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head Flashcards

1
Q

how many cranial nerves

A

12 pairs, numbered using roman numerals in rostro-caudal direction

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2
Q

what are the cranial nerves

A

I - olfactory for smell
II - optic for sight
III - occulomotor for movement eyeballs
IV - trochlear for movement eyeballs
V - trigeminal
VI - abducent for movement eyeballs
VII - facial for expression muscs
VIII - vestibulo-cochlear for balance + hearing
IX - glossopharyngeal for 1st part swallowing
X - vagus for thorax + GI
XI - accessory
XII - hypoglossal for movement tongue

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3
Q

development mesoderm in trunk

A

mesoderm cavitation results splanchnic + somatic lateral plate mesoderm enclosing coelomic cavity around gut tube

mesoderm gives rise to muscs

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4
Q

development mesoderm in head

A

no cavitation, lateral plate mesoderm stays as solid tiss belt around gut tube
* intermediate mesoderm fails develop (disappears) - in trunk it forms kidneys + other structures

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5
Q

segments of head

A
  1. ectoderm = skin
  2. somites (sk musc) (in S1-7)
  3. endoderm = gut tube lining
  4. lateral plate mesoderm (sk musc) (in A1-6)
  5. segmental arteries -> blood
  6. neuraxis forms brain
  7. merves

adult appears not to have

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6
Q

distinguishing bet segments

A

marked externally by lateral indentations (pharyngeal clefts)
* 1st segment no have
* equiv to gill slits (sep segments in fish), just no perforate in mammals

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7
Q

ectoderm

A

forms outer epithelial covering (skin)
* somatic sensation - press, temp, pain
* innervated by somatic afferents to brain

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8
Q

how is ectoderm of segments 1 + 2 special

A

deeply invaginated into them, forming stomodeum (oral opening)
* means segments 1 + 2 no endoderm + oral opening lined ectoderm so has conscious sensory innerv

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9
Q

oral plate

A

thin plate tiss where stomodeal ectoderm meets pharyngeal endoderm
* @ boundary bet seg 2 + 3

has perforate so can swallow

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10
Q

how does control vary in mouth

A

somatic voluntary control front lined ectoderm
back lined endoderm = involuntary

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11
Q

endoderm

A

forms inner epithelial covering w unconscious involuntary control
* sensation via autonomic afferents (AA)
* motor via autonomic efferents (AE) - symp + parasymp

= gut tube

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12
Q

parts of endoderm

A

cephalic (1st) part -> pharynx
6 divisions marked by internal gill slits
* fish = perforate -> external gill slits
* mammals = no perforation but still slits on inside = pharyngeal pouches

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13
Q

lateral plate mesoderm

A

6 belts sk musc each surrounding pharynx all segs except 1
* each belt = ring donut, sepped by pharyngeal cleft externally + pharyngeal pouch internally
* each belt = pharyngeal arch
* forms special visceral musc of gut tube, e.g. muscs of chewing
* innervated by special visceral efferents (SVE) = conscious voluntary control

nerve fibres = functionally equiv to those from somite (SE)

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14
Q

SE vs SVE

A

functionally equivalent conscious voluntary motor control to structures derived from somites vs lateral plate mesoderm

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15
Q

somites

A

each seg has pair
* form sk musc of eyeball + tongue
* innerv by somatic efferents (SE) - voluntary conscious control

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16
Q

segmental arteries

A

all but 1st seg have pair
* form 6 pairs aortic arches embedded in lat plate mesoderm
* innerv by AA/AE for sensory + constrict/dilate

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17
Q

neuraxis

A

differentiates into brain
* each segment of it = meuromere

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18
Q

which head structures disappear

= obliterated

A
  • somites 4 + 5 (w associated nerves)
  • pharyngeal arch 5 (+ associated ectoderm, endoderm, lateral plate mesoderm, nerves + arterial arches)
  • arterial arches 1 + 2
  • phrayngeal clefts + pouches 5 = 6
  • ectoderm of segs 6 + 7

+ therefore no nerves supplying structures that would arise from here

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19
Q

which structures of head fail to develop further

A
  • endoderm of arch 2 stays as narrow band
  • ectoderm of segs 3-5
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20
Q

which structures of head migrate

A

somites 6 + 7 move away from original location to floor mouth to give rise muscs tongue

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21
Q

development oral + nasal cavity

A
  1. paired nasal pits invaginate from ectoderm
  2. nasal cavity breaks through to oral cavity
  3. palatine process grows w palatine bone + endodermal soft palate (develops from inside)

R + L nasal cavities sepped by nasal septum

vertical dotted line = boundary bet ectoderm + endoderm
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22
Q

what happens if lateral palatine folds fail develop

A

cleft palate
* since palate seps oral + nasal cavities this means milk -> nasal cavity -> out nostrils
* can surgically repair but specialist + spenny

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23
Q

formation tongue epithelium

A
  • front = ectoderm of arch 1
  • back = endoderm of arch 3

endoderm of arch 2 fails develop further = tiny band bet others

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24
Q

development tongue musc

A

migration of paired somites 6 + 7
* loads = tongue super mobile w intrinsic + extrinsic to move + contract it

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25
Q

how do larynx, trachea + lungs form

A
  1. depression in floor of arches 4 + 6 forms laryngo-tracheal groove
  2. trachea + lungs develop from this

their epithelial lining = endodermal

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26
Q

where are pharyngeal clefts

A

1 = external ear w boundary @ ear drum
2 - 4 disappear

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27
Q

where are pharyngeal pouches

A

1 = middle ear cavity
2 = palatine tonsil
3 = parathyroid + thymus
4 = parathyroid, thymus + ultimobranchial body

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28
Q

which areas do diff seg ectoderms form

A

1 = skin of top of head
2 = rest of skin of head
3,4,5 = small area skin in external ear
6 + 7 fail to develop

only 1 + 2 significant

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29
Q

what do diff somites form

A

S1 = all rectus muscs (except lateral rectus) + ventral oblique
S2 = dorsal oblique
S3 = lateral rectus + retractor oculi (pulls eyeball deeper into socket so 3rd eyelid can move across)
S4 + 5 disappear
S6 + 7 = muscs of tongue - intrinsic + extrinsic (-glossus)

1,2,3 = extrinsic muscs of eye

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30
Q

what does lateral plate mesoderm form

diff parts

A

arch 1 = chewing muscs (malleus + incus)
arch 2 = facial muscs (stapes + hyoid)
arch 3 = stylopharyngeus musc/hyoid
arch 4 = pharyngeal muscs + cricothyroid musc + laryngeal cartilages
arch 5 disappears
arch 6 = laryngeal muscs + cartilages

arch 1 = seg 2, 2 = 3 … 6 = 7

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31
Q

what do aortic arches form

A

1 + 2 disappear
3 = internal carotid, carotid sinus + body
4: R = subclavian, L = aortic arch, baroreceptor site + aortic bodies
5 disappears
6 = pulm trunk + ductus arteriosus

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32
Q

what does each cranial nerve pair have

A

dorsal + ventral branch

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33
Q

diff bet segmental nerves trunk + head

A
  • head = dorsal + ventral root nerves no join (trunk = -> single spinal nerve w all 4 nerve types)
  • head = 5th neuronal component - SA, SE, AA, AE and SVE (via dorsal root)
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34
Q

ventral vs dorsal root nerves

A

VRN innervate somites = only SE neurons
DRN innerv all structures (pharyngeal arches) = cont SA, AA, AE + SVE neurons

each segment has DRN + VRN

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35
Q

unusual VRNs/DRNs of segments

A

1 = no pharyngeal arch = borrows DRN from seg 2 = opthalmic division of CN V
2 = DRN splits -> maxillary + mandibular divisions of CN V (for upper/lower 1/2 mouth)
4/5 lost somites = no VRN
6 lost pharyngeal arch = no DRN
6 + 7 somites unite form tongue muscs = VRN unites too (CN XII)
5 + 7 share DRN (X/XI)

hence trigeminal (V) has 3 branches

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36
Q

special sense nerves

A

CN I = olfactory nerve for smell
CN II = optic nerve for sight
CNVIII = vestibulo-cochlear nerve for balance + hearing

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37
Q

segment 1 ventral root nerves

A

III (occulomotor)
* SE -> somites forming orbital muscs (all rectus bar lateral) + ventral oblique
* AE parasymp -> ciliary musc (constricts pupil)
* SVE -> levator palpebrae superioris (raises upper eyelid)

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38
Q

segment 1 dorsal root nerve

A

opthalmic branch of V (trigeminal)
* SA - ectoderm forming skin top nof head above eye
* no AA< AE or SVE

no pharyngeal arch so borrowing from segment 2

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39
Q

branches of SA opthalmic division V

A
  1. skin forehead + upper eyelid = zygomaticaotemporal + frontal
  2. cornea = long ciliary (multiple)
  3. medial eyelid/canthus = infratrochlear
  4. dorsal turbinates = ethmoidal (invagination ectoderm)
  5. base of ox horn (cornual)

all SA = conscious feel sensation

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40
Q

segment 2 ventral root nerve

A

IV (trochlear)
* SE -> somite forming dorsal oblique orbital musc (moves eyeball)

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41
Q

segment 2 dorsal root nerve

A

V (trigeminal) - lost autonomic fibres
* division of mouth = trigeminal further split maxillary (SA) + madicbular (SA + SVE)
* SA - ectoderm forming most skin of face + rostral 2/3 tongue
* SVE -> pharyngeal arch forms muscs of chewing

still auto structs, e.g. salivary glands = borrow nerve supply other seg

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42
Q

maxillary branch of V branches

A

ectoderm eyelids -> upper jaw = SA only
* skin lower eyelid = zygomatic
* mucosa nasal cavity = caudal nasal
* mucosa hard palate = major palatine
* mucosa soft palate = minor palatine
* cheek + incisor teeth upper jaw = maxillary alveolar (multiple)
* upper lips, vibrissae (whiskers), muzzle = cutaneous branches
* vestibule of nostril = rostral nasal

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43
Q

mandibular division of V branches

A

ectoderm = SA
* lining cheeks = buccinator
* lower teeth + lower lip = mandibular alveolar + mental (multiple)
* auricular + temporal regions = auricular + temporal branches
* rostral 2/3 tongue = lingual

muscs chewing = SVE

below mouth

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44
Q

muscs of chewing

from mandibular V, SVE

A

jaw closers
* masseter m. - prominent in dogs w strong bite
* pterygoid m. (medial + lateral)
* temporalis m.

jaw openers
* rostral belly of digastricus = mylohyoid n.
* caudal belly from arch 2 = innerv VII (SVE)

others
* tensor tympani m.
* tensor veli palatini m.

