Pharynx and GIT Muscle Anatomy Quiz
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Questions and Answers

What type of muscle takes over the gastrointestinal tract (GIT) starting from the second third of the oesophagus?

  • Striated muscle
  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle (correct)

    • Which pharyngeal constrictor originates from the greater horn of the hyoid?

  • Inferior constrictor
  • Middle constrictor (correct)
  • Laryngeal constrictor
  • Superior constrictor

    • What is the name of the only muscle in the pharynx that is innervated by the glossopharyngeal nerve?

  • Palatopharyngeus
  • Stylopharyngeus (correct)
  • Salpingopharyngeus
  • Inferior constrictor

    • During which stage of swallowing does the epiglottis close to separate the larynx from the laryngopharynx?

    <p>Stage 2</p> Signup and view all the answers

    Which muscle extends from the nasopharynx to the back of the pharynx?

    <p>Salpingopharyngeus</p> Signup and view all the answers

    Which structure is associated with the pterygomandibular raphe?

    <p>Buccinator muscle</p> Signup and view all the answers

    What type of contractions are involved in the swallowing process?

    <p>Voluntary and involuntary contractions</p> Signup and view all the answers

    Where do the neurovasculature structures associated with the pharynx primarily originate?

    <p>Posterior cranial fossa</p> Signup and view all the answers

    What are the three segments of the pharynx named after?

    <p>The cavities they are connected to</p> Signup and view all the answers

    Which structure is directly connected to the pharynx and aids in equalizing ear pressure?

    <p>Eustachian tube</p> Signup and view all the answers

    How do the muscles of the pharynx assist in the passage of food?

    <p>By pushing food distally and contracting longitudinally</p> Signup and view all the answers

    What is the primary role of the lymphatic tissue in the pharynx?

    <p>Protect against infections</p> Signup and view all the answers

    Where does the pharynx open inferiorly?

    <p>Oesophagus</p> Signup and view all the answers

    What constitutes Waldeyer's ring?

    <p>A collection of lymphatic tissues</p> Signup and view all the answers

    What is the function of the torus or folds within the pharynx?

    <p>To form bulges that reflect underlying structures</p> Signup and view all the answers

    What complication arises from the shared pathway of air and food in the pharynx?

    <p>Choking hazards</p> Signup and view all the answers

    What is the primary embryological origin of the pharynx?

    <p>Endoderm</p> Signup and view all the answers

    Which part of the pharynx is located at the border between the vestibule and the laryngopharynx?

    <p>Epiglottis</p> Signup and view all the answers

    What anatomical structure is responsible for the production of speech sounds?

    <p>True vocal folds</p> Signup and view all the answers

    Which space is formed by the tucking of mucosa between the thyroid and cricoid cartilage?

    <p>Piriform recess</p> Signup and view all the answers

    Which of the following structures are non-functional in adults?

    <p>Vestibular folds</p> Signup and view all the answers

    What is the function of the aryepiglottic fold?

    <p>To contain skeletal muscle fibers</p> Signup and view all the answers

    What is located between the ventricular and vestibular folds?

    <p>Ventricle space</p> Signup and view all the answers

    What is the primary nerve responsible for general sensory innervation in the anterior nasal cavity?

    <p>Anterior ethmoidal nerve</p> Signup and view all the answers

    Which structure is located in the roof of the nasal cavity and responsible for smell?

    <p>Olfactory foramina</p> Signup and view all the answers

    Which of the following muscles is responsible for closing the nasopharynx during swallowing?

    <p>Levator veli palatini</p> Signup and view all the answers

    What is the function of the torus tubarius in the pharynx?

    <p>Supports the pharyngotympanic tube</p> Signup and view all the answers

    How does the tensor veli palatini receive its innervation?

    <p>From the mandibular division of the trigeminal nerve</p> Signup and view all the answers

    Which structure acts as a connection between the pharynx and the middle ear?

    <p>Eustachian tube</p> Signup and view all the answers

    Which tonsil is known to be located in the roof of the pharynx?

    <p>Pharyngeal tonsil</p> Signup and view all the answers

    What is the role of the salpingopharyngeus muscle?

    <p>To influence overlying mucosa in the pharynx</p> Signup and view all the answers

    Which structure is NOT involved in the innervation of the nasal cavity?

    <p>Bilateral tonsils</p> Signup and view all the answers

    What happens during ear popping?

