|Lecture: 13 Head and neck Dr. Omar Riadh
Lies behind the oral cavity and extends from the soft palate to the upper border of epiglottis. It has a roof, floor, anterior wall, posterior wall and lateral wall.
The roof:- formed by the undersurface of the soft palate and the pharyngeal isthmus.
The floor:- formed by posterior 1/3 of the tongue and the interval between the tongue and the anterior surface of the epiglottis. The is an elevation in the midline between the tongue and epiglottis called median glossoepiglottic fold, and two lateral glossoepiglottic fold, the depression on each side of glossoepiglottic fold called the vallecula.
The anterior wall:- opens into the mouth through the oropharyngeal isthmus which is the interval between the two palatoglossal arches which mark the boundaries between the mouth and oropharynx.
The posterior wall:- is supported by the bodies of C2 and C3 cervical vertebrae.
The lateral wall:- on each side there are the palatoglossal and palatopharyngeal arches or folds and the palatine tonsils between them. Both palatoglossal and palatopharyngeal folds are folds of mucous membrane covering the underlying palatoglossus and palatopharyngeus muscles.
The tonsillar sinus is a triangular recess on the lateral wall of oropharynx between the palatoglossal fold in front and palatopharyngeal fold behind, it is occupied by the palatine tonsil.
Palatine tonsil:- pairs of lymphoid tissue located in the lateral wall of oropharynx in the tonsillar sinus.
Anteriorly:- palatoglossal fold.
Posteriorly:- palatopharyngeal fold.
Superiorly:- the soft palate.
Inferiorly:- posterior 1/3 of the tongue.
Medially:- the cavity of oropharynx.
Laterally:- the capsule separates it from the superior constrictor muscle by loose areolar tissue, the internal carotid artery is 2.5 cm behind and lateral to the tonsil.
Arterial supply:-by tonsillar artery which is branch of facial artery.
Lymphatic drainage:- to the jugulodigastric lymph node which lies below and behind the mandible.
It lies behind the opening of the larynx and the posterior wall of the larynx, it extends from the upper border of epiglottis to the lower border of cricoid cartilage, it has an anterior wall, posterior wall and lateral wall.
Anterior wall:- forms by the inlet of the larynx and the mucous membrane covering the posterior surface of the larynx.
Posterior wall:- supported by the bodies of C3, C4, C5 and C6 cervical vertebrae.
Lateral wall:- is supported by thyroid cartilage and thyrohyoid membrane. There is a small groove situated in the mucous membrane on each side of laryngeal inlet called the piriform fossa.
Muscles of the pharynx:-
Superior constrictor muscle.
Middle constrictor muscle.
Inferior constrictor muscle.
The superior constrictor arises from the medial pterygoid plate, pterygoid hamulus and mylohyoid line of mandible.
The middle constrictor arises from the greater and lesser horn of hyoid bone and stylohyoid ligament.
The inferior constrictor arises from the lamina of thyroid cartilage and cricoid cartilage.
These three constrictor muscles are paired muscles, all ends or inserted in median pharyngeal raphe (fibrous band extends from the pharyngeal tubercle of occipital bone to the lower limit of inferior constrictor muscle.
Pharyngeal plexus:- formed in the middle constrictor muscle opposite to the greater horn of hyoid bone by the following:-
Pharyngeal branch of glossopharyngeal nerve (sensory).
Vagus nerve (motor).
Superior cervical sympathetic ganglia. (vasomotor).
Glossopharyngeal nerve (9th cranial nerve):-
It concerns with the tongue and pharynx. It arises from medulla oblongata in a series with the vagus and accessory nerve. It leaves the skull through the jugular foramen, it has superior and inferior ganglia, it communicates with the inferior ganglia with the following:-
Superior cervical sympathetic ganglia.
Auricular branch of vagus.
Superior vagal ganglia.
With the facial nerve.
Components of glossopharyngeal nerve:-
General visceral efferent:- motor innervation to styloglossus muscle.
Special visceral efferent:- parasympathetic to parotid gland synapses in the otic ganglia.
General visceral afferent:- sensation of parotid gland, carotid body and sinus, pharynx, middle ear and posterior 1/3 of the tongue.
Special visceral afferent:- taste fibrous from the posterior 1/3 of the tongue.
General somatic afferent:- cutaneous sensation from external ear.
Tympanic nerve:- arises from the inferior ganglia and ascends between the carotid canal and jugular foramen to enters the tympanic plexus. Then emerges from the tympanic plexus as lesser petrosal nerve which passes to the otic ganglia.
Carotid sinus nerve.
Lingual branch to the posterior 1/3 of the tongue.
Tympanic plexus:- it located in the promontory of the medial wall of the middle ear. Its formed by:-
Tympanic nerve of glossopharyngeal nerve.
Caroticotympanic branch of internal carotid sympathetic plexus.
Nerve from ganglia of facial nerve.
The sensory fibers distribute to the mucous membrane of middle ear cavity, auditory tube, mastoid air cell, tympanic membrane, rounded and oval window.
Part of respiratory system lies between the pharynx and trachea, it forms a sphincter to protects the orifice of trachea and also modified to produces voice by the presence of vocal cords. The skeleton of the larynx is formed by a number of cartilages which connected by membranes and ligaments and move by muscles.
The larynx lines by mucous membrane, it lies in the anterior portion of the neck in front of C4, C5 and C6 vertebra and presents a median laryngeal prominence (Adam`s apple), this is more prominent in male. The larynx lies between the carotid sheath laterally and is covered anteriorly by the thyroid gland and infrahyoid muscles.
Cartilages of the larynx:-
It consist of three single and three paired cartilage.
The thyroid cartilage:-
Consist of two lamina connected together anteriorly forming the laryngeal prominence (Adam`s apple), these two lamina unit anteriorly but deficient from above forming what is called superior laryngeal notch, also at the external surface of each lamina there is the oblique line which gives attachment to sternothyroid, thyrohyoid and inferior constrictor muscles.
The two lamina have projection upward and below forming what is called superior and inferior horn of thyroid cartilage. The thyroid cartilage attached above to the hyoid bone by thyrohyoid membrane which is thicken at the middle and at the side forming median and lateral thyrohyoid ligaments respectively. The thyrohyoid membrane is pierces by the internal laryngeal nerve and superior laryngeal artery.