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45
Q

digastricus musc

A

2 bellies, rostral 1 originates segment 2, other seg 3
* = innerv 2 diff CNs - fibres from V vs VII

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46
Q

innerv nasal cavity

A
  1. dorsal turbinates = invag = ectoderm seg 1 = ethmoidal n. from opthalmic V
  2. rest from ectoderm seg 2 = caudal nasal n. + rostral nasal n. from maxillary V

1 = upper supply, 2 = lower supply

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47
Q

segment 3 ventral root nerve

A

VI (abducent)
* SE - somite forming lateral rectus (eyeball away from midline) + retractor oculi/bulbi (move eyeball back into head)

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48
Q

segment 3 dorsal root nerve

A

VII (facial)
* SA - ectoderm forming small area skin in external ear cavity
* SVE - phar arch muscs facial expression
* AA - taste from rostral 2/3 tongue + palate (territory of V as lost auto component), running thru middle ear cavity (infection = damage)
* AE -> mandibular/sublingual glands, nasal cavity glands, lacrimal gland

major branches subcut = easy damage - buckle, lat recumben, anaesthetic

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49
Q

branches of facial nerve SA

A

internal auricular n. = skin of external ear

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50
Q

branches of facial nerve AA

A
  • taste rostral 2/3 tongue = chorda tympani
  • taste from palate = major petrosal

taste buds

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51
Q

branches facial nerve AE

A
  • mandibular/sublingual salivary glands = chorda tympani
  • nasal/lacrimal glands = major petrosal
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52
Q

what do autonomic efferents usually cause

A

glands secrete or sm musc contract

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53
Q

branches facial nerve SVE

A
  • caudal auricular nerves -> caudal muscs ears to move
  • auriculopalpebral -> auricular n. (rostral muscs ear)/palpebral n. -> muscs eyelid/face (wink, shut eyes)
  • dorsal/ventral buccal -> facial muscs (flare nostrils, lips, cheek)
  • -> caudal belly of digastricus
  • branch -> stylohyoid musc
  • branch -> stapedius musc
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54
Q

how does facial nerve invade territory of CN V

A
  1. major petrosal nerve -> pterygopalatine ganglion
  2. chorda tympani (AA + AE) -> lingual n. in mandibular V
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55
Q

how does major petrosal nerve run

A

-> pterygopalatine ganglion then
* AE -> lacrimal piggybacking on opthalmic V
* AE -> nasal glands piggbacking on caudal nasal n. (maxillary V)
* AA for taste from palate piggyback on palatine n. (maxillary V)

all thru middle ear cavity

out skull as facial then jumps across to area of trigeminal

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56
Q

what do muscs facial expression control

A

move:
* eyelids
* lips
* cheeks
* nostrils
* ears

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57
Q

nostril muscs

A

dilate in breathing
* super important in race horse as obligate nasal breathers + need incr RR + intake - damage = retire

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58
Q

cheek muscs

A

buccinator - like diaphragm to keep cheek taught
* damage = chew + food no forced into mouth, goes into cheeks + drops out if head down = quidding in horses

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59
Q

lip muscs

A

oval slit w flaps above + below
1. close = orbicularis oris
2. lift upper flap = levator labii superioris
3. depress lower flap = depressor labii inferioris

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60
Q

eyelid muscs

A

oval slit w flaps above + below
1. close = orbicularis oculae
2. lift upper flap = levator palpebrae superioris
3. depress lower flap = depressor palpebrae inferioris
4. medial lifter = levator anguli oculis
5. retractor laterally = retractor anguli oculis

also extra bundles sm musc to lift upper lid/depress lower

autonomic = protect w/o thinking

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61
Q

eyelid muscs innerv

A

mainly facial but:
* levator palpebrae superioris = occulomotor branches (VRN, SVE)
* sm musc = symp from cranial cervical ganglion

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62
Q

ptosis

A

drooping of upper eyelid
* partial if damage to facial nerve as still have innerv from occulomotor

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63
Q

ear muscs

A
  • pull ear forwards + abduct = auricular n.
  • pull ear backwards + adduct = caudal auricular + C1/C2 via great auricular n.
    • cervicoauricularis musc pulls ear back + attached laterally to cartilage so rotates ear outwards - some innerv cervical asw so ear stuck like this (esp just one) = sign CN VII damage)

back + rotated out = sign horse pissed off

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64
Q

segment 4 ventral root nerve

A

none - somite 4 lost

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65
Q

segment 4 dorsal root nerve

A

IX (glossopharyngeal)
* SA - ectoderm forms small area in ear canal
* SVE - phar arch 3 forms stylopharyngeus musc (only pharyngeal dilator, w/o it can’t swallow)
* AA - endoderm forms pharynx lining + caudal 1/3 tongue + aortic arch 3 (internal carotid, carotid sinus + bod) (taste)
* AE -> parotid salivary gland + initiate swallowing reflex

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66
Q

specific branches glosso-pharyngeal nerve

A
  • SA -> external ear = tympanic n.
  • AA taste + sensation caudal tongue = lingual
  • AA sensation pharynx = pharyngeal branch
  • AA -> chemo/baroreceptors = carotid sinus n.
  • AE -> parotid salivary gland contract + secr saliva = minor petrosal n.
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67
Q

segment 5 VRN

A

none - somite 5 lost

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68
Q

segment 5 DRN

A

X (vagus) + XI (accessory) == vagal-accessory complex
* SA - ectoderm forms small area ear canal
* SVE - phar arch 4 forms rest pharyngeal muscs + cricothyroid musc
* AA - endoderm forms lining common pharynx + larynx, aortic arch root aorta/R subclavian
* AE - endoderm GI tract (constr, dil)

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69
Q

SA nerve of vagal-accessory complex

A

auricular nerve for conscious sensation external ear

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70
Q

AA nerves vagal-accessory complex

A
  1. recurrent laryngeal n. for epithelium oes, caudal larynx, trachea
  2. cranial laryngeal n. for cranial larynx + taste in surrounding mucosa
  3. pulmonary branches for lungs
  4. aortic n. for chemo/baroreceptors in aorta
    epithelium of GI tract -> transverse colon asw
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71
Q

SVE nerves of vagal-accessory complex

A
  1. pharyngeal n. -> muscs of pharynx
  2. recurrent laryngeal n. -> muscs of larynx
  3. cranial laryngeal n. -> cricothyroideus m.
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72
Q

segment 6 VRN

A

XII (hypoglossal) - migrates to embed under tongue
* SE -> somite forming muscs of tongue

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73
Q

segment 6 DRN

A

none - phar arch 5 lost

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74
Q

segment 7 VRN

A

XII (hypoglossal)
* SE -> somite 7 forming muscs of tongue

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75
Q

segment 7 DRN

A

X/XI (vagal-accessory complex)
* SA none
* SVE - phar arch 6 forms rest laryngeal muscs
* AA - endoderm forms lining larynx caudal to vocal folds inc resp sys
* AE -> endoderm GI tract

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76
Q

which parts endoderm does AA DRN seg 7 innerv

A

trachea, lungs, GI tract, aortic arch 6 forming pulm art + ductus arteriosus

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77
Q

all segments w innerv + parts present/not

table

A
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78
Q

skin of head innerv

A

1 = ectoderm seg 1 = opthalmic V
2,3,4 = ectoderm seg 2

2 = maxillary V, 3 = zygomatic branch max. V, 4 = mandibular V

SA, 3 = opthalmic V in dog

mouth = division middle of eye (horizontallyish) = division

5 = cervical spinal nerves

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79
Q

damage to trigeminal =

A
  • loss sensation - SA
  • inability chew - SVE
  • dropped lower jaw in dogs (sometimes)
  • -> temporalis musc wastage = ridged appearance to crown of head

where on nerve damage determines extent of effects, e.g. branches trigem

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80
Q

what causes musc wastage

A

atrophy due to there being no nerve supply

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81
Q

torn lower lip horse - how + what do?

