Region 7: Oral Cavity and Larynx



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Region 7: Oral Cavity and Larynx

Oral Cavity

--vestibule: smaller external portion

*roof: hard and soft palates

*tongue occupies most of the oral cavity

*Floor of sublingual region contains:

a. lingual frenulum (anchors tongue to the floor)

b. sublingual folds (either side of frenulum)

c. sublingual carnuncles (each side of frenulum containing opening of the submandibular/Wharton’s ducts

Palate


--hard palate (bony palate)

*formed by palatine processes of maxillae (anterior) and horizontal plates of the palatine bones (posterior)

*contains greater palatine vessels, greater palatine and nasopalatine nerves

--soft palate

*fibromuscular tissue suspended from the posterior edge of the hard palate

*continuous laterally w/ palatoglossal and palatopharyngeal arches

*sensory inn by lesser palatine n.

*uvula projects downward n median plane

*Muscles of the soft palate

a. Levator veli Palatini

--O: cartilage of auditory tube

--I: upper surface of palatine aponeurosis

--Inn: cranial portion of accessory n. through vagus and pharyngeal plexus

b. tensor veli palatini

--O: scaphoid fossa at base of medial pterygoid plate

--its tendon goes around pterygoid hamulus

--I: tendons of opp. sides expand and attach to posterior border of hard palate (forming palatine aponeurosis)

--Inn: mandibular n.

c. palatopharyngeus

--O: posterior border of palatine aponeurosis

--occupies palatopharyngeal arch

--Inn: cranial portion of accessory n. through vagus and pharyngeal plexus

d. palatoglossus muscle

--O: inferior surface of palatine aponeurosis

--I: mucous mem. of tongue

--Inn: cranial portion of accessory n. through vagus and pharyngeal plexus

e. musculus uvulae

--O: palatine aponeurosis

----Inn: cranial portion of accessory n. through vagus and pharyngeal plexus

*Sensory Innervation: lesser palatine nerve

Tongue

--apex/tip: rests against incisor teeth



--dorsum: related to palate

*Sulcus terminalis (v shaped groove divided into anterior (2/3 oral part) and posterior (1/3 pharyngeal part)

*Circumvallate papillae: arranged in a row in front of the sulcus terminalis (contains taste buds)

*faramen cecum: located in mid-point of sulcus

--inferior surface of tongue attached to floor of mouth by lingual frenulum

--Extrinsic Muscles of the Tongue

a. Genioglossus

*O: immediately above geniohyoid

*Act: protracts the tongue

b. Hyoglossus

*hypoglossal and lingual nerves pass superficial/lateral to it

*Act: depresses the tongue

c. Styloglossus

*I: into lateral and inferior aspect of tongue

*Act: retracts the tongue

--Intrinsic muscles of the tongue

a. longitudinal

b. vertical

c. transverse

--Innervation

*Motor: all muscles (except palatoglossus) hypoglossal nerve

*General Sensation:

a. anterior 2/3: lingual nerve (from CN V)

b. posterior 1/3: glossopharyngeal n. (CN IX)

*Taste:

a. anterior 2/3: facial n. through chorda tympani n.



b. posterior 13: glossopharyngeal n. (CN IX)

--Blood Supply

*lingual artery

Larynx


--Cartilages of the Larynx

a. Thyroid cartilage (shield like shape)

*composed of right and left laminae

*laryngeal prominence (adam’s apple)

*superior thyroid notch

*superior cornu/horn: attached to greater horn of hyoid bone

*inferior cornu/horn: articulates with the cricoid cartilage

*oblique line: crosses the lateral surface of the laminae, gives attachments to sternothyroid, thyrohyoid and inf. constrictor mm.

b. Cricoid cartilage (signet ring shape)

*at level of C6

*attached above to the thyroid cartilage by the cricothyroid ligament

c. Epiglottis cartilage (leaf shape)