    <p>Levator veli palatini and salpingopharyngeus function to open the tube</p> Signup and view all the answers

    Which muscle is primarily responsible for increasing the tension of the vocal ligament and raising the pitch?

    <p>Cricothyroid muscle</p> Signup and view all the answers

    Which structure primarily drains mucous from the nasal cavity into the pharynx?

    <p>Ciliated respiratory epithelium</p> Signup and view all the answers

    What is the function of the posterior cricoarytenoid muscle?

    <p>Abduct the vocal ligaments</p> Signup and view all the answers

    What is the role of the paranasal sinuses in relation to the nasal cavity?

    <p>They produce mucus that drains into the nasal cavity.</p> Signup and view all the answers

    How does the lateral cricoarytenoid muscle affect the vocal ligaments?

    <p>It adducts the vocal ligaments</p> Signup and view all the answers

    What effect does the Valsalva maneuver have on the vocal ligaments?

    <p>It seals off the rheunagmullitis</p> Signup and view all the answers

    Which condition is likely to occur if the openings of the sinuses become occluded?

    <p>Sinus headache</p> Signup and view all the answers

    Which arteries supply the anterior and posterior aspects of the nasal cavity?

    <p>Maxillary and ethmoidal arteries</p> Signup and view all the answers

    Which component of the arytenoid muscle is NOT mentioned as part of its structure?

    <p>Superior part</p> Signup and view all the answers

    Which of the following is NOT a function of the nasal cavity?

    <p>Regulating blood pressure</p> Signup and view all the answers

    What is the primary effect of whispering on the arytenoid muscles?

    <p>They relax while lateral cricoarytenoids contract</p> Signup and view all the answers

    Which laryngeal muscle runs the length and is parallel to the true vocal fold?

    <p>Vocalis muscle</p> Signup and view all the answers

    What structure directly connects the orbit to the nasal cavity?

    <p>Nasolacrimal duct</p> Signup and view all the answers

    Which nerve is primarily responsible for innervating the cricothyroid muscle?

    <p>External laryngeal nerve</p> Signup and view all the answers

    What is the largest paranasal sinus?

    <p>Maxillary sinus</p> Signup and view all the answers

    Which nerve provides sensory innervation to the larynx above the vocal folds?

    <p>Internal laryngeal nerve</p> Signup and view all the answers

    Which structure is responsible for the turbinate airflow in the nasal cavity?

    <p>Nasal conchae</p> Signup and view all the answers

    What happens to the vocal ligaments when the thyroarytenoid muscle contracts?

    <p>They are slightly slackened</p> Signup and view all the answers

    Which of the following correctly describes the superior nasal concha?

    <p>It is part of the ethmoid bone.</p> Signup and view all the answers

    Where is the semilunar hiatus located?

    <p>Middle meatus</p> Signup and view all the answers

    What type of mucosa lines the nasal cavity and its extensions?

    <p>Respiratory mucosa</p> Signup and view all the answers

    What is the primary function of the tensor veli palatini during contraction?

    <p>To pull the palate taut</p> Signup and view all the answers

    The group of nerves responsible for innervating the larynx includes which of the following?

    <p>Vagus nerve</p> Signup and view all the answers

    Which nerve gives rise to the greater petrosal nerve?

    <p>Facial nerve</p> Signup and view all the answers

    What is found in the sphenoethmoidal recess?

    <p>Opening for the sphenoid sinus</p> Signup and view all the answers

    What is the primary vascular supply to the nasal septum?

    <p>Sphenopalatine artery</p> Signup and view all the answers

    How do sympathetic nerves innervate the nasal and palatal mucosa?

    <p>They synapse at the superior cervical ganglion</p> Signup and view all the answers

    Which structure serves as the boundary of the oral cavity?

    <p>Fauces</p> Signup and view all the answers

    What artery mainly supplies the hard palate?

    <p>Greater palatine artery</p> Signup and view all the answers

    Which innervates the palatoglossus muscle of the tongue?

    <p>Vagus nerve</p> Signup and view all the answers

    From where does the nasopalatine nerve derive its innervation?

    <p>Pterygopalatine ganglion</p> Signup and view all the answers

    What muscle primarily retracts and elevates the tongue's lateral aspect?

    <p>Hyoglossus</p> Signup and view all the answers

    Which part of the tongue contains the lingual tonsil?

    <p>Root of the tongue</p> Signup and view all the answers

    Which arteries supply the tonsillar bed?