A

cut on nail holding hay net when pulling to eat

mental foramen palpable on outer mandible w mental nerve supplying SA -> lower lip
* inject anaesthetic around it (not in) to desensitise area + stitch up

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82
Q

vagal-accessory complex components which innerv

A

vagus (X) = SA, AA, AE -> head + AA, AE -> thorax/abdom

cranial accessory (XI) = SVE -> head
spinal accessory = SE -> neck + forelimb

treated as single bc makes up complex w all 4 nerve types

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83
Q

facial nerve paralysis

A

buccal nerves + auriculopalpebral nerves subcut = prone damage ->
* loss tone in muscs lips + nostrils, can’t constrict = drool
* quidding + bulging of food in cheek as can’t contract buccinator
* slight ptosis
* weak palpebral/corneal reflex (shutting of eyelids) bc orbicularis oculi paralysed
* ear stuck rotated out + back as C1/C2 supply intact

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84
Q

components of skull

A
  1. face = bone extension enclosing nasal cavity + roof of mouth
  2. cranium = bone box protecting brain
  3. mandible = lower law bone
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85
Q

bones of skull

A

PAIRED
* temporal - houses inner ear
* frontal
* parietal
* exoccipital = occipital bones
* nasal
* incisive - incisors out of
* maxilla - side nasal cavity + mouth roof
* zygomatic
* palatine
* lacrimal - front of eye where tear ducts run
* pterygoid
* mandible
* dorsal turbinates
* ventral turbinates
* ethmoturbinates

UNPAIRED
* supraoccipital
* basioccipital
* basisphenoid
* presphenoid
* ethmoid
* vomer

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86
Q

label

A

dog skull

incomplete bony orbit - ligamentous structure completes it
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87
Q

which bones make up zygomatic arch

A
  1. zygomatic
  2. temporal
    • small part (zygomatic process) of maxilla

only zygomatic + temporal in horse

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88
Q

which bones make up external nares

A

nasal + incisive

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89
Q

which bones make up hard palate

A

incisive, maxilla + palatine

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90
Q

what does hyoid apparatus articulate w

A

rotrally: temporal bones just caudal to external auditory meatus
ventrally: w thyroid cartilage of larynx

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91
Q

which bones are smaller in brachycephalic

A

bones of face: incisive, nasal, maxilla, palatine, lacrimal, vomer

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92
Q

sagittal crest

A

only on larger dogs, made from frontal + parietal bones

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93
Q

label

A

horse skull

complete bony orbit
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94
Q

what makes up hard palate

A
  • palatine processes of incisive bones
  • palatine processes of maxillae
  • horizontal plates of palatine bones
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95
Q

label

A

ventrodorsal view

hard palate circled, covere by soft tiss irl

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96
Q

development hard palate

A

primary palate = lip + incisive bone
secondary palate = hard + soft palate
1. prim grows in from rostral end
2. secondary grows in from sides
3. all fuse

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97
Q

cleft lip

A

palatoschisis type where primary palate fails to close
-> abnormal comms bet oral + nasal cavity - congenital oronasal fistula

= milk suckled -> lungs

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98
Q

cleft palate

A

palatoschisis type where secondary palate fails to close
-> abnormal comms bet oral + nasal cavity - congenital oronasal fistula

= milk suckled -> lungs

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99
Q

occipital bone

A

4 parts that fuse

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100
Q

caudal view structures skull

A
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101
Q

syringomyelia

A

congenital condition w undersized occipital bone (hypoplasia)
-> cerebellum pressed against foramen magnum
== interrupted flow cerebrospinal fluid
-> pockets CSF build up in brain, causing neurological conditions

head tilt, phantom scratch back of head

notably cavaliers, just bc inbreeding over time, doesn’t appear til late

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102
Q

structures dorsal aspect skull

A

palpate foramen, important for nerve block

dog horse
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103
Q

ox skull differences

A

massive frontal bone
lacrimal more kinda rectangular

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104
Q

mandible features

A

genu = sharp turn at front
mental foramen = nerve for sensation front teeth, lower lip + chin (inferior alveolar)
inferior alveolar foramen = inferior alveolar nerve, sensory to teeth

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105
Q

how is herbivore mandible different

A

more vertical coronoid process
massive slab of bone w/o angular process

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106
Q

label

A

palpable landmarks:
* nasoincisive notch
* zygomatic arch
* facial crest

cattle = facial tuberosity instead of facial crest

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107
Q

young vs mature animal skull

A

young = temporary dentition + identifiable skull suture lines
mature = permanent dentition, fused skull suture lines
* temporozygomatic suture remains unfused = radiographically visible

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108
Q

tympanic bulla

A

part of temporal bone, filled w air + conts middle ear
* laterally bounded by tympanic mem (eardrum) covering external auditory meatus (ear hole)
* dark bc air filled = radiographically visible

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109
Q

hyoid apparatus

A

series small bones + cartilages forming suspensory mech for tongue + larynx

radiographically visible palpable, but not if conscious bc painful

paired bones, w same structure twice, plus singular basihyoid joining them
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110
Q

how does hyoid sit in skull dog

A
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111
Q

how is hyoid different horse

A
  • stylohyoid fused w epihyoid in adult
  • extra sticky outy lingual process of basihyoid

mostly sits under mandible

blue arrow = where epihyoid is
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112
Q

foramina dog/cat

A
  1. infraorbital -> infraorbital nerve of max. trigeminal
  2. inferior/mandibular alveolar foramen -> mandibular alveolar of mandib. trigem
  3. mental foramen -> mental nerve of mandib. trigem

palpable

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113
Q

foramina in herbivores

A
  1. infraorbital
  2. inferior alveolar
  3. mental
  4. supraorbital -> supraorbital branch of frontal n. of orbital trigem
2/3 each side in ruminants, 1 in horse
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114
Q

other foramina

A
  1. ethmoidal foramina for ethmoid branches of opthalmic V
  2. optic canal for CNII
  3. orbital fissure for CNIII, CNIV, opthalmic V, CNVI
  4. rostral alar foramina for maxillary CNV
  5. caudal alar foramina for maxillary CNV
  6. oval foramen for mandib CNV
  7. jugular foramen/tympano-occipital fissure for CN IX, X, XI
  8. stylomastoid foramen for CNVII
  9. hypoglossal foramen for CNXII
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115
Q

dog head shapes

A
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116
Q

problems due brachycephalic dog skull

A
  • stenotic nares w too much cartilage + soft tiss for tinu nasal bones = hard breathe thru nose (often have to go thru mouth)
  • long soft palate (not reduced w skeletal support), occludes larynx = hard breathe
  • usual no. teeth in smaller space at unusual orientations = hard eat, incr dental disease. mandib less reduced that max. = malocclusion
  • exopthalmic eyes - bulging bc shallow sockets = prone damage, lid can’t close properly = ulceration, more prone proptosis (eye way forward
  • wrinkly skin bc proportionally more soft tiss => skin infections, inward turning eyelids bc too big (entropian)
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117
Q

cat head shapes

A

brachycephalic cats have similar problems but live more sedentary = less of an issue

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118
Q

horse head shapes

A
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119
Q

nasal cavity structure + functions

A
  1. large SA for water + heat exchange to warm + humidify air -> lungs (body temp)
  2. hairs at entrance to trap large particles + surface covered mucous trap small = filter particles from air so no -> lungs
  3. loads sensory receptor cells to detect odour mols on air - food safe?, mating
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120
Q

anatomy nasal cavity

A

divided 2 fossae (spaces) by nasal septum (cartil sheet rostral, ethmoid bone caudal 1/3)
* in space = scroll-shaped turbinate bones (== nasal conchae) + meatii (spaces) bet them

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121
Q

purpose turbinate bones

A

incr A nasal cavity = more surface to humidify, warm, filter air

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122
Q

structure turbinate bones

A

thin scrolls originating from nasal + maxillary walls
1. ethmoturbinates (up to 30 each side) = small, towards back nasal cavity, attached nasal septum, lateral nasal wall + cribriform plate of ethmoid bone
2. dorsal turbinate = single scroll attached nasal wall/bone (= from it)
3. ventral turbinate = double scroll attached maxilla (= from it)

general plan as in sheep

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123
Q

cribriform plate

A

dividing wall bet nose + brain
* has holes for stuff brain -> nose - several branches CNI bc majority receptors on ethmoturbinates

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124
Q

where do meatii go

A

dorsal -> olfactory mucosa
middle -> sinus sys
ventral -> principal airway
common = middle communication part

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125
Q

how are dog turbinates different

A

multiple leaflets arising from ventral w v little ventral space

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126
Q

sagittal section dog turbinate bones

A
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127
Q

how are horse turbinates different

A

ventral turbinate bottom scroll lost = larger ventral space, easy put stuff up

@ level 1st premolar
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128
Q

paranasal sinuses are

A

air-filled extensions (diverticula) of nasal cavity
* spaces bet inner + outer tables of bone = w/in bone
* retain connection nasal cavity via narrow opwnings = prone blockage by inflamm or congestion
* continuous w nasal cavity = lined nasal epithel
* share innerv w nasal cavity - branches of opthalmic + max. of trigeminal

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129
Q

functions of paranasal sinuses

A

enlarge skull to allow more SA musc attachments, larger oral cavity for larger teeth (take in more food) w/o adding weight
* mean outside head diff shape to inside

not acc sure

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130
Q

main sinuses

A
  1. frontal w/in frontal bone
  2. maxillary w/in maxilla
  3. sphenopalatine w/in sphenoid + palate
  4. lacrimal w/in lacrimal bone
  5. ethmoidal w/in ethmoid
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131
Q

frontal sinus

A

up to 5 sep compartments
* ox/sheep, 1 compart = cornual process, entending into horn (air -> nasal cav -> sinus -> horn)
* all domestic except horse comms directly w nasal cavity thru openings at caudal end nasal cavity bet ethmoturbinates

reduced or absent in brachycephalics
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132
Q

frontal sinus on radiograph

A
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133
Q

horns vs antlers

A

horns = permanent
antlers shed annually

horns in male + female, often larger in male

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134
Q

ox frontal sinus

A

horn arises from cornual process of frontal bone + base invaded by frontal sinus (less in small ruminants)
* extensive sinus, often invaginating parietal + occipital asw
* -> 1 major caudal frontal sinus + 4 minor rostral, each w sep opening -> caudal nasal cavity

