pterygoideus to posterior part of linea mylohyoidea mandibulae

Question 20

Rudimentary muscles

Answer 20

• Of the external ear
• temporoparietalis, auricularis anterior, auricularis superior and auricularis posterior
• Also innervated by the facial nerve (CN V)