|Affected Nerve in Clinical deficit: Absent gag reflex ||CN IX via tonsillar N (sensory limb of gag reflex). CN X (motor limb of gag reflex via pharyngeal plexus)|
|Affected Nerve in Clinical deficit: Absent taste on posterior 1/3 of tongue ||CN IX (via Lingual branches)|
|Affected Nerve in Clinical deficit: Paresis in swallowing and Dysphagia ||CN IX (Stylopharyngeus) and CN X (all other muscles of soft palate and pharynx minus TVP. Without CN X, there is no motor limb to the pharyneal plexus: soft palate would sag, uvula deviated to contralateral side)|
|Affected Nerve in Clinical deficit: Dysphonia and aphonia ||CN X: External branch of superior laryngeal N: cricothyroid M, Inferior Laryngeal N (From Recurent Laryngeal Ns) provide somatic motor to the rest of the laryngeal muscles.|
|Affected Nerve in Clinical deficit: Hoarseness ||CN X (recurrent laryngeal N)|
|Affected Nerve in Clinical deficit: Protrusion of the tongue to one side ||CN XII (Genioglossus on one side will be inactive, tongue will deviate towards ipsilateral side of lesion since genioglossus wags the tongue towards contralateral side when activated)|
|Ligaments associated with the Larynx ||1.Cricothyroid: cricoid cartilage to thyroid cartilage (lateral).
2.Vocal: thing ligament running from vocal process of cricoid cartilage to the apex of thyroid cartilage.
3.Vestibular: runs same course as vocal ligament but lies superior.|
|2 Main functions of the Larynx ||1.Guarding the Airway (most important).
|Function of the Arytenoid cartilages in the larynx ||(two horns coming up from the cricoid cartilage) Alter the position of the true vocal cords during phonation.|
|Cartilages associated with the Larynx ||1.Thyroid (C4).
|Location of the Hyoid bone ||C3 within the superior part of Larynx|
|Internal Larynx: Glottis ||Vocal apparatus consisting of:
1.Vocal folds (all vocal muscles and ligaments).
2.Rima glottidis (space b/w the vocal and vestibular folds).
3.Vestibular folds (false vocal folds superior to true vocal folds. Protect the airway via Vestibular ligaments|
|Muscles of the larynx: Adductors ||1.Lateral Cricoarytenoid M, 2.Arytenoids (transverse and oblique). These are innervated by inferior laryngeal N (CN X). **Both adduct vocal cords to lower volume to whisper during phonation.|
|Muscles of the larynx: Abductors ||1.Posterior Cricoarytenoid: Innervated by the inferior Laryngeal N. **Actions: abducts vocal folds allowing more air to pass through and increasing the volume.|
|Muscles of the larynx: Tensor ||1.Cricothyroid M: Innervated by the External branch of superior Laryngeal N. Action: tilts the thyroid anteriorly which increases tension in vocal folds (RAISES PITCH)|
|Muscles of the Larynx: Relaxer ||1.Thyroatenoid M: Pulls arytenoid cartilages forward, shortening vocal cords & lowering pitch.
2.Vocalis M: Medial to thyroarytenoid, lateral to vocal fold, makes minute adjustments to volume and pitch.
**Both Innervated by Inferior Laryngeal N|
|Branches of CN X that innervate the Larynx ||1.Superior Laryngeal N: gives off 2 branches: Internal and External Laryngeal N (they innervate the larynx as well as the root of the tongue and epiglottis).
2.Recurrent Laryngeal N: gives off the Inferior Laryngeal N that innervates the Larynx.|
|Internal Laryngeal N ||Sensory: Vestibule and middle cavity (Inferior pharynx and larynx, root of the tongue). It travels with the Superior laryngeal A into the Thyrohyoid membrane.
**Taste from eiglottis region|
|External Laryngeal N ||MOTOR: to the Cricothyroid M, inferior pharyngeal constrictor M (via pharyngeal plexus). Travels the superior thyroid A.|
|Inferior Laryngeal N ||SENSORY: to infraglottic cavity.
MOTOR: almost all the laryngeal muscles (except cricothyroid).