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135
Q

innerv horn

A
  1. cornual n. of zygomaticotemporal of opthalmic of trigem - block for dehorn
  2. cornual branch of infratrochlear of opthalmic trigem - also need block
  3. frontal n. of opthalmic trigem
  4. cutaneous from C1/C2

all cattle have 1, most 2, far less have 3

cornual just ventral to trigem
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136
Q

euthanasia by shooting

A

aim for medulla oblongata bc resp + CV centre = humane bc gone fast
== avoid midline on species w strong bony midline septum
* also consider brain not at top head bc frontal sinus

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137
Q

how is frontal sinus horse diff

A
  • extends into lacrimal + nasal bones
  • drains into caudal max. sinus not nasal cav
  • extends rostrally into ‘closed’ caudal part dorsal turb == conchofrontal sinus
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138
Q

spaces w/in turbs

A

as move caudally scrolls of dorsal/ventral turns curl round on selves to encapsulate more space
* space w/in each curl divided to rostral + caudal part by thin septum

caudodorsal space comms w frontal sinus (-> conchofrontal sinus)

caudoventral space comms w rostromaxillary sinus

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139
Q

maxillary sinus basic structure

A

comms w nasal cavity via middle meatus

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140
Q

maxillary sinus dogs/cats

A

== maxillary recess bc comms v freely w nasal cavity

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141
Q

passage air in horse nose

A

caudal + rostral ends max sinus sepped by bony plate = no comm

nasal cavity -> frontal sinus -> caudal max. -> nasal cavity
nasal cavity -> rostral max. -> nasal cavity

max. sin. thin bony outer follows form teeth = can be broken down by infec
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142
Q

further sections max. sin.

A

ventral parts split medial + lateral spaces by bony plate supporting infraoorbital canal
* medial boundary = ventral turbinate
* frontal sinus fuses w closed part dorsal turb bone

horse older = cheek teeth wear + move down + bone remodels = bigger lateralmax. sin.
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143
Q

ways sinus infection

A
  1. resp tract infection nose -> sinuses
  2. tooth root infection breaks down thin bone layer -> sinus infec
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144
Q

why is max. sin. prone infection

A
  1. resp tract infection nose -> sinuses (breathe in infec)
  2. tooth root infection breaks down thin bone layer -> sinus infec (near cheek teeth)
  3. warm, moist, w ventilation not too intense = ideal for infec
  4. lots pus build up b4 starts naturally drain bc just lil exit right at top
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145
Q

trephine pts horse

A

frontal + max. sin. can be opened via these in case of infection to drain
* max. sin can also be used to access unerupted parts cheek teeth to aid extraction

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146
Q

label

A
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147
Q

dorsal + ventral conchal (= turbinate) bullae

A

sep compartment w/in concha formed from curling of turbs
* no comm w sinus
* rostral to sinuses
* can become infected

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148
Q

general structure tooth

A
  • bulk tooth = dentine
  • pulp chamber inside (cont bvs, nerves, lymphatics)
  • enamel above gumline
  • cementum lining outside below gumline
  • sits in bony socket (alveolar process) - innerv inferior alveolar n.
  • bet socket + cementum = peridontal ligament made collagen = can move sligtly = less chips
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149
Q

enamel

A

hard outer part tooth projecting above gums
* ectodermal origin
* formed by ameloblasts
* acellular + can’t regen (chip = stay chipped)

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150
Q

dentine

A

bulk of tooth, formed odontoblasts
* mesodermal origin
* structure like bone but odontoblasts no stay in matrix, recede from new formed + remain as layer on surface of pulp cavity = prod 2° dentine (darker) = pulp cavity decr in size thru life

2nd hardest tooth mat

151
Q

3° dentine

A

may occur at sites injury, also darker than 1°

152
Q

cementum

A

formed from calcified CT (= softer) -> outer lining of tooth in socket (brachydont), whole covering (hypsodont)
* mesodermal origin
* continuously proded (slowly) = thicker in older

153
Q

pulp cavity

A

central part cont bvs, nerves, lymphatics
* present in each tooth root
* open at apical foramen (top in upper arcade, bottom in lower)
* smaller in older as filled 2° dentine

154
Q

peridontium

A

= gingiva (gum) + peridontal ligament + cementum + alveolar bone
–> anchor tooth in skull + suspensory apparatus to absorb stress from biting (support)

155
Q

gingiva

A

oral mucosa covering alveolar processes + neck of teeth
* keratinised stratified eipthel

free = coronal to cemento-enamel junction
attached = tightly attached to periosteum of alveolus

156
Q

periodontal ligament

PDL

A

collagen fibres bet cementum + alveolus
* fibres in sling formation = shock absorbers + allow small teeth movements in mastication

157
Q

alveolar bone

A

layer next to PDL v dense = lamina dura

radiographically visible as thin white line

teeth >1 root = white + dark lines diff roots may be superimposed
158
Q

teeth innerv

A

upper teeth = maxillary/superior alveolar n. from max. from trigem
lower teeth = mandibular/inferior alveolar from mandibular from trigem

159
Q

mammalian teeth categories

A

deciduous + permanent = diphyodont (= milk + adult)

diff types specialised teeth = heterodont

160
Q

standard mammal teeth types + nos.

A

incisors 3/3
canines 1/1
premolars 4/4
molars (permanent only) 3/3

total = 44

only 1 side mouth upper/lower

161
Q

hypsodont

A

long crowned w unerupted crown lying beneath gum in all but v aged
* root usually shorter than crown
* crown has cementum as outer layer (worn away at occlusal surface)

all herbivores have at least some

162
Q

brachydont

A

low crowned = all of crown erupted by adulthood
* root of tooth longer than crown
* crown fully covered enamel as outer layer

those of dog, cat, human no reserve crown

163
Q

aradicular/elodont

A

teeth grow throughout life + never develop true roots = open rooted
* always hypsodont

164
Q

radicular/anelodont

A

teeth have true anatomical root + don’t continuously grow throughout life (finite amount wear)
* hypsodont or brachydont

165
Q

clinical vs anatomical crown

A

clinical = exposed part of tooth, regardless of structure
anatomical = enamel covered part of teeth, regardless of location (could be below gum)

166
Q

labial tooth surface

A

surface next to lips

167
Q

buccal tooth surface

A

surface next to cheek

168
Q

lingual tooth surface

A

surface next to tongue

169
Q

mesial tooth surface

A

surface touching tooth in front

170
Q

distal tooth surface

A

surface touching tooth behind

171
Q

occlusal tooth surface

A

masticatory surface == table, in contact w food

172
Q

carnivore dentition

A

radicular brachydont
* incisors for grooming + nibbling
* canines to pierce flesh - hold/kill prey
* premolars/molars to cut like scissors == carnassials
* molars cut/crush (even bones to extract marrow)

173
Q

canine adult + deciduous teeth nos

A

I 3/3 C 1/1 P 4/4 M 2/3 ==> 42

I 3/3 C 1/1 P 3/3 M 0/0 ==> 28

adult then deciduous

174
Q

cats dental formulae

A

I 3/3 C 1/1 P 3/2 M 1/1 ==> 30

I 3/3 C 1/1 P 3/2 M 0/0 ==> 26

adult then deciduous

175
Q

ferret dental formulae (= small carnivore)

A

I 3/3 C 1/1 P 3/3 M 1/2 ==> 34

I 3/3 C 1/1 P 3/3 M 0/0 ==> 28

more teeth + more heterodont than cat but less than dog

all adult erupted by 9 months

adult then deciduous

176
Q

pig dental formulae

A

I 3/3 C 1/1 P 4/4 M 3/3 ==> 44

I 3/3 C 1/1 P 3/3 M 0/0 ==> 28

born w U + L I3 + C (= 8) - sharp + point forward
no gain full adult dentition til at least 18mo = deciduous at slaughter

adult then deciduous

177
Q

when do teeth erupt approximately dogs + cats

A

all dog/cat deciduous @ 6 weeks
all dog permanent @ 7 months
all cat permanent @ 6 months

178
Q

anatomy of dentition w/in head

A

carnassials = sectorials = cut food as move past each other
* at most powerful (widest) part jaw (1/3 along from back)

179
Q

how does cat dentition differ from dog

A
  • much more sectorial bc more carnivorous so less processing of food in oral cavity
  • not much differentiation bet cheek teeth (P +M)
180
Q

features that show mouth is healthy

A
  1. normal occlusion w space bet UP + LP so no clash
  2. pH 7.5 (dogs + cats)
  3. saliva maintains pH + conts enzs, lysozymes, immunoglobulins to moderate bac colonisation + mechanically wash teeth (+ antiviral + antifungal - preventative)
181
Q

congenital malocclusions

A

= teeth don’t meet as should
1. prognathism bc lower jaw too long (brachycephalics)
2. brachygnathism bc lower jaw too short (doliocephalics)

can still eat + drink - no fatal

182
Q

tooth fractures

A

due trauma, e.g. stones etc

can’t do much - if in pain, remove tooth, otherwise leave it

183
Q

periodontal disease

A

disease of gingiva, periodontal lig, cementum + alveolar bone

stage 1: gingivitis = inflammation of gingiva
stage 2: early periodontis = inflammation gingiva + PDL
stage 3: further brakdown of support tiss -> tooth mobility -> tooth loss

advanced in upper arcade, esp of canines can lead oronasal fistulas

v common

184
Q

fistula

A

abnormal opening bet 2 organs

185
Q

plaque

A

= biofilm on teeth formed by bac colonising dental pellicle
-> inorganic substances from saliva deposited into bacterial plaque, forms calculus (= tartar)
-> surface calculus readily colonised by plaque ….

