Anatomy of Oral Cavity I & Palate

Comprehensive practice flashcards covering the anatomy of the gastrointestinal tract overview, mouth cavity, tongue muscles, innervation, vasculature, embryology, palate, and dentition from Lecture 1 (Oral Cavity I & Palate).

Anatomically and functionally, what are the two main divisions of the digestive system?

1) A tubular gastrointestinal tract (GI tract) 2) Accessory digestive glands

What is the total length and extension of the gastrointestinal tract?

It is a continuous tube measuring $9\,\text{m}$ in length that extends from the mouth to the anus, traversing the thoracic cavity and entering the abdominal cavity at the level of the diaphragm.

What is the sequential order of organs forming the gastrointestinal tract?

Oral cavity $\rightarrow$ Pharynx $\rightarrow$ Esophagus $\rightarrow$ Stomach $\rightarrow$ Small intestine $\rightarrow$ Large intestine

Which structures are categorized as accessory digestive glands?

1) Salivary glands 2) Liver 3) Pancreas

What are the anatomical boundaries of the mouth (oral) cavity?

• Superiorly: Hard palate – soft palate • Inferiorly: Floor of the mouth • Anteriorly and sides: Lips – cheeks • Posteriorly: Oro-pharyngeal isthmus between palatoglossal folds

What anatomical structures form the floor of the mouth cavity?

1) Mylohyoid muscle 2) Anterior $\frac{2}{3}$ of the tongue

What are the two divisions of the mouth cavity and their boundaries?

1) Vestibule: The cavity between lips and cheeks externally, and teeth and gums internally. 2) Mouth Cavity Proper: The cavity enclosed internally by the teeth and gums.

What is the frenulum of the tongue and what does it connect?

It is a median fold of mucous membrane that connects the under surface of the tongue to the floor of the mouth.

What structures open at the sublingual papilla and sublingual fold?

The salivary duct openings.

What are the origin and insertion of the mylohyoid muscle?

• Origin: Mylohyoid line of the mandible • Insertion: Fibers decussate in a median fibrous raphe (mylohyoid raphe); some posterior fibers attach to the body of the hyoid bone

What is the innervation and primary action of the mylohyoid muscle?

• Innervation: Mylohyoid branch of the inferior alveolar nerve • Actions: Elevates the floor of the mouth in the first stage of deglutition; may also elevate the hyoid bone and depress the mandible

Which arteries provide the arterial supply to the oral cavity?

Branches of the external carotid artery: 1) Facial artery 2) Lingual artery 3) Maxillary artery

What is the nerve supply to the roof, floor, and cheek of the oral cavity?

• Roof & upper teeth: Branches from the maxillary nerve • Floor: Lingual nerve (branch of mandibular nerve) • Cheek: Buccal nerve (branch of mandibular nerve)

Where do lymphatics from the oral mucous membrane drain?

1) Submental lymph nodes 2) Submandibular lymph nodes 3) Upper deep cervical lymph nodes

What anatomical relationship does the lingual nerve have as it enters the oral cavity?

It enters by passing just below the last molar adjacent to the medial surface of the mandible, passes deep to the gingiva, and loops under the submandibular duct before ascending into the tongue.

What are the three main anatomical parts of the tongue?

1) Tip: Tapering anterior free end 2) Root: Transmits vessels and nerve supply to the tongue 3) Surfaces: Dorsal surface and ventral (inferior) surface

How is the dorsal surface of the tongue divided, and what characterizes each part?

It is divided by a V-shaped sulcus terminalis into: • Anterior $\frac{2}{3}$ (oral part): Possesses lingual papillae of different shapes. • Posterior $\frac{1}{3}$ (pharyngeal part): Possesses elevations formed by lymphoid tissue nodules (lingual tonsil).

What is the foramen caecum of the tongue?

A small pit located at the apex of the sulcus terminalis.

What structures run on each side of the frenulum on the inferior surface of the tongue?

The lingual vessels and the lingual nerve.

What are the four intrinsic muscles of the tongue?

1) Superior longitudinal muscle 2) Inferior longitudinal muscle 3) Vertical muscle 4) Transverse muscle

What are the four extrinsic muscles of the tongue?

1) Genioglossus 2) Hyoglossus 3) Styloglossus 4) Palatoglossus

What are the origin, insertion, and actions of the genioglossus muscle?

