HNS60 Larynx Flashcards
Functions of larynx
Laryngeal inlet: prevent foreign bodies getting into trachea
Vocal cord: phonation, sneezing, coughing, increase abdominal pressure (Valsalva’s maneuvre)
Skeleton of larynx
- Cartilage
- Epiglottis (Yellow cartilage)
- Thyroid (Hyaline: ossify at old age)
- Cricoid (Hyaline: ossify at old age)
- Corniculate (Hyaline: ossify at old age)
- Arytenoids (Hyaline: ossify at old age) - Fibrous (hold structures together)
- Ligaments
- Membranes
***Extrinsic muscles of Larynx
Movement of WHOLE larynx
Elevation:
- Suprahyoid (attach to hyoid bone)
1. Stylohyoid (CN7)
2. Geniohyoid (floor, C1)
3. Mylohyoid (floor, CNV3) - Others
1. Stylopharyngeus (Pharyngeal plexus)
2. Salpingopharyngeus (Pharyngeal plexus)
3. Palatopharyngeus (Pharyngeal plexus)
4. Thyrohyoid (C1) (Elevate larynx but Depress hyoid)
5. Digastric (Anterior belly: CNV3, Posterior belly: CN7)
Depresses:
- Strap / Infrahyoid muscles (Thyrohyoid also a part)
1. Sternohyoid (Ansa cervicalis, C1-3 Cervical plexus)
2. Sternothyroid (Ansa cervicalis, C1-3 Cervical plexus)
3. Omohyoid (Ansa cervicalis, C1-3 Cervical plexus)
***Intrinsic muscles of Larynx
Movement of PART of larynx e.g. Laryngeal inlet / Vocal cord
Modify laryngeal inlet (記: TAO)
- Thyroepiglottic (pull epiglottis down)
- Aryepiglottic (narrow laryngeal inlet)
- Oblique arytenoid (narrow laryngeal inlet)
Act on vocal cords Open / Close cord (記: PLT): 1. Posterior cricoarytenoid (aBduct) 2. Lateral cricoarytenoid (aDduct) 3. Transverse arytenoid (aDduct)
High / Low pitch (記: CTV):
- Cricothyroid (tense —> high pitch)
- Thyroarytenoid (relax —> low pitch)
- Vocalis (relax / tense —> low pitch)
Cricoid cartilage
Anterior: Arch
Posterior: Lamina
Thyroid cartilage
- Laryngeal notch (superior depression)
- Laryngeal prominence (Adam’s apple)
- Superior horn
- Oblique line
- attachment of ***Inferior pharyngeal constrictor - Inferior horn
- Lamina (L/R)
- between midline and inferior horn (piece of cartilage) - Posterior side
- attachment of vocal cord to Arytenoid vocal process
Arytenoid cartilages
- Apex (Superior 向上指)
- attachment of ***Quadrangular membrane from Epiglottis - Vocal process (Anterior)
- attachment of ***Vocal cord to posterior thyroid cartilage - Muscular process (Lateral)
- attachment of intrinsic muscles
Cartilage and joints
Hyaline cartilages (ossify):
- Thyroid cartilage
- Cricoid cartilage (below thyroid cartilage)
- Corniculate (on top of apex of arytenoid)
- Arytenoid (on top of posterior side of cricoid cartilage)
- **Synovial joints (allow free movement):
1. Cricothyroid joint (anterior —> posterior movement of cricoid, thyroid cartilage)
2. Cricoarytenoid joint (medial / lateral movement)
***Cartilages, membranes and muscles
Membrane:
- Thyrohyoid membrane
- Hyoid bone to Thyroid cartilage
- opening into larynx: **Superior laryngeal vessels + **Internal laryngeal nerve - Quadrangular membrane / ligament
- hangs down from Epiglottis —> attach to Apical process of Arytenoid (後) + Thyroid cartilage (前)
- lower borders hang freely (中間條條fing)
- lined by epithelium
- inferior edge: thicken —> **Vestibular ligament + Epithelium —> **Vestibular fold (False cord) - Conus elasticus / Cricothyroid membrane / ligament
