Muscle Group Muscle Innervation



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Muscle

Group

Muscle

Innervation

Action

Attachments/ comments

Sphincteric





Recurrent Laryngeal (CN X + fibers from XI)

Close off larynx during swallowing







Thyroarytenoideus

Relaxes vocal fold

O: one arytenoid cartilage

I: opposite arytenoid cart.



Aryepiglotticus

Ensure that the arytenoid cartilages are brought together at the same time as the epiglottis is pulled inferiorly toward these cartilages

O: arytenoid cart.

I: aryepiglottic fold



* continuation from oblique interarytenoideus

Thyroepiglotticus

Widens inlet of larynx

O: internal surface of thyroid cart.

I: laterally on epiglottic cart.



Interarytenoideus (oblique fibers)

Closes inlet of larynx

O: one arytenoid cart.

I: opposite arytenoid cart.

* two bundles that cross each other


Adjustors of larynx and vocal cords







Open and close the rima glottidis (space b/t vocal folds)







Lateral cricoarytenoideus

Recurrent laryngeal

(CN X + fibers from CN XI))



Pull muscular processes anteriorly, rotating arytenoids so that their vocal processes swing medially  vocal fold adduction (closure of rima glottidis)

O: arch of cricoid cart.

I: muscular process of arytenoid cart.






Posterior cricoarytenoideus

Rotate arytenoid carts.  lateral deviation  abduction of vocal folds  (widening of rima glottidis)

O: posterior surface of lamina of cricoid cart.

I: muscular process of arytenoid cart.



Interarytenoideus (transverse fibers)

Adducts vocal folds, and closes inlet of larynx

O: one arytenoid cartilage

I: opposite arytenoid cart.



* only unpaired muscle of the larynx

Vocalis

Pulls arytenoid cartilage anteriorly  relaxation of vocal folds

O: Angle b/t lamina of thyroid cart.

I: Vocal process of arytenoid



Cricothyroideus

External laryngeal n. (CN X + fibers from XI)

Pull thyroid cart. anteriorly on the cricoid cart  increased distance b/t thyroid and arytenoid carts. tensing of vocal folds (elongation/tightening of vocal ligaments

O: anterolateral cricoid cart.

I: Inf. horn of thyroid cart.





Skeleton


  • Hyaline cartilages

  1. Thyroid

  • l/r laminae

  • superior cornu (horn)

  • inferior cornu (horn)  articulates w/ cricoid @ cricothyroid joint (synovial hinge)

  1. Cricoid:

  • complete ring (anterior arch + posterior lamina)

  1. Arytenoids

  • paired

  • muscular process – projects laterally, attaches to lateral and posterior cricoarytenoid muscles

  • vocal process – projects forward, attaches to vocal ligament and vocalis muscle

4. & 5. Corniculate & Cuneiform

  • not important

  • on top of arytenoid cartilages

  • Elastic cartilage

  1. Epiglottic – attached to posterior surface of thyroid cart. by thyroepiglottic ligament

  • Membranes

  1. Thyrohyoid

  • contains foramen for superior laryngeal n. (branch of CN X) & superior laryngeal artery

  • connects larynx to hyoid

  1. Cricotracheal ligament

  • connects larynx to trachea

  1. Cricothyroid ligament

    - connects cricoid cart. to thyroid cart.

  1. Intrinsic membranes: fibroelastic

  1. Quadrangular/aryepiglottic membrane

  • connects epiglottic and arytenoid cartilages

  • upper free border covered by mucous membrane = aryepiglottic fold (@ entrance to larynx)

  • lower free margin covered by mucous membrane = vestibular ligament (false vocal cord)

  1. Triangular/cricothyroid membrane

    - lateral to cricothyroid ligament, runs interiorly from cricoid cart.

  • connects cricoid, thyroid, and arytenoid cartilages (@ vocal processes)

  • upper free border: vocal ligament (true vocal cord)

  • forms lateral edge of rima glottidis

  • lower free border: cricoid cartilage

  • right + left  form conus elasticus (looks like triangle from a posterior view)

    Interior Larynx:

  • entrance = aditus

  • cavity: superior to inferior

    aditus  vestibule  vestibular folds  ventricle  vocal folds infraglottic cavity  lower cricoid border



  • rima vestibuli: opening b/t vestibular folds

  • rima glottidis: opening b/t vocal folds

  • glottis: rima glottidis + vocal folds

    Innervation:

    CN X – motor, sensory and parasympathetic

    Branches:



  1. Superior Laryngeal Nerve – divides w/in carotid sheath into two terminal branches:

  1. External laryngeal nerve:

  1. Internal laryngeal nerve:

  • sensory and preganglionic parasympathetic supply to mucosal lining

    of larynx to level of vocal cords

  • pieces thyrohyoid membrane w/ superior laryngeal artery

  1. Recurrent Laryngeal Nerve:

  • motor to all intrinsic laryngeal muscles (except cricothyroideus)

  • sensory and preganglionic parasympathetic supply to mucosal lining of larynx below vocal cords

  • ascends in groove b/t trachea and esophagus giving branches to pharynx, esophagus, and trachea

  • terminal part: inferior laryngeal nerve

  • damage  reduces voice to whisper

    Functions:

  1. Sphincter: swallowing, coughing, abdominal straining

  2. Phonation:

    Vibration of vocal folds: anterior vibrations  high pitch

    Primary muscles: cricothyroid and vocalis



    Random stuff:

    Vocal fold = vocal ligament, conus elasticus, muscle fibers, + mucous membrane

    A cute little way to remember innervation of larynx and pharynx:

    both end w/ x, x = X, X = vagus

    Muscles which move larynx as a whole:

    Infrahyoid muscles (omohyoid, sternohyoid, sternothyroid) – depressors

    Suprahyoid muscles (stylohyoid, digastric, mylohyoid, geniohyoid,) +

    stylopharyngeus  elevate hyoid bone and larynx

    Cricothyrotomy: incision made through skin and cricothyroid ligament for relief of

    respiratory obstruction

    Tracheotomy – insertion of metal tube into the trachea

    Laryngectomy: removal of larynx


  • esophageal speech possible (regurgitating ingested air)

    Puberty: walls of larynx strengthen, laryngeal cavity enlarges, vocal folds lengthen and thicken (particularly in males), laryngeal prominence becomes conspicuous in males

    Swallowing (you might want to read this section along w/ the notes on the pharynx):

    Two stages:



  1. Voluntary:

    CN V –

  1. sense food in oral cavity

  2. grind food w/ muscles of mastication

  3. elevate floor of oral cavity w/ mylohyoid

    CN VII – push food b/t teeth by buccinator muscle

    CN XII – tongue shaped for swallowing, pushes food past

    palatoglossus arches


  1. Involuntary

    Nasopharynx closed off:

    CN V – soft palate tenses from tensor palatini muscle

    CN X –

    Soft palate elevates from levator palatini muscle



    Contraction of palatopharyngeus and upper fibers of

    superior constrictor muscles

    CN X: Larynx and pharynx elevated: stylopharyngeus,

    salpingopharyngeus, palatopharyngeus, and

    thyrohyoid muscles

    Peristaltic-like contraction of constrictors moves food to

    laryngopharynx

    Aditus of larynx constricted by contraction of oblique

    arytenoid muscles and thyroarytenoid muscles

    Epiglottis covers aditus

    Food passes to either side through epiglottic valleculae

    Lasts about 2 sec.







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