    <p>Numerous arteries including facial and lingual</p> Signup and view all the answers

    What is the function of the intrinsic musculature of the tongue?

    <p>Keep the tone and shape</p> Signup and view all the answers

    Which component is NOT involved in the swallowing mechanism?

    <p>Pterygoid canal</p> Signup and view all the answers

    What structure lies between the palatoglossal and palatopharyngeal arches?

    <p>Palatine tonsil</p> Signup and view all the answers

    Which nerve innervates the muscles of the anterior 2/3 of the tongue?

    <p>Hypoglossal nerve</p> Signup and view all the answers

    Which nerve is primarily responsible for general sensation from the body of the tongue?

    <p>Lingual nerve</p> Signup and view all the answers

    What functions does the chorda tympani nerve perform regarding the tongue?

    <p>Carries presynaptic parasympathetic fibers to the submandibular ganglion</p> Signup and view all the answers

    Which structure crosses over the lingual nerve in the sublingual space?

    <p>Submandibular duct</p> Signup and view all the answers

    What is the main role of the vocal ligaments within the larynx?

    <p>Vibrate during speech production</p> Signup and view all the answers

    Which nerve carries taste sensations from the posterior 1/3 of the tongue?

    <p>Glossopharyngeal nerve</p> Signup and view all the answers

    Where is the lingual artery located in relation to the lingual nerve?

    <p>Between hyoglossus and genioglossus muscles</p> Signup and view all the answers

    What type of cartilage mainly composes the larynx?

    <p>Hyaline cartilage</p> Signup and view all the answers

    What component of the larynx protects the airway during swallowing?

    <p>Epiglottis</p> Signup and view all the answers

    What is the location of the submandibular gland?

    <p>Anterior neck below the thyroid cartilage</p> Signup and view all the answers

    Which part of the tongue is innervated by the vagus nerve for special sensory information?

    <p>Epiglottis</p> Signup and view all the answers

    Which gland is the largest among the salivary glands?

    <p>Parotid gland</p> Signup and view all the answers

    What structure does not provide a bony boundary for the larynx?

    <p>Thyrohyoid membrane</p> Signup and view all the answers

    What anatomical feature assists in the joint movement between thyroid and cricoid cartilages?

    <p>Arytenoid cartilage</p> Signup and view all the answers

    Which relationship best describes the position of the submandibular duct relative to the lingual nerve?

    <p>It crosses below the lingual nerve</p> Signup and view all the answers

    Study Notes

    Pharynx

    • The pharynx marks the beginning of the digestive tract and is situated at the base of the cranium, extending inferiorly into the neck.
    • This structure serves as a common pathway for air and food.
    • It is connected to the middle ear via the pharyngotympanic (Eustachian) tube.

    Nasopharynx

    • The nasopharynx is the uppermost portion of the pharynx, situated behind the nasal cavity.
    • It contains the pharyngeal tonsil (adenoid) and tubal tonsils.
    • The torus tubarius is a medial extension of the pharyngotympanic tube, which contributes to the bulge in the lateral aspect of the pharyngeal wall.
    • The salpingopharyngeal fold drapes over the cartilage of the Eustachian tube and continues into the pharynx.
    • The pharyngeal tonsil is located in the roof of the nasopharynx, while the tubal tonsils are distributed throughout the nasopharynx.

    Oropharynx

    • The oropharynx is the middle portion of the pharynx, located behind the oral cavity.
    • It contains the palatine tonsils on either side of the oropharynx and the lingual tonsils on the posterior 1/3 of the tongue.
    • The palatoglossal and palatopharyngeal folds help separate the oropharynx from the oral cavity.

    Laryngopharynx

    • The laryngopharynx is the lowest portion of the pharynx, situated behind the larynx.
    • It extends from the level of the hyoid bone inferiorly to the esophagus.
    • The piriform recess is a space created by the draping of the mucosa lateral to the laryngeal inlet.

    Muscles of the Pharynx

    • The muscles of the pharynx play a vital role in the passage of food.
    • There are three constrictor muscles: superior, middle, and inferior constrictors, which overlap each other to prevent food from escaping.
    • The longitudinal muscles, like the stylopharyngeus, help contract the tube ahead in acceptance of a bolus.

