Muscles Of Larynx

TYPES OF LARYNNGEAL MUSCLES:
  1. Extrinsic muscles — which move the entire larynx,
  2. Intrinsic muscles — which move the vocal cords.
EXTRINSIC MUSCLES:
  • ELEVATORS OF THE LARYNX:
  1. Thyrohyoid muscles
  2. Digastric
  3. Stylohyoid
  4. Mylohyoid
  5. Geniohyoid
  6. Hyoglossus
  7. Genioglossus
  • DEPRESSORS OF THE LARYNX:
  1. Sternohyoid
  2. Sternothyroid
  3. Omohyoid

MUSCLES ORIGIN INSERTION INNERVATION
Digastric
Ant. Belly
Post. Belly
Intermediate tendon
Mastoid process
Inner surface of mandible
Intermediate Tendon
Trigeminal
Facial
Stylohyoid Styloid Process Hyoid bone Facial nerve
Mylohyoid Mylohyoid line of mandible Hyoid bone Trigeminal Nerve
Geniohyoid Genial tubercle of mandible Hyoid bone Trigeminal nerve
Thyrohyoid Oblique line of thyroid cartilage Hyoid bone c1-c2(ansa)
Genioglossus Genial tubercle of mandible Tongue Hypoglossal
Sternohyoid Sternum Hyoid Ansa Cervicalis
Sternothyroid Below sternohyoid on manubrium Oblique line of thyroid cartilage Ansa Cervicalis
Omohyoid Suprascapular notch Hyoid bone Ansa Cervicalis
INTRINSIC MUSCLES:
  1. Cricothyroid
  2. Posterior cricoarytenoid
  3. Lateral cricoarytenoid
  4. Arytenoid with its transverse and oblique fibers
  5. Thyroarytenoid and its thyroepiglottic and components

MUSCLES ORIGIN INSERTION INNERVATION ACTION
Cricothyroid
(Located on external aspect)
Anterolateral part of cricoid cartilage Inferior margin & inferior horn of thyroid cartilage External laryngeal stretches & tenses vocal fold
Post. cricoarytenoid
(Safety muscle of larynx)
Post. surface of lamina of cricoid cartilage Muscular process of arytenoid cartilage Reccurent laryngeal Abduct vocal fold
Tensor of vocal cord during phonation
Lateral cricoarytenoid Arch of cricoid cartilage Muscular process of arytenoid cartilage Reccurent laryngeal Adduct vocal fold
Arytenoidtransverse oblique fibers One arytenoid cartilage Another arytenoid cartilage Reccurent laryngeal Close intercartilagenous part of rima glottidis
Adduct vocal cord
control laryngeal inlet
Thyroarytenoid Post. surface of thyroid cartilage Muscular process of arytenoid cartilage Reccurent laryngeal Relaxes vocal cord
Vocalis Depression b/w laminae of thyroid cartilage Part of vocal ligament & vocal process of arytenoid cartilage Reccurent laryngeal Relaxes pot. vocal ligament while maintaining tension of ant. part
  • Muscles Controlling the Laryngeal Inlet are Oblique arytenoid Aryepiglottic muscle
BLOOD SUPPLY :
  • ARTERIAL SUPPLY
  1. Upper Larynx
  2. External carotid artery
  3. Superior thyroid artery
  4. Superior laryngeal artery
  • Lower Larynx
  1. Subclavian artery
  2. Thyrocervical artery
  3. Inferior thyroid artery
  4. Inferior laryngeal artery
  5. VENOUS DRAINAGE:
  6. Upper Larynx
  7. Superior laryngeal vein
  8. Superior thyroid vein
  9. Internal jugular vein
  • Lower Larynx
  1. Inferior laryngeal vein
  2. Inferior thyroid vein
  3. Subclavian vein
LYMPHATIC DRAINAGE:
  • SUPRA GLOTTIC AREA
  1. Superior lymphatics drain to the upper deep cervical nodes, located at the level of the carotid bifurcation.
  2. Some drainage passes to prelaryngeal nodes.
  • INFRA GLOTTIC AREA
  1. Drain to the pretracheal lymph nodes of the proximal trachea anteriorly paratracheal nodes laterally and then to the deep cervical and superior mediastinal nodes.
  • GLOTIC AREA ( VOCAL FOLDS)
  1. It is relatively devoid of lymphatics.
  2. The space deep to the thin mucosa of the true vocal cords, which is called Reanke's space, has no direct lymphatic drainage.
  3. The spread of carcinoma is, likewise and fortunately, retarded until an invasive process involves tissue peripheral to the true vocal cord.
  • DELPHIAN NODE :
  1. A midline prelaryngeal lymph node, adjacent to the thyroid gland, enlargement of which is indicative of metastasis from thyroid or laryngeal carcinoma.
NERVE SUPPLY:
  • Supplied by Vagus nerve:
  1. Superior laryngeal nerve
  2. Internal branch (sensory) – areas above the glottis
  3. External branch (motor and sensory)
  4. Motor – Cricothyroid muscle
  5. Sensory – Anterior infraglottic larynx at level of cricothyroid membrane
  6. 2. Inferior (recurrent) laryngeal n.
  7. Motor – all intrinsic laryngeal muscles of SAME side (except cricothyroid) and interarytenoid muscle of Both sides
  8. Sensory – areas below the glottis
Exam Question
  • Posterior arytenoid is the abductor of vocal cord
  • Sternothyroid & thyrohyoid are attached to oblique line of thyroid
  • Tensor of vocal cord are Cricothyroid and internal thyroarytenoid
  • Cricothyroid is the only muscle that is located on the external aspect of larynx.
  • Posterior cricoarytenoid is the Tensor of vocal cord during phonation
  • Posterior cricoarytenoid is the Safety muscle of larynx
  • Lateral cricoarytenoid adduct vocal cord.
  • Cricothyroid is the only Intrinsic muscle of larynx supplied by External laryngeal nerve.
  • Thyrohyoid , Digastric ,Stylohyoid, Mylohyoid, Geniohyoid, Hyoglossus & Genioglossus are elevator muscles of larynx
  • Sensory nerve supply of larynx below the level of vocal cord is recurrent laryngeal
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