Head and Neck Lecture Notes

Transcription

1 Head and Neck Lecture Ntes THE SKULL Cranium The cranium is a clsed chamber with rigid walls and acts t prtect the brain. The rf, sides, frnt and back walls are smth and f unifrm thickness this is the calvaria. The flr f the chamber is cmparatively irregular, and is knwn as the cranial base. 8 bnes cntribute t the cranium: 2 paired: Parietal bne Tempral bne 4 unpaired: Frntal bne Ethmid bne Sphenid bne Occipital bne The frntal bne is a brad, cnvex plate f bne that frms the frnt f the cranium and rf f the rbits. In fetal skulls, a metpic suture divides the tw halves f the frntal bne. 1. Squama underlies the scalp f the frehead 2. Suprarbital margins upper brder f the rbits 3. Zygmatic prcesses fund at the lateral ends f the suprarbital margins 4. Tempral line extends up and back frm the zygmatic prcesses 5. Glabella central part between the supraciliary arches 6. Ethmidal ntch central part between superciliary arches It articulates with the tw parietal bnes at the crnal suture, the nasal bnes at the frntnasal suture, and als the zygmatic, lacrimal, ethmid and sphenid bnes. Apertures t the frntal air sinuses can be fund n either side f the ethmidal ntch. These are part f a cmplex set f cavities knwn as the paranasal sinuses they are lined with mucus membrane and cmmunicate with the nasal cavity. The parietal bnes are dmed t frm large parts f the walls f the calvaria. They articulate with each ther in the median plane at the sagittal suture. 1. Parietal eminence central, runded, and prtruding n the wall 2. Superir tempral line attachment f tempral fascia 3. Inferir tempral line attachment f the tempralis muscle 4. Vascular grves fr the ant and pst branches f the middle meningeal vessels 5. Grve fr the transverse sinus They articulate with the ccipital bne at the lambdid suture, the frntal bne, the tempral bnes and the greater wings f sphenid bne. The ccipital bne frms much f the base and psterir aspect f the skull the back half enclses the cranium, the frnt half extends twards the sphenid. 1. Squama pentagnal part psterir t the framen magnum a. Superir/Inferir nuchal lines b. 4 fssae 2 superir (ccipital ples) and 2 inferir (cerebellar hemispheres) 2. Cndylar part lateral t the framen magnum a. Jugular prcess upper surface b. Occipital cndyle anterirly, articulate with C1 (atlas) i. Hypglssal canal in the base f the ccipital cndyle 3. Basilar part anterir t the framen magnum The tempral bnes frm parts f the sides and base f the skull. Each is cmprised f 4 distinct parts that fuse during develpment. 1. Squama external t the lateral surface f the tempral lbe a. Mandibular fssa (fr head f mandible) inferir surface 2. Petrmastid a blck enclsing the internal ear and mastid cells a. Mastid prcess (nte the mastid ntch between this and stylid)

2 Head and Neck Lecture Ntes b. Internal auditry meatus c. Grve fr the sigmid sinus 3. Tympanic part a. External auditry meatus 4. Stylid prcess attachment t ligaments and muscles a. Stylmastid framen psterlateral t stylid b. Jugular fssa medial t stylid They articulate at sutures with the parietal, ccipital, sphenid and zygmatic bnes nte the zygmatic prcess, which articulates with the tempral prcess f the zygmatic bne t frm the zygmatic arch. The sphenid is a wedge-shaped bne it is a key bne in the cranium as it articulates with eight ther bnes (frntal, parietal, tempral, ccipital, vmer, zygmatic, palatine and ethmid. 1. Bdy a. Sella turcica rf f the paranasal sinuses i. Anterir clinid prcesses (prminent, part f lesser wing) ii. Drsum sellae (back f the saddle) 1. Psterir clinid prcesses b. Left and right sphenidal sinuses 2. Lesser wing arises frm the superlateral margin f the bdy 3. Greater wing arises frm the lwer margin f the bdy a. Framen vale and framen spinsum (lateral) b. Superir rbital fissure (between greater and lesser wings) c. Framen rtundum (belw superir rbital fissure) d. Pterygid prcess i. Medial pterygid plate ii. 1. Pterygid canal (belw and medial t framen rtundum) Lateral pterygid plate The ethmid bne lies between the rbits and underlies the frntal bne. On each side is a rectangular blck (ethmidal labyrinths), and these are jined at their upper edges by the cribrifrm plate (transmits bundles f lfactry nerve). The crista galli rises up int the cranium. Facial Skeletn 9 bnes cntribute t the facial skeletn: 4 paired: Nasal bne Zygmatic bne Maxilla Palatine bne 1 unpaired: Mandible Nte that the maxillary and ther paranasal sinuses are essentially nt present in the newbrn skull these frm large spaces in the adult facial skeletn, hwever. The maxillae frm the skeletn f the face between the muth and eyes, surrunding the anterir nasal apertures, and articulating with each ther at the intermaxillary suture. 1. Bdy base frms the lateral wall f the nse a. Maxillary sinus anterir/psterir walls, rf (flr f rbit) b. Nasal, rbital, infratempral and anterir surfaces c. Infrarbital framen d. Incisive fssa 2. Zygmatic prcess articulates with zygmatic bne 3. Frntal prcess articulates with the frntal, nasal and lacrimal bnes 4. Palatine prcess 5. Alvelar prcesses sckets fr the maxillary teeth