    Swallowing

    • Swallowing is a complex process involving both voluntary and involuntary muscle contractions.
    • It occurs in three stages:
      • Stage 1: Voluntary - The bolus is pressed against the palate and pushed from the mouth into the oropharynx.
      • Stage 2: Involuntary - The pharynx widens to accept the bolus, while the posterior tongue and bolus of food forcibly close the epiglottis, separating the larynx from the laryngopharynx.
      • Stage 3: Involuntary - The constrictor muscles contract in sequence to deliver the bolus to the esophagus.

    Nasal Cavity

    • The nasal cavity is a bilateral cavity separated by the nasal septum.
    • It is lined with mucosa, which is highly vascularized in areas, contributing to its role in warming, moistening, and cleaning the airflow.
    • Nasal conchae serve to turbinate airflow, increasing contact with the mucosa to warm and moisturize the air.
    • The mucus secreted by the mucosa traps particles, which are then transported toward the pharynx by ciliary action.

    Paranasal Sinuses

    • These are air-filled cavities within the skull that are lined with mucosa.
    • Sinuses are named for the bone in which they reside, such as the frontal, ethmoid, maxillary, and sphenoid sinuses.

    Drainage of Paranasal Sinuses

    • Proper drainage of the paranasal sinuses is crucial, as they are also filled with mucus.
    • Occlusions or inflammation of the sinuses can lead to mucus buildup, increased pressure, and sinus headaches.

    Nasolacrimal Duct

    • This duct connects the orbit to the nasal cavity allowing tears to drain into the nose.

    Neurovasculature of the Pharynx

    • The posterior and lateral aspects of the pharynx contain neurovasculature that originates from the cranial foramina of the posterior cranial fossa.
    • This includes the jugular foramen, carotid canal, and hypoglossal foramen, which transmit structures like the internal carotid artery, internal jugular vein, glossopharyngeal nerve, vagus nerve, accessory nerve, hypoglossal nerve, and cervical sympathetic chain.

    Nerves of the Nasal Cavity

    • The nasal cavity is innervated by both sensory and olfactory nerves.
    • General sensory innervation comes from the trigeminal nerve.
      • The ophthalmic division (V1) innervates the anterior nasal vestibule.
      • The maxillary division (V2) innervates the posterior nasal cavity.
    • Special sensory (olfactory) nerves are located in the roof of the nasal cavity and transmit olfactory signals via bipolar neurons to the olfactory bulb.

    Eustachian Tube

    • This tube is a passage that connects the middle ear to the nasopharynx.
    • The Eustachian tube serves to equalize pressure between the middle ear and the atmosphere.
    • It is formed embryologically from the first pharyngeal pouch.

    Function of the Veli Palatini Muscles

    • The tensor veli palatini and levator veli palatini are responsible for closing off the nasopharynx during swallowing.
    • They both insert onto the raphe, formed by their contralateral partners.
    • The levator veli palatini is innervated by the vagus nerve, while the tensor veli palatini is innervated by the mandibular division of the trigeminal nerve.
    • These muscles also play a role in opening the Eustachian tube, relieving pressure within the middle ear.

    Tensor Veli Palatini

    • Tensor veli palatini muscle initially descends onto the palate but alters its force of contraction by slinging around the pterygoid hamulus and moving medially.
    • Contraction of the tensor veli palatini pulls the palate taut.
    • The slinging action around the pterygoid hamulus contributes to the tautness of the palate.

    Autonomics in Nasal Cavity and Associated Cavities

    • Nasal and palatal mucosa are innervated by autonomic nerves, responsible for secretion (parasympathetic) and inhibition (sympathetic) of mucus production.
    • Parasympathetic nerves originate from the brainstem, pass through the facial nerve, and give off the greater petrosal nerve.
    • The greater petrosal nerve travels through the middle cranial fossa and the pterygoid canal.
    • Presynaptic parasympathetic fibers synapse at the pterygopalatine ganglion.
    • Postsynaptic fibers from the ganglion travel through the nasopalatine and lateral posterior nasal nerves to the nasal mucosa and also reach the palatal mucosa.
    • These fibers also travel alongside the maxillary division of the trigeminal nerve (V2) to reach the lacrimal gland.
    • Sympathetic nerves synapse at the superior cervical ganglion, the most superior point in the neck.
    • Sympathetic fibers travel with arteries to reach the head and neck.
    • They can travel as the deep petrosal nerve, joining the nerve in the pterygoid canal (vidian nerve), passing through but not synapsing at the pterygopalatine ganglion.
    • They can also travel via other arteries to reach the nasal and palatal mucosa.
    • In the pterygopalatine fossa, they can jump into V2 and travel to the lacrimal gland.

