Head 2 (muscles) Flashcards
1) Zygomaticus
2) Levator nasolabialis
3) Orbicularis oris
4) Cutaneous facei
5) Cutaneous colli
6) Platysma
Buccinator insertions and action
Attaches to the mandible & maxilla @ the alveolar margins of the teeth.
It draws cheeks inward against teeth as in suckling and whistling.
Supports cheek and helps keep food in the oral cavity (even though not technically muscle of mastication), but if injured then food will pool in the cheeks/oral vestibule
Levator nasolabialis action
Dilate nostril and elevate upper lip
Orbicularis oris fiber orientation and action
fibers run longitudinally
around the mouth opening.
It draws the lips together into “O” shape (“muscle of kissing”)
Name the two components of the platysma
Cutaneous facei
Cutaneous colli
Name where the levator labii superioris originates and where it inserts
originate @ Infraorbital foramen → upper lip & nostril
1) Zygomaticus
2) Levator nasolabialis
3) Levator labii superioris
4) caninus
5) orbicularis oris
6) Buccinator
1) Buccinator
2) Caninus
3) Levator labii superioris
4) levator nasolabialis
5) zygomaticus
Caninus muscle action in dog and horse
Dog = snarling (show canines)
Horse: Flaring/dilation of nostrils
1) Levator nasolabialis
2) Caninus
3) Levator labii superioris
4) Orbicular oris
5) Buccinator
6) Zygomaticus
7) Depressor labii inferioris
Clin sig of levator nasolabialis
Muscle flaps used to close maxillary sinus defects
1) levator nasolabialis
2) levaotor labii superioris
3) orbicularis oris
4) buccinator
1) Levator nasolabialis
2) levator labii superioris
3) caninus
4) depressor labii superioris
5) orbicularis oris
6) buccinator
Clin sig of levator labii superioris (maxillaris) m
Covers the IOF. (push it dorsally to palpate the for. & block the infraorbital n).
Levator labii superoris species difference in pig and horse
In equine: the 2 tendons join → aponeurosis → upper lip. Important in eating (horses) Lips are the 1ry organs for food prehension in horse (the tongue in case of ox)
It is important in rooting activity (pigs) as it moves the rostrum or snout (the muscle
is attached to the os rostri)
Which muscles close the mouth
Masseter, temporalis, pterygoid (medial and lateral)
Which muscle(s) opens the mouth
Digastricus (rostral and caudal belly)
occipitomandibularis in horses only
Describe innervation for muscles of facial expression
all by CN 7 (facial)
Describe innervation for muscles of mastication
Mandibular br of trigeminal nerve (5)
Note: caudal belly of digastricus supplied by facial (7)
1) Temporalis
2) Masseter
3) Digastricus
4) Pterygoids
Describe the location of the masseter m
Palpable subcutaneously, ventral to zygomatic arch, cranial to parotid sg and caudal to facial v.
From zygomatic arch to lateral ramus of mandible
Name this muscle
Masseter m
Clin sig of masseter muscle
Due to thick fascia –> can be a cause of compartment syndrome
Atrophy can be a sign of CN5 disease
Which is the largest masticastory muscle in carnivores
Temporalis m
Name the location and origin/insertion of the temporalis m
- It fills the temporal fossa and gives the area
the rounded appearance.
Origin (1): from bones of temporal fossa Insertion (2) : the coronoid process of
mandible
Clin sig of temporalis m
Can be used to fill in defect left by removing an eyeball (cosmetic sx) by transpositioning a muscle flap to cover the orbit
Can be done because the cr and ca parts have their own blood and nerve supply
Name this muscle
Temporalis m
Clin sig of digastricus m
If Paralyzed → jaw being locked in a closed-mouth position.
Species difference of digastricus m
- in carnivores it has no 2 visible bellies
Horses have a “third” part called occipitomandibularis m
What muscle is this
Digastricus m
1) rostral belly
2) Fibrous intersection
3) Caudal belly
4) Digastricus
1) Rostal belly of digastricus
2) intermediate tendon
3) caudal belly of digastricus
4) occipitomandibularis (unique to horses)
Pterygoid origin and insertions
Origin: pterygopalatine fossa
Insertion:
* The medial → angular process of the mandible
* The lateral → pterygoid fovea
Pterygoid action
Assists masseter in closing mouth and horizontal/lateral chewing
Name this muscle
Pterygoid muscle
1) lateral pterygoid
2) medial petrygoid
3) medial pterygoid
4) lateral petygoid
Describe tongue innervation
Hypoglossal (CN 12) innervates all muscles (intrinsic and extrinsic)
Describe the intrinsic tongue muscles
Longitudinal, vertical & transverse muscle bundles intermixed with fat
This fat is very resistant to mobilization in starvation
when contract stiffens the tongue
Name the extrinsic tongue muscles
Hyoglossus
Genioglossus
Styloglossus