Anatomy 2 Parotid Gland: "refer to previous sheet for extra details." Its pyramidal in shape, apex is toward pharynx. Its Medial surface is divided into Anterio-medial and posterio-medial and its posterio-medial surface forms the parotid bed. Parotid bed (V.imp): meaning that gland is sleeping on structures and they are: 1- Facial nerve and its 5 branches (Most Superficial structure) 2- Retromandibular vein 3- External carotid artery (most deep structure) Note: External carotid gives its 2 terminal branches at neck of mandible and they are: maxillary and superficial temporal. Retromandibular vein: is formed in parotid and it s the middle structure in parotid bed. It's formed from maxillary and superficial temporal veins at lower border of gland. Its anterior division joins facial vein forming common facial vein and then drain into internal jugular vein. Its posterior division joins posterior auricular vein forming external jugular vein that drains into subclavian vein. Parotid gland is covered by 2 capsules in which the outer capsule is tough and fibrous..therefore during infections, it will enlarge and cause pain; enlargement is limited by the capsule. During a viral infection such as Mumps; Rest, Vitamins and sedative drugs are used to treat infection since mumps can cause sterility of ovaries if not treated. Also during Parotid cancer, the gland will enlarge affecting its anatomy.
Surface Anatomy: Parotid Duct crosses masseter muscle then pierces buccinator and is 1 finger below zygomatic arch. Then this duct open in vestibule at level of upper second molar. This duct can become blocked by stones. Lemon is given to patient and excessive secretions can be seen plus swelling, confirming the block of gland. Note: Above parotid duct lies temporal and zygomatic branches of facial nerve and below duct lies the buccal branch. Clinical Point: Stem of facial nerve divides the parotid into Superficial and deep lobes and is then branched into 5 branches that supply muscles of facial expression. After surgery to parotid, surgeon should make sure that no nerve branch is injured or facial palsy might form. He is supposed to ask the patient to due few movements to make sure he is fine.. Examples: patient is told to close his eye to insure working orbicularis occuli muscle..if an eye didn t close this might lead to dryness of cornea. He is also told to blow out to check orbicularis oris muscle..if he didn t blow, drooping of saliva might take place due to injury to that muscle. He is also told to show his teeth for buccinator muscle activity. HOWEVER, patient should be able to clench his teeth even if he has facial palsy as this movement is controlled by muscles of mastication that are supplied by mandibular nerve NOT Facial. Anatomical relations (V.Imp): Anteriomedial and posteriomedial structures related to parotid are very important.
Anteriomedial structures related to parotid are: 1- Ramus of mandible 2- Masseter muscle 3- Medial pterygoid muscle. Posteriomedial structures related to parotid are: 1- Stylohyoid muscle 2- Posterior belly of Digastric. 3- Most important: one third of carotid sheath containing internal carotid, internal jugular vein and externa carotid artery. 4- Last 4 cranial nerves. Auricolotemporal nerve is found in upper part of gland and carry sensory plus secretomotor (parasympathetic). Secretomotor Innervation of gland: Parasympathetic secretomotor supply arises from the Glossopharyngeal nerve. The pre-ganglionic from the lesser petrosal nerve, then to otic ganglion and the post-ganglionic fibers are from the Auricolotemporal nerve. Parotid lymph nodes can also be seen. Submandibular Gland: Is Located in Digastric or Submandibular triangle. Triangle's borders: anterior belly, posterior belly of Digastric muscle and lower border of mandible. It s a mixed gland (serous+ mucus), duct coming from deep part will open under the tongue in sublingual papillae.
