Anatomy of upper GI Tract Flashcards
What type of joint is the TMJ and what are the articular surfaces?
Modified hinge type of synovial joint. Articular surfaces: mandibular fossa and articular tubercle of temporal bone superiorly and head of the mandible inferiorly.
What are the 3 pairs of jaw closing muscles?
Masseter
Temporalis
Medial Pterygoid
What is the jaw opening muscle called?
Lateral Pterygoid
State the course of CN V3
Mandibular division of trigeminal nerve - formed by union of sensory fibres from trigeminal ganglion and the motor root. originates from lateral surface of the pons - exits cranial cavity through foramen ovale in greater wing of sphenoid - enters infratemporal fossa. Carries sensation from face and supplies muscles of mastication.
Describe the oral cavity
Two parts - the oral vestibule and the oral cavity proper. Oral vestibule - slit-like space between teeth, gingivae, lips, and cheeks. Oral cavity proper - limited laterally and anteriorly by dental arches (maxillary and mandibular alveolar arches and the teeth they bear). The roof of mouth is formed by the palate which separates oral cavity from nasal cavity. Posteriorly the oral cavity communicates with the oropharynx.
What are the name of the two arches
Palatopharyngeal arch (internal) and palatoglossal arch (external).
Describe adult dentation
4 quadrants: UR, UL, LR, LL. 32 teeth, all erupted by 18 yrs. Molars - 6,7,8 pre-molars - 4,5 Canine - 3 incisor - 1,2. First molars are first to erupt (6-7 yrs). By 12 years all the teeth erupt except for 3rd molar which erupts between 13-25 yrs.
What are the 3 salivary glands?
Parotid, submandibular, sublingual.
Describe the parotid gland
Located lateral and posterior to the rami of the mandible and masseter muscles, pours secretion by duct that opens in oral vestibule opposite second maxillary molar teeth.
Describe the submandibular gland
Lie along the body of the mandible in relation with mylohyoid muscle and pours secretion by duct that opens on a small sublingual papilla beside the base of the frenulum of the tongue.
Describe the sublingual gland
Lies in the floor of the mouth
between the mandible and the genioglossus muscle. Numerous small sublingual ducts open into the floor of the mouth along the sublingual folds.
In terms of sensation, what do the inferior and superior half of the oral cavity consist of?
Superior half: gingivae and palate, general sensation - CN V2.
Inferior half: gingivae and floor of mouth, general sensation - CN V3.
Describe the gag reflex
Protective reflex. Sensory part carried by nerve fibres within CN IX.
Motor part carried by nerve fibres within CN IX & CN X. Function: constricts the pharynx, as the patient attempts to cough.
State the course of CN V2
Maxillary nerve - only sensory - from lateral pons - exits cranial cavity through foramen rotundum - enter pterygopalatine fossa and gives off branches to pterygopalatine ganglion - continues anteriorly, entering orbit through inferior orbital fissure. Supplies skin of face, upper lip, inferior lid and conjunctiva, maxillary teeth.
State the course of CN IX
Glossopharyngeal nerve - from lateral aspect of medulla - through jugular foramen - follows stylopharyngeus & enters pharynx. Supplies: stylopharngeus muscle (only muscle it supplies) - somatic motor, parasympathetic secretomotor to parotid gland - visceral motor/parasympathetic, general sensation from middle ear, auditory tube, oropharynx, tonsils, posterior 1/3 of tongue (somatic sensory) and taste sensation from posterior 1/3 of tongue (special sensory). Also supplies supplies baroreceptors of carotid sinus and chemoreceptors of carotid body (Visceral sensory).
In terms of sensation, what is the tongue divided into?
Anterior 2/3rds in oral cavity: general sensory = CN V3, special sensory = CN VII. Posterior 1/3rd in oropharynx: general and special sensory = CN IX.
State the course of CN VII
Facial nerve - from pontomedullary junction - exits cranial cavity at internal acoustic meatus - travels through facial canal to the mastoid foramen - passes through parotid gland & supplies muscles of facial expression. Chorda tympani: branch of CN VII - connects to lingual nerve branch of CN V3 & contains: taste axons (ant. 2/3rds of tongue) & parasympathetic axons (salivary glands).
State the functional modalities of CN VII
somatic motor - muscles of facial expression & auricular muscles visceral motor - Secretomotor supply to lacrimal, nasal, palatine glands, nasopharynx and sublingual and submandibular salivary glands
Somatic sensory - concha of auricle
Special sensory - taste sensation from anterior 2/3 of tongue
What are the 4 pairs of extrinsic muscles of the tongue and what are their function?
palatoglossus
styloglossus
hyoglossus
genioglossus
Modify the position of the tongue
What are the 4 pairs of skeletal intrinsic muscles of the tongue and what are their function?
superior longitudinal, inferior longitudinal, transverse and vertical muscles.
Modify the shape of the tongue
What are the muscles of the tongue supplied by?
CN XII (hypoglossal) except palatoglossus - supplied by CN X
State the course of CN XII
Hypoglossal nerve - from medulla - through hypoglossal canal - to intrinsic and extrinsic muscles of tongue (except palatoglossus)
Describe the posterior view of the pharynx
Circular constrictor muscles: superior, middle, and inferior. External layer. Overlap each other. voluntary muscles, Contract sequentially. Innervated by CN X. All insert onto the midline of raphe.
Describe the longitudinal muscles of the pharynx
Inner layer. Supplied mainly by CN X & CN IX. Elevate pharynx & larynx: attach to larynx, contract to shorten pharynx, raise larynx to close over laryngeal inlet. Salpingopharyngeus, palatopharyngeus and stylopharyngeus. Stylopharyngeus is supplied by CN IX and rest two by CN X.