prevent periodontal disease = plaque control = mechanical - chew coarse food + brush teeth

186
Q

dental pellicle

A

prot film on teeth surface formed by saliva + food

187
Q

tooth decay

A

== caries
* caused by bac
* less common in carnivores than humans

188
Q

tooth abcesses

A

due periodontal disease or tooth disease/fractures
-> facial/mandibular swellings (clinical signs)

189
Q

normal dentition pigs

A
  • more generalised (not specialised so much)
  • lower incisors point forwards to root in soil
  • canines = tusks = open rooted in male (grow throughout life) U + L rub against to keep edge sharp
  • canines = tusks = open root 2 yrs in female then stop growing
  • P + M similar but teeth larger towards caudal mouth - v tubercular occlusal surface to crush food in oral cavity
190
Q

horse dentition

A

radicular (finite growth, true roots) + hypsodont (long-crowned)
* cellulose made available to microbes by crushing vegetation = wear to teeth so erupt through life (hence hypso) w bone growing to fill socket/max sin expands (for UP4 + UM1-3)
* cementum covers whole crown but soft so wears = ridging for chew due diff hardness enamel, dentine

191
Q

ruminant tooth type

A

brachydont (all crown out by adulthood) incisors/canines
radicular (finite) + hypsodont (long crown) premolars + molars

192
Q

horse dental formula

A

I 3/3 C 0-1/0-1 P 3-4/3-4 M 3/3 == 36-44

I 3/3 C 0/0 P 3/3 M 0/0 == 24

adult (small ones variable) then deciduous

193
Q

when do horse teeth erupt by

A

most deciduous by 6 weeks, I3 6-9 months
most permanent by 4.5 years, canines by 6 years

194
Q

arrangement teeth horse

A

canines all 4 often present male but absent/vestigial female

PM1 = wolf tooth, more common upper but can be both = deciduous PM not shed

incisors to chop grass, PM/M to grind

upper row cheek teeth curved out slightly toward cheek, lower row = straighter
* both rows curve up at caudal end cavity = curve of Spee

195
Q

horse incisor structure

A
lower incisor
196
Q

how horse incisors used age horses

A

horse ages, teeth wear down what was pulp cavity but now filled 2° dentine (dark) = exposed = dental star
* further wear = 3° dentine visible in middle

Once worn to bottom infundibulum, reach enamel spot = bright white

197
Q

other methods used age horses

A
  1. incomplete occlusion => incisor hook @ 5-7yrs, maybe recur 11-13yrs
  2. Galvayne’s groove in horses >10yrs, 1/2 way down @ 15, full down at 20
  3. profile angle bet U + L incisors increasingly acute as ages

NEITHER RELIABLE

198
Q

horse cheek teeth

A
  • = PM + M - all v similar (except wolf tooth)
  • 6 upper (plus wolf tooth maybe)
  • 6 lower (LPM1 rare)
  • ~2-3mm wear per year
  • each erupts w 1 pulp cavity, then sep -> 5-8 w varying intercomms (bvs, nerves) bet them
199
Q

diastemata

A

gap bet cheek teeth in large herbivore due pathology or grown apart or fracture
* leads build up food -> periodontal disease

200
Q

cheek teeth occlusion horse

A

upper wider + squarer, lower narrower + more rectangular
-> upper arcade wider + mouth closed 1/3 upper in contact 1/2 occ of lower

occlusal surface angled down towards cheek (= linguo-buccal direction) - steeper caudally than rostrally

201
Q

structure cheek teeth horse

A

upper arcade = 2 infundibula surrounded dentine

lower = enamel infoldings not tru infundibula, open on lingual surface

occlusal surfaces
202
Q

how does overall wear appear horse cheek teeth

A

12 transverse ridges w upper + lower arcade interdigiting

mildly exaggerated but normal
203
Q

tooth extraction large herbivores

A
  1. per os (thru oral opening) - I, C, PM, wolf
  2. Buccotomy = through soft tiss of cheek then remove bone overlaying lateral side - PM
  3. repulsion - thru skull/mandible w metal punch on root to drive tooth out - caudal PM, M - can cause more problems bc fractures
204
Q

superficial structures to be aware of

A

literally just under skin + thin layer cutaneous musc

205
Q

cattle/sheep dental formula

A

I 0/3 C 0/1 P 3/3 M 3/3 == 32

I 0/3 C 0/1 P 3/3 M 0/0 == 20

canine = corner incisor (same shape as incisor) to grip + pull grass
dental pad instead of upper I/C to chew against

adult then deciduous

206
Q

why are large herbivore deciduous premolars larger than permanent

A

unsupported by molars + do all of grinding work in young animal

207
Q

when do cattle + sheep teeth come in

A

all deciduous cattle in 3wks, sheep in 4

all permanent cattle in 3.5yrs, sheep most by 2.5yrs, Cs by 4yrs

208
Q

which nerves convey sensory info from frontal sinus

A

opthalmic + maxillary divisions of trigem

209
Q

how do you landmark maxillary sinus

A
  1. draw line bet medial canthus of eye + nasoincisive notch for top boundary
  2. line bet infraorbital foramen + rostral limit facial crest for rostral limit

to enter it surgically

210
Q

what passes through holes in cribriform plate

A

olfactory nerve branches for sensory from nasal cavity (mostly ethmoturbinates)

olfactory nerve (+ vestibulocochlear) never exits inside of skull

211
Q

which tooth roots are associated w maxillary sinus

A

upper molars 1-3
UPM4 w rostral - less in old, not all individuals anyway

212
Q

prehension =

A

siezing + conveying food into oral cavity using:
* lips
* cheek
* tongue
* teeth

213
Q

horse prehension

A

sensitive, mobile lips = main prehensile structures
* drawing grazing drawn back + incisors sever grass at base
* use vibrissae to locate food

214
Q

cattle prehension

A

long, roughened (lots papillae) tongue = main prehensile organ
1. curves round grass + draws it into mouth then held bet incisors + dental pad
2. sideways head movement rips grass

bigger, less rubbery, less sensitive lips w limited movement
* insensitivy = swallow foreign objects - stones, wire -> reticulum/wall = puncture = fatal

215
Q

sheep prehension

A

use tongue then head rip like cattle but cleft upper lip = crop grass more closely + tend no swallow foreign objects

216
Q

pig prehension

A

root w snouts + use pointed lower lip to transfer food -> mouth

217
Q

dog/cat prehension

A

v long, mobile tongue + teeth main means
* also use tongue lap up liquid - other domestics all use suction

lips relatively unimportant

218
Q

muscs of food prehension

A

lip/labium (all innerv facial)
* orbicularis oris
* levator labii superioris
* depressor labii inferioris
* levator nasolabialis
* caninus
* zygomaticus

cheeks/buccae:
* buccinator

219
Q

orbicularis oris

A

ring musc around mouth to close it + for sucking
innerv: facial (dorsal + ventral buccal branches)

220
Q

levator labii superioris

A

lift upper lip
innerv: facial

covers infraorbital foramen

221
Q

levator nasolabialis

A

lift upper lip + nostril
innerv: facial

222
Q

depressor labii inferioris

A

depress lower lip
innerv: facial

not in carnivores - done by part buccinator

tendon covers mental foramen

223
Q

caninus

A

retract upper lip + nostril
innerv: facial

224
Q

zygomaticus

A

retract caudal commissure (corner) of lip, runs across zygomatic arch
innerv: facial (auriculopalpebral branch)

exposes carnassial teeth

225
Q

buccinator

A

grp muscs acting as one form diaphragm across cheek so food pushed back into oral cavity
* act in opposition or conjuction w tongue
innerv: facial (dorsal buccal branch)

226
Q

sensory supply lips + cheek

A

lips: trigem nerve - upper = max., lower = mandib. branch

cheeks (internal mucosa + external skin): buccinator n. of mandib. of trigem

227
Q

tongue functions

A
  • manipulation foodstuff w/in + outside mouth
  • tasting
  • lapping water
  • grooming
  • vocalisation/articulation of sound
228
Q

species variation tongue

A
  1. free end wider + rounder (spatulate) horses + dogs vs pointed ox, sheep, pig
  2. ruminants have torus linguae = mound on caudal part to squash food on roof mouth
  3. soft surface in horse, pig, dog vs rough in cats, ruminants
  4. dogs have median sulcus = line running down middle
  5. dogs have lyssa = white cartilagenous rod in ventral tip to shape tongue, e.g. bowl to lap water
229
Q

extrinsic muscs of tongue

A

3 pairs:
1. genioglossus
2. styloglossus
3. hyoglossus

all innerv hypoglossal XII

230
Q

genioglossus

A

from genu - tongue
puts tongue out
innerv: hypoglossal

231
Q

styloglossus

A

from styloid process hyoid -> tongue
retracts tongue
innerv: hypoglossal

232
Q

hyoglossus

A

from basihyoid -> tongue
depresses + retracts tongue
inner: hypoglossal

233
Q

geniohyoids

A

pair muscs lying below tongue
genu -> hyoid
contracts = hyoid forward = tongue forward
innerv: hypoglossal