Travels with inferior laryngeal A inferior to inferior border of pharyngeal constrictor.|
|Lesions to CN X: effects on the thoraco-abdominal region ||1.Increased HR.
2.Lack of peristalsis & sounds|
|Lesions to CN X: effects on taste ||Sensory taste cell bodies from the epiglottis lie in the inferior vagal ganglion. Therefore taste would be lost but would NOT be noticed unless tested.|
|Lesions to CN X: effects on Ear and meninges ||CN X has somatosensory fibers from the external auditory canal and the dura in the POSTERIOR cranial fossa. Both would be lost.|
|Lesions to CN X: effects on the carotid body and sinus ||Since CN X only give a minor fiber contribution, the carotid body and sinus would remain functional and relatively unaffected.
**Damage to CN IX would cause BL pH and BP issues|
|Arteries to the Larynx ||1.Superior Laryngeal A (branch off Sup thyroid A) penetrates the thyrohyoid membrane.
2.Cricothyroid A (Branch off Sup Thyroid A.)
3.Inferior Thyroid A (From Thyrocervical Trunk) supplies the inferior larynx)|
|Branches of the thyrocervical Trunk ||Arises from the 1st part of Subclavian near medial border of Ant Scalene.
1.Inferior thyroid A.
2.Ascending cervical branch
4.Cervicodorsal Trunk (bifricates into superficial cervical A and Dorsal scapular A).|
|Lymphatics of Larynx ||Located above and below the vocal folds. SUPERIOR: Superior deep cervical nodes.
INFERIOR: Pretracheal and Paratracheal lymph nodes drain to the inferior cervical lymph nodes.|
|Lesion on which nerve would cause a lack of sensation in the vestibule? ||Internal Laryngeal N|
|Lesion on which nerve would cause a lack of sensation in the middle laryngeal cavity? ||Internal Laryngeal N|
|Lesion on which nerve would cause a lack of sensation in the Infraglottic Cavity? ||Inferior Laryngeal N|
|Lesion on which nerve would cause an inability to raise pitch? ||External Laryngeal N (Cricothyroid M)|
|Lesion on which nerve would cause an inability to lower pitch, raise volume, and lower volume? ||Inferior Laryngeal N|
|Laryngeal Vestibule ||The opening to the larynx|
|Function of the Middle part of laryngeal cavity ||Phonation.
**Laryngeal Ventricle is the space b/w the sup and inf folds making up the middle laryngeal cavity.|
|Ifraglottic cavity ||Below the folds. Includes lateral thyroid cartilage and inferior cricoid cartilage.|
|Pathway of CN IX ||Medulla, Jugular foramen, Sup & Inf glossopharyngeal ganglia, to either: 1.Carotid sinus/body 2.Stylopharyngeus muscle 3.tympanic N.|
|Parasymp innervation of Parotid Gland pathway ||Medulla, Jugular foramen, Sup & Inf glosopharyngeal ganglia, tympanic N, Tympanic plexus, lesser petrosal N, foramen ovale, otic ganglia, Auriculotemporal N, Parotid gland|
|Lesions on CN IX ||1.(Carotid sinus N) Cause regulation issues of carotid sinus (BP) and carotid body (pH).
2.(lingual) Lose of SENSORY from post 1/3 of tongue.
3.(On tympanic N) Loss of GSA from middle ear and Eustacian tube, dec salivation of parotid|
|Pathway of CN XI ||Anterior Root C1-5, Superiorly through foramen magnum, jugular foramen, descends along internal carotid A, enters SCM, then Trapezius|
|Pt presents with weakness in turning their head against resistance, where could the lesion be ||Unilatreal CN XI lesion|
|Pathway of CN XII ||Medulla, Hypoglossal canal, travels with the cervical plexus (superior loop of Ansa Cervicalis) to middle angle of the mandible, enters the tongue
**Innervates all glossus muscles except palatoglossus|
|Lesion on CN XII ||tongue will deviate TOWARDS the AFFECTED side. Also the tongue would protrude due to an inability to retrude.
**Makes it hard to swallow**|