The Larynx and Pharynx
The pharynx and larynx are enclosed in the visceral layer of the deep cervical fascia (a.k.a. pretracheal fascia)
- towards skull it is called the buccopharyngeal fascia
Pharynx
muscular tube, closed in back, open to nose and oral cavity in front. From the base of the skull to C6 (cricoid level) common tube for air, fluids, and food. Divided into nasopharynx, oropharynx, and laryngopharynx.
(1) Divisions
– base of skull to inferior border of soft palate. Location of the opening of estuation tubes
- pharyngeal tonsils are in the back of the nose (called Adenoids when enlarged)
Orophanynx – lower border of soft palate to upper border of epiglottis
- Palatoglossus
and palatopharyngus – make up the anterior and posterior tonsillar pillars respectively
- From front to back: Palatoglossus fold
Þ pharyngeal tonsils Þ palatopharnygeal fold
uvula – pendulant portion of the soft palate. Helps propel food into the esophagus
Laryngopharynx – from the epiglottis to the esophagus, where the laryngeal inlet is located (anterior C4-6)
(2) Structures
Pterygoid hamulus – pulley for a muscle that tenses the palate
Mylohyoid line – on the inside of the mandible, separates the lingual, and submandibular gland
Lingula – entrance of mandibular canal on the inside of the mandible
Pterygomandibular raphe – where two muscles come together, superior constrictor of the pharynx and buccinator
(3) Nerves
buccal branch of cranial nerve V innervates the mucosa on the inside of the cheek
pharyngeal plexus of nerves, located on outer surface of middle constrictor receives contributions from: pharyngeal branches of IX (primarily sensory) and X (primarily motor), and postganglionic sympathetics from superior cervical sympathetic ganglion (vasomotor)
plexus provides:
- (1) innervation of skeletal musculature of soft palate and pharynx except: tensor veli palatini (V3) and stylopharyngeus (IX)
- (2) sensory innervation of mucosa of nearly all of pharynx and of Eustachian tube
- (3) parasympathetic innervation of glands in mucosa of pharynx accomplished via CN IX
(4) Muscles
– right in front of prevertebral fascia
- superior
(from pterygomandibular raphe, inserts on pharyngeal tubercle on the base of the occipital)
- medial
(origin from hyoid)
- inferior
(origin from cricoid) – inferior constrictor gets thick near its inferior border (sometimes called cricopharyngeus, acts as a sphincter)
3 longitudinal muscles – names end in"pharyngeus", originate from the first ½ of name:
- salpingpharyngeus
- palatopharyngeus
- stylopharngeus –
(innervated by CN IX)
(5) Structures Entering the Pharynx
Pharyngobasal fascia – portion of superior constrictor that inserts onto the skull
- Above superior constrictor
Þ levator palati and (cartilaginous part of) auditory tube
Spine of the sphenoid – marks the bony part of the estuation tube. Rest of the tube is cartilaginous
Þ stylopharyngeus muscle and CN IX
Above inferior constrictor Þ internal branch of superior laryngeal nerve (vagus), superior laryngeal artery
Below inferior constrictor Þ recurrent laryngeal nerve and inferior laryngeal artery
Larynx
interface between the pharynx and the trachea (and respiratory tree). Shorter than pharynx, epiglottis at top
- primary function – to keep the airway patent.
- secondary function – the production of sound in phonation
(1) Laryngeal Skeleton
3 single cartilages
- (1) epiglottis-thin, leaf shaped cartilage, located posterior to the root of the tongue.
- (2) thyroid cartilage – two lamina that form Adam’s apple
- (3) cricoid- shaped like a signet ring, most inferior cartilage, articulates on its lateral surface with the inferior horns of the thyroid cartilage in a synovial jointernal
3 paired cartilages
- (1) Arytenoid cartilages- pyramidal in shape, articulate with the lateral parts of the lamina of the cricoid cartilage.
- Vocal process – attaches the vocal ligament, narrowest portion of airway
- Muscular process – attaches muscles
- (2) Corniculate- in the Quadrate membrane (makes up the vestibule of the larynx)
- (3) Cuneiform- sit on top of cricoid cartilages, synovial joints, slip back and forth, allow movement of vocal cords.
(2) Membranes
Larynx is suspended from the hyoid by the thyrohyoid membrane
Conus elastus made of three ligaments, an elastic membrane that extends from the cricoid to the vocal ligaments.
- Cricothyroid ligament
– connect the arch of the cricoid cartilage with the thyroid cartilage
- Median cricothyroid ligament
– soft spot inferior to the thyroid cartilage where airway is closest to the skin
- Vocal ligament
- forms the skeleton of the vocal fold
Quadrangular membrane – from the epiglottis to the arytenoid cartilages, lies superior to the vocal cords.
- The free inferior edges of the quadrangular membrane is the vestibular ligament or false cords (sup to real cords)
Cricotracheal ligament – connects the cricoid with the 1st tracheal ring
(3) Glottis
The two vocal cords and the space between them. The functional larynx concerned with voice production
Rimi glottidis – the space between the vocal cords.
(4) Muscles
- Posterior cricoarytinoid muscles
- CN X, pulls the muscular processes together abduct the vocal cords
Lateral cricoarytinoid -adduct the vocal cords
Cricothyroid – only outside muscle innervated by superior laryngeal nerve (X)
(5) Nerves
- Vagus
- Superior laryngeal nerve
– 2 branches
- (1) external branch
– motor to the cricothyroid and to the cricopharyngeus portion of the inferior constrictor
- (2) internal branch
– sensory to the interior of the larynx to the level of the subglottic space
Recurrent laryngeal nerve – motor to all muscles of larynx (except cricothyroid) sensory to subglottic area
(6) Arteries
- Superior laryngeal artery
– a branch of the superior thyroid, travels with the superior laryngeal nerve
Inferior laryngeal artery – a branch of the inferior thyroid, travels with the recurrent laryngeal nerve
(7) Miscellaneous Information
all intrinsic muscles of the larynx are innervated by the recurrent laryngeal of CN X except cricothyroid (superior laryngeal)
interarytenoid (transverse arytinoid) – connects the posterior aspects of the arytenoid cartilages; adducts vocal cords; only unpaired muscle in the larynx
thyro-arytenoid – run from posterior surface of the medial aspect of the thyroid cartilage to the anterolateral surfaces of the arytenoid cartilages; pulls the arytenoid cartilages forward to relax the vocal cords
vocalis: slips of muscle from the thyroarytenoids go directly to the vocal cords and make fine adjustments
oblique arytenoid – run from the posterolateral process of one arytenoid to the superior part of the other; fibers continue to the epiglottis as the aryepiglottic mm; result is that contraction both closes the vocal cords, and depresses the epiglottis thus closing the trachea in two ways when swallowing
ventricle – space between the true and false vocal cords; ends in a blind pouch that contains glands to moisten the cords