- extend upward from Cricoid cartilage to Thyroid cartilage
- lined by epithelium
- superior edge: **Vocal cord + Epithelium —> **Vocal fold
- anterior edge: Cricothyroid ligament —> ***Cricothyrotomy (access to airway)
Cartilages:
- Aryepiglottic fold
- ***Cuneiform cartilage
- epithelium enclosing edge of Quadrangular membrane
- from Epiglottis to Arytenoid
Muscles:
- Thyroepiglottic muscle (of Thyroarytenoid)
- interior side of Quadrangular membrane
- extend upward from Thyroid cartilage to side of Epiglottis
- ***Pull epiglottis down —> Close Laryngeal inlet - Aryepiglottic muscle (of Oblique arytenoid)
- upper border of Quadrangular membrane / side of Epiglottis —> Apical process of Arytenoid
- **Narrowing of Laryngeal inlet
- extend across to other side of Arytenoid —> **Oblique arytenoid - Oblique arytenoid muscle
- Muscular process to Apical process (交叉)
- ***Narrowing of Laryngeal inlet - Posterior cricoarytenoid muscle
- back of Cricoid cartilage (lamina) to Muscular border of Arytenoid
- ***ABducts vocal cord —> Open vocal folds - Lateral cricoarytenoid muscle
- Cricoid cartilage to Muscular process of Arytenoid (internal to thyroid lamina)
- ***ADducts vocal cord - Transverse arytenoid muscle
- between Apical processes
- **Approximate posterior end of arytenoid
- **ADducts vocal cord - Cricothyroid muscle
- from arch of Cricoid cartilage extend upward to back of Thyroid cartilage (lamina)
- ***Tenses vocal cord (lengthen and thinner) - Thyroarytenoid muscle
- Thyroid cartilage internal lamina to Muscular process of Arytenoid
- Lateral + Parallel to vocal ligament
- ***Relax vocal cord - Vocalis
- runs obliquely between Thyroarytenoid muscle and Vocal cord
- insert into Vocal cord
- Lateral + Parallel to vocal ligament
- **Relaxes / Tenses vocal cord (Presumably)
- **Elevate vocal cord during abduction (Presumably)
Tracheostomy
Cut away first few tracheal cartilage to gain access to airway
- long term purpose
Epiglottis
Yellow cartilage —> do NOT ossify
Space between 2 vocal cords
Rima glottidis
- entrance to lower respiratory tract
Supraglottic area, Glottic area, Subglottic area
Supraglottic area / Subglottic area divided by imaginary line across vocal fold
Supragottic area / Vestibule area (laryngeal inlet —> vestibular fold):
- Superior laryngeal artery (***ECA —> Superior thyroid artery)
- Superior laryngeal vein —> IJV
- Internal laryngeal nerve (CN10 —> ***Superior laryngeal nerve)
- Superior cervical deep LN
Subglottic area (vocal fold —> lower border of cricoid):
- Inferior laryngeal artery (***Subclavian artery —> Thyrocervical trunk —> Inferior thyroid artery)
- Inferior laryngeal vein —> IJV
- Recurrent laryngeal nerve (CN10 from thorax)
- Inferior cervical deep LN
Glottic area:
- Saccule
—> sac like structure from herniation of mucosa
—> Sinus (opening)
—> Mucous glands inside moisten vocal folds to prevent damage
Summary
ALL intrinsic muscles of larynx: ***Recurrent laryngeal nerve
except Cricothyroid muscle: **External laryngeal nerve (branch of **Superior laryngeal nerve)
Vocal folds: Recurrent laryngeal nerve
(Superior laryngeal nerve —> Internal (sensory to Supraglottic area)+ External laryngeal nerve (motor to Cricothyroid muscle))