*in front of laryngeal inlet

*b/w epiglottis and base of tongue are spaces called valleculae

d. Arytenoid cartilages (pyramidal shape and 2 of them)

*base is articulated with the upper border of the lamina of the cricoid cartilage

*apex supports the corniculate cartilage

*base projects anteriorly as vocal process that gies attachment to the vocal ligament

*lateral projection of the base has the muscular process

e. Corniculate cartlages

*situated on the apices of the arytenoid cartilages

f. Cuneiform Cartilages

*located in aryepiglottic fold

--Membranes and Ligaments of the Larynx

a. thyrohyoid membrane

*connects thyroid cartilage to hyoid bone

*membrane pierced by internal laryngeal n. and superior laryngeal a.

b. cricothyroid ligament

*connects arch of cricoid to thyroid cartilage

*in acute respiratory obstruction, cricothyroid lig. is separated by piercing it with a sharp instrument to make a temporary airway

c. conus elasticus

*arises from the upper border of the arch of the cricoid cartilage and runs medially and upward

*anteriorly, its upper margins are attached to inner surface of the thyroid cartilage, deep to cricothyroid ligament

*posteriorly, its upper margins are attached to vocal processes of the arytenoid cartilages

d. vocal ligaments

*upper thickened edges of the conus elasticus

*anterior attachment to thyroid cartilage is fixed but its posterior attachment to vocal process of the arytenoid is moveable

*epithelial coverings over the vocal ligament form the vocal folds/true vocal cords

--Joints of the Larynx

a. cricothyroid joint: synovial joints on both sides b/w cricoid and inferior horns of the thyroid cartilages

--Interior of the Larynx

a. inlet/aditus/entrance of the larynx

*piriform recesses of pharynx are lateral to laryngeal inlet

b. vestibule: extends from inlet to vestibular folds

*vestibular/ventricular folds (aka false vocal cords): extend from thyroid cartilage anteriorly to arytenoid cartilages posterior (above vocal process)

*rima vestibuli: space /w the vestibular folds

c. ventricle: on each side extends from vestibular folds to vocal folds

*saccule: upward extension of the ventricle

*laryngocele: enlarged saccule

d. glottis: consists of vocal fold and space b/w (rima glottidis)

*vocal fold/true voal cords: below the ventricles, contain vocal ligament, vocal processes of the arytenoid cartilages, and vocalis m.

*rima glottidis: narrowest part of the larnygeal cavity, its shape and size are altered by movement of the arytenoid cartilages

e. subglottic/infraglottic cavity

*extends from rima glottidis

--Sensory Inn. of Larynx

a. internal laryngeal branch of superior laryngeal n: supplies mucous mem. as far down as vocal folds

b. recurrent laryngeal n: supples mucous mem. below the vocal fold

--Extrinsic Muscles of the Larynx

--Intrinsic muscles of the Larynx

a. cricothyroid m.

*O: external surface of the arch of cricoid cartilage

*Act: act on cricothyroid joints to tilt the lamina of the cricoid cartilage backward and slide the thyroid cartilage slightly forward thus lengthening, tensing, and adducting the vocal fold

*Inn: external laryngeal branch of the superior laryngeal n.

b. lateral cricoarytenoid m.

*Inn: recurrent n.

*Act: adductor of vocal fold

c. thyroarytenoid m.

*Inn: recurrent n.

*Act: adductor of vocal fold

d. vocalis m.

*Inn: recurrent n.

*Act: adductor of vocal fold

e. arytenoideus m.

*Inn: recurrent n.

*Act: adductor of vocal fold

f. posterior cricoarytenoid m.

*Inn: recurrent n.

*only abductor of the vocal folds

--Blood Supply of the Larynx

a. superior laryngeal branch of superior thyroid a (branch from external carotid a.)



b. inferior laryngeal branch of the inferior thyroid a (branch from thyrocervical trunk off of subclavian a)




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