    Oral Cavity and Oropharynx

    Oral Cavity

    • The oral cavity is bordered by the hard and soft palates superiorly, cheeks laterally, and the mylohyoid muscle forms its floor.
    • It opens to the exterior through the vestibule and to the pharynx through the fauces.

    Anterior View

    • The fauces consist of the soft palate superiorly and the uvula dangling inferiorly.
    • Laterally, two pillars are present: the palatoglossal arch anteriorly and the palatopharyngeal arch posteriorly.
    • Between these arches lies the palatine tonsil, a mass of lymphoid tissue.

    Mid Sagittal Section

    • The palatoglossal arch, palatopharyngeal arch/folds, and palatine tonsil within the tonsillar bed are visible.
    • The lingual tonsil, the fourth lymphoid mass, is situated on the posterior 1/3 of the tongue.
    • The superior extent of the epiglottis is visible.
    • The space between the posterior tongue and epiglottis is called the vallecula.

    Removing Mucosa from the Posterior Oral Cavity

    • Mucosal folds are formed over underlying muscles of the same name.
    • The palatoglossus muscle connects the soft palate to the tongue.
    • The palatopharyngeus muscle is a longitudinal muscle of the pharynx.
    • The salpingopharyngeus muscle is also visible.
    • The superior and middle constrictor muscles form the posterior and lateral aspects of the oropharynx.
    • The superior constrictor has two raphes (midline pharyngeus for right and left) and a lateral raphe where it attaches to the buccinator muscle.
    • The stylopharyngeus muscle slips between the middle and superior longitudinal muscles.
    • This arrangement helps muscles work together during swallowing, including the tensor and levator veli palatini.

    Tonsillar Bed

    • The tonsillar bed is highly vascularized, receiving blood supply from multiple arteries: facial artery, lingual artery, lesser palatine artery, and ascending pharyngeal artery.
    • The glossopharyngeal nerve innervates the area as it enters the pharynx with the stylopharyngeus muscle and continues to the posterior 1/3 of the tongue.
    • This vascularization and innervation highlight the need for skilled surgeons during tonsillectomy, as miscalculations can lead to severe bleeding and loss of special/general sensory innervation to the posterior tongue.

    Neurovasculature to Palate

    • Palate receives primary supply from superior structures.
    • The maxillary artery gives off the descending palatine artery in the pterygopalatine fossa.
    • The artery travels through the palatine canal (between the palatine and sphenoid bones).
    • It bifurcates to enter one of the two palatine foramina.
    • Although these arteries anastomose, the greater palatine artery mainly supplies the hard palate, and the lesser palatine artery primarily supplies the soft palate.

    Nerves of the Palate

    • Nerves follow a similar path as arteries but are separated higher in the palatine canal.
    • Greater and lesser palatine nerves originate from V2, the maxillary division of the trigeminal nerve, and the pterygopalatine ganglion.
    • They travel separately in the palatine canal: greater palatine nerve for the hard palate and lesser palatine nerve for the soft palate.

    Neurovasculature of the Palate (Continued)

    • Palatine neurovasculature originates from two locations:
      • Greater/lesser palatine foramina at the back
      • Incisive canal/foramen at the front, receiving neurovasculature from the nasopalatine and sphenopalatine nerves.
    • The posterior side is supplied by palatine nerves and the descending palatine artery.

    Embryological Context

    • The primary palate (superior and midline aspect) and the secondary palate are derived from the maxillary prominences.
    • They fuse together, hinging upwards to divide the nasal and oral cavities.
    • This embryological theme corresponds to the neurovascular bundle:
      • Primary palate (anterior): Supplied by the spheno or incisive canal
      • Posterior palate, including soft palate: Supplied posteriorly through the palatine foramina.

    Summary

    • The primary palate receives neurovasculature from the nasopalatine and branches of the sphenopalatine nerve, traveling through the incisive canal.
    • The secondary palate is supplied by the descending palatine artery, with greater and lesser palatine nerves traveling through the greater/lesser palatine foramina.

