Pharynx_Larynx_and_Hyoid_Apparatus_Part_1_2023.V1.pptx

Pharynx, Hyoid Apparatus, and Larynx, Part I Drake, et al., 2nd ed. Session Goals 1. Learn the anatomical context, structural components, and organization of the pharynx and hyoid apparatus, and how they function as part of the respiratory and GI systems. 2. Learn the basic structural components a...

Pharynx, Hyoid Apparatus, and Larynx, Part I Drake, et al., 2nd ed. Session Goals 1. Learn the anatomical context, structural components, and organization of the pharynx and hyoid apparatus, and how they function as part of the respiratory and GI systems. 2. Learn the basic structural components and relationships of the larynx, and how they enable its function as part of the respiratory system and in communication. Learning Objectives 1. Describe the location and organization of the pharynx as a whole and name, locate, and describe the boundaries, features, and contents of each of its regions. anterior Sadler, 13th edition Lateral view of embryonic respiratory tract, showing diverticulum developing out of gut tube. Region shared between both the GI and respiratory tract = future pharynx. Mid-sagittal section showing region of common tube share between GI and respiratory tract = pharynx. Note: position of the pharynx is immediately anterior to the vertebral column. Pharynx • common pathway shared by respiratory and digestive tracts • three regions: 1. nasopharynx 2. oropharynx 3. laryngopharynx Lateral view Pharynx: Posterior View Nasopharynx, opening into nasal cavity Oropharynx, opening into oral cavity Laryngopharynx opening into larynx Intact Opened in mid-sagittal plane to demonstrate continuity with nasal & oral cavities & larynx. Nasopharynx * • Extends from cranial base to soft palate • anterior boundary=choanae* (open into nasal cavity; often called the ‘internal nostril’) • Passageway for air only • lined with nasal mucosa eatures/Contents of the Nasopharynx Pharyngeal recess Pharyngeal tonsil (adenoid)-lymphatic tissue Torus tubarius (cartilage capping the anterior end of eustachean, aka auditory or pharyngotympanic tube – a passageway directly connecting the nasopharynx to the middle ear) Tubal tonsils (submucosal lymphatic tissue surrounding the opening to the eustachean tube)- not shown here Salpingopharyngeal fold (‘salpinx’=Gr. ‘tube’) – m covering the small salpingopharyngeus muscle which tugs on the torus tubarius to alter the shape of the auditory tube opening and equalize pressure in middle ear Note: posterior to the torus tubarius and the salpingopharyngeal fold is a distinct vertical concavity in the pharyngeal wall known as the pharyngeal recess. The wall of the Oropharynx * • Superior boundary: soft palate • Inferior boundary: epiglottis of the larynx • Anterior boundary=fauces* (opening from oral cavity into oropharynx) • Common passageway for food & air - lined with oral epithelium Features/Contents of the Oropharynx Palatoglossal arch mucous membrane overlying the palatoglossus muscle (helps form the lateral boundary of the oropharynx) Palatopharyngeal arch mucous membrane overlying the palatopharyngeus muscle (also in lateral wall of the oropharynx) Palatine tonsils –submucosal lymphoid tissue between the palatoglossal and palagopharyngeal arches Lingual tonsils (not pictured here) –found on poste (pharyngeal) portion of the dorsum of the tongue; consist of submucosal lymphoid tissue Laryngopharynx Laryngeal inlet • Extends from epiglottis to inferior border of larynx (cricoid cartilage) • Anterior boundary in part formed by laryngeal inlet • Inferiorly, continuous with esophagus Learning Objective 1: Application Describe the location and organization of the pharynx as a whole and name, locate, and describe the boundaries, features, and contents of each of its regions. Ask yourself: • What are the boundaries between the various regions of the pharynx? • What structures does each region of the pharynx contain? Learning Objectives 2. Name, describe and locate: the hyoid bone and its component parts; the ligaments and muscles that suspend it in the neck, including their attachments, innervation, and actions; explain how the hyoid bone is functionally integrated into the structure of the neck. ocating the Hyoid Bone Approx. Vertebral Level: C3 Drake, et al., 2nd ed. natomy of the Hyoid Bone Gilroy, 3rd ed. actured Hyoid of a Strangulation Victim https://www.slideshare.net/nashwamahmpud/presentation-forensic-radiology Hyoid Fracture due to blunt neck trauma https://ars.els-cdn.com/content/image/1-s2.0-S2211558712000349-gr1.jpg Ligamentous Connections of the Hyoid Bone (1) Stylohyoid ligament - Connects the lesser horn of the hyoid to the styloid process of the temporal bone (of the skull) above (1) (1) http://www.i-l-fitness-jp.com/aboutbody/ligament/illust-l/phalynx-1-2.JPG Bilateral calcification of the stylohyoid ligament http://www.srmjrds.in/articles/2012/3/4/images/ SRMJResDentSci_2012_3_4_275_114976_u2.jpg Ligamentous Connections of the Hyoid Bone (2) Thyrohyoid membrane and ligaments - Connect the body and greater horns of the hyoid to the thyroid cartilage of the larynx below (2) (2) http://www.i-l-fitness-jp.com/aboutbody/ligament/illust-l/phalynx-1-2.JPG d muscles are organized into two groups: Suprahyoids Infrahyoids Suprahyoid muscles (1) Digastric (2) Stylohyoid (3) Mylohyoid (3) (1) (4) Geniohyoid (not visible here, Clemente, but lies deep to mylohyoid) 4th ed., Fig. 854 (2) prahyoid Muscles (cont.) (2) (1) Digastric (1) (2) Stylohyoid (3) Mylohyoid (4) Geniohyoid (not visible here, but lies deep to mylohyoid) Gilroy, 3rd ed. (1) (3) Suprahyoid Muscles (cont.) 1) Digastric (not visible in mid- sagittal section) 2) Stylohyoid (not visible in mid-sagittal section) (1) 3) Mylohyoid 4) Geniohyoid (4) (3) (3)Mylohyoid Gilroy, 3rd ed. ions of the supra- and infrahyoid muscles Suprahyoids Infrahyoids Suprahyoid Muscle Action (1) Digastric (not visible here) (2) Stylohyoid (not visible here) (3) Mylohyoid (4) Geniohyoid (4) (3) these elevate the hyoid bone and pull it forward (4) (3) Drake, et al., 2nd ed. uprahyoid Muscles - Innervation Digastric anterior belly: Mandibular branch of the trigeminal N. ( Cranial nerve V3) posterior belly: Branch of the facial N. (VII) Stylohyoid Mylohyoid Geniohyoid Branch of the facial N. (Cranial nerve VII) Mandibular branch of the trigeminal N. (Cranial nerve V3) Nerve to Geniohyoid - C1 off the Hypoglossal N. (Cranial nerve XII) Infrahyoid Muscles (aka, Strap Muscles of the Neck) Action (1) Sternohyoid (2) Omohyoid Superficial layer (3) (3) Thyrohyoid Deep layer (4) (4) Sternothyroid (1) (2)  these depress/lower the hyoid bone Gilroy, 3rd ed. nfrahyoid Muscles - Innervation Sternohyoid Omohyoid ansa cervicalis superior belly from upper limb of ansa cervicalis inferior belly, directly off ansa cervicalis Thyrohyoid Sternothyroid C1 off the ansa ansa cervicalis Cervical plexus -formed by ventral rami of C1-C5 spinal nerves -branches include -phrenic N. (C3, 4, and 5) -ansa cervicalis (’ansa’ = ‘loop’) -also called the ansa hypoglossi -superior limb/root from C1 -inferior limb/root from C2, C3, C4 Note: the relationship of the C1 ventral ramus to the Hypoglossal N. (XII) Gilroy, 3rd ed. poglossal Nerve is Cranial N. XII -cervical nerve axons accompany the hypoglossal via the superior limb of the ansa cervicalis -Nerve to Geniohyoid (C1 off Hypoglossal) -Nerve to Thyrohyoid (C1 off Hypoglossal) -Directly off the Ansa: -N. to superior belly of omohyoid -N. to sternohyoid -N. to inferior belly of omohyoid Note: The N. to geniohyoid and the N. to thyrohyoid contain NO axons of XII – they simply run alongside hypoglossal fibers for part of their course together through the neck Learning Objective 2: Application Name, describe and locate: the hyoid bone and its component parts; the ligaments and muscles that suspend it in the neck, including their attachments, innervation, and actions; explain how the hyoid bone is functionally integrated into the structure of the neck. Ask yourself: • What action do the infrahyoid muscles have on the larynx? Suprahyoids? • A lesion of the nerve to the right geniohyoid would weaken what movement of the hyoid bone? Learning Objectives 3. Name, locate, and identify: the muscles of the pharynx, including their attachments, innervations, and functions; the gaps between the pharyngeal constrictors and the structures they transmit; explain the vulnerabilities resulting from this structural arrangement. Muscles of the pharynx -primarily two groups: 1. constrictors 2. elevators 3 constrictors: superior (S)- begins superiorly at base of the skull; approximately ends at level of mandible (where it partially attaches); innervation: Vagus N. and pharyngeal plexus middle (M)- approximately at level of hyoid bone (where it attaches); innervation: Vagus N., pharyngeal plexus. inferior (I) – at level