Digestive System: Oral Cavity & Esophagus

Digestive System: Oral Cavity & Esophagus

• The digestive system is responsible for digestion.
• It consists of the digestive tract and accessory glands.
• The digestive tract includes the oral cavity, pharynx, esophagus, stomach, small intestine, large intestine, and anus.
• The accessory glands include salivary glands, liver, pancreas, and spleen.

Digestive Tract

• The digestive tract is a pathway for the passage of food.
• It's responsible for digestion, absorption, and defecation.
• The digestive tract also plays a role in endocrine and immunological functions.
• The structures of the digestive tract are: Oral cavity, Pharynx, Esophagus, Stomach, Small intestine, Large intestine, Colon, and Anus.

Accessory Glands

• Accessory glands produce substances necessary for digestion.
• Salivary glands produce saliva.
• The liver produces bile.
• The pancreas produces pancreatic juice.
• These glands have additional roles, including hormonal and immunological functions.

Oral Cavity

• The oral cavity is the first part of the digestive tract.
• The vestibule is the area between the teeth, lips, and cheeks.
• The oral cavity proper includes the alveolar process with teeth, and the isthmus of the fauces.
• The hard palate includes the palatine process of the maxillae and palatine bones.
• The soft palate includes a complex of muscles and uvula.
• Key structures include: Hard palate, Soft palate, Tonsil, Uvula, Tongue, and Gingiva.

Esophagus

• The esophagus is a fibromuscular tube connecting the pharynx to the stomach.
• It's approximately 18-25 cm long.
• The esophagus's primary function is to transport food from the mouth to the stomach.
• It does not participate in digestion.
• It extends from the pharynx (cricoid cartilage) to the gastroesophageal junction (stomach).
• The esophagus has three parts: Cervical, Thoracic, and Abdominal.

Oral Cavity: Teeth

• The teeth are part of the oral cavity.
• Different types of teeth exist, including incisors, canines, premolars, and molars, each with a specific role in chewing and biting food.

Oral Cavity: Tongue

• The tongue is a muscular organ in the oral cavity.
• Intrinsic muscles control its shape.
• Extrinsic muscles (palatoglossus, styloglossus, genioglossus, hyoglossus) move the tongue.
• The tongue has sensory receptors for taste and also aids in mechanical aspects of digestion.
• The tongue's nerve supply and muscle components are crucial for function.

Salivary Glands

• The parotid glands drain through the buccinator muscles, relate to the facial nerve.
• Submandibular glands drain at the floor of the mouth and relate to the lingual nerve.
• Sublingual glands drain at the floor of the mouth.

Esophagus: Constrictions

• The esophagus has multiple constrictions.
• The cervical constriction is close to the pharynx.
• The thoracic constriction is where the esophagus passes through the aortic arch and left bronchus.
• The diaphragmatic constriction is where the esophagus passes through the diaphragm.
• Key points for these areas include the dimensions, location, and surrounding structures.

Esophagogastric Junction

• The purpose of the esophagogastric junction is to prevent reflux and keep gastric contents within the stomach.
• Vital components are the lower esophageal sphincter (LES), crura of the diaphragm, and the angle of His, which is essential for preventing reflux.

Esophagus: Curvatures

• The esophagus has two anteroposterior curvatures that correspond to the cervical and thoracic vertebral columns.
• Two curves are present in the coronal plane.
• The first curve inclines to the left, then returns to the midline.
• The second curve typically bends to the left.
• It crosses the descending thoracic aorta.

Esophagus: Lymphatic Drainage

• Lymphatic drainage in the esophagus can happen throughout the length from neck to abdomen.
• Lymph from below the brachial bifurcation usually travels to the abdomen.
• Lymphatic from above the tracheal bifurcation tends to travel to the neck.

Esophagus: Innervation

• The esophagus receives sympathetic innervation from the thoracic chain.

• Parasympathetic innervation is from the vagus nerves, branching in front of the esophagus to form the esophageal plexus.

• The left vagus nerve moves to the anterior area, turning to an anterior vagal trunk.

• The right nerve moves posteriorly becoming a posterior vagal trunk.

• Esophagus arterial vascularization derives from thoracic aorta branches.

• Venous drainage is similar in arrangement to the arterial system.