    The Tongue

    • The tongue occupies most of the oral cavity.
    • It is divided into two parts:
      • Body (anterior 2/3): Contains lingual papillae (not taste buds).
      • Root (posterior 1/3): Primarily composed of the lingual tonsil.
    • The terminal sulcus separates the body and root.
    • The vallecula lies posterior to the tongue, followed by the epiglottis.

    Tongue - Extrinsic Musculature

    • The tongue is covered by mucosa and contains complex musculature.
    • The hypoglossal nerve primarily innervates this musculature.
    • Lateral retraction is achieved by the hyoglossus and styloglossus muscles.
    • Genioglossus, a fan-shaped muscle located in the body of the tongue, protrudes the tongue anteriorly.
    • The palatoglossus muscle retracts and elevates the tongue laterally.
    • The palatoglossus is innervated by the vagus nerve (the only one not innervated by the hypoglossal nerve).

    Intrinsic Musculature of the Tongue

    • Intrinsic muscles maintain tone and shape.
    • This musculature is intricately interwoven.
    • The tongue collaborates with the palate, salivary glands, and teeth to prepare food for swallowing.

    Innervation of the Tongue

    • The lingual nerve, a branch of the mandibular division of the trigeminal nerve, is present in the infratemporal fossa.
    • The lingual nerve is joined by the chorda tympani.
    • Together, these fibers enter the oral cavity and head towards the tongue.

    General and Special Sensory Map of the Tongue

    • General sensation from the body is carried by the lingual nerve fibers (CNV3).
    • The glossopharyngeal nerve carries sensation from the root of the tongue.
    • The vagus nerve carries general sensory information from the epiglottis.

    Tongue and Taste

    • Taste perception is an evolutionary adaptation for discriminating between beneficial and potentially harmful chemicals.
    • Chemoreceptive information from the body of the tongue travels through the chorda tympani (a branch of the facial nerve that originates in the middle ear), reaching the anterior 2/3 of the tongue.
    • The posterior 1/3 of the tongue is innervated by the glossopharyngeal nerve.
    • The vagus nerve carries special sensory information from the epiglottis (which can taste!).

    Salivary Glands

    • There are three major salivary glands:
      • Parotid: The largest, located on the lateral aspect of the face, anterior to the auricle of the ear. It has a single duct to deliver its secretions through the cheek.
      • Submandibular: The second largest, situated in the oral cavity and extending into the anterior neck. It has a single duct that delivers secretions to the sublingual caruncle at the base of the tongue.
      • Sublingual gland: Completely within the oral cavity, on the lateral aspect of the base of the tongue. It has multiple openings lateral to the tongue.

    Submandibular Duct and Lingual Nerve Relationship

    • The submandibular duct and lingual nerve cross each other, forming an X-shape.
    • The submandibular duct runs from the posterior oral cavity inferiorly to the caruncle.
    • The lingual nerve travels from the infratemporal fossa superiorly down to the lateral aspect of the tongue.
    • This crossover occurs in the sublingual space.

    Sublingual Space

    • All nerves to the tongue, as well as the sublingual and submandibular glands, are located in the sublingual space.
    • This space lies lateral to the tongue between the mucosa and the mylohyoid muscle.
    • The submandibular duct and lingual nerve are present after their crossover, with the hypoglossal nerve being the deepest structure.
    • Surgical interventions in this space, such as removing an infected/obstructed duct, require careful consideration of these other structures.

    Lingual Artery

    • The lingual artery is not located in the sublingual space.
    • It lies between the hyoglossus and genioglossus muscles.
    • This location protects it during interventions in the sublingual space.

    Autonomic Innervation to Oral Cavity Targets

    Palatal Mucosa

    • Parasympathetic nerves to the palatal mucosa originate from the brainstem, travel through the facial nerve, and give off the chorda tympani.
    • The chorda tympani carries presynaptic parasympathetic fibers and special sensory fibers from the anterior 2/3 of the tongue.
    • It joins the lingual nerve in the infratemporal fossa, and together they enter the oral cavity.
    • Presynaptic parasympathetics leave the special/general sensory fibers and reach the submandibular ganglion, where they synapse with their postsynaptic counterparts.
    • They then innervate the submandibular and sublingual glands.

    Submandibular and Sublingual Glands

    • Sympathetic nerves synapse at the superior cervical ganglion, and they travel with arteries to reach the head and neck.
    • They often climb onto the facial artery (which passes through the submandibular gland to the face) or the lingual artery (which enters the oral cavity).