Mylohyoid muscle -originating from mylohyoid line of mandible- divides gland into superficial part and deep part. Mylohyoid also separates the sublingual fossa from Submandibular fossa which lies beneath it. Superficial part itself is divided into 2 parts: 1- Upper part hidden in Submandibular fossa 2- Lower part below the lower border of mandible. Secretomotor Innervation of gland: Parasympathetic secretomotor supply is from the facial nerve. The preganglionic fibers form the chorda tympani joining lingual nerve, then to submandibular ganglion and the postganglionic fibers pass directly to the gland OR through lingual nerve. Submandibular anatomical relations: Hypoglossus and mylohyoid muscles are both related to deep part of gland. Structures found between mylohyoid and Hypoglossus: 1- Submandibular deep part 2- Submandibular ganglia 3- Submandibular duct 4- Lingual nerve 5- Hypoglossal nerve Note: BECAREFUL this Question always comes in the exam and it might be asked indirectly.. For Example: "Structures deep to mylohyoid" or "Structures superficial to Hypoglossus" or "structures between Hypoglossus and mylohyoid" SO TAKE CARE Remember: Only Structure deep to BOTH muscles is: LINGUAL ARTERY
Triple relation between lingual nerve and Submandibular duct: Lingual nerve is at first superficial to duct, then comes below it and as they open to mouth at end its medial to it. Note: Chorda tympani joins the lingual nerve at the far beginning Sublingual Gland: The right and left gland meet at midline and are covered by mucosa. Gland is mostly mucus. Duct opens directly into mouth or through Submandibular duct Medial structures related to it: 1- Lingual nerve (most medial) 2- Submandibular duct 3- Genioglossus muscle Posterior and below is the mylohyoid muscle. Its parasympathetic innervation is the same as Submandibular. PHARYNX: Is made up of 3 parts: Nasopharynx, oropharynx and laryngopharynx (also called hypopharynx). It s a muscular tube that originates from the base of skull below sphenoid and occipital base till the 6 th cervical vertebrae. It then continues as esophagus. Difference between pharynx and esophagus is that pharynx is open anteriorly where as esophagus is a complete muscular tube.
It has a length of 5 inches and is funnel in shape meaning it's wide superiorly and narrow inferiorly. Pharynx is made up of 3 constrictor muscles; superior, middle and inferior in which one overlaps the other and so the inferior constrictor muscle has the widest base of them all. Together with those constrictor muscles we have stylopharyngeus muscle and salpyngopharyngeus.. They are all innervated by Pharyngeal plexus EXCEPT Stylopharyngeus muscle by GLOSSOPHARYNGEAL NERVE. These muscles are inserted into Pharyngeal raphe which is a tough fibrous tissue that originates from pharyngeal tubercle located anterior to foramen magnum. Constrictor muscles are circular in shape for peristaltic movements and to help propagation of bolus where as stylopharyngeus and salpyngopharyngeus are longitudinal in shape. They all have the same action EXCEPT a small part from inferior constrictor muscle. Inferior constrictor muscle is made up of 2 parts: 1- Upper oblique part 2- Lower part called Cricopharyngeus muscle; this muscle is circular and is always contracted to prevent passage of AIR! It only opens when bolus reaches it. It acts as sphincter for the esophagus and that s why it s the only part having different action than other muscles of pharynx Killian's dehiscence: is the area on the posterior pharyngeal wall between the upper propulsive part of the inferior constrictor and the lower sphincteric part, the Cricopharyngeus.
Origin and insertion of Pharynx muscles: 1) Superior constrictor Origin: Medial pterygoid plate, pterygoid hamulus, pterygomandibular ligament, mylohyoid line of mandible Insertion: Pharyngeal tubercle of occipital bone, raphe in midline posteriorly Innervation: Pharyngeal plexus Action: Aids soft palate in closing off nasal pharynx, propels bolus downward 2) Middle constrictor Origin: Lower part of stylohyoid ligament, lesser and greater cornu of hyoid bone Insertion: Pharyngeal raphe Innervation: Pharyngeal plexus Action: Propels bolus downward 3) Inferior constrictor Origin: Lamina of thyroid cartilage, cricoid cartilage Insertion: Pharyngeal raphe Innervation: Pharyngeal plexus Action: Propels bolus downward 4) Cricopharyngeus Origin: Lowest fibers of inferior constrictor muscle Insertion: Sphincter at lower end of pharynx
5) Stylopharyngeus Origin: Styloid process of temporal bone Insertion: Posterior border of thyroid cartilage Innervation: Glossopharyngeal nerve Action: Elevates larynx during swallowing 6) Salpingopharyngeus Origin: Auditory tube Insertion: Blends with palatopharyngeus Innervation: Pharyngeal plexus Action: Elevates pharynx 7) Palatopharyngeus Origin: Palatine aponeurosis Insertion: Posterior border of thyroid cartilage Innervation: Pharyngeal plexus Action: Elevates wall of pharynx, pulls palatopharyngeal arch medially Inferior of the Pharynx: A) In NasoPharynx: 1- Choanae: is the posterior opening of nasal cavity 2- On the lateral wall is the opening of the Eustachian tube, the elevated ridge of which is called the tubal elevation. Remember: infection or vomiting in babies can reach middle ear from this tube and lead to Otitis Media.
