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Sc 23 - Head and neck Neuroanatomy > Pharynx and Larynx > Flashcards

Flashcards in Pharynx and Larynx Deck (21):
1

Pharynx

  •  pharynx extends from the cranial base to the lower border of the cricoid cartilage where it becomes continuous with the oesophagus.
  • The pharynx is a mucosa lined muscular tube lying behind and communicating with the nasal, oral and laryngeal cavities

2

Nasopharynx

  • lies above the soft palate and behind the nares.
  • floor is formed by the soft palate which is elevated during swallowing and the superior constrictor muscle forms the major part of the posterior wall.
  • On the lateral wall is the opening of the pharyngotympanic (auditory) tube and behind it lies a small mass of lymphoid tissue.
  • In the roof there is more lymphoid tissue, the adenoid or pharyngeal tonsil.

3

Oropharynx

  • lies beneath soft palate and communicates anteriorly with the oral cavity.
  • can be separated from the nasopharynx by the raising of the soft palate
  • palatoglossal and palatopharyngeal arches lie anteriorly in the oropharynx and the palatine tonsil sits in the space between the arches
  • palatine tonsil is supplied by the lingual, ascending pharyngeal and lesser palatine arteries which anastomose freely in the tonsil and therefore haemorrhaging poses a threat during tonsillectomy.

4

Laryngopharynx:

  • Larynx project upwards into the pharynx and that part lying adjacent to it is the laryngopharynx.
  • laryngopharynx ends at C6 by funnelling into the oesophagus
  • epiglottis and piriform recess will be discussed with the larynx.

5

pharynx:

Structurally belongs to the digestive system even though air passes through it. It has the same 4 layers found in the rest of the digestive system:

1. Mucosal coat

2. Submucosa which contains a tough fibrous coat which anchors the pharynx to the base of the skull.

3. A muscular coat consisting of 5 pairs of muscles which form an outer semicircular layer and two inner longitudinal muscles.

4. An areolar coat covers the exterior of the pharynx termed the buccopharyngeal fascia.

6

Constrictor muscles of the Pharynx

The constrictor muscles

1. Superior

2. Middle

3. Inferior

During swallowing the muscles contract sequentially as peristaltic waves. The nerve supply is the vagus nerve with the motor fibres contributed by the cranial part of the accessory.

7

Longitudinal Muscles of the Pharynx

Palatopharyngeus muscle:

  • rises from the palatal aponeurosis and the auditory tube
  • passes inferiorly to insert into the posterolateral part of the pharynx and also the posterior part of the hyoid bone and thyroid cartilage.

Stylopharyngeus muscle:

  • originates from the styloid process and passes inferomedially through the gap between the superior and middle constrictors and enters the pharynx where its fibres mingle with those of the palatopharyngeus muscle and insert in a similar fashion

These muscle raise the pharynx and larynx during swallowing.

8

Nerve to the Pharynx: 

Nerve Supply

Motor:

All muscles of the pharynx except stylopharyngeus are supplied by the pharyngeal branches of the vagus nerve.

Stylopharyngeus is supplied by the glossopharyngeal nerve.

Sensory

glossopharyngeal nerve: main sensory supply to the pharynx

maxillary division of the trigeminal supplying the soft palate and the roof of the pharynx

vagus supplying the area around the pharyngeal inlet. 

9

Blood supply to the Pharynx

Blood Supply 

blood supply is from the:

  • ascending pharyngeal
  • superior thyroid
  • inferior thyroid
  • facial
  • maxillary arteries 

​provide a rich anastomosis. 

Venous Drainage 

  • veins form a plexus on the pharynx and communicate with the pterygoid plexus

10

Lymph Drainage Pharynx

Many of the lymph vessels pass to the deep cervical lymph nodes

some posterior ones enter the retropharyngeal nodes which lie between the prevertebral and buccopharyngeal fasciae

11

Larynx

  • lies anterior to the laryngeal part of the pharynx.
  • extends from the base of the tongue (C3) to the trachea (C6)
  • inlet lies immediately behind the posterior third of the tongue
  • larynx acts as an air passageway linking the pharynx with the trachea
  • also acts as a sphincter to prevent food from entering the trachea and is the organ of phonation.
  • walls of the larynx are supported by the a series of cartilages.
  • three large cartilages: 
    • thyroid
    • cricoid
    • epiglottis (unpaired)
    • and three small paired cartilages
      • arytenoid, cuneiform, and corniculate.

12

Larynx

Thyroid and Cricoid

Thyroid:

  • largest and consists of two plates joined anteriorly in the midline.
  • In males union gives an acute angle and the cartilage is usually a prominent feature of the neck (Adam’s apple).
  • In females union is much more obtuse.

Cricoid:

  • sits immediately below the thyroid cartilage at the level of C6 and is shaped like a signet ring, i.e. a thin band with a quadrilateral plate.
  • plate faces posteriorly.
  • only cartilage which completely encircles the larynx.

13

Larynx

Epiglottis, Arytenoid (Paired), Corniculate (paired), Cuneiform (plate)

Epiglottis:

  • fibroelastic cartilage shaped like a leaf with the stem anchored into the angle of the thyroid laminae
  • broad leaf is orientated upwards and backwards lying behind the hyoid bone and reaching to the posterior part of the tongue.

