sensory and motor innervation of upper airway

Sensory and Motor Innervationof Upper Airway

R.Srihari

Topics for discussion

• Nose

• Pharynx

• Larynx

• Oral Cavity

Nose

• Parts:

– External nose

– Nasal Septum

Nasal Cavity

– Lateral Wall

• External Nose:– Parts: .Root .Dorsum .Tip .Ala .Anterior Nares

.Nasal Septum .Columella

– Partly cartilaginous Superior and Inferior nasal Cartilage

Septal Cartilage

Partly Bony .Nasal bones .Bridge of nose

.Frontal process of maxilla

• Sensory innervation:

TRIGEMINAL

Ophthalmic Maxillary

(Infratrochlear, External Nasal) (Infraorbital)

Branch of Ant. Ethmoidal

• Motor Supply:

BUCCAL BRANCH OF FACIAL NERVE

• Nasal Cavity:

– Two parts:

• Nasal Septum

• Lateral Wall

• Nasal Septum:

• Lateral Wall:

• Summary of nasal innervation:– Infratrochlear nerve: Ophthalmic branch of Trigeminal

nerve

– Infraorbital nerve: Maxillary branch of Trigeminal nerve

– Anterior ethmoid nerve: Continuation of nasociliarynerve from ophthalmic nerve

– Anterior superior alveolar nerve: Branch of infraorbital nerve

• Posterior superior nasal nerves: branch of maxillary nerve

• Palatine nerves: sensory branches of maxillary nerve

Pharynx

• Muscles of pharynx:

– Constrictors

• Superior

• Middle

• Inferior

– Stylopharyngeus

– Palatophayngeus

– Salpingopharyngeus

• Nerve Supply:

– Motor

– Sensory

– Special Sensory (Taste)

• Pharyngeal plexus:

– Pharyngeal br. Of Vagus carrying fibresOf cranial accessory N.

- Pharyngeal br. Of Glossopharyngeal N.

-Pharyngeal br. Of SuperiorCervical ganglion

• Motor fibres:

– Derived from cranial accessory nerve via branches of vagus

SUPPLIES ALL MUSCLES OF PHARYNX EXCEPT STYLOPHAYNGEUS

SUPPLIED BY GLOSSOPHAYNGEAL N.

• Inferior Constrictor receives additional branches from external and recurrent laryngeal nerve

• Sensory Supply:

– Nasopharynx Maxillary nerve via pterygopalatine ganglion

– Oropharynx Glossopharyngeal nerve and partly via vagus

– Laryngopharynx internal laryngeal nerve (Vagus)

• Taste sensations:

– From vallecula and epiglottis – internal laryngeal branch of vagus

– Parasympathetic secretomotor fibres to the pharynx from greater petrosal nerve (VII CN)

Clinical Relevance

• Gag reflex:– The pharyngeal reflex or gag reflex is a reflex contraction of the back

of the throat, evoked by touching the roof of the mouth, the back of the tongue, the area around the tonsils and the back of the throat. It, along with other aero digestive reflexes such as reflexive pharyngeal swallowing, prevents something from entering the throat except as part of normal swallowing and helps prevent choking.

Reflex:– the sensory limb is mediated predominantly by CN IX

(glossopharyngeal nerve)– the motor limb by CN X (vagus nerve).

Larynx

Muscles of larynx:

• Posterior cricoarytenoid – Abductor

• Lateral cricoarytenoid – Adductor

• Transverse arytenoid – Adductor

• Oblique arytenoid – Adductor

• Aryepiglotticus - Closing inlet of larynx

• Thyroepiglotticus- Opening inlet of larynx

• Thyroarytenoid- Relaxation

• Cricothyroid- Tensor

• Nerve Supply:

• Motor Supply:

– Superior laryngeal nerve

– Recurrent laryngeal nerve

• Superior laryngeal nerve:

– Arises from the inferior ganglion of vagus with small branch from the superior cervical ganglion

– Descends in the lateral wall of the pharynx passing posterior to internal carotid artery at the level of greater horn of hyoid

– Giving rise to internal and external branches

• Internal branch is entirely sensory except for a motor filament to the arytenoid muscle

• Divides into superior and inferior branches

• Superior branch supplies lower part of pharynx, epiglottis, valleculla, vestibule of larynx

• Inferior branch supplies the aryepiglottic fold and mucous membrane of posterior part of rima glottidis (opening between aryepiglotticfold and true cords)

• External branch supplies motor fibres to the cricothyroid muscle

• Recurrent laryngeal nerve:– Goes along the laryngeal branch of inferior thyroid

artery and traverses upwards deep to the lower pharynx

– Supplies all muscles of the larynx except cricothyroid

– Provides sensory supply to the mucous membrane below the level of the vocal cords

Clinical Aspects

• During swallowing the inlet of the larynx is protected by aryepiglotticus

• Coughing/Sneezing Full adduction of vocal cords during expiration leading to increased intrathoracic pressure followed by sudden abduction of the cords

• Sensory stimulation of the laryngeal region during laryngoscopy can stimulate vagusnerve BRADYCARDIA if severe can lead to cardiac arrest

Oral Cavity

• Parts :

– Vestibule

– Lips

– Cheeks

– Oral cavity proper

• Palate:– Hard : Greater palatine and nasopalatine branch of

pterygopalatine ganglion (Maxillary nerve)

– Soft:• Muscles-

– Tensor palati –tightens soft palate

– Levator palati – elevates soft palate and opens eustacian tube

– Musculae uvulae- lifts the uvula

– Palatoglossus – closes the orophryngeal isthmus

– Palatopharyngeus- pulls up wall of phaynx and shortens it during swallowing

• Nerve Supply:

– Motor Supply:

• All except tensor veli palatiCranial part of accessory via Vagus nerve

• Tensor veli palatiMandibular nerve

– Sensory innervation:

• Glossopharyngeal nerve

• Middle and posterior lesser palatine nerves Branches of Maxillary nerve via Pterygopalatine ganglion

– Special Sensory:

• Via Greater petrosal nerve to Geniculate ganglion of Facial nerve

– Secretomotor fibres:

• Lesser palatine nerves Superior salivatory nucleus via greater petrosal nerve

Thank You