3- Salpyngopharyngeal fold is a vertical fold of mucous membrane covering the salpyngopharyngeus muscle. B) Oral Pharynx: Have the tonsils in it lateral walls Relation between epiglottis and tongue: They are related by 3 folds; medial glossoepiglottic fold and 2 lateral glossoepiglottic folds. In between these folds lies the vallecula. While bolus is in mouth; base of tongue goes downward pushing epiglottis down and the aryepiglottic fold has aryepiglotticus muscle that contracts, and larynx move upwards by Suprahyoid muscle. This will lead to complete closure of larynx. The soft palate will close the nasopharyngeal isthmus. Some of the food slides down through the Piriform fossa. Piriform fossa is a depression of mucosa that is anterior to pharynx or posterior to larynx. Foreign bodies can lodge in this depression especially Fish bones. Sensory supply of pharyngeal mucous membrane: Nasal pharynx: The maxillary nerve (V2) Oral pharynx: The Glossopharyngeal nerve Laryngeal pharynx (around the entrance into the larynx): The internal laryngeal branch of the Vagus nerve
Note: Vagus nerve gives rise to Superior laryngeal nerve. In turn superior laryngeal divides into: 1- Internal branch; found inside larynx and is sensory. It penetrates the membrane between middle and inferior constrictor muscles. 2- External branch; outside larynx. It supplies the CRICOTHYROID muscle. Another Note: between superior and middle constrictor muscles are 3 structures: 1- Glossopharyngeal nerve 2- Stylopharyngeus muscle 3- Mandibulo-pharyngeal ligament. Blood Supply of the Pharynx: Ascending pharyngeal, tonsillar branches of facial arteries, and branches of maxillary and lingual arteries Lymph Drainage of the Pharynx: Directly into the deep cervical lymph nodes or indirectly via the retropharyngeal or paratracheal nodes into the deep cervical nodes.
Palatine Tonsils: The palatine tonsils are two masses of lymphoid tissue, each located in the depression on the lateral wall of the oral part of the pharynx between the palatoglossal and palatopharyngeal arches. Its medial surface is covered by mucous membrane (stratified squamous non-keratinized epithelium). Crypts can be seen on medial surface due to infections. Its lateral surface is covered by capsule. During tonsillectomy lateral capsule is opened and by the use of surgeon's finger, tonsil is pulled out and then ligation of tonsillar artery and vein takes place. Veins can cause problems such as bleeding! External palatine Vein or also called "Para-tonsillar Vein" descends from the soft palate in this tissue to join the pharyngeal venous plexus. Patient is kept under observation with ice cream given to cause vasoconstriction of vessels. However, bleeding might take place sometimes as this vein pierces the superior constrictor muscle and so need to be ligated. This vein can't be seen easily except after operation. Note: tonsillitis is the inflammation of tonsils due to an infection. This infection is usually due to Streptococcus species. If infection is continuous meaning takes place more than 4 times per year.. Tonsillectomy is recommended. This is because streptococcus infection can become chronic affecting heart and causing endocarditis, it can also cause inflammation in knee joint and in kidneys. Lateral to the superior constrictor muscle lie the styloglossus muscle, the loop of the facial artery, and the internal carotid artery. (msh 3arfeh hay esh elha dakhal bl nos.)
Blood Supply of tonsil Artery: The tonsillar branch of the facial artery. Veins: The veins pierce the superior constrictor muscle and join the external palatine, the pharyngeal, or the facial veins. Lymph Drainage of the Tonsil The upper deep cervical lymph nodes, just below and behind the angle of the mandible. Waldeyer's Ring of Lymphoid Tissue: The lymphoid tissue that surrounds the opening into the respiratory and digestive systems forms a ring The lateral part of the ring is formed by the palatine tonsils and tubal tonsils (lymphoid tissue around the opening of the auditory tube in the lateral wall of the Nasopharynx) The pharyngeal tonsil(adenoid) in the roof of the Nasopharynx forms the upper part, and the lingual tonsil on the posterior third of the tongue forms the lower part. Remember: Enlargement of adenoids in babies can lead to snoring and difficulty in breathing and should be removed. Please refer to the slides as the doctor didn t mention everything in them!! Imagine that :P! Good Luck Done by: Sara Kussad