Arytenoid (Paired)

  • two pyramid –shaped cartilages lies on the posterior lamina of the cricoid cartilage and articulate with it in a synovial joint.
  • provide attachment for the vocal process and have several muscle insertions.

Corniculate (Paired)

  • tiny elastic cartilages sit atop the apices of the arytenoid cartilages extending their length.

Cuneiform (Paired)

  • found in the aryepiglottic folds.

14

Ligaments of the Larynx

Thyrohyoid membrane

vocal ligament

ventricular ligaments

aryepiglottic ligaments

quadrangular membrane

cricothyroid membrane

Thyrohyoid Membrane

  • fibroelastic sheet joining the inferior surface of the hyoid bone to the superior aspect of the thyroid cartilage. The lateral borders are free and thickened and may devolved nodule of cartilage.

Vocal Ligaments

  • thick bands of elastic fibres running from the vocal processes of the arytenoid to the thyroid cartilage and are covered by mucous membrane, the vocal folds.

Ventricular Ligaments

  • two bands of fibres run from the lateral borders of the arytenoid cartilages to the internal lamina of the thyroid cartilage
  • folds, which run above the vocal ligaments are also covered by mucous membrane and are the ventricular folds (false vocal folds).

Aryepiglottic Ligaments

  • pass upwards from the apices of the arytenoid cartilages to the lateral border of the epiglottis.

Quadrangular Membrane

  • thin fibroelastic sheet filling the space between the aryepiglottic ligament and ventricular ligament.

Cricothyroid Membrane

  • fibroelastic sheet filling the space between the vocal folds and the cricoid cartilage (conus elasticus)

15

Muscles of the Larynx

Extrinsic muscles

 have a remote origin but insert into the larynx or hyoid bone.

actions are to move the larynx up or down

  • supra and infrahyoid muscles.

16

Muscles of the Larynx

Intrinsic Muscles

  1. Posterior cricoarytenoid
  2. Lateral cricoarytenoid
  3. Transverse cricoarytenoid
  4. Vocalis
  5. Cricothyroid

 

intrinsic muscles perform 3 separate functions:

A. Open the rima to allow the passage of air in or out.

B. Close the vestibule and rima glottidis during swallowing to prevent aspiration of food.

C. Control of the tension in the vocal folds for phonation.

17

Nerve supply to the Larynx

  • External Laryngeal n
  • Internal Laryngeal n
  • Recurrent Laryngeal n

 

18

Nerve and Blood supply to the Larynx

Motor Nerves

  • All of the intrinsic muscles of the larynx are supplied by the laryngeal branches of the vagus nerve
  • external branches supplies the cricothyroid and the remainder are supplied by the recurrent laryngeal nerve.

Sensory Nerves

  • vagus nerve is sensory to the larynx.
  • internal laryngeal nerve supplies the mucous membrane above the vocal fold while the recurrent laryngeal nerve supplies below the vocal fold.

Arteries

  • larynx receives its blood supply form the superior and inferior thyroid arteries
  • superior gives off an internal laryngeal branch while the inferior gives of an inferior laryngeal branch which accompanies the recurrent laryngeal nerve into the larynx.

Veins

  • laryngeal veins drain into the superior and inferior thyroid veins.

19

Lymphatic Drainage of the Larynx

submucosal lymphatic plexus of the larynx is drained by two sets of vessels.

Above the vocal folds they pierce the thyrohyoid membrane to reach the upper deep cervical lymph nodes while below they join the lower deep cervical lymph nodes

20

Phonation

Phonation normally takes place during expiration. It is possible during inspiration but it is not efficient and cannot be maintained for long.

The breathing rate is about 15 cycles per minute with the time almost equally divided between inspiration and expiration.

During speech the rhythm is altered with inspiration occurring rapidly.

Phonation consists of converting an even flow of expired air passing through the larynx into an oscillating flow with a frequency of 16-20,000 Hz which is within the range of human hearing.

To achieve this the vocal folds are adducted obstructing air flow. Pressure then builds up from below until it forces the folds apart allowing the air to escape. The cycle is repeat and converts the air into a series of puffs at a frequency determined by the sub-glottal pressure and the mass and tension on the vocal ligaments. The frequency of the oscillating air also determines the pitch which varies to allow intonation and expression.

21

Articulation

Articulation is produced by the tongue and lips.

Vowel Sounds

These are formed by a continuous flow of air through the oral cavity the shape of which is modified by the muscles of the tongue and lips.

Consonants

Formed by constrictions of the vocal tract.

1. Labial- contact between the lips – BPM

2. Labiodentals- Lower lips & Upper incisors – FV

3. Lingopalatal-

 a) tip of tongue and anterior part of hard palate – DTR  b) dorsum of tongue and posterior part of hard palate – JL

 c)Dorsum of tongue and soft palate –K

Sibilants

S, SH, & Z air passes through a narrow space between tip of the tongue and the hard palate.

M & N are achieved by expelling air through the nose. Loss of teeth and denture effect articulation but most people adapt.

A cleft palate or a short lingual frenulum may make speech unintelligible