Head and Neck Anatomy PDF

Pharynx Relations: Oropharynx → oropharyngeal isthmus → oral cavity Nasopharynx ○ → choanae → nasal cavity ○ → pharyngotympanic tube → middle ear Laryngopharynx → laryngeal inlet (gated by epiglottis) → larynx Oesophagus (at...

Pharynx Relations: Oropharynx → oropharyngeal isthmus → oral cavity Nasopharynx ○ → choanae → nasal cavity ○ → pharyngotympanic tube → middle ear Laryngopharynx → laryngeal inlet (gated by epiglottis) → larynx Oesophagus (at C5-6)  Structure The pharynx is a common pathway for air and food running from the base of the skull to C5-6 (where it transitions into the oesophagus) It is divided into the nasopharynx, oropharynx and laryngopharynx. These are separated by: Choanae - nasopharynx/nasal cavity Oropharyngeal isthmus - oropharynx/oral cavity ○ = Palatoglossal folds, soft palate, sulcus terminalis (tongue) Laryngeal inlet - laryngopharynx/larynx Pharyngeal isthmus - nasopharynx/oropharynx ○ = palatopharyngeal sphincter Structures can isolate or close off certain areas: Soft palate elevation = closure of pharyngeal isthmus = isolation of nasopharynx and nasal cavity Soft palate depression (+ tongue elevation) = closure of oropharyngeal isthmus = isolation of oral cavity Epiglottis can isolate the larynx Structure Structure Where is it attached? The pharynx is made up of soft tissue, so it needs to be attached! C shaped attachment to base of skull - from medial plate of pterygoid process of sphenoid, petrous part of temporal bone, pharyngeal tubercle Superiorly: Pterygomandibular raphe (superior constrictor → buccinator) Posteriorly: Pharyngeal raphe joins pharyngeal muscles from each side, running from oesophagus → pharyngeal tubercle Anteriorly: Middle part largely by muscles and ligaments related to the hyoid bone including: ○ Stylohyoid, thyrohyoid, hyoepiglottic l. ○ Geniohyoid, mylohyoid, stylohyoid, thyrohyoid, sternohyoid, omohyoid ○ Digastric ○ Hyoglossus, genioglossus Inferiorly: Thyroid/cricoid cartilages Tonsils Collections of lymphoid tissue that drain into the deep cervical nodes Form the Waldeyer’s ring  Pharyngeal Muscles Consist of constrictor (circular) and longitudinal (vertical) muscles Muscles from each side are joined by pharyngeal raphe All innervated by pharyngeal branch of vagus n. except stylopharyngeus (glossopharyngeal n.) Constrictor Muscles Constrictor muscles - superior middle and inferior Arranged like telescope (inferior most outside) Forms 2 sphincters ○ Palatopharyngeal sphincter (pharyngeal isthmus) ○ Inferior constrictor acts as a sphincter Oropharyngeal triangle (superior/middle) - oral cavity ○ Glossopharyngeal, stylopharyngeus, lingual nerves Between middle/inferior constrictors - into larynx ○ Internal laryngeal n ○ Laryngeal a.v. Under inferior constrictor ○ Recurrent laryngeal n./v. Longitudinal Muscles (-pharyngeus) Stylopharyngeus - from styloid process (glossopharyngeal) Salpingopharyngeus - from pharyngotympanic tube (cartilage part) Palatopharyngeus - from soft palate ○ Forms palatopharyngeal arch - landmark for palatine tonsil ○ Also closes oropharyngeal isthmus All run from the pharyngeal aponeurosis on the inside of the inner constrictor and function to elevate pharyngeal wall - pull it up and over bolus during swallowing Pharyngeal Spaces Parapharyngeal Internal maxillary a. Base of skull to greater horn of hyoid Ascending bone pharyngeal a. Pterygoid venous plexus Mandibular division of trigeminal n. Retropharyngeal Retropharyngeal l.n. Posterior to pharynx/oesophagus Fat and vessels between pretracheal and prevertebral fascia (alar fascia runs through) Joins C6-T5 → posterior mediastinum Danger Space Potential path of infection Posterior to retropharyngeal space from pharynx to superior between alar fascia and prevertebral and posterior mediastinum fascia Joins skull → thorax, superior mediastinum → base of diaphragm Pharyngeal Spaces Parapharyngeal Internal maxillary a. Base of skull to greater horn of hyoid Ascending bone pharyngeal a. Pterygoid venous plexus Mandibular division of trigeminal n. Retropharyngeal Retropharyngeal l.n. Posterior to pharynx/oesophagus Fat and vessels between pretracheal and prevertebral fascia (alar fascia runs through) Joins C6-T5 → posterior mediastinum Danger Space Potential path of infection Posterior to retropharyngeal space from pharynx to superior between alar fascia and prevertebral and posterior mediastinum fascia Joins skull → thorax, superior mediastinum → base of diaphragm Vasculature Arteries: external carotid branches Ascending pharyngeal Branches of facial, lingual, maxillary Major blood supply to palatine tonsil is from tonsillar branch of facial artery Veins form pharyngeal venous plexus and drain: Superiorly → pterygoid plexus → retromandibular v → IJV Inferiorly → IJV  Innervation Pharyngeal Plexus Located over middle constrictor in retropharyngeal space Function: pharynx and soft palate ○ All motor for pharynx is vagus [X] except stylopharyngeus via branch of glossopharyngeal [IX] ○ All sensory via glosssopharyngeal [IX] except: Anterior/superior nasopharynx via maxillary x. [V2] Inferior laryngopharynx via internal branch of vagus [X] ○ Therefore: gag reflex = 9 in 10 out Formed by: ○ Pharyngeal branches [X] - major motor branch ○ External laryngeal n. [X] - from superior laryngeal branch ○ Pharyngeal branches [IX] ○ Cervical sympathetic ganglion  Pharyngeal Fistula/Cyst Congenital abnormality - when pharyngeal cleft doesn’t completely degenerate Sac is on lateral neck, medial to sternocleidomastoid Tends to present at older age due to decreased tone of muscles with aging Presentation: Finding chewed (but undigested) food on pillow Halitosis (bad breath)