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
Where does the hyoglossus attach and what is its action
Basihyoid bone → tongue
- Draws tongue caudally
Where does the genioglossus attach and what is its action
Chin to tongue
- Draws tongue rostrally and ventrally
Where does the styloglossus attach and what is its action
- Stylohyoid bone to tongue
- Draws tongue caudodorsally
1) Hyoglossus
2) genioglossus
3) Styloglossus
List the muscles of the soft palate
Tensor veli palatini
Levator veli palatini
palatinus (intrinsic m of the soft palate)
1) tensor veli palatini
2) levator veli palatini
3) palatinus
Tensor veli palatini action and innervation
Depress
Mandibular n.(V3)
Levator veli palatini action and innervation
Elevate
IX,X
Palatinus action and innervation
Shorten
IX,X
List the hyoid muscles
(…hyoideus)
Sterno
Genio
Mylo
Stylo
Thyro
Omo (horse)
1) geniohyoidus
2) Mylohyoideus
What innervates the mylohyoid m
Mylohyoid nerve of CNV3
What innervates the geniohyoideus
CN 12
Describe the sternohyoideus physical characteristic
Strap like (on ventral aspect of trachea) - Longest hyoid M. (from manubrium to basihyoid -
Sternohyoideus action and innervation
Draws the tongue caudally -
Cervical spinal nerves & XII
Thryohyoideus origin and insertion
From lamina of thyroid cartilage to thyrohyoid bone
Thyrohyoideus action and innervation
retracts hyoid apparatus & tongue -
Nerve XII
1) Sternohyoideus
2) Thyrohyoideus
Describe the boundaries of the oropharynx
from palatoglossal arches- to base of the epiglottis.
* The root of the tongue is the ventral boundary.
Describe the nasopharyngeal opening
auditory “Eustachian” tube
- Connects nasopharynx to middle ear
- In the horse, it is guarded by salpingeopharyngeal
fold and leads to the guttural pouch (GP) - Tubal tonsil surround the opening.
What marks the junction of laryngopharynx and esophagus
Pharyngoesophageal limen
Pharyngoesophageal limen
List the rostral pharyngeal constrictor muscles
Pterygopharyngeus
palatopharyngeus
List the middle pharyngeal constrictor muscles
hyopharyngeus
List the caudal pharyngeal constructor muscles
Thyropharyngeus
Cricopharyngeus
List the dilator pharyngeal muscle
Stylopharyngeus
1) Pterygopharygeus
2) Stylopharyngeus
3) Cricopharyngeus
4) Median raphe
Where do all pharyngeal muscles insert?
pharyngeal raohe
List where the pharyngeal muscles originiate
Pterygopharyngeus (from pterygoid bone)
Palatopharyngeus (from aponeurosis of soft
palate)
Hyopharyngeus (from hyoid bone)
Thyropharyngeus (from thyroid cartilage)
Cricopharyngeus ( from cricoid cartilage)
stylopharyngeus (styloid bone)
What orientation are the fibers in the rostral pharyngeal muscles
longitudinal
What orientation are the fibers in the caudal pharyngeal muscles
circular
What innervates the pharyngeal muscles
CN 9 (stylopharyngeus) and 10
1) Tensor veli palatini
2) Levator veli palatini
3) Pterygopharyngeus
4) Palatopharyngeus
1) Pterygopharyngeus
2) Stylopharyngeus caudalis
3) Hyopharyngeus
4) Thyropharyngeus
5) Cricopharyngeus
cricopharyngeus clinical significance
Should remain contracted to prevent reflux of food unless swallowing
Not contracting can lead to esophageal reflux
Tonic contraction or dysfunction of this muscle can lead
to dysphagia. This is called Cricopharyngeal Achalasia
List the lymph nodes of the head
parotid ln
mandibular ln
lateral retropharyngeal ln
medial retropharyngeal ln
Describe location of parotid ln
Rostral to or embedded in the parotid SG.
Describe location of mandibular ln
Rostral to mandibular SG., near the linguofacial V.
In the horse, in the intermandibular space
Describe the location of the lateral retropharyngeal ln and species differences
constant in cats (inconstant in dogs)
- caudal to & covered by parotid SG. & caudal to tubus auris
Clin sig of medial retropharyngeal ln
collecting center of the head in the cat, dog and horse
all other head lnn drain here
In ruminants it is the lateral one that is the main ln
describe the location of the medial retropharyngeal ln and what important structures are nearby
medial to mandibular SG. -
ventromedial to wing of atlas (ventral to longus colli m.)
- related to:
- The terminal part of common carotid a.
- The dorsolateral aspect of the pharynx
1) parotid ln
2) mandibular ln
3) lateral retropharyngeal ln
4) medial retropharyngeal ln
What does the parotid ln drain
- Superficial structures of dorsal head (dorsal to palate) and ear
What does the mandibular ln drain
Drain superficial and deep structures of ventral
head.
What does the retropharyngeal ln (medial and lateral) drain
Deep structures of the head (tongue, larynx, pharynx)
and other lnn of head
Clin sig of mandibular and retropharyngeal ln in horses
Mandibular: V shape in intermandibular space
Palapable in strangles
retropharyngeal: on medial and caudal aspect of guttural pouches
In diseases such as ‘strangles’, these nodes enlarge & cause dyspnea
and/or dysphagia
Clin sig of medial retropharyngeal ln in ruminants
Enlarged medial retropharyngeal lnn. can compress nasopharynx and cause airway obstruction
Where are lingual tonsils found
Glossoepiglotic fold
Where are tonsils of the soft palate foudn
ventral surfa ce of soft palate
clin sig of tonsils of the soft palate
is clinically significant in the pig (the soft palate is collected at slaughter to monitor for Classic Swine Fever, “Hog Cholera”).
Where is the palatine tonsil found
on floor of oropharynx lateral to the median glossoepiglottic fold
& extends to base of epiglottis.
Species differences with location of palatine tonsil
Lie within tonsillar sinus covered by semilunar fold,
lie within tonsillar fossa in ruminants
Indistinct in horse, but clear in young foals.
Note: NOT the palatine sinus (this is the sinus in ruminant skulls)
How many parathyroid glands in the thyroid
Each lobe of the thyroid gland is associated
with one external (superior) and one internal
(inferior) parathyroid gland in dogs.
two per thyroid lobe (four total)
Thyroid species differences
Pig has one mass not a right and left lobe
What connects the thyroid lobes
isthmus on ventral side (either glandular or fibrous)
Where is the thyroid located
Lies dorsolateral on the trachea just caudal
to the larynx
Thyroid and parathyroid clin sig
The thyroid lobes are loosely connected to the trachea by fascia - in case of thyroid tumor, the gland may gravitate towards the lower neck.
The parathyroids are important organs. If the thyroid lobes were to be removed, the external parathyroids may be retained in-situ, because they have distinct separate blood supply. In case blood supply is compromised, the parathyroid gland can be sliced into small bits & injected subcutaneously, & the gland will function normally.
