Gross - Facial Muscles, Eyelid & Ear

Front 1

Back 1

Circumoral glands in the cat

- large sebaceous glands

- more numerous in lower lip

- secretions used for scent marking

Front 2

Muscles of the head

Back 2

Somatic mm. develop from somites

- extrinsic eye mm., tongue mm.

Visceral mm. develop from pharyngeal arches

- mm. of mastication (1st PA)

- mm. of facial expression (2nd PA)

- pharyngeal constrictors (3rd PA)

- mm. of pharynx, larynx, esophagus (4th PA)

- COST mm., laryngeal mm. (5th & 6th PA)

Front 3

Facial muscles

Back 3

Involved with facial expression

- different from mm. of mastication (which raise/lower mandible to open/close mouth)

- innervated by CN VII (facial n.)

Front 4

Back 4

1) Facial n.(CN VII)

- exits skull caudal to acoustic meatus through stylomastoid foramen

- brs. into:

2) auriculopalpebral n.

3) dorsal buccal br.

4) ventral buccal br.

5) cervical br.

Front 5

Back 5

Platysma m. (a cutaneous m.)

O: dorsal median raphe of neck

I: angle of the mouth; radiates into orbicularis oris m.

N: dorsal & ventral buccal brs. & caudal auricular br. of facial n.

A: draw commissure of lips caudally

Front 6

Back 6

Orbicularis oris m.

- located along free border of lips around angle of mouth

N: dorsal & ventral buccal brs. of facial n.

A: close mouth, pull nose downward during sniffing, dilate nostril

Front 7

Back 7

Buccinator m.

- forms foundation of cheek (deep to platysma and partly deep to orbicularis oris)

I: alveolar margins of mandible & maxilla, & buccal mucosa

N: dorsal and ventral buccal brs. of facial n.

A: move food from vestibule to masticatory surface of teeth

Front 8

Back 8

Levator nasolabialis m.

O: frontal region btwn orbits & maxillary bone

I: edge of upper lip & external naris (nostril)

N: auriculopalpebral br. of facial n.

A: dilate nostril, raise upper lip

Front 9

Back 9

Zygomaticus m.

O: rostral angle of scutiform cartilage

I: commissure of lip

N: auriculopalpebral br. of facial n.

A: draw commissure of mouth dorsocaudally; draw scutiform cartilage (and ear) rostrally

Front 10

Back 10

Parotidoauricularis m.

O: caudal to laryngeal region, on or near ventral midline (blends with cervical fascia)

I: antitragus of ear

N: facial n.

A: depress the ear

Front 11

Eyelids

Back 11

Palpebra (pl - palpebrae)

1) superior eyelid

2) inferior eyelid

Palpebral fissure - opening btwn palpebrae

Commissures (canthi) = corners

3) lateral palpebral commissure

4) medial palpebral commissure

Front 12

Eyelids

Back 12

Lacrimal caruncle

- triangular prominence at medial angle of eye

- has small, fine hairs & sebaceous glands

Front 13

Eyelids

Back 13

2) Medial palpebral ligament

- attaches medial palpebral commissure to frontal bone

1) Lateral palpebral ligament

- attaches lateral palpebral commissure to zygomatic bone

Eyelashes

- present on superior palpebra, absent on inferior palpebra

Front 14

Tear film:

Superficial layer

Back 14

- Lipids secreted by tarsal (Meibomian) and ciliary glands located in palpebrae

- Limits evaporation of underlying aqueous layer

- Provides binding effect for tear film b/c of high surface tension

Front 15

Tear film:

Middle aqueous layer

Back 15

- Watery substance from lacrimal gland & superficial gland of 3rd eyelid

- Flushes foreign material from conjunctival sac & lubricates palpebral/corneal interfaces

Front 16

Tear film:

Inner mucoid layer

Back 16

-Mucoproteinaceous product of conjunctival cells

-Located btwn aqueous layer and cornea

-Binds aqueous film to cornea

Front 17

Back 17

*Tarsal (Meibomian) glands

-modified sebaceous glands

-secrete lipids, part of superficial layer of tear film

-better developed in superior eyelid

**Ducts open at eyelid margin

Front 18

Back 18

1) Lacrimal gland - dorsolateral to eye

2) Superficial gland of 3rd eyelid - ventromedial to eye

-both produce aqueous portion of tears

-innervated by facial n. (parasympathetic)