• Origin: Superior genial tubercle • Insertion: Whole length of tongue and body of the hyoid bone • Actions: Bilateral contraction protrudes the tongue; unilateral contraction protrudes and pushes the tongue to the opposite side

What clinical sign results from a hypoglossal nerve lesion causing unilateral genioglossus paralysis?

The tongue deviates toward the side of the lesion upon protrusion.

What is the anatomical cause and clinical consequence of tongue-tie?

It occurs when an abnormally short lingual frenulum restricts tongue movements; in severe cases, it causes difficulty suckling in infants and is corrected surgically.

What are the arterial supply and venous drainage of the tongue?

• Arterial Supply: Lingual artery (originating from the external carotid artery) • Venous Drainage: Lingual vein (draining into the internal jugular vein)

How is lymphatic drainage organized across the different parts of the tongue?

• Tip of the tongue: Submental lymph nodes $\rightarrow$ Deep cervical lymph nodes • Anterior $\frac{2}{3}$: Submandibular lymph nodes $\rightarrow$ Cervical lymph nodes • Posterior $\frac{1}{3}$: Deep cervical lymph nodes

What is the motor nerve supply to the muscles of the tongue, and what is the single exception?

All intrinsic and extrinsic muscles are supplied by the hypoglossal nerve, except the palatoglossus muscle, which is supplied by the pharyngeal plexus (vago-accessory complex).

What nerves provide general and taste sensation to the anterior two-thirds of the tongue?

• General sensation: Lingual nerve • Taste sensation: Chorda tympani

What nerve supplies both general sensation and taste sensation to the posterior one-third of the tongue?

Glossopharyngeal nerve

Which cranial nerve provides sensory innervation to the most posterior part of the tongue?

Vagus nerve

From which embryonic structures do the muscles of the tongue originate?

Occipital myotomes

In the embryonic development of the tongue shown here, what swellings form the anterior two-thirds and posterior one-third of its mucous membrane?

• Anterior $\frac{2}{3}$: Derived from the 1st pharyngeal arch via 3 lingual buds (tuberculum impar and two lateral lingual swellings). • Posterior $\frac{1}{3}$: Formed by the copula (2nd arch) and hypobranchial eminence (3rd and 4th arches).

What embryonic structure indicates the line of fusion between the anterior two-thirds and posterior one-third of the tongue?

The sulcus terminalis (a V-shaped groove).

What separates the anterior part of the developing tongue from the floor of the mouth?

The alveolo-lingual groove

Which two bones form the hard palate?

1) Palatine process of maxillae 2) Horizontal plate of palatine bones

What are palatal rugae and what is their functional role?

Transverse mucosal folds on the hard palate that serve as friction ridges against which the tongue rests and pushes during swallowing.

What is the palatine uvula?

A cone-shaped muscular projection suspended from the middle lower border of the soft palate.

What are the two palatal arches and what lymphoid structure lies between them?

• Anterior fold: Palatoglossal arch • Posterior fold: Palatopharyngeal arch • Structure between them: Palatine tonsil

What are the five muscles of the soft palate?

1) Tensor palate 2) Levator palati 3) Palatoglossus 4) Palatopharyngeus 5) Musculus uvulae

What nerve innervates the muscles of the palate, and what is the exception?

All palatal muscles are innervated by the pharyngeal plexus (vago-accessory complex), except the tensor palate, which is innervated by the mandibular nerve.

What arteries and sensory nerves supply the palate?

• Arterial supply: Palatine branches of the maxillary artery • Sensory innervation: Branches of the pterygopalatine ganglion

How many deciduous (milk) teeth develop, when do they typically erupt, and when is dentition complete?

There are 20 deciduous teeth; they begin appearing around the 6th month and are completed by the 2nd year.

How many permanent teeth are present in an adult, and when does the last molar (wisdom tooth) typically erupt?

There are 32 permanent teeth (appearing starting at the 6th year); the last molar (wisdom tooth) erupts between 17 and 25 years of age.

Which nerves and artery supply the teeth and gingivae?

• Innervation: Branches of the trigeminal nerve (Maxillary nerve for upper teeth; Mandibular nerve for lower teeth) • Arterial supply: Branches of the maxillary artery