234
Q

sternohyoids

A

pair muscs sternum -> basihyoid
contract = hyoid caudal = tongue caudal
run up neck so innerv: cervical

235
Q

intrinsic muscs tongue

A

propria linguae = musc bundles running longitudinal, transverse + vertical
-> tongue change shape + rigidity
innerv: hypoglossal

236
Q

tongue innerv

A

motor: SE in hypoglossal
sensory:
rostral 2/3 = lingual n. of mandib trigem (SA bc ectoderm of arch 1)
caudal 1/3 glossopharyngeal + vagus (AA for endoderm arch 3)
taste (special sense):
rostral 2/3 = chorda tympani of facial (AA)
caudal 1/3 = glossopharyngeal + vagus (AA)

chord tymp runs w lingual

237
Q

label

A
238
Q

tongue mucosa

A

tongue lining = stratified squamous keratinised
* thinner on ventral than dorsal
* dorsal surface + margins covered mucosal projections = papillae cont taste buds or just for rough surface
* vallate papillae (5 or 7) mark division bet rostral 2/3 + caudal 1/3

arrows = vallate papillae
239
Q

mastication

A

tearing, grinding + chewing food inc:
* teeth
* temporomandibular + symphysial joints
* masticatory muscs

240
Q

temporomandibular joint (TMJ)

A

condyle sits in concave surface
* one each side, sat bet temporal bones
* can’t move independently of each other

241
Q

TMJ joint capsule

A
  1. laterally thickened form mandibular ligament
  2. divided into upper (meniscotemporal) + lower (meniscomandibular) compartment by fibrocartilagenous disc

holds joint together

242
Q

movement at TMJ

A
  • hinge movement bet mandible + articular disc
  • lateral movement (translations) bet disc + temporal bone
243
Q

how is TMJ diff in herbivores

A
  • disc thicker
  • joint capsule larger
  • no retroglenoid process that in dogs prevents backwards movement jaw = temporal surface large + flat

-> accomodate greater range movements

244
Q

symphysial joint

A

joins 2 halves mandible at rostral end
* allows small changes angulation lower teeth = aids prehension
* most unfused carnivores + cattle, most fused horses (= more vs less changes)

dislocated in RTAs + wired back into position

245
Q

muscs of mastication

A

from mesoderm phar arch 1 + innerv mandib trigem (SVE):
* temporalis
* masseter
* pterygoids

digastricus from arch 1 (rostral, trigem) + arch 2 (caudal, facial) - SVE, banana shape

246
Q

temporalis

A

temporal fossa on lateral cranium -> coronoid process mandible
== jaw upward = jaw closer
innerv: mandibular branch trigem

largest + strongest in carnis, side zygomatic arch to allow for bulk

247
Q

masseter

A

zygomatic arch -> large area insert on caudal mandible
* lies lateral to mandible, ventral to zygomatic arch
* 3 layers w fibres running diff directions w slight diff functions in herbis

moves jaw up = jaw closer AND moves laterally in herbis
innerv: mandib trigem

largest of head in herbis, smaller carnis bc less lateral movement

248
Q

pterygoids

A

large medial + small lateral
pterygoid fossa on pterygoid palatine + sphenoid bones -> medial aspect mandible
== mandible up, medial + forward = jaw closer
inner: mandib trigem

herbis: functioning pair w contralateral masseter (other side) to move jaw to functioning side

pterygoid fossa then musc
249
Q

digastricus

A

paracondylar processes of exoccipital bones -> ventral border mandible
== jaw opener
innerv: rostral mandib V, caudal VII

occipitomandibularis in horses = division of digas + does same function

250
Q

compare muscs mastication carnis + herbis

A

carnis = large area origin for temporalis (A), small area insertion for masseter + digastricus (B)

herbis = opposite

temporalis musc herbis feels thin

251
Q

small salivary glands

A

labial, buccal, lingual, pharyngeal, oesophageal
* all around oral cavity, constant low-level mucous secr acting locally keep area oral cavity moist, clean, healthy

252
Q

large salivary glands

A
  1. parotid - serous all species (mixed mainly serous carnis)
  2. mandibular - mixed (mainly mucous carnis)
  3. sublingual - mixed
  4. zygomatic (carnis)/buccal (herbis) - mixed

one of each on L + R

253
Q

nerve supply salivary glands

A

SYMP from cranial cervical ganglion = decr prod = dry mouth

PARASYMP from salivatory nuclei in brainstem, then via facial or glosspharyngeal, then trigem
-> normal production + incr when in presence food

all symp to head from cranial cervical ganglion

254
Q

parotid salivary gland

A

lobulated, next to ear, duct runs over masseter to open in mouth near UPM4 (upper carnassial) bc lots action here (esp in carnis) so want lots saliva

255
Q

mandibular salivary gland

A

duct runs w sublingual duct (deeper) + opens on small papillae (sublingual crauncles) at rostral end frenulum on floor mouth

256
Q

frenulum

A

connects tongue to floor mouth

257
Q

sublingual salivary gland

A

duct of monostomatic part runs -> sublingual caruncles

polystomatic parts (lots smaller bubbles of glands) secr directly into oral cavity

258
Q

zygomatic salivary gland

A

ducts (1 major, up to 4 minor) open near last UM

only carnis (analogous buccal in other species)

green where zygomatic arch been removed
259
Q

arrangement salivary glands dog/cat

A
260
Q

arrangement salivary glands horse

A

v large parotid w duct running ventral to masseter not across
dorsal + ventral buccal glands, ventral lies near sublingual

261
Q

arrangement salivary glands pig

A

dorsal + ventral buccal glands, ventral lies near sublingual

262
Q

arrangement salivary glands ruminant

A

v large mandibular

263
Q

upper resp tract components

A
  • nasal cavity + paranasal sinuses
  • mouth
  • pharynx
  • larynx
  • trachea + bronchi
264
Q

functions upper resp tract

A
  1. modify inspired air
  2. defend bod against harmful substances
  3. olfaction + gustation
  4. vocalisation
265
Q

how is air modified upper resp tract

A
  1. -> body temp bc large A w good blood supply
  2. humidify, picking up water from evap from mucous covering airway
  3. remove particulate matter
266
Q

how does upper resp tract defend against harmful substances

A
  • filtration
  • coughing + sneezing
  • reflex closure glottis @ entrance to larynx on mech stim
  • continuous movement cilia
  • mucous conts lysozyme which may destroy some bac
  • lymphoid tiss: palatine tonsils in mouth for food + pharyngeal in nasal cavity for air - trap pathogens + phagocytose –> retropharyngeal node
267
Q

how does olfaction work

A

air drawn -> caudal part nasal cavity to pass over ethmoturbs
* mucosa conts lots olfactory cells (-> AA)
* axons AAs thru cribriform plate -> olfactory bulb brain

268
Q

gustation

A

== taste

269
Q

sniffing

A

deliberately bringing air in contact w ethmoturbs

270
Q

palatine fissure

A

opening in incisive bone (paired), either side midline
* almost completely covered soft tiss w small raised incisive papilla at midline
* = entrance to both L + R incisive ducts

in hard palate

271
Q

incisive duct

A

== nasopalatine duct
small tubes linking oral + nasal cavities
* in all domestic species except equids

272
Q

vomeronasal organ

A

small, paired, detect pheromones
* arises caudally from incisive duct, lying on floor nasal cavity, embedded in hard palate
* innerv: olfactory CNI + max trigem

273
Q

how is vomeronasal organ diff in horses

A

ducts to it (nasopalatine) only comm w nasal cavity, not oral

274
Q

flehmen behaviour

A

air cont pheromones drawn over vomeronasal organ = scent detection

275
Q

vocalisation

A

caused by vibration of vocal chords lying w/in larynx
* v important for communication + behaviour

276
Q

obligate nasal breathers

A

v long soft palate so epiglottis sits above soft palate (except when swallowing)

horses, domestic cats, lagomorphs, rodents

277
Q

mods to upper resp tract horses in exercise

A
  1. dilation external nares comma -> circle shape
  2. vasoconstriction nasal mucosa - v vascular to = common + ventral meatii dilate
  3. dilation glottis (airway w/in larynx)
278
Q

horse nostril structure

A

alar fold = open bit, made up alar cartilages to control shape

279
Q

how does nostril dilate

A

alar cartilage pulled medially w laminar part pulled dorsally by dilator naris labialis
* caninus + levator nasolabialis + dilator naris apicalis + lateralis nasi all dilate nostril

all innerv facial

280
Q

vasoconstriction nostril mucosa

A

false nostril = soft tiss structure - constricts = more space for air

281
Q

how does larynx widen horse exercise

A

arytenoid cartilages of larynx abduct = more air thru

282
Q

pharynx is

A

chamber continuation of oral + nasal cavities
* functions during nasal breathing, mouth breathing, swallowing, vomiting
* size + shape changeable bc walls made soft tiss

283
Q

hard palate

A

bony shelf made of incisive, maxilla + palatine bones, dividing nasal + oral cavity

284
Q

soft palate

A

caudal continuation hard palate
* made soft tiss w muscs, salivary glands, covered mucosa - resp on dorsal surface, oral mucosa on ventral

285
Q

larynx is

A

gateway to trachea
* made 4 cartilages - epiglottis, arytenoids, thyroid, cricoid

286
Q

pharynx parts

A
  1. nasopharynx - above soft palate
  2. oropharynx - space below soft palate
  3. laryngopharynx - space above larynx
287
Q

nose breathing

A

epiglottis in downward position so trachea open + air down
* epiglottis tip above soft palate = can see underside epiglottis as look in oral cavity, can’t see airway = tube in mouth, lift epiglottis + insert

