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lec 1.Parotid region & temporal fossa.pptx

  1. Parotid region & temporal fossa DR.ALI AL GURAH C.A.B.S,H.D.S. 1
  3. The parotid region Site: it lies below auricle occupying thedeep between the ramus of mandible and sternomastiod. Boundaries  Superiorly :Zygomatic arch.  inferiorly : Angle and inferior border of the mandible.  posteriorly: External ear and anterior border of the sternocleidomastoid.  Anteriorly Anterior border of the. masseter muscle  medially Ramus of the mandible. 3
  4. Boundaries 4
  5. Parotid region Contents 1. Parotid gland and duct. 2. Facial nerve (CN VII). 3. Retromandibular vein. 4. External carotid artery. 5. Masseter muscle. 5
  6. Parotid Gland :  Largest of the 3 main salivary glands in the head & neck  Composed mostly of serous acini.  Enclosed within a tough, unyielding, fascial capsule, the parotid sheath (capsule), derived from the investing layer of deep cervical fascia. 6
  7. Surface anatomy of the parotid gland : 4points:  A-point on the tragus of the ear.  B-point at center of the mastoid process.  C-point 2cm below and behind angle of the mandible.  D-point at the centre of the mandibular notch. 7
  8. Surface anatomy of the parotid gland Borders :  Upper end : extend a curved line around the ext.auditory meatus from tragus to centre of mastiod process.  The posterior border : astraight line along the ant. Border of stern.mastiod muscle.  The anterior border : is by 2 lines aline from the piont below the angle of mandibleto the centre of mandibular notch and Second line from the last point to the tragus of the ear. 8
  9. Parotid Gland  The apex is posterior to the angle of the mandible.  The base is related to the Zygomatic arch. 9
  10. Parotid Gland Relations  Extends down to the lower border of the mandible and up to the zygomatic arch.  Posteriorly it covers the anterior part of the sternocleidomastoid muscle and continues anteriorly to halfway across the masseter muscle.  The stylomandibular ligament separates the parotid gland from the submandibular gland . 10
  11.  Embedded within the substance of the parotid gland,  from superficial to deep: 1. Facial nerve (CN VII) and its branches. 2. Retromandibular vein. 3. External carotid artery.  The facial nerve divides the gland into superficial and deep lobes. 11 Parotid Gland
  12. 12 Parotid Gland
  13.  Passes horizontally from the anterior edge of the gland.  It runshorizontal at the anterior surface of the masseter, the duct turns medially, sharply 13 Parotid duct
  14. Parotid duct  pierces the following structures  The Buccal pad of fat.  the Buccopharyngeal fascia .  the buccinator muscle(oppesite the upper 2nd upper molar tooth.  Buccal mucosa and enters the oral cavity through a small orifice (opposite the 2nd upper molar tooth.) 14
  15. Parotid duct  Surface anatomy:  The duct is represented by the middle 1/3 of a line extending from the tragus of the auricle to a point midway between the ala of nose & angle of the mouth.  The oblique passage of the duct in the buccinator muscle acts as a valve-like mechanism & prevents inflation of the duct during blowing 15
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  17. N.S. of parotid gland A Sensory  The auriculotemporal nerve supply parenchyma  The great auricular nerve; innervates the parotid capsule as well as the overlying skin. 17
  18. N.S. of parotid gland B autonomic 1- The parasympathetic (secretomotor): 18 It’s a component of the IX CN supplies presynpatic secretory fibers to the otic ganglion. The postsynaptic parasympathetic fibers are conveyed from the ganglion to the gland and joining with the auriculo-temporal nerve.