Front 19

Back 19

Third eyelid

-aka plica semilunaris or nictitating membrane

-comprised of a fold of palpebral conjunctiva and a T-shaped piece of cartilage

-lymphoid tissue located on medial surface

Front 20

Back 20

Superficial gland of the 3rd eyelid

-surrounds ventral portion of 3rd eyelid

Front 21

Conjunctiva

Back 21

Mucous membrane

-Produces inner mucoid layer of tear film

-Palpebral conjunctiva (10) covers inner surface of palpebraa

-Bulbar conjunctiva (11) covers rostral part of sclera, continuous with outer layer of cornea (8)

-Conjunctiva fornix (12) junction of palpebral & bulbar conjunctiva

-Conjunctival sac is space btwn eyeball & palpebra

Front 22

Aqueous tear flow

Back 22

-Lacrimal gland > thru ducts in superior palpebra >over anterior surface of eyeball > conjunctival sac located ventrally

-through superior & inferior lacrimal ducts (canaliculi)

-through lacrimal sac w/in lacrimal fossa of lacrimal bone

-through nasolacrimal duct > nasal vestibule

Front 23

Back 23

Nasolacrimal duct

-begins at lacrimal sac, located in lacrimal fossa of lacrimal bone

-courses through lacrimal canal of lacrimal & maxillary bones

-rostral to conchal crest, courses deep to nasal mucosa, along side of maxilla

-ends in nasal vestibule on ventral aspect of alar fold

Front 24

Eyelid muscles

Back 24

1) Orbicularis oculi m.

- encircles the eye, closes palpebral fissure

2) Levator anguli oculi medialis m.

- dorsomedial to eye, raises the eyelid

3) Retractor anguli oculi lateralis m.

- covers lateral palpebral ligament

- retracts lateral angle of eye caudally (squint)

Innervation: palpebral brs. of auriculopalpebral br. of facial n. (CN VII)

Front 25

Extrinsic ear mm.

Back 25

3 groups:

-Rostral auricular mm.

-Dorsal auricular mm.

-Caudal auricular mm.

Front 26

External ear

Back 26

1) auricle (aka pinna)

2) ear canal (external acoustic meatus)

- 2 parts: vertical & horizontal canals

Front 27

External ear:

-auricular cartilage

Back 27

-funnel shaped

-forms vertical ear canal, part of horizontal ear canal

Front 28

External ear:

-annular cartilage

Back 28

-btwn auricular cartilage and external acoustic meatus of temporal bone

-forms part of horizontal ear canal

Front 29

External ear:

-scutiform cartilage

Back 29

-small plate in muscles rostral and medial to the ear

Front 30

External ear (right)

Back 30

Helix

-lateral and medial borders

Front 31

External ear (right)

Back 31

Anthelix

-transverse ridge on inner aspect of auricle

Front 32

External ear (right)

Back 32

Marginal cutaneous sac

-aka cutaneous marginal pouch

-skin pouch

Front 33

External ear (right)

Back 33

1) Pretragic incisure

2) Tragus

3) Intertragic incisure

4) Antitragus

Front 34

Back 34

Middle ear - air filled

1) tympanic bulla

2) tympanic cavity

3) Internal auditory (Eustachian) tube-connects to nasopharynx

4) tympanic membrane (ear drum)

5) epitympanic recess

6) malleus

7) incus

8) stapes

Front 35

Middle ear - Cat

Back 35

Septum bullae divides tympanic bulla into two compartments

Front 36

Middle ear mm.

Back 36

Tensor tympani m.

-attaches to malleus

Stapedius m.

-attaches to stapes

-smallest m. in the body

Front 37

Back 37

Inner ear - in petrous temporal bone

-Vestibular system:

1) semicircular canals

2) vestibule

-Hearing

3) cochlea

Front 38

Inner ear fluids

Back 38

Perilymph - fills white spaces

Endolymph - fills blue spaces