3 Head and Neck Lecture Ntes They als articulate with the vmer, sphenid and palatine bnes. The zygmatic bnes frm the prminences f the cheeks, and the anterlateral and infrarbital parts f the rbits. 1. Orbital margin/surface (120 ) a. Zygmaticfacial framen b. Zygmatic-rbital framina 2. Frntal prcess a. Zygmatictempral framen 3. Tempral prcess unites with the zygmatic prcess f the tempral bne They articulate medially with the greater wings f the sphenid bne, as well as the frntal, maxilla and tempral bnes. The mandible is a U-shaped unpaired bne that frms the skeletn f the lwer jaw. It is the largest and strngest facial bne. 1. Bdy (U-shaped bne, represented anterirly as the chin) a. Alvelar prcess b. Mental framen belw the premlar teeth 2. Ramus a plate behind and lateral t the last mlar tth a. Crnid prcess attachment fr tempralis muscle (anterir) b. Cndylar prcess carries the head f the mandible (psterir) c. Mandibular ntch between the crnid and cndylar d. Mandibular framen inner surface f the ramus i. Mylhyid grve/sulcus The palatine bne makes up the psterir third f the palate it cnsists f tw plates (hrizntal and perpendicular). The perpendicular plate verlies the psterir third f the medial wall f the bdy f maxilla, and articulates with the pterygid prcess f the sphenid. The nasal bne is small and trapezidal. The lacrimal bne is a scale-like val f bne. The vmer frms the psterir part f the nasal septum The inferir cncha spans the lwer part f the pening f the maxillary sinus, and articulates with the palatine bne, maxilla and uncinate prcess f the ethmid. Nte the superir and middle cnchae are part f the ethmidal labyrinth. CERVICAL FASCIAE, POSTERIOR TRIANGLE, ROOT OF THE NECK Cervical Fasciae The deep fascia f the neck is divided int three layers investing, pretracheal and prevertebral. These frm natural lines f cleavage thrugh which tissues may be separated, and limit the spread f pus frm infectins in the neck. The investing layer f deep cervical fascia frms a cllar arund the neck, lcated between the superficial fascia and the muscular layer. It is attached: Superirly superir nuchal line, external ccipital prtuberance, mastid prcess, lwer brder f the mandible Inferirly spine f the scapula, acrmin prcess, clavicle, manubrium Psterirly ligamentum nuchae, C7 spine Anterirly symphysis menti, bdy f hyid The investing layer splits t enclse:

4 Head and Neck Lecture Ntes 2 muscles trapezius, sterncleidmastid 2 salivary glands partid, submandibular 2 spaces suprasternal, supraclavicular Where it splits t enclse the partid gland (between the angle f the mandible and mastid prcess), the superficial partid fascia extends t the zygmatic arch; while the deep lamina frms the stylmandibular ligament. It prevents extensin f abscess t the surface, which usually spreads laterally. Nte that if it is in the anterir triangle, it may enter the suprasternal space r anterir mediastinum. The pretracheal layer is attached: Superirly hyid bne, blique thyrid cartilage, cricid cartilage Inferirly arch f the arta (superir mediastinum) Laterally fuses with the cartid sheath Infectins f the head and neck can spread psterir t the esphagus t the psterir mediastinum, r anterir t the trachea t the anterir mediastinum. Similarly air frm a ruptured trachea r esphagus can spread t the neck, leading t cervicfacial emphysema. The prevertebral layer frms part f a fascial sleeve fr the prevertebral muscles. Nte that the cervical plexus and prximal parts f the brachial plexus are deep t it. It is attached: Superirly base f the skull Inferirly bdy f T4 vertebrae Pus frm an abscess psterir t the prevertebral fascia may extend laterally, deep t this layer t frm a swelling psterir t the sterncleidmastid muscle. The cartid sheath enclses the cmmn and internal cartid arteries, internal jugular vein and vagus nerve. The sympathetic chain is lcated psterir t (and utside) the sheath. Psterir Triangle The psterir triangle is bunded by: Apex superir nuchal line Base middle 1/3 f clavicle Anterir brder psterir brder f sterncleidmastid Psterir brder anterir brder f trapezius Rf investing cervical fascia Flr prevertebral fascia (ver splenius capitus, levatr scapulae, scalenus medius) It cntains: 3 nerves spinal accessry nerve, brachial plexus, cervical plexus 4 arteries subclavian artery (3 rd part), transverse cervical artery, suprascapular artery, ccipital artery 1 vein external jugular vein Lymph ndes Cervical plexus: C1 nerve t genihyid, nerve t thyrhyid C1-3 ansa cervicalis (infrahyid muscles) C2 lesser ccipital nerve C2-3 great auricular nerve C2-3 transverse cervical nerve C3-4 supraclavicular nerve C3-5 phrenic nerve

5 Head and Neck Lecture Ntes External jugular vein is nly visible when there is increased ventricular pressure (heart failure) Lesins f the accessry nerve (trauma, tumur, fractures invlving the jugular framen, neck laceratins) result in unilateral paralysis f trapezius and an inability t shrug the shulders and abduct the arm past hrizntal. The nerves f the cervical plexus receive rami cmmunicantes (mainly frm the sympathetic superir cervical ganglin) interruptin leads t Hrner syndrme Cervical blck inject alng the psterir brder f sterncleidmastid Brachial blck inject superir t the midpint f the clavicle (avid subclavian) Rt f the Neck The rt f the neck is the junctin between the neck and thrax imprtant structures are the superir thracic aperture, cervical pleura and scalenus anterir muscle. Bundaries f the thracic inlet: Psterir T1 vertebra Lateral 1 st rib and cstal cartilage Anterir manubrium Cntents f the rt f the neck: 1. Nerves a. Vagus nerve and recurrent laryngeal nerve b. Sympathetic chain c. Phrenic nerve (n scalenus anterir, deep t prevertebral fascia) 2. Arteries a. Right brachicephalic trunk ( right subclavian, right cmmn cartid psterir t sternclavicular jint) b. Left subclavian artery c. Left cmmn cartid artery d. Subclavian artery (medial, psterir and lateral parts by scalenus anterir) i. Vertebral artery, internal thracic artery, thyrcervical trunk ii. Cstcervical trunk (frm 1 st part n the left) iii. Suprascapular and/r drsal scapular arteries 3. Veins (unite psterir t sternclavicular jint) a. Subclavian vein b. Internal jugular vein 4. Lymphatics a. Left side thracic duct b. Right side jugular, subclavian, brnchmediastinal lymph trunks ( right lymphatic duct) 5. Viscera a. Trachea b. Oesphagus c. Apex f the lung (and pleural cupula) 6. Muscles a. Lngus clli b. Sternal ends f sterncleidmastid, sternhyid, sternthyrid c. Scalene muscles (marginal) Hrner syndrme: Pupillary cnstrictin (paralysis f dilatr pupillae muscle) Ptsis (paralysis f smth muscle in levatr palpebrae superiris) Sinking in f the eye (paralysis f rbitalis muscle) Vasdilatin and absence f sweating n the face and neck

6 Head and Neck Lecture Ntes ANTERIOR TRIANGLE, THYROID GLAND C1 Hard palate; transverse prcess palpable behind the mastid prcess C2 C3 Hyid bne C4 Upper brder f thyrid cartilage C5 Lwer brder f thyrid cartilage; cricthyrid membrane C6 Cricid cartilage, pharyngeal-esphageal junctin, laryngeal-tracheal junctin Anterir Triangle f the Neck The anterir triangle is bunded by: Base lwer brder f mandible; line frm the angle f mandible t mastid prcess Apex Jugular ntch Anterir brder midline Psterir brder anterir brder f sterncleidmastid Rf skin, superficial fascia, investing layer f deep cervical fascia Flr pharynx, larynx, prevertebral fascia Cntents f the anterir triangle: 1. Muscles a. Hyid muscles i. Suprahyid muscles mylhyid, genihyid, stylhyid, digastric ii. Infrahyid muscles mhyid (superir belly), sternhyid, sternthyrid, thyrhyid 2. Nerves a. Cranial nerves IX, X, XI and XII b. Ansa cervicalis c. Sympathetic trunk 3. Arteries - Cmmn cartid, internal cartid, external cartid 4. Veins - Anterir jugular vein, internal jugular vein 5. Viscera a. Pharynx esphagus b. Larynx trachea 6. Glands a. Partid, submandibular, thyrid, parathyrid The superir belly f mhyid and digastric muscles divide the anterir triangle int 4 further triangles: 1. Submental triangle median triangle frmed between the anterir bellies f digastric and the hyid bne. The mylhyid muscle frms its flr. Cancer f the lip metastasises t submental (central lip) and submandibular (ther parts) lymph ndes 2. Digastric triangle a. Bundaries i. Anterir anterir belly f digastric ii. Psterir psterir belly f digastric iii. Base base f mandible; line frm angle t mastid prcess iv. Rf skin, superficial fascia, deep fascia v. Flr mylhyid, hyglssus, middle cnstrictr f pharynx 3. Cartid triangle a. Bundaries i. Anterinferir superir belly f mhyid ii. Psterir anterir brder f sterncleidmastid iii. Superir psterir belly f digastric and stylhyid iv. Rf skin, superficial fascia, deep fascia v. Flr thyrhyid, hyglssus, middle and inferir cnstrictrs f pharynx

7 Head and Neck Lecture Ntes b. Cartid sheath cmmn and internal cartid arteries, internal jugular vein, vagus nerve c. Cartid sinus barreceptr at the bifurcatin f the cmmn cartid, innervated by the sinus branch f CN IX d. Cartid bdy chemreceptr psterir t the bifurcatin f the cmmn cartid reflex change in respiratin Imprtant surgical apprach fr cartid arteries, internal jugular vein, vagus nerve, hypglssal nerve, cervical sympathetic trunk Pressure n the cartid sinus syncpe, cessatin f heart beat Cartid pulse absence indicates cardiac arrest 4. Muscular triangle a. Bundaries i. Inferlateral anterir brder f sterncleidmastid ii. Superlateral superir brder f mhyid iii. Medial midline b. Cntains the infrahyid muscles these are all innervated by the ansa cervicalis except thyrhyid, which is innervated by C1 nerve. Surgical apprach fr thyrid, larynx, trachea and esphagus (deep t this triangle) Midline structures f the neck: 1. Bdy f the hyid bne a. Median thyrhyid ligament b. Laryngeal prminence 2. Cricid cartilage a. Cricthyrid ligament b. Cricthyrid muscle 3. 1 st tracheal ring 4. Isthmus and pyramidal lbe f the thyrid gland 5. Inferir thyrid veins 6. Jugular venus arch (jins the tw anterir jugular veins) 7. Thyrid ima artery Thyrid Gland The thyrid gland is the largest f the endcrine glands, and cnsists f tw lateral lbes, an isthmus and a pyramidal lbe (smetimes). Features: 1. Levatr glandulae thyridea muscle between pyramidal lbe and hyid bne (remnant f the thyrglssal duct) 2. Isthmus verlying the 2 nd -4 th tracheal rings 3. Lateral lbes (medial parts) verlying the larynx, trachea, esphagus, inferir cnstrictr f pharynx, cricthyrid muscle 4. Extends nt the cartid sheath psterirly, infrahyid muscles cver the gland anterirly 5. Parathyrid glands psterir brder, near the anastmsis f superir and inferir thyrid arteries Arteries 1. Superir thyrid artery 2. Inferir thyrid artery 3. Thyrid ima artery (smetimes) Veins 1. Venus plexus n the surface f the gland a. Superir thyrid vein internal jugular vein b. Middle thyