Head and Neck Lecture for Dentistry Students PDF

0 The Temporal Region(Fossa)  The region (depressed area) that situated on the side of the head. The superior temporal line  Filled by Temporalis muscles. Boundaries: The inferior temporal line  Anteriorly:  Frontal process of the zygomatic bone & zygomatic process of the Frontal bone. ...

0 The Temporal Region(Fossa)  The region (depressed area) that situated on the side of the head. The superior temporal line  Filled by Temporalis muscles. Boundaries: The inferior temporal line  Anteriorly:  Frontal process of the zygomatic bone & zygomatic process of the Frontal bone.  Superior & posterior:  From the root of the zygomatic process of Frontal bone.  We have two lines arch posteriorly that known as Superior temporal line & Inferior temporal line.  The superior temporal line: is one of the borders of the temporal fossa and curves(arches) posteriorly over the frontal, parietal and temporal bones and ends in the supra-mastoid crest.  Inferiorly:  Zygomatic arch: zygomatic process of temporal bone + temporal process of zygomatic bone.  We have a gap between zygomatic arch and the side of the skull resemble the handle of the jug.  Therefore, when we delve deeper into the zygomatic arch, we will find two roots:  Go deep to the ramus of the mandible  infra-temporal fossa(region).  Go superficial to the ramus of mandible face region.  The Temporal fossa continues inferiorly deep to the zygomatic arch with the region known as the infra-temporal fossa.  So the gap bounded by zygomatic arch connects two regions with the Temporal fossa.  Remember:  Temple region: the area located on the side of the head.  Temporal related to time and The first place where the gray hair appears (hence the name). 1 Bony Component of Temporal Region Pterion (black arrow):  The area of the (H-shaped) suture in the side of the skull that’s the weakest point of the skull.  Made by articulating between four bones:  Frontal bone.  Parietal bone.  Squamous part of the temporal bone.  Greater wing of sphenoid bone.  These bones form the Floor of the temporal fossa (region). Contents of Temporal Region Temporalis muscle:  Fan-shaped muscle and filled the temporal fossa.  The largest muscle of mastication. Temporal fascia:  Covered the temporal region.  Divided into:  Deep temporal fascia: is the same as temporalis fascia.  Superficial temporal fascia. Deep temporal arteries & nerves:  The deep temporal artery is a branch from the maxillary artery (2nd part).  The deep temporal nerve is branch from anterior division of mandibular nerve (V3).  They are both located in the infratemporal fossa, so they ascend from the infratemporal fossa to the temporal fossa due to the connection between the two fossae.  The middle temporal artery:  A branch from superficial temporal artery.  superficial temporal artery: One of the terminations of the ECA passes into the roof of the temporal fossa under the skin. 2  Notes:  We don’t have the superficial temporal nerve; we only have the deep temporal nerve.  The superficial nerve (cutaneous nerve) that runs with the superficial artery is known as Auriculotemporal nerve. (help in the lab) Superficial Temporal a. & v:  Pass posterior to TMJ & anterior to External Auditory Meatus. Auriculotemporal nerve:  Branch from the posterior division of mandibular nerve(V3).  Passes posterior to superficial vessels.  Here it divides to allow passage of the middle meningeal. a  Cutaneous nerve that supplies:  Skin over temple region.  The auricle and the external auditory meatus.  The lateral surface of the tympanic membrane.  Notes: in general, these structures (superficial vessels & Auriculotemporal nerve) Pass between TMJ & External Auditory Meatus(EAM). Fascia in Temporal Region Superficial temporal fascia:  Also known as Temporoparietal Fascia.  Lateral continuation of Epicranial aponeurosis (the third layer of the SCALP).  Extend from superior temporal line to zygomatic arch.  Within this layer running superficial temporal vessels. Deep temporal fascia:  Also known as Temporalis Fascia.  Fascia surrounding temporalis muscle. 3  Middle temporal artery passes between the deep temporal fascia and temporalis muscle.  Deep temporal arteries pass between temporalis muscle and bone (deep to muscle itself).  Split into two layers:  Superficial layer of Temporalis fascia: which connects to the lateral surface of the zygomatic arch.  Deep layer of Temporalis fascia: which connects to the medial surface of the zygomatic arch.  Between them we have a Superficial Temporal Fat Pad.  In the picture we have TP fascia (Temporoparietal Fascia) = Superficial temporal fascia Location of Temporal artery:  Superficial temporal arteries and veins pass in superficial temporal fascia (TP fascia).  Middle temporal artery passes between the deep temporal fascia and temporalis muscle.  Deep temporal arteries pass between temporalis muscle and bone (Epicranium). Temporalis Muscle Origin:  Bony component forming the floor of temporal fossa &laterally from deep temporal fascia. Insertion:  The fibers will converge with each other and insert the coronoid process of the mandible and descend down along the anterior surface of the ramus until to the level of the last molar. 4  Notes:  The inferior temporal line marks the attachment temporalis muscle fibers.  The superior temporal line marks the attachment of the temporalis fascia.  Temporalis Muscle  occupy temporal region. Innervation:  Two temporal branches from anterior division of mandibular nerve of trigeminal (V3). Action:  Anterior fibers  vertical closes the mouth (elevate mandible).  Posterior fibers  horizontal  retract mandible (retraction and protrusion). Movement of the mandible:  Protrusion movement the mandible forward closes the mouth.  Retraction movement the mandible backward.  Elevation  movement the mandible upward.  Depression  movement the mandible downward opens the mouth. Retro-molar Fossa  Tendons of temporalis muscles is inserted to the coronoid process of the mandible and descend downward along anterior border of the ramus of the mandible.  Distal to last molar tooth the tendon will split into two bands in the region called Retro-molar trigon (triangle).  So Retro – molar fossa located between two bands of tendons of temporalis muscle.  Extension of denture must not reach or retro-molar fossa. (because tendons are movable which affect the stability of denture). 5 Parotid Region  Parotid gland  occupy parotid region.  Region which extends between:(Boundaries).  Anteriorly: ramus of mandible.  Posterior: mastoid and styloid processes of temporal bone.  Superiorly: EAM and TMJ with part of zygomatic arch.  Inferiorly (imaginary line): to neck (angle of the mandible) and overlapping posterior margin of masseter and posterior belly of digastric muscle.  The region where the parotid gland is situated is known as the Parotid Bed. Contents of Parotid gland  Parotid Gland& Structures inside it.  Deep part of masseter muscle: arises from medial surface of zygomatic arch.  Stylohyoid and posterior belly of digastric muscle medially to parotid gland. Structures Within Parotid Gland: 1. Facial nerve (Superficial):  Form plexus inside parotid.  Within or before enters parotid: 1.Tempor-o-facial division.  Temporal branch: superior to parotid gland.  Zygomatic branch: anterior to parotid gland.  Buccal branch: anterior to parotid gland (the first half). 2.Cervic-o-facial division.  Buccal branch: anterior to parotid gland (the second half).  Marginal Mandibular branch: anterior to parotid gland.  Cervical branch: inferior to parotid gland.  These five terminal branches arise from gland.  Facial nerve divides the gland into superficial lobe (lateral to facial nerve) and deep lobe (medial to facial nerve). 6 2. Retromandibular Vein(Middle):  Forms and divide within the gland.  Formed by union superficial temporal vein with the maxillary vein inside the parotid gland.  Go downward and divides into Anterior and Posterior divisions:  Anterior division joins to facial vein to form Common facial vein which drains into Internal jugular vein.  Posterior division joins to posterior auricular vein to form EJV which drains into Subclavian vein. 3.External carotid artery (Deep):  Located deep to the retromandibular vein.  Its terminations into maxillary artery and superficial temporal artery occurs inside the parotid gland. 4.Parotid lymph nodes:  Distributed within & on the gland.  Known as pre-auricular lymph nodes.  In the cervical region we have both:  Superficial cervical lymph nodes: passing along the course of external jugular vein.  The deep cervical lymph nodes: passing along the course of internal jugular vein.  Superficial cervical lymph nodes drain into Deep cervical lymph nodes.  Deep and superficial lymph nodes in relation to Sternocleidomastoid m. Parotid Gland  It is the largest among the major salivary glands.  Salivary glands are categorized as follows:  Major salivary glands include the parotid, submandibular, and sublingual glands.  Minor salivary glands are distributed throughout the oral cavity, including the soft palate, floor of the mouth, lips, and cheeks." 7  Wedge-shaped gland:  Base of the wedge: directed superiorly under the zygomatic arch.  Apex of the wedge: directed inferiorly towards the neck.  It overlaps masseter muscle anteriorly and overlaps SCM posteriorly.  It is covered by C.T. sheath called parotid capsule which derived from the investing layers of deep cervical fascia.  Investing layer also gives the capsule of submandibular gland. Processes of The Parotid Gland  Extensions of parotid tissue into certain regions. Glenoid Process:  Triangular process projects superiorly(upward) into the mandibular fossa (glenoid fossa).  For this reason, the superior process is called the glenoid process. Pterygoid process:  Anterior projection (forward deeply).  between ramus and medial pterygoid muscle Facial process:  Anterior projection toward the face (forward superficially).  over the masseter muscle.  Sometimes the facial process makes separate part Known as Accessory part of parotid gland:  A small part of facial process.  That separates from the main gland and it has its own duct.  It drains into the main duct. Relations to Parotid Gland Superficial (laterally):  Skin.  Superficial fascia and Great auricular nerve “supplies area over the mandible and the skin over parotid gland comes anterior rami (C2, C3)” within it, and Parotid fascia (capsule). 8 Superior:  External auditory meatus (EAM).  Temporomandibular joint(TMJ). Antero-medial:  structure deep to parotid gland:  Masseter muscle.  Posterior Part of Ramus.  Medial pterygoid muscle: inside the ramus.  Notes: The ramus of the mandible is situated between two muscles:(like sandwich)  Masseter muscle (located laterally). ‫الصورة مهمة جدا‬  Medial pterygoid muscle (situated medially). Postero-medial:  Carotid sheath and its content:  Internal carotid artery.  Internal jugular vein.  Vagus nerve.  Deep Cervical Lymph Nodes.  Additionally, at this anatomical level, we observe cranial nerves IX (glossopharyngeal nerve), XI (accessory nerve), and XII (hypoglossal nerve) situated in the carotid sheath.  Styloid process and the muscles attachment to it: Stylohyoid ,Styloglossus, Stylopharyngeus.  Mastoid process and the muscles attachment to it: Sternocleidomastoid (laterally), Posterior belly of digastric(medially).  Note: Medial structures to parotid gland are termed The Parotid Bed. Parotid Duct (Stensen's duct)  It originates from the anterior border of the parotid gland, courses anteriorly and horizontally over the masseter muscle, running parallel to the zygomatic arch (one fingerbreadth below).  Then turns medially, piercing the buccinators muscle to enter the oral cavity. 9  Opens into oral cavity opposite to 2nd maxillary molar where it forms the parotid papilla.  Inside the cheek the duct runs anteriorly and obliquely in buccal mucosa forming valve like action to prevent inflation of gland in blowing. Accessory Parotid Duct:  Drains  Accessory part  Opens into  main duct (Stensen’s Duct). Parasympathetic Innervation of Parotid:  The secretomotor fibers responsible for innervating the parotid gland originate from the glossopharyngeal nerve.  These fibers then form a branch known as the lesser petrosal nerve, which extends towards the otic ganglion for synapse.  From the otic ganglion, the post-ganglionic fibers emerge, accompanying the Auriculotemporal nerve, and penetrate the gland to provide innervation specifically to the parotid gland itself. Blood supply of parotid  It takes from ECA and its terminations:  Superficial temporal artery.  Maxillary artery.  Also takes from Transverse facial artery branch of the superficial temporal artery.  Drainage  retromandibular vein.  Lymph  parotid lymph nodes  DCLN. Clinical: Mumps  A viral infection affecting the parotid gland leads to swelling and pain.  The pain arises due to swelling within the constricted parotid fascia (parotid capsule richly innervated).  Discomfort intensifies during chewing as the inflamed gland becomes compress between the mandibular ramus and mastoid process when the mouth is opened.  Additionally, obstruction of the parotid duct by stones (calculi) can occur, resulting in painful swelling. 10 Parotidectomy  Surgical removal of the parotid gland.  Most common cause: cancer.  80% of salivary gland tumors occur in Parotid gland.  Risks of surgery:  Facial n. (VII).  External carotid artery(ECA).  Retromandibular vein.  Important steps in Parotidectomy:  Identifying the structures, we mentioned to avoid any risks.  Isolating them.  Preserving these structures to prevent injury during the Parotidectomy procedure. If you have any questions don’t hesitate to contact us The End 11