Larynx Anatomy Overview

Overview of the Larynx

• Located in the anterior neck
• Anterior to the cervical esophagus
• Connects the pharynx and trachea
• Air passes through
• Located at C3–C6 vertebrae, and sit higher in females/children

Larynx Functions

• Protects airways from large, swallowed material
• Involved in phonation (sound production)

General Anatomy

• Laryngeal inlet is the entrance from pharynx

Three Main Spaces

• Vestibule is the most superior, extends from laryngeal inlet to vestibular folds
• Ventricle is the middle/smallest, located between vestibular and vocal folds
• Infraglottic cavity is most inferior, extending from vocal folds to first tracheal ring

Rima Glottidis

• Opening between vocal folds and arytenoid cartilages

Larynx Cartilages

• Unpaired: epiglottis, thyroid, cricoid
• Paired: arytenoid, corniculate, cuneiform

Epiglottis specific

• Leaf-shaped elastic cartilage
• Posterior to hyoid bone, anterior to laryngeal inlet
• Closes laryngeal inlet when swallowing so food doesn't enter airways
• Free superior part is broad and rounded, and can have a notch
• Attached inferior stem-like part joins thyroid cartilage via thyroepiglottic ligament

Thyroid Cartilage

• Largest cartilage, made of hyaline cartilage laminae fused in midline
• Laryngeal prominence located in the inferior two-thirds (Adam's apple)
• Epiglottis cartilage located on prominence posterior aspect
• Superior thyroid notch located above prominence, V-shaped
• Superior and inferior horns have posterolateral extensions (superior and inferior cornua)

Cricoid Cartilage

• Complete ring of hyaline cartilage
• Located between thyroid cartilage and trachea
• Anterior arch is curved
• Posterior lamina is flattened

Arytenoids

• Located on cricoid cartilage
• Hyaline cartilage
• Pyramidal shape, tapering to apex
• Articulates with corniculate cartilage
• Attachment sites located on the vocal and muscular processes located on the arytenoid cartilage
• Vocal process: elongated, sharp anterior projection
• Muscular process: rounded, posterolateral projection

Corniculate Cartilages

• Located on top of arytenoid cartilages
• Conical shape
• Considered minor

Intrinsic Structures: Quadrangular Membrane

• Submucosa layer; broad, thin connective tissue sheets
• Extends from lateral epiglottis edges to arytenoid cartilages, covered in mucosa
• Superior free border: aryepiglottic fold
• Forms lateral border of laryngeal inlet
• Cuneiform tubercle (inferior aryepiglottic fold) contains cuneiform cartilages

Vestibular Fold

• Inferior free edge of quadrangular membrane
• The "false" vocal cord

Conus Elasticus

• Connective tissue between superior cricoid & thyroid cartilage rims
• Superior free edge forms vocal ligament

Vocal Ligaments

• Superior free edges of conus elasticus
• Extends from arytenoid cartilages to inner thyroid cartilage surface
• Covered by mucous membrane
• Ligament + mucous membrane = vocal folds
• Vocal folds essential for sound production

Pharynx Overview

• Muscular column
• Posterior to oral, nasal cavities + larynx
• Lined by mucosa + muscle fibers
• Important for voice + passageway for food/air

Nasopharynx Specifics

• Uppermost part of pharynx
• Posterior to nasal cavity, behind conchae
• Communicates with nasal cavity through nasal conchae
• Torus tubarius: auditory tube (Eustachian) elevation
• Torus levatorius: below torus tubarius, elevation from levator veli palatini muscle
• Pharyngeal recesses located behind Eustachian tube
• Salpingopharyngeal folds: ridges from salpingopharyngeus muscle
• Soft palate located posterior to hard palate, contains tensor veli palatini muscle
• Palatine uvula: conical posterior soft palate projection, hangs into oropharynx
• Pharyngeal tonsil: adenoids; lymphatic tissue in nasopharyngeal area

Oropharynx

• Between nasopharynx and laryngopharynx
• Just behind oral cavity
• Extends from soft palate to hyoid bone
• Vallecula epiglottica: fossa between lateral/median glossoepiglottic folds, epiglottis
• Palatopharyngeal arches are 2 mucous membrane folds overlying palatopharyngeal muscle, which depresses palate
• Root of tongue is posterior part, anchoring tongue to mandible/hyoid
  • Vallate papillae contain taste buds
  • Lingual tonsils
• Palatine tonsils contain lymphoid tissue aka mucosa-associated lymphoid tissue (MALT)

Laryngopharynx

• Behind larynx
• Extends from oropharynx to esophagus
• Piriform recess
• Located on both sides of laryngopharynx
• Epiglottis is elastic cartilage, covered by mucous membrane
  • Closes during swallowing
  • Open when breathing
• Laryngeal inlet opens from pharynx to larynx, which epiglottis closes to entering respiratory tract
• Aryepiglottic folds at opening of larynx
  • Mucosal folds overlying aryepiglottic muscle aid in phonation
• Interarytenoid notch is depression found between arytenoid cartilage apices
  • Covered by mucosa
• Cuneiform tubercles are mucosa-covered prominences
  • Formed by underlying cuneiform cartilage located on the posterior part of the aryepiglottic folds
• Corniculate tubercles are eminences formed by underlying corniculate cartilage
  • Covered by mucosa
• Piriform fossa/piriform recess is located between the aryepiglottic folds and the thyroid cartilage on either side of the laryngeal inlet.
  • The mucosa houses a branch of the superior laryngeal nerve

External Nose General Structure

• Pyramidal with root superior & apex inferior
• Root connects to anterior head surface
• Dorsum is part between root & apex
• Nares (nostrils) are openings inferior to apex
• Separated by nasal septum + laterally bounded by ala nasi (nostril wings)
• Bony nasal root formed by nasal, maxillae, and frontal bones

Cartilaginous Nose

• Alar cartilages
  • major alar cartilage (nose apex)
  • minor alar cartilages (ala nasi support)
• Lateral cartilage forms the dorsum
• Septal cartilage bounds nares medially

Nasal Cavity Anatomy

• Contained with the external nose and adjacent skull and is made up of 12 cranial bones
• Anterior openings: nares
• Posterior openings: choanae, communicate with nasopharynx

Nasal Cavity Roof

• Ethmoid bone

Lateral Wall, Nasal Cavity

• Nasal conchae (inferior, middle, superior) and project into nasal cavities
  • 3 bony shelves attached to lateral walls
  • Divide each nasal cavity into 4 air channels

Air Channels, Nasal Cavity

• Inferior nasal meatus
  • Between floor and inferior concha
• Middle nasal meatus
  • Located between inferior and middle concha
• Superior nasal meatus
  • Between middle and superior concha
• Sphenoethmoidal recess
  • Located between superior concha and nasal cavity roof
• Common nasal meatus
  • Between conchae and nasal septum

Nasal Cavity Regions

• Vestibule
  • Located inside anterior external nose opening
  • Contains hair follicles
• Olfactory Region
  • Small area
  • At superior cavity apex
  • Lined by olfactory epithelium
• Respiratory Region
  • Remainder of cavity
  • Largest region
  • Lined with respiratory epithelium

Paranasal Sinuses

• Bony recesses communicating with nasal cavities
• Named for containing bones
• Covered by respiratory mucosa
• Innervated by trigeminal nerve (CN V)
  • Sphenoidal, maxillary, frontal, ethmoidal

Nasal Cavity Blood Supply

• Apex and dorsum: External carotid artery branches
• Sphenopalatine
• Greater palatine
  • Superior labial
• Lateral nasal
• To Olfactory region and surrounding external nose: Internal artery branches
  • Anterior and posterior ethmoidal arteries

Nasal Cavity Nerve Supply

• Three cranial nerves innervate
  • Olfactory (CN I) - olfactory function
  • Trigeminal (CN V) - general sensation
  • CN VII (parasympathetic fibers) - innervates serous glands in nasal mucosa
• Sympathetic T1 spinal cord level Regulates blood flow through nasal mucosa