288
Q

mouth breathing

A

panting animals
* soft palate elevated - horses can’t do

289
Q

swallowing diagram

A

tongue to back = epiglottis up = food up to oes dorsal to trachea

290
Q

pharynx arches

A

folds mucosa in lateral wall running ventrally = wall thickenings
1. glossopalatine bet oropharynx + oral cavity
2. pharyngopalatine bet nasopharynx + laryngopharynx

291
Q

radiography pharynx

A

soft palate pushed up + epiglottis pushed down by ET tube

292
Q

tonsils tongue

A

lymphoid tiss performing protectice role against pathogens

pala
293
Q

auditory tubes

A

comm bet pharynx + middle ear
* entrance = ostia = a slit then tubes go up

294
Q

pharynx muscs do

A

alter size + shape chamber
* 3 pairs constrict
* 2 pairs shorten
* 1 pair dilates

all innerv: glossopharyngeal et vagus complex

295
Q

pharynx constrictors

A

sequentially constrict to push bolus caudally in swallowing
1. rostral: hyopharyngeus from thyrohyoid + ceratohyoid -> pharynx wall
2. middle: thyropharyngeus from thyroid cartilage -> pharynx wall
3. caudal: cricopharyngeus from cricoid cartilage -> pharynx wall

296
Q

pharynx shorteners

A

during swallowing to bring oes opening closer to caudal part tongue = close off laryngeal airway
1. palatopharyngeus from soft palate -> dorsal wall pharynx (also constrict to form palatophar arch for cuff round larynx in nose breathing)
2. ptergopharyngeus from pterygoid process -> dorsal wall pharynx

297
Q

pharynx dilator

A

widens pharynx in swallowing to accomodate food bolus
1. stylopharyngeus from stylohyoid bone -> lateral wall pharynx

contract, bone no move, soft tiss will = pharynx dilates

298
Q

soft palate muscs

A
  1. tensor veli palatini tenses soft palate - e.g. pull tight when lifting it, mandib trigem SVE
  2. levator veli palatini elevates - glossophar + vagus complex
  3. palatinus shortens soft palate - glossophar + vagus complex
299
Q

nerve supply mucosa soft palate + pharynx

A
  • sensation + taste = glossophar + vagus complex (AA)
  • glands = parasymp motor fibres from facial, glossophar + vagus/symp from cranial cervical ganglion
300
Q

articulation hyoid bone

A

dorsally = petrous temporal bone just caudal to tympanic bulla
ventrally = articulates w larynx (thyrohyoid bones to thyroid cartilage of larynx)

301
Q

muscs hyoid apparatus

A
  1. sternohyoideus = move hyoid caudal (cervical n.)
  2. thyrohyoideus = move hyoid caudal (cervical n.)
  3. mylohyoideus = move hyoid rostral (trigem)
  4. geniohyoideus = move hyoid rostral (hypoglossal)

some other small ones asw

302
Q

radiography hyoid apparatus

A
303
Q

larynx is

A

cartilagenous muscular tube suspended from skull by hyoid apparatus
* some cartilages mobile so shape can be altered

primary role = protect lower resp tract from foreign bods
* secondary = phonation (voice production)

304
Q

airway of larynx components

A
  1. vestibule = rostral, funnel shaped part
  2. glottis = narrow vertical slit
  3. infragottic cavity = wide from glottis -> trachea
305
Q

vestibule

A

entrance from common pharynx = laryngeal aditus (circularish)
* ventral floor of opening = epiglottis, roof of arytenoid cartilages + lateral aspects aryepiglottic fold

306
Q

aryepiglottic fold

A

joins epiglottis to arytenoids

307
Q

glottis

A

technically wall of slit + actual airway = rima glottidus

walls ventrally formed by paired vocal folds + dorsally arytenoid cartilages

can just say whole thing = glottis

308
Q

larynx cartilages

A
  1. epiglottis (unpaired) - forms spout-like entrance to larynx
  2. arytenoid (paired) - can widen/narrow glottis
  3. thyroid (unpaired) - v big, articulates w cricoid
  4. cricoid (unpaired) - signet ring shape (narrow bottom, wide top)

other ones not important + vary size/shape/if there bet species

309
Q

label

A
310
Q

mucosal folds of larynx

A
  1. vestibular fold marks caudal end of vestibule
  2. vocal fold = vocal chord = responsible for vocalisation by vibration
  3. aryepiglottic fold from epiglottic to arytenoid
311
Q

laryngeal muscs general

A
  • 7 pairs close glottis reflexively v fast if eating to protect airway
  • 1 pair opens glottis
  • others vary tension on vocal chords
  • all innerv = recurrent laryngeal but cricothyroid (closes) = cranial laryngeal - both branches of vago-accessory complex (SVE)
312
Q

cricoarytenoideus dorsalis

A

abducts arytenoids + opens glottis (only one)
innerv: recurrent laryngeal

313
Q

cricoarytenoideus lateralis

A

one that closes glottis
innerv: recurrent laryngeal

314
Q

label

A
315
Q

larynx nerve supply

A

vagus accessory complex (X/XI)
1. cranial laryngeal nerve
2. recurrent laryngeal nerve

316
Q

cranial laryngeal nerve

A

branch of vagus as runs cranium -> pelvic inlet
1. AAs from larynx rostral to vocal cords
2. AEs parasymp to mucosal glands
3. SVEs -> cricothyroideus musc

317
Q

recurrent laryngeal nerve

A
  1. AAs from larynx mucosa caudal to vocal folds
  2. AE parasymp -> mucosal glands
  3. SVE -> all larynx muscs but cricothyroideus

R + L branches given off vagus in thorax, curve round a structure then go back up to innerv larynx
* L round ligamentum arteriosum
* R curves round R subclavian artery

318
Q

swallowing reflex

A
  1. afferents glossopharyngeal + vagus (cr/rec laryngeal) initiate. cranial laryngeal coveys stim from rostral larynx for reflex closure glottis
  2. vagus-accessory complex (via pharyngeus nerve of vagus) = efferents -> pharyngeal muscs except stylopharyngeus (glossopharyngeal)
  3. then bolus pharynx -> stom
319
Q

laryngeal saccule

A

deep blind ending pocket of mucosa in lateral wall larynx (one each side)
* opening bet vestibular + vocal fold = laryngeal ventricle, saccule w/in that space

320
Q

BOAS dogs

A
  1. stenotic nares
  2. abnormal shape/position nasal turbinates
  3. extra long soft palate
  4. hypoplastic (narrow) trachea
  5. tracheal collapse
  6. everted laryngeal saccules = stick out into glottis bc breathing so hard (bc long soft palate etc) been pulled out, then obstruct airway = even harder breather
321
Q

dorsal displacement soft palate

A

should lie ventral to epiglottis, on top = inhaled into larynx => coughing, gurgling, affects performance

in horses

322
Q

possible surgeries for DDSP

A
  1. tie forward = sutures bet basihyoid + thyroid cartilage so larynx more rostral + dorsal
  2. induction of palatal fibrosis = thermal/laser cautery, stiffening soft palate
  3. staphylectomy = partial soft palate resection by trimming caudal part w scissors

1 currently best option (60% horses back to race performance)

323
Q

recurrent laryngeal neuropathy

A

unilateral paralysis (usually L) arytenoid cartilage as cricoarytenoideus dorsal musc fails contract + abduct
* only abduct in exercise, wouldn’t notice in normal life

324
Q

surgical options for recurrent laryngeal paralysis

A
  1. hobday = remove ventricle + vocal cord that side to widen airway - improves noise but not improve airflow = owner thinks it’s good but no
  2. tie back = suture bet cricoid cartilage + muscular process left arytenoid to mimic action musc so permanently abducted
325
Q

laryngeal reflexes

A

mucosa v sensitive to mech stim from small particles => coughing, reflex closure glottis
* severe stim = prolonged closure due spasm laryngeal muscs
* so local anaesthetic for cats + rabbits to intubate bc their mucosa v v sensitive

326
Q

adnexa of eye

A

structures associated w movement, protection + support of eye

327
Q

label

A

nictation mem = 3rd eyelid

328
Q

palpebral fissure

A

space bet eyelids when open, not there when eyes closed

329
Q

eyelid structure

A
  1. external skin
  2. musculofibrous layer - phar arch muscs, somite musc, sm musc, CT, glands
  3. palpebral conjunctiva (conts across front of cornea as bulbar conjunctiva) = mucous mem lining inside
330
Q

tarsal plate

A

stiff plate CT supporting free edge each lid w tarsal glands in it

331
Q

tarsal gland

A

small openings in upper (~40) + lower (~30) lids
* secr thin film waxy substance form waterproof barrier stop tears spilling out onto face