    Larynx and Laryngopharynx

    • Unlike the nasal/oral cavities, the larynx is primarily constructed of hyaline cartilage and dense connective tissue membranes, not relying heavily on bone.
    • The hyoid bone, a delicate C-shaped ring, is present at the superiormost extent of the larynx.
    • The hyoid does not articulate with any other bone but provides support for the tongue and keeps the airway/inferior pharynx open.
    • The shield-shaped thyroid cartilage, inferior to the hyoid, consists of two plates joined anteriorly and open posteriorly.
    • From an anterior view, the thyroid cartilage is triangular, with the anterior extent converging.
    • Superior and inferior limbs of the thyroid cartilage are present, with the inferior limb forming a joint with the subsequent cartilage.
    • The thyroid cartilage has an obliquely raised portion for muscle attachment (inferior constrictor, sternothyroid, thyrohyoid).
    • Between the hyoid bone and thyroid cartilage lies the thyrohyoid membrane, named for its attachments, which encloses the opening for laryngeal neurovasculature.
    • The cricoid cartilage, inferior to the thyroid, is a continuous ring of cartilage (unlike the thyroid or tracheal rings).

    Mid Sagittal View

    • The thyroid cartilage is open posteriorly, while the cricoid cartilage forms a continuous ring.
    • The cricoid cartilage is short anteriorly and tall posteriorly.
    • The leaf-shaped epiglottis, located inside the larynx, protects the airway during swallowing. The epiglottis is primarily made of elastic cartilage because it needs to bend frequently.
    • Two pairs of bilateral cartilages are located on top of the posterior cricoid cartilage:
      • Boot-shaped arytenoid cartilage
      • Corniculate cartilage (above the arytenoid)
    • The vocal ligament extends from the tip of the arytenoid cartilage to the internal aspect of the thyroid cartilage. These structures vibrate during speech or noise production.

    Posterior View of Larynx

    • The joint between the thyroid and cricoid cartilages is visible.
    • The arytenoid cartilage is located superior to the cricoid cartilage.
    • Vocal ligaments attach to the tip of the arytenoid cartilage.
    • This arrangement reveals one of the primary larynx functions: speech!

    Larynx with Overlying Mucosa

    • The same structures observed in the mid-sagittal view are present.
    • The epiglottis, hyoid, thyroid cartilage (open posteriorly), cricoid cartilage (tall back), and a fold of mucosa overlying the arytenoid and corniculate cartilages are visible.
    • The mucosa draped over these structures forms the aryepiglottic fold, a fold of mucosa between the epiglottis and the arytenoid/corniculate cartilages, containing some skeletal muscle fibers.
    • The space formed laterally to the laryngeal inlet by the tucking of mucosa between the thyroid and cricoid cartilage is the piriform recess.
    • Upon entering the laryngeal inlet, the vestibule is reached, and two more inferior folds of mucosa are observed:
      • Vestibular (false vocal) folds: Non-functional in adults
      • Ventricular folds (true vocal): Underlying these are the vocal ligaments!

    Ventricular Folds

    • Vibrating the two true vocal folds together produces speech sounds.
    • Between the ventricular and vestibular folds lies the ventricle.

    Posterior View in Corner

    • The cricoid cartilage is cut and splayed open, revealing wires.
    • From superior to inferior:
      • Epiglottis
      • Laryngeal inlet
      • Vestibule space
      • Vestibular folds
      • Ventricular (true vocal) folds (under which lie the vocal ligaments)

    How is Speech Produced?

    • Six muscles control the position and tension of the vocal ligaments:
      • Cricothyroid muscle: Located mainly on the exterior of the larynx. It originates on the external aspect of the cricoid cartilage and slips to reach the deep aspect of the thyroid cartilage.

    Other Intrinsic Laryngeal Muscles (5)

    • Two muscles span the cricoid to arytenoid cartilages:

      • Posterior
      • Lateral cricoarytenoid muscles

    • One muscle crosses the arytenoid cartilages:

      • Arytenoid muscle: Has several components: transverse, oblique, and aryepiglottic parts (aryepiglottic part not pictured)
      • Vocalis muscle: Runs parallel to the true vocal fold (vocal ligament).
      • Thyroarytenoid muscle: Broader than other muscles, lateral to the vestibule, runs from the internal thyroid to the arytenoid cartilages.

    Function of the Intrinsic Laryngeal Muscles

    • Cricothyroid muscle tilts the thyroid cartilage anteriorly over the cricoid cartilage.
    • This tilting action increases the tension of the vocal ligament, raising the pitch.

    Posterior and Lateral Cricoarytenoid

    • These muscles are antagonistic.
    • The posterior cricoarytenoid abducts the vocal ligaments by externally rotating the arytenoid cartilages.
    • This widens the space between vocal folds (rima glottidis), facilitating maximum airflow through the larynx during heavy breathing.
    • The lateral cricoarytenoid muscle adducts the vocal ligaments by internally rotating the arytenoid cartilages.

    Arytenoid Muscle

    • Works with the lateral cricoarytenoid to adduct the vocal ligaments.
    • It directly adducts the arytenoid cartilages (not via rotation) – remember lateral = rotation, arytenoid = direct adduction.
    • These muscles cooperate to bring the vocal folds close together without sealing the rima glottidis, allowing speech or phonation.

    Valsalva Maneuver

    • Stronger contraction of the arytenoid and lateral cricoarytenoid muscles completely seals the rima glottidis during a Valsalva maneuver.
    • This sealing of the airway allows abdominal muscles to increase abdominal pressure, useful for defecation or labor.

    Whispering

    • During whispering, the arytenoid muscles are relaxed, and the lateral cricoarytenoids are contracted.
    • This partially seals the vocal ligaments, allowing air to escape behind the arytenoid cartilages, producing a toneless speech.
    • Everyone has a unique tone, which makes it difficult to discern who is speaking when whispering, as the tone is removed.

    Vocalis and Thyroarytenoid

    • These muscles slacken the vocal ligaments by protracting the arytenoid cartilages or decreasing the tilt of the thyroid cartilage.
    • This slackening results in lower pitches.

    Posterior View of Larynx (Without Mucosa)

    • Underlying musculature is visible, showcasing only the posterior cricoarytenoid and arytenoid muscles.

    Lateral View (+ Neurovasculature!)

    • The thyroarytenoid and lateral cricoarytenoid muscles are visible.
    • Laryngeal neurovasculature is also present.
    • These muscles are innervated by branches of the vagus nerve.
    • High in the cranial base, the vagus gives off the superior laryngeal nerve, which bifurcates into internal and external laryngeal nerves.
    • The internal laryngeal nerve, alongside the superior laryngeal artery, enters the larynx through the opening in the thyrohyoid membrane. The superior laryngeal artery is a branch of the superior thyroid artery, which itself is a branch of the external carotid artery.
    • The internal laryngeal nerve provides sensory innervation to the larynx ABOVE the vocal fold.
    • The external laryngeal nerve carries motor fibers, stays outside the larynx, and innervates the cricothyroid muscle.

    Recurrent/Inferior Laryngeal Nerves

    • The vagus nerve distally gives off the recurrent laryngeal nerves, which loop around the arch of the aorta (left) or the right subclavian artery (right).
    • They ascend the neck and access the larynx by running deep to the inferior constrictor muscle.
    • After ascending the neck, they become known as inferior laryngeal nerves.
    • They innervate the remaining five laryngeal muscles (all except the cricothyroid) and provide sensory innervation to the larynx INFERIOR to the vocal folds.

    Internal Laryngeal Nerve

    • The internal laryngeal nerve enters the larynx through the hole in the thyrohyoid artery, alongside the superior laryngeal artery.
    • The external laryngeal nerve, outside the larynx, innervates the cricothyroid muscle (motor).
    • Inferiorly, in the cleft between the trachea and esophagus, lies the recurrent laryngeal nerve, passing under the inferior constrictor muscle.

    Recurrent Laryngeal Nerve and Thyroid Surgery

    • The recurrent laryngeal nerve lies extremely close to the thyroid gland and inferior thyroid vasculature.
    • Any surgical manipulation of the thyroid or ligation of the inferior thyroid arteries/veins during a thyroidectomy could potentially traumatize this nerve.
    • Damage to this nerve could lead to serious complications, affecting the motor innervation of 5/6 of the laryngeal muscles and sensory innervation to the larynx inferior to the vocal folds.

    Infratemporal Fossa and the Ear

    • We will discuss this in a separate section.

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    Test your knowledge on the muscles and structures associated with the gastrointestinal tract and pharynx. This quiz covers various aspects, including types of muscle, innervation, and the swallowing process. Challenge yourself to see how well you understand these critical systems in human anatomy.

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