Pharynx and Larynx Flashcards
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
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.
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.
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.
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:
- Mucosal coat
- Submucosa which contains a tough fibrous coat which anchors the pharynx to the base of the skull.
- A muscular coat consisting of 5 pairs of muscles which form an outer semicircular layer and two inner longitudinal muscles.
- An areolar coat covers the exterior of the pharynx termed the buccopharyngeal fascia.
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.
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.
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.
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
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
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.
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.
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.
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)
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.