332
Q

eyelid muscs

A

palpebral branch of auriculopalpebral of facial (SVE):
* orbicularis oculi closes eyelid = tears across front = eye clean + moist (fail = corneal ulcers)
* superciliaris lifts upper eyelid + eyebrow
* retractor anguli occuli draws lateral canthus caudal (= narrow palpebral fissure)

occulomotor (SE):
* levator palpebrae superioris lifts upper eyelid

cranial cervical ganglion at top neck symp nerves (AE) -> sm musc U + L lids

diff innervs = facial nerve paralysis only => partial eyelid drooping

333
Q

sensory supply region around eye

A

all trigem
* frontal + zygomaticotemporal of opthalmic to upper lid
* zygomatic of maxillary to lower lid

dog: zygomaticotemporal = branch of maxillary

334
Q

entropion

A

inward rolling of eyelid margin (L or U)
–> conjunctivitis + corneal ulcers as fur brushed front eye

correct w surgery

335
Q

ectropian

A

eversion of eyelid margin (usually L)
-> exposed conjunctiva -> epiphora (excessive tear prod, not drained = down face) + conjuctivitis

sorrect w surgery

esp in breeds w ‘droopy’ eyes

336
Q

conjunctival flap

A

to treat deep corneal ulcers

conjunctiva from inner surface eyelid partially detached + swung round (keep blood supply) + sewn on cornea
= blood supply -> cornea = can repair itself

after several weeks connection cut + flap conjunctiva dies + drops off

337
Q

lacrimal apparatus

A

lacrimal gland, small associated glands, 3rd eyelid gland, lacrimal duct

tears sit corner eye = lacrimal lake, heald back by waxy from tarsal - too much = overflow -> face

338
Q

lacrimal gland

A

flat, lobulated, secr serous + mucous
* moisten eye + supply cornea w some nutrients
* innerv: AE from facial via pterygopalatine ganglion onto opthalmic division of trigem
* symp run along bvs from cranial cervical ganglion

339
Q

nasolacrimal duct

A

series tubes to drain lacrimal lake -> lacrimal sac -> lacrimal duct -> nasal cavity -> ultimately just inside external nares where fluid drips
* initially thru maxilla wall then on internal surface covered mucosa rostral 1/3 nas cav

340
Q

finding nasolacrimal duct horse

A

basically straight line from medial canthus eye -> nasoincisive notch

follow infraorbital canal on radiograph + nasolacrimal duct = black tube following rostrally from end (bc layers on top of each other in 3D horse)

341
Q

what happens w nasolacrimal duct rabbits

A

poor diet/husbandry = not wearing teeth = press from occlusion = grow back into sockets = occlude duct = blocked = backflow tears -> lacrimal lake = watery eyes

342
Q

nictitating mem

(3rd eyelid)

A

T shaped cartilage supporting fold conjunctiva that passively sweeps across cornea when eyeball retracted
* at rest situated at medial canthus of eye, retracts back by contraction sm musc w/in (innerv: symp that run thru middle ear)
* has lacrimal gland (gland of 3rd eyelid) associated

343
Q

prolapsed 3rd eyelid

A

== cherry eye, need surgically remove

344
Q

periorbital fascia

A

cone shaped fibrous tunic surrounding eye + extraocular muscs made 3 layers:
1. periorbita = most superficial
2. 2nd = superficial muscular fascia (envelops levator palpebrae superioris + lacrimal gland)
3. deep muscular fascia, reflecting round extraocular muscs + optic nerve

345
Q

extraocular muscs

A
  • 4 rectus (dorsal, medial, ventral, lateral), inserting rostral to equator = pull that direction
  • 2 oblique - dorsal + ventral, insert rostral to equator
  • 1 retractor - retractor bulbi, inserts caudal to equator

all but ventral oblique originate from region of optic canal + orbital fissure
ventral oblique arises from ventromedial wall of orbit

all join at bottom ice cream cone w eyeball as ice cream

all work in conjunction not isolation + movement eyeball complex

346
Q

retractor bulbi musc

A

pull eyeball back in socket - blink, eye back, mic mem across

divided 4 fasciculi (continuous ring in herbis)

innerv: mix occulomotor + abducent nerves

347
Q

rectus muscs

A

dorsal = dorsal tilting of pupil
ventral = ventral tilting of pupil
lateral = abduction of pupil (move out away midline of bod)
medial = adduction of pupil (to bod midline)

lateral innerv = abducent CNVI
others innerv: occulomotor CNIII

348
Q

oblique muscs

A

dorsal = dorsal part eyeball moved medially + ventrally (bc pulls back of eye up so front down)
innerv: trochlear CNIV (all it does)

ventral = ventral part moved medially + dorsally
innerv: occulomotor CNIII

pulley mech
349
Q

cartilages of external ear

A

space running inside -> tympanic mem = external auditory/acoustic meatus (ear canal)
* curved = tricky see tympanic mem

350
Q

muscs of external ear

A

3 grps:
1. pre auricular move ear forward
2. ventral auricular move ear ventrally
3. post auricular move ear caudally + medially

e.g. scutuloauricularis superficial accessorius, medius, dorsalis; parotidoauricularis (over parotid + important veins)

351
Q

parotidoauricularis

A

depresses ear
innerv: palpebral branch of facial

352
Q

motor nerve supply external ear

A

rostral ear muscs = rostral auricular nerve
caudal ear muscs = caudal auricular nerve
also great auricular nerve for C2 to caudal ear muscs

353
Q

sensory nerve supply external ear

A
  1. auriculotemporal branches of mandib trigem do small rostral part external ear + deep ear canal
  2. cervical spinal do rest of ‘outside of ear
  3. internal auricular branch of facial supplies inside of ear canal

ear flap = pinna = top flop of ear

354
Q

root facial nerve

A

root near base ear + ear surgery common so be careful no cut thru
* spreads everywhere
* lies deep to parotid salivary gland

355
Q

middle ear

A

cavity that lies w/in temporal bone
* ventral floor = tympanic bulla
* laterally lies tympanic mem (eardrum)
* medially + dorsally lies petrous (dense) temporal bone housing inner ear

facial nerve runs on dorsal part of cavity, inc chorda tympani

356
Q

tympanic mem

A

seps inner + outer ear

middle ear bone visible = handle of malleus
357
Q

auditory tube

A

bet middle ear cavity + wall nasopharynx
* stabilise air press either side tympanic mem - press outside incr = swallowed air forced in so press in mid cav incr (or air forced out nose) = balance
* bc entrance (ostia) opened w yawning/swallowing

358
Q

guttural pouch general

A

only found perrisodactyla (odd-toed ungulates, e.g. horses)

== air-filled ventral diverticulum of auditory tube w capacity 300-500ml air
* ventral part divided medial 2/3 + lateral 1/3 by stylohyoid bone

one on each side

359
Q

what does guttural pouch do

A

not known, probs another air-filled space so head structures can be where they need to w/o being heavy bone, maybe also:
* reg internal carotid artery press
* cool blood flow to head

360
Q

location guttural pouch

A

dorsal = skull + C1
ventral = pharynx + retropharyngeal lymph nodes
medial = median septum bet L + R (v thin soft tiss sheet)
lateral = pterygoid muscs, parotid + mandibular salivary glands

opens cranially into nasopharynx, entrance = ostia

361
Q

structures associated w walls guttural pouch

A

lateral:
* external carotid artery
* maxillary artery
* facial nerve
* mandibular trigeminal nerve

medial:
* internal carotid artery
* cranial cervical ganglion + symp nerves
* glossopharyngeal nerve
* vagus nerve
* accessory nerve
* hypoglossal nerve
* longus capitus musc

362
Q

drainage of guttural pouch

A

lined mucosa = always proding mucous so moist = needs open regularly + drain

ostia dorsal to most of pouch when head horizontal = only drain when head down
need be swallowing so ostia open

363
Q

surgical approach guttural pouch

A

Viborg’s triangle:
1. caudal border = tendon on insertion of sternocephalicus
2. 2 ventral border = linguofacial vein
3. cranial border = caudal mandible

obvs don’t cut into veins etc

364
Q

diseases of guttural pouch

A
  1. tympany = air distension if ostia no closing properly = not all air out, more in = soft tiss expands like balloon (down neck)
  2. empyema = bac infec
  3. mycosis = fungal infec => erosion of artery, cann affect nerves in wall

diagnosis by endoscopy + radiography

365
Q

signs of guttural pouch disease + causes

A
  1. epistaxis (nonsebleed) - internal/external carotid artery affected
  2. nasal discharge (could be due nasal or sinus disease)
  3. nerve dysfunction
  4. swelling/dyspnoea (struggling to breathe) due pharyngeal wall/roof collapse

unilateral but thin septum = easily destroyed + spread

366
Q

nerve dysfunction caused guttural pouch disease

A
  1. dysphagia (difficulty swallowing) - pharyngeal branch of vagus/glossopharyngeal
  2. laryngeal paralysis - vagus nerve
  3. ptosis (drooping eyelid) + miosis (constricted pupil) = horners syndrome - symp nerves
  4. facial asymmetry - facial n. + symp nerves
367
Q

guttural pouch empyema

A

often spreads from retropharyngeal node

=> fluid (pus) in (horizontal line radiograph bc gravity)
* can get chondroids = inspissated purulant mat (solid balls pus) as pus coagulates over time

368
Q

platysma

A

origin: fascia covering clavicle
insert: commissural portion of lips
function: retract caudal lip commissure (eating, panting, behavioural)
innerv: dorsal + ventral buccal of facial in head region, cervical spinal in neck region

damage = caudal commissure droops, drop food/water

369
Q

head veins

A

jugular
-> maxillary -> caudal auricular/superficial temporal
-> linguofacial -> lingual/facial -> deep facial/ventral labial

maxillary + linguofacial lie either side of mandibular salivary gland
370
Q

what does lingual vein drain

A

tongue

371
Q

what does ventral labial vein drain

A

lower lip

372
Q

main facial nerve branches

A

ventral buccal = SVE -> muscs of lower lip

auricular also -> internal auricular (= sensory SA)
373
Q

buccinator branch

A

of mandib trigem
sensory to mucosal surface inside cheek + skin surface

374
Q

what type of nerve is infraorbital

A

sensory SA -> upper muzzle

NSF (22 decks)

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