  19. N.S. of parotid gland  The nerves reach the gland via the tympanic branch, the lesser petrosal nerve, the otic ganglion, and the auriculotemporal nerve.  Stimulation of the parasympathetic fibers produces a thin, watery saliva. 19
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  21. B Autonomic 2- Sympathetic  Fibers are derived from the cervical ganglia through the external carotid nerve plexus on the external carotid artery.  The vasomotor activity of these fibers may reduce secretion from the gland. 21 N.S. of parotid gland
  22. Parotid Gland  Arterial supply: External carotid artery & its terminal branches  Venous drainage: Into the retro-mandibular vein  Lymph Drainage: Into the parotid & then into the deep cervical lymph nodes 22
  23. Relations of parotid gland A-The postero-med surface: 1-mastiod process,the 2muscles attached to it -Sterno-mastoid -Post belly of diagastric 2-styloid process . 3-the carotid sheath and contents. Internal carotid artery Internal jugular vein Last 4 craniaL nerves 23
  24. Relations of parotid gland B-The antero medial surface: Master m on outer surface of ramus of mandible Medial pterygoid m Maxillary artery Post. Border of the ramus of Mandible. 24
  25. Relations of the parotid gland (C)The superficial (lateral )surface; Related to skin. Superficialfascia (platysma,great auricularnerve, preauricular L.N.S). 25
  26. D)Relations of the upper end:  Posterioly related to cartilagenous part of the ext.auditory meatus.  Anteriorly it gives exit to: a)Temporal br. of facial nerve b)superficial temporal vessels c)auriculo-temporal N. 26 Relations of the parotid gland
  27. Relations of the parotid gland Relations lower end 1-it lies on post belly of digastric m. 2-Structures appear under cover of itExt. carotid a. 3-branches of retromand .v.(descend) 4-cervicalbr.of facial n. 27
  28. Relations of the parotid gland Relations of the anterior border:  It is overlaps master m and gives exit to the following : 1.zygomatic branches of facial n. 2.transverse facial artery 3-parotid duct 4.buccal br. Of facial n 5.marginal mandibular br of facial n. 28
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  30. Temporal fossa Is the region on the side of the head (the space on side of calvaria) above the external ear canal, which is covered by the temporalis muscle. 30
  31. Temporal fossa Temporalis fascia  Tough fascia  Covers the temporalis muscle  Attaching : 1. superiorly: superior temporal line. 2. Inferiorly: the fascia splits into two layers, which attach to the lateral and medial surfaces of the zygomatic arch. 3. The temporalis fascia also tethers the zygomatic arch Superiorly.  When the powerful masseter muscle, which is attached to the inferior border of the zygomatic arch, contracts and exerts a strong downward pull on the zygomatic arch, the temporalis fascia provides resistance. 31
  32. Temporal fossa Boundaries:  superiorly: superior temporal line .  Inferiorly: infra temporal crest medially, & zygomatic arch Laterally  Anteriorly: frontal process of zygomatic bone & the zygomatic process of the frontal bone.  Floor: formed by 4 bones: frontal, parietal, temporal, and sphenoid forming pterion.  Laterally; it is limited by the temporalis fascia. 32
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  34. The temporal fossa Contents: 1. Temporalis muscle. 2. Deep temporal nerves and vessels. 3. Zycomaticotemporal nerve. 4. Auriculotemporal nerve. 5. Superficial temporal vessels. 34
  35. Temporalis muscle  Is a large fan-shaped muscle.  Origin : superiorly; the inferior temporal line and laterally temporal fascia.  Insertion : on the anterior surface of the coronoid process and along the related margin of the ramus of the mandible, almost to the last molar tooth. 35
  36. Temporalis muscle Action 1. Powerful elevator of the mandible. 2. Retracts the mandible or pulls it posteriorly. 3. Participates in side-to-side movements of the mandible. 36
  37. Temporalis muscle  NS:  Deep temporal nerves mandibular nerve [V3] in the infratemporal fossa and then pass into the temporal fossa.  Blood supply:  Deep temporal arteries, which travel with the nerves, and the middle temporal artery, which penetrates the temporal fascia at the root of the zygomatic arch. 37
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  39. Deep temporal nerves  Two in number  Originate from the anterior trunk of the mandibular nerve [V3] in the infratemporal fossa.  They pass superiorly and around the infratemporal crest of the greater wing of the sphenoid to enter the temporal fossa deep to the temporalis muscle, and supply it. 39
  40. Zygomaticotemporal nerve  Zygomaticotemporal zygomatic nerve  maxillary nerve [V2], which originates in the pterygopalatine fossa.  Branches of the zygomaticotemporal nerve pass superiorly between the bone and the temporalis muscle to penetrate the temporal fascia and supply the skin of the temple. 40
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  42. Deep temporal arteries  Two in number  originate from the maxillary artery in the infratemporal fossa and travel with the deep temporal nerves around the infratemporal crest of the greater wing of the sphenoid to supply the temporalis muscle.  They anastomose with branches of the middle temporal artery. 42
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  44. Middle temporal artery  Originates from the superficial temporal artery just superior to the root of the zygomatic arch between this structure and the external ear.  It penetrates the temporalis fascia and travels superiorly on the deep surface of the temporalis muscle.  The middle temporal artery supplies temporalis muscle and anastomoses with branches of the deep temporal arteries. 44