FOOD PREHENSION Flashcards
Food pretension horse
very sensitive and mobile lips are the main prehensile structures when feeding from the manger. During grazing the lips are drawn back and the incisors sever the grass at its base. Use of vibrissae to locate food
FOOD PREHENSION CATTLE
less mobile and sensitive lips with more limited lip movement. The
tongue is the main prehensile organ, it is long and roughened with lots of
papillae. This curves round grass and draws it into the mouth when it is held
between the incisors and the dental pad. Sideways movement of the head then
rips the grass. The insensitivity of the prehensile organs of cattle means that
they often swallow foreign objects (stones, wire, glass etc) that may be harmful
(often lodge in the reticulum or puncture reticulum wall and cause fatal
complications)
FOOD prehension sheep
similar to cattle but they have a cleft upper lip that allows them to crop
the grass more closely. They tend not to swallow foreign objects.
Food prehension pigs
root with their snouts and use the pointed lower lip to transfer food into
mouth.
FOOD prehension dogs and cats
Dogs and cats – lips relatively unimportant. Tongue (very long and mobile) and
teeth main means of prehension. In these species the tongue is used for lapping
liquid – in all other domestic species liquid is drawn into the mouth by suction.
Muscles of the lip
Orbicularis oris– a ring of muscle around the mouth to close it. Also important for sucking i.e.
when drinking
• Levator labii superioris– lift the upper lip
• Levator nasolabialis- lifts upper lip and nostril
• Depressor labii inferioris– depress the lower lip. Absent in carnivores where this function is
performed by part of the buccinator muscle.
• Caninus– retractor of upper lip and nostril
• Zygomaticus – retractor of caudal commisure of the lip.
• All these muscles are innervated by the FACIAL nerve
Cheeks muscle
Buccinator-forms a diaphragm and innervated by the facial nerve
Teeth innervation
SA
-Upper: maxillary trigeminal nerve
-Lower: mandibular trigeminal nerve
Tongue used for
-grooming
-lapping water
-vocalisation
-tasting
-manipulation
Extrinsic muscles of the tongue
-Genioglossus– puts tongue out
• Styloglossus – retracts tongue
• Hyoglossus– depresses and retracts tongue
Extrinsic muscles of the tongue innervation
Hypoglossal nerve XII
4th and 5th pair of muscles tongue extrinsic
A fourth pair of muscles – the geniohyoids, lie below the tongue, but as it inserts on to the
hyoid, when it contracts it pulls the hyoid and therefore the tongue forward. Also
innervated by the hypoglossal nerve
A fifth pair of muscles – the sternohyoid, pull the hyoid caudally and so pulls the tongue
caudally . Runs from the sternum ventrally up the neck so innervated by cervical
nerves.
Intrinsic muscles of the tongue
Propria linguae– consists of many muscular bundles that run in longitudinal,
transverse and and vertical systems and allow the tongue to change shape and
rigidity
• Innervated by the hypoglossal nerve XII
Innervation tongue
Motor
Innervated by the hypoglossal nerve – Somatic efferents (SE) from somites
Sensory 1)
• rostral 2/3tongue - trigeminal mandibular lingual nerve (SA ectoderm arch
• caudal 1/3 glossopharyngeal and vagus (AA endoderm arch 3)
Taste
• rostral 2/3 –the chorda tympani branch of the facial (it runs with the lingual branch of the mandibular trigeminal) SVA/AA
• caudal 1/3 glossopharyngeal and vagus SVA/AA
Mucosa of the tongue
-lining: stratified, squamous keratinised epithelium
-thinner ventrally than dorsally
-dorsal covered by papillae
Masticatory apparatus consists off
The masticatory apparatus consists of the
•teeth, discussed in earlier lectures
•temporomandibular and symphysial joints
•the masticatory muscles
The temporomandibular joint
-2 condyles that sit in 2 concave surfaces between the temporal bones of the skull
-one on each side, cannot move independently
-attached by mandibular ligament
Temporomandibiular joint subdivisions
-upper (meniscotemporal) and lower (meniscomandibular) compartment by a fibrocartiginous articular disc
Retroglenoid process role
Prevents backwards movement of the jaw
Symphysial joint
-unites two halves of the mandible at the rostral end
Muscles of mastication
Temporalis
• Masseter
• Pterygoids
Arising from the mesoderm of
pharyngeal arch 1 and so
innervated by trigeminal nerve
(mandibular branch) (SVE).
• Digastricus
Digastricus has a dual origin with
the the first and second
pharyngeal arches and so is
innervated by 2 nerves – the
rostral part – trigeminal. The
caudal part – facial. (Both SVE)
Temporalis
•The largest and strongest muscle of the head in carnivores where there is a
wide zygomatic arch to allow for its bulk.
•Arises from a large part of the lateral cranium and inserts on the coronoid
process of the mandible.
•Moves jaw upward – a strong jaw closing muscle
•Innervated by the mandibular branch of the trigeminal nerve
Masseter
• The largest muscle of the head in herbivores.
• Lies lateral to the mandible and ventral to the zygomatic arch
• Has a large area of insertion on the caudal mandible (especially large in herbivores).
• Is multipennate and has 3 layers each with fibres running in different directions – the
different layers do contrasting functions in herbivores.
• Moves jaw upward – a strong jaw closing muscle, but also moves jaw laterally to the active side in herbivores.
• Smaller in carnivores that have less lateral movement (note smaller area of insertion i.e.
smaller caudal mandible).
• Innervation Mandibular trigeminal.
Pterygoids
• Comprising a large medial pterygoid and a small lateral pterygoid.
Regarded as one structure in the carnivores but separate and distinct in herbivores.
• Lie medial to the mandible and runs from the pterygopalatine region to
insert on the medial aspect of the mandible.
• Draws the mandible upwards, medially and forward.
• In herbivores it works as a functioning pair with the contralateral masseter to
move the jaw to the active side.
• Innervated by mandibular V
Digastricus
• A jaw opening muscle. In horses another muscle, occipitomandibularis, which is a division of the digastricus, also performs this function.
• Arises from the paracondylar processes (sometimes called the jugular process) of the exoccipital bones of the skull and inserts on the ventral border of the mandible.
• Larger in herbivores – more chewing.
• Innervation – rostral part – mandibular V, caudal part - facial nerve
• Digastricus has a dual origin (hence the name) from the mesoderm of the
first 2 pharyngeal arches. The division forms a narrow line visible in carnivore digastricus muscles.
Saliva is produced by
Small Salivary Glands:
• Labial, buccal, lingual, pharyngeal and oesophageal – these
produce a mucous secretion that acts locally to keep their area of
the oral cavity moist.
Large Salivary Glands:
• Parotid – serous in all species (mixed but still mainly serous in the
carnivore),
• Mandibular – mixed (mucous predominates in carnivores)
• Sublingual - mixed
• Zygomatic (carnivores) or buccal (herbivores) - mixed
Nerve supply to salivary glands
Salivary glands receive sympathetic and parasympathetic nerve supply.
Sympathetic;
•from the cranial cervical ganglion
•fight or flight - slows down saliva production – dry mouth
Parasympathetic;
•from the salivatory nuclei in the brainstem then via the facial or
glossopharyngeal nerves, then the trigeminal nerve
•normal production of saliva including increased flow when in the presence of
food