of larynx (attaches to cricoid cartilage of larynx); innervation: Vagus N., pharyngeal plexus, and external and recurrent laryngeal branches of vagus. - the most inferior fibers of this constrictor form the cricopharyngeus muscle S M I constrictors function to constrict the pharyngeal walls and move ingested material inferiorly towards the esophagus via p In the pharynx, the hyoid is closely related to the middle constrictor muscle, and helps support the lateral walls of the oropharynx and laryngopharynx. Pharynx: Posterior View Note: All 3 constrictors send fibers posteriorly, to Insert in a midline tendinous seam, called the pterygopharyngeal raphe. Pterygopharyngeal raphe S M I Elevators of the pharynx: Pharynx: Posterior View 1. Visible externally on posterior aspect of pharynx: stylopharyngeus -runs from styloid process of temporal bone to superior border of thyroid cartilage of larynx Innervation: Glossopharyngeal N. (Cranial N. IX) 2. Visible internally: salpingopharyngeus -runs from torus tubarius to palatopharyngeus Innervation: Vagus N. and pharyngeal plexus palatopharyngeus -runs from hard palate to thyroid cartilage of larynx Innervation: Vagus N. and pharyngeal plexus Note that all 3 elevators have fibers with a primarily vertical orientation so that, upon contraction, they pull up to lift (and will Moore, et al., 7 also slightly widen), the pharynx. th ed., Fig. 8.47 Gaps in the pharyngeal wall 1. Superior to the superior constrictor, in between it and the base of the skull. Transmits: levator veli palatini muscle eustachean (pharyngotympanic) tube ascending palatine artery Note: this gap is occupied by a thin sheet of fascia, covered with mucous membrane to form the wall of the pharyngeal recess. Lateral view Gaps in the pharyngeal wall 2. Between the superior and middle constrictors. Transmits: stylopharyngeus muscle glossopharyngeal N. (cranial N. IX) stylohyoid ligament Lateral view Gaps in the pharyngeal wall 3. Between the middle and inferior constrictor. Transmits: internal laryngeal N. (this is a branch of the superior laryngeal branch of the Vagus N. ) superior laryngeal artery & vein Note: these structures pass through this gap but must perforate the thyrohyoid membrane to enter/exit the larynx. Lateral view Gaps in the pharyngeal wall 4. Between the inferior constrictor (cricopharyngeus, portion, comprised of horizontal fibers) and the esophagus. Transmits: recurrent laryngeal branch of the vagus N. inferior laryngeal artery & vein Lateral view Gaps in the pharyngeal wall These are sites where the pharyngeal wall is comprised only of a thin sheet of fascia and pharyngeal mucosa; as such, they are weak locations subject to pathologies such as herniations. Note: In addition, the boundary between the upper (oblique) and lower (horizontal) portions of the inferior constrictor is a weak spot. During peristaltic contractions of the pharynx during swallowing, it is crucial that pharyngeal wall constriction occurs in a coordinated sequence. If the cricopharyngeus fails to relax when the upper fibers of the inferior constrictor contract, the lining mucosa of the pharynx may bulge against and rupture the weak part of the pharyngeal wall (dehiscence) where the fiber directions change, forming a Lateral view AMPLE: Zenker’s diverticulum/Killian’s dehiscence Location of dehiscence https://www.radiology.vcu.edu/programs/residents/quiz/GICases/case1.htm Lateral view of swallowing study, showing posterior outpouching as mucosa bulges out between the upper portion of the inferior pharyngeal constrictor and its lower (cricopharyngeus) portion. https://www.radiology.vcu.edu/programs/residents/quiz/GICases/case1.h Anterior view from swallow study, demonstrating size of mucosal diverticulum containing retained contrast medium. Learning Objective 3: Application Name, locate, and describe the muscles of the pharynx, including their attachments, innervations, and general functions and explain that the pharyngeal constrictors do not form a continuous muscular wall, leaving four gaps through which structures enter and exit the pharynx. Further, name and locate each of these gaps, the structures they transmit, and explain the vulnerabilities resulting from this structural arrangement. Ask yourself: • An instrument perforating the mucosa of the pharyngeal recess will pass between what two musculoskeletal structures? • A neoplasm growing into the space between the superior and middle constrictors might compress which nerve? • What do the constrictors do? Are they voluntary or involuntary? Learning Objectives 4. Describe the neurovascular supply of the pharynx. Innervation of the Pharynx Nerves innervating the pharynx: 1. Pharyngeal plexus -supplies motor and most sensory innervation -contains motor fibers from the pharyngeal branch of Vagus (X) to supply all pharyngeal muscles EXCEPT stylopharyngeus, which receives its motor supply from the Glossopharyngeal (IX) and some of the inferior constrictor that is supplied by the external and recurrent laryngeal branches of the Vagus. -contains sensory fibers from the Glossopharyngeal (IX), supplying the majority of the pharyngeal mucosa except for the anterior & superior portions of the nasopharynx which receives sensory innervation from the maxillary division of the Trigeminal (V) 2. Glossopharyngeal (IX) branch independent of pharyngeal plexus - motor to stylopharyngeus - sensory to the mucosa of the oropharynx; afferent limb of the gag reflex 3. Vagus (X) branches independent of pharyngeal plexus - external laryngeal N. (from superior laryngeal N.) and recurrent laryngeal N. (aka inferior laryngeal N.) which is motor to lowest fibers of the inferior constrictor 4. Trigeminal (V) branches from the maxillary division of cranial N. V transmit sensory information from the anterosuperior portion of the nasopharyngeal mucosa Drake, et al., 2nd ed. Posterior view teries supplying the pharynx are direct and indirect branches of the external carotid and subclavian arteries External Carotid system - Ascending pharyngeal artery - Tonsillar branch of the facial artery - Branches of the superior thyroid artery Superior thyroid artery Subclavian system - Branches of Inferior thyroid artery Drake, et al., 2nd ed. Venous drainage of the pharynx - Pharyngeal venous plexus, with multiple tributaries connecting to the internal jugular system Drake, et al., 2nd ed. Learning Objective 4: Application Describe the neurovascular supply of the pharynx. Ask yourself: • Are the constrictors voluntary or involuntary? What part of the nervous system provides them with motor innervation? • Touching the back of the oropharynx will elicit a gag reflex. What nerve transmits such sensory information from this region? What nerve(s) transmit sensory information from other regions of the pharyngeal mucosa? Learning Objectives 5. Describe the functions of the larynx, its location and context within the neck and relative to the pharynx; name, identify, locate, and describe the subdivisions of the laryngeal cavity, including the boundaries of each. The LARY NX …more than just the voicebox…. - Part of conducting portion of respiratory tract - Sphincters regulating and guarding entrance to the lower airway - Facilitates elevating intra-abdominal pressure - Voice production Approx. Vertebral Levels (C3) surface landmar k C3-C6 vertebral levels (C6) (C5) Laryngopharynx Laryngeal inlet • Extends from epiglottis to lower border of cricoid cartilage, posterior to the laryngeal inlet Pharynx: Posterior View larynx Intact Opened in mid-sagittal plane to demonstrate continuity with nasal & oral cavities & larynx. ryngoscope providing view into laryngeal inlet posterior tongue epiglottis laryngeal inlet https://headandneckcancerguide.org/adults/introduction-to-head-and-neck-cancer/throat-cancer/laryngopharyngeal-cancer/hypopharyngeal-cancer/doctors-visit/ ryngoscope providing view into laryngeal inlet anterior posterior tongue epiglottis laryngeal inlet https://headandneckcancerguide.org/adults/introduction-to-head-and-neck-cancer/throat-cancer/laryngopharyngeal-cancer/hypopharyngeal-cancer/doctors-visit/ Larynx: Coronal Section ventricle Laryngeal vestibule Vestibular folds (aka false vocal cords) Laryngeal ventricle Vocal folds (contain vocal cords) Infraglottic space Rima glottidis Learning Objective 5: Application Describe the functions of the larynx, its location and context within the neck and relative to the pharynx; name, identify, locate, and describe the subdivisions of the laryngeal cavity, including the boundaries of each. Ask yourself: • What lies inferior to the infraglottic space? What is the superior boundary of this same space? • What is the location and what are the boundaries of the laryngeal ventricle. What layer of tissue covers it internally? • What part of the GI tract is the laryngeal ventricle continuous with?