the larynx, which leads to the trachea and the hypopharynx, which leads to the esophagus
trachea level and length
- C6-T5 and is 10-15cm in length
- supported by 16 to 20 horseshoe shaped cartilages
may see webbing on both sides of the larynx in which type of patients?
- someone w/ gastric reflux
- lies deep to the STERNOTHYROID and STERNOHYOID muscles from the level of C5-T1
- it consists of LEFT and RIGHT lobes located ANTERIOR to the larynx and trachea
- is HIGHLY VASCULAR and blood supply is from the SUPERIOR and INFERIOR thyroid arteries that arise from the EXTERNAL CAROTID arteries and the SUBCLAVIAN arteries
- parathyroid glands secrete parathyroid hormone (concerned w/the metabolism of CALCIUM and PHOSPHORUS)
- small, ovoid endocrine glands usually lie OUTSIDE the THYROID CAPSULE on the median half of the posterior surface of each thyroid lobe
- usually there are 2 pair of parathyroids on each side (4 total - 2 SUPERIOR and 2 INFERIOR), but the total number varies btwn TWO and SIX
- is located in the anterior part of the neck (C3-C6), and C1@ birth
- in FEMALES, its increase after puberty is only slight (angle is 120)
- in MALES, it undergoes considerable increase; all the cartilages are enlarged and the THYROID cartilage becomes PROMINENT, while the length of the RIMA GLOTTIS is nearly doubled (angle is 90 - more prominent)
- connects the ANTERIOR part of the PHARYNX w/ the TRACHEA
laryngeal skeleton consists of
the hyoid bone and 9 cartilages
- is NOT part of the larynx
- U shaped
- located at the 3rd CERVICAL VERTEBRA in the adults
- located just ABOVE the THYROID cartilage in the anterior wall of the hypopharynx
- it is made up of a BODY, B/L GREATER and LESSER CORNUA
- does NOT articulate w/ any other cartilaginous or bony structure
- compromises the anterior aspect of the preglottic space and is the point of attachment for muscles and ligaments essential to laryngeal function
- STEADY or MOVE the hyoid bone and larynx
- they are divided into the SUPRAhyoid and INFRAhyoid muscles
- includes the mylohyoid, geniohyoid, stylohyoid and digastric muscles
- SUPERIOR to the hyoid bone and connect it to the CRANIUM
- ELEVATION of the floor of mouth and tongue during swallowing and speaking
- SHORTENING floor of mouth and WIDENING the pharnyx
- ELONGATING floor of mouth and STEADY the mandible during swallowing and speaking
infrahyoid muscles (strap muscles)
- includes the sternohyoid, omohyoid, sternothyroid and thyrohyoid
- INFERIOR to the hyoid bone and ANCHOR the hyoid bone, sternum, and clavicle and DEPRESS the hyoid bone and larynx during swallowing and speaking
- also work w/ the SUPRAhyoid muscles to steady the hyoid bone, providing a firm base for the tongue
9 cartilages of the Larynx
- 3 pairs- arytenoid, corniculate and cuneiform
- LARGEST of the UNPAIRED cartilages
- extends LATERALLY but is NOT continuous posterior (does NOT form a complete ring)
- composed of two QUADRILATERAL LAMINAE fused together in the anterior midline where there is a DIP called the SUPERIOR THYROID NOTCH → protects the thyroid gland
- this DIP projects anteriorly to form the LARYNGEAL PROMINENCE
- in males- 90 degree angle - more prominent "Adams apple"
- in females- 120 degree angle - less prominent
- shape determines length of the vocal cords and consequent pitch (SHORTER in women and thus a HIGHER PITCH)
thyroid cartilage's LATERAL margins....
- are the OBLIQUE lines running from the SUPERIOR to INFERIOR tubercles
thyroid cartilage's SUPERIOR border....
- attaches to the HYOID bone by the THYROhyoid membrane
thyroid cartilage's INFERIOR horns......
- articulate w/ the LATERAL CRICOID at the CRICOTHYROID joints
thyroid cartilage's INTERIOR part....
- deep to the superior notch is the point of attachment for the STEM of the EPIGLOTTIS, the VOCAL and VESTIBULAR ligaments, and three intrinsic muscles of the larynx: THYROARYTENOID, THYROEPIGLOTTIC and VOCALIS
- UNPAIRED SIGNET-ring-shaped cartilage
- NARROW band, the ARCH, facing ANTERIORLY
- BROADENED signet portion, the LAMINA, facing POSTERIORLY
- its the ONLY COMPLETE RING of cartilage to encircle any part of the airway
- it attaches to the THYROID cartilage by the median CRICOTHYROID ligament and to the trachea below by the CRICOTRACHEAL ligament
cricoid cartilage borders....
- the ANTERIOR and LATERAL borders attach to the CRICOTHYROID muscle (TENSES the vocal cords - help CONTROL PITCH)
- the POSTERIOR border attaches to the INFERIOR PHARYNGEAL CONSTRICTOR muscle
- apply firm pressure (appr. 5kg) over the cricoid cartilage prior to induction
- the esophagus is collapsed, and passively regurgitated gastric fluid cannot reach the hypopharynx
- excessive cricoid pressure (beyond that which can be tolerated by a conscious person) applied during active regurgitation has been assoc. w/ rupture of the posterior wall of the esophagus
- is composed of ELASTIC cartilage
- does NOT OSSIFY, remains flexible +/o life
- LEAF shaped and provides the elastic skeleton of the epiglottis
- it is suspended by a series of ligaments and does NOT articulate directly w/ any of the surrounding bony or cartilaginous structures
epiglottic cartilage surface is...
- penetrated by multiple small holes that transmit TINY BLOOD VESSELS and FIBROUS TISSUE attachments from its laryngeal surface to the preglottic space
- the laryngeal surface is covered w/ tightly adherent MUCOPERICHONDRIUM and provides almost no soft tissue
epiglottic cartilage's ANTERIOR/LINGUAL surface....
- is the POSTERIOR wall of the preepiglottic space (vallecula), which contains LOOSE AREOLAR TISSUE and FAT (areolar tissue - consists of a MESHWORK of THIN FIBERS that interlace in all directions, giving the tissue both ELASTICITY and STRENGTH)
epiglottic cartilage's INFERIOR end....
- is attached to the inner surface of the thyroid by the strong thyroepiglottic ligament
epiglottic cartilage's ANTERIOR and SUPERIORLY.....
- is attached to the inner surface of the body of the HYOID bone by the midline HYOEPIGLOTTIC ligament
epiglottic cartilage's LATERALLY...
- is attached to the musculature of the BASE of the TONGUE by the less prominent GLOSSOEPIGLOTTIC ligaments
the bilateral pouch like mucosal reflections btwn the median HYOEPIGLOTTIC ligament and these lateral GLOSSOEPIGLOTTIC ligaments are referred to as the.....
- pyriform fossa
- are PAIRED THREE-SIDED, pyramid shaped bodies
- lie on the POSTERIOR SUPERIOR margin of the CRICOID CARTILAGE
- ANTEROMEDIAL, pointed portion is referred to as the VOCAL PROCESS
- the LATERAL angle ends in the MUSCULAR PROCESS, which is attached to the POSTERIOR and LATERAL CRICOARYTENOID muscles
- stretching btwn the POSTERIOR surfaces of the two arytenoids are the TRANSVERSE and OBLIQUE arytenoids muscles
- attached to the ANTEROLATERAL surface of the arytenoids are the VOCALIS and THYROARYTENOID muscles
- the UPRIGHT PROCESS/APEX of the arytenoid cartilage points ANTEROMEDIALLY and serves as the posterior attachment of the ARYEPIGLOTTIC FOLD
- SMALL PAIRED cartilages that sit on top of the APICES of the ARYTENOIDS
- provide support
- PAIRED, ROD shaped bodies in the ARYEPIGLOTTIC FOLD lateral to the epiglottis
- provide support
C3-C6 in adults and C1@ birth
the internal cavity of the larynx may be divided into three parts:
the vestibule, the ventricle, and the infraglottic area
- also called SUPRAGLOTTIC region, stretches from the free margin of the EPIGLOTTIS and ARYEPIGLOTTIC folds inferiorly to the lower margin of the ventricular bands (usually referred to as the FALSE cords)
(a cavity of a bodily part or organ) of the larynx is the laterally directed sac btwn the undersurface of the ventricular bands and superior to the vocal folds the - true vocal folds from the RIMA GLOTTIS
- 15mm long in males and 10mm long in females
the infraglottic area
- is the inferior cavity of the larynx that extends from the VOCAL folds to the inferior border of the CRICOID cartilage where it is cont. w/ the cavity of the trachea
extrinsic muscles of the larynx
- INFRAHYOID and SUPRAHYOID muscles
- they interlock at the HYOID bone and to a lesser extent at the THYROID cartilage
- they are capable of moving the entire laryngotracheal complex as much as one whole
vertebral body in going through a full range of two to two and one-half octaves
infrahyoid group of muscles (aka the depressor group of muscles)
- displaces the larynx down during the INSPIRATORY phase of respiration
suprahyoid group of muscles (aka the elevators)
- lift the larynx during swallowing
- when the elevator muscles move the larynx both forward and superiorly which, assoc. w/ the downward movement of the base of the tongue, the epiglottis is compressed. This is one of the major mechanisms to prevent aspiration
the inferior pharyngeal constrictor muscle, the cricothyroideus muscle and cricopharyngeus muscle
- have their attachments on the larynx but play their role almost entirely during the ACT OF SWALLOWING
- the cricopharyngeus muscle may be regarded as an extrinsic muscle of respiration in that if it does not function properly, it favors spilling over of swallowed material directly into the glottis
Intrinsic Muscles of the Larynx
- are concerned w/ the movements of laryngeal parts
- they make alterations in the LENGTH and TENSION of the VOCAL CORDS and the size and shape of GLOTTIS
- all of the intrinsic muscles are innervated by the RECURRENT LARYNGEAL NERVE w/ the exception of the cricothyroid which is innervated by the SUPERIOR LARYNGEAL NERVE
Cricothyroid Muscles (paired)
- located on the external surface of the larynx. Arise from the anterior arch of the cricoid cartilage and fibers travel backward and upward to insert into the inferior border of the thyroid cartilage
- action: pulls the thyroid cartilage DOWN and TOWARD the cricoid
- result: increases the distance btwn the artenoids and the thyroid cartilage, TENSING the VOCAL folds-helps CONTROL PITCH
Posterior Cricoarytenoid muscles (paired)
- lie on the dorsal surface of the cricoid cartilage
- fibers originate near the posterior midpoint, and run laterally from there in both directions
to attach to the back of the muscular processes of the arytenoids cartilages
- action: when muscles contract, they pull the muscular processes posterior and the vocal processes laterally
- result: abduction of the vocal folds these are the ONLY ABDUCTORS of the vocal folds. w/o them, the vocal folds adduct permanently, and you suffocate (inhibited during laryngospasm)
→ PCA pulls cords apart
Lateral Cricoarytenoid muscles (paired)
- originate from the upper anterior border of the cricoid cartilage. fibers pass posterior left and right and insert on the anterior aspect of the muscular processes of the arytenoids cartilages
- action: muscular processes are pulled anterior and vocal processes are pulled medially
- result: adduction of vocal folds (stimulated during laryngospasm)
Transverse Arytenoid muscle (unpaired)
- a single muscle attaching the posterior surfaces of the arytenoids to one another
- action: upon contraction, pulls the arytenoids medially (toward each other)
- result: adduction of the vocal folds
Thyroarytenoid muscles (paired)
- border the vocal ligaments. arise from the anterior inner surfaces of the thyroid laminae, deep to the laryngeal prominence, and insert on the lateral borders of the arytenoids cartilages
- action: pull arytenoid cartilages closer to the thyroid cartilages
- result: reduced tension of the vocal ligament. in the process of SHORTENING, these muscles also thicken which helps to seal the glottis
- they are considered sphincters of the glottis (stimulated during laryngospasm)
- is composed of the fibers of THYROARYTENOID muscle closest to the vocal ligaments
- each vocalis attaches to the elastic tissue of the vocal ligament
- action: contraction affects frequency of vibration of the vocal ligaments
- result: CONTROL of PITCH and the fine adjustments required in VOCALIZATION
the function of both the Feeding and Respiratory systems can be modified by the use of Valves
- each system contains a series of valves, which change the shape or configuration of the system to protect it
valves created by the lips and tongue.....
- keep food in the mouth and in place prior to swallowing
the valve created by the cricopharyngeous muscle at the top of the esophagus.....
- keeps air out of the digestive system during breathing
the valve created by the soft palate.....
- keeps food out of the nasal airway during swallowing
- the valves created by the false and true vocal folds and the epiglottis.....
- prevent food from entering the airway during swallowing
what are the innervated nerves of the larynx?
- internal and external branches of the superior laryngeal nerve and the inferior laryngeal branch of the recurrent laryngeal nerve, which are all divisions of the vagus nerve
Superior Laryngeal nerve: Internal branch
- the PRINCIPAL SENSORY nerve of the larynx above the vocal cords (afferent/efferent)
- sends fibers from the mucous membrane of the larynx and epiglottis
- responsible for inducing the cough reflex when something other than air enters the larynx
- the superior laryngeal nerve's internal branch also sends parasympathetic fibers (afferent/efferent) to the mucous glands of epiglottis, base of tongue, aryepiglotti fold, and most of the interior larynx and stimulates production of saliva and mucous
Superior Laryngeal nerve: External branch
- ONLY innervates the CRICOTHYROD muscle (afferent/efferent)
→ afferent- away efferent- brings back
- comes off just before the point at which the nerve pierces the thyrohyoid membrane
- function: provides MOTOR innervation to the cricothyroid muscle
- the cricothyroid muscle is the ONLY TENSOR of the VOCAL CORDS and helps CONTROL VOCAL PITCH.
Inferior Laryngeal nerve
- is the continuation of the left and right RECURRENT laryngeal nerves
- it innervates all intrinsic muscles of the larynx except cricothyroid as it travels superiorly, it supplies the trachea and esophagus
the recurrent laryngeal nerves are vulnerable to what type of injuries.....
- during operations in the neck that include: thyroid surgery, carotid endarectomy, surgery on vertebrae in the neck
- as well as cardiac surgeries and other surgeries around the aorta, it may be damaged
- the nerve can also be compressed by tumors or other growths anywhere along its path
- it can also be injured during endotracheal intubation as well as by misplacement of the ETT
(cuff to high) causing a neuroplaxia (a transient episode of motor paralysis w/ little or no sensory or autonomic dysfunction)
- injury to the inferior laryngeal nerve - b/c it innervates the muscles moving the vocal
cords, injury to the nerve results in vocal cord paralysis
Unilateral Vocal Fold Paralysis
- the weakened vocal fold often cannot move well enough to meet the other fold in the midline during speech and as a result air leaks out too quickly
- the voice to sound breathy (MOST COMMON sign) and weak, and also makes it necessary for the speaker to take breaths more often during speech
- they will only be able to sound the letter "E" for about 6-8 sec vs the person w/ no paralysis who can hold the sound for 20 sec
- can also lead to choking and coughing, esp. after eating or drinking liquids. the weakened fold cannot fully close the larynx during swallowing and food or water may leak into the lungs
- they may find it harder to cough and to "bear down" during lifting or straining. all of these actions require that the vocal folds be brought together for a tight seal
Bilateral Nerve Injury - the WORST!!!!
- may lead to bilateral vocal fold paralysis
• both folds may be in the midline position and closed (adducted)
• this makes it very difficult to breathe and can lead to serious problems
- in some cases a tracheotomy is necessary to establish an airway
- vocal cords in humans may close if both recurrent laryngeal nerves are accidentally cut during surgery
- this can result in a closed glottis and inability of the patient to breathe; immediate airway control (intubation and subsequent tracheotomy may be necessary)
- however, if both folds are near the center, the voice may be quite good
- laryngospasm is a forceful involuntary spasm of the larygeal musculature caused by sensory stimulation of the INTERNAL BRANCH of the SUPERIOR LARYNGEAL nerve
- partial laryngospasm is characterized by HIGH PITCHED phonation or CROWING
- total occlusion is characterized by NO SOUNDS but signs of airway obstruction such as retraction of the trachea or flaring of the nostrils, chest rocking
- during a fully formed laryngospasm, the FALSE CORDS and EPIGLOTTIC body come together firmly. there is no air flow, no vocal sounds and the true vocal cords cannot be seen
- large negative intrathoracic pressures generated by the struggling patient in laryngospasm can result in development of pulmonary edema even in healthy young adults → NPPE
→ most times it occurs on EMERGENCE and not on induction d/t stimulation of secretions
when may a laryngospasm occur?
- during light levels of anesthesia
- when the larynx is irritated by secretions or when the patient experiences a painful stimulus
→ also may occur w/ loud noises in the background (dropping instruments or music playing) d/t to the patient being to lightly anesthesized
prevention of laryngospasm
- suctioning foreign material from the oropharynx, prior to extubation (USE SOFT SUCTION
- positive pressure extubation
- preventing noxious stimulus during stage 2
- removing any painful stimulus
treatment of laryngospasm
- 1st applying positive pressure to the airway
- 2nd increasing the inhalational agent and positive pressure ventilation (100% oxygenation)
- 3rd placing the fingers behind the angles of the mandible to thrust the jaw forward at the "LARYNGOSPASM NOTCH"
- if these measures do not resolve the laryngospasm quickly, a rapidly acting muscle relaxant is usually adm i.e. succinylcholine (0.25-1.0mg/kg). hypoxia and hypercarbia decrease postsynaptic potentials and brainstem output to the laryngeal nerves, resulting in less vigorous glottic closure → thus, laryngospasm eventually ceases spontaneously as hypoxia and hypercarbia develops
in summary laryngospasm.....
laryngospasm is defined as a sudden, prolonged, forceful apposition of the vocal cords, and it is believed to be the result of a laryngeal reflex response to noxious stimuli. the reflex arc consists of an afferent limb carried by the stimulated superior laryngeal nerve (SLN) and an efferent limb carried by the recurrent laryngeal nerve (RLN)
which muscles are innervated by the superior laryngeal nerve (external branch)?
which intrinsic muscles are inhibited during laryngospasm?
posterior cricoarytenoid muscles
which intrinsic muscles are stimulated during laryngospasm?
lateral cricoarytenoid and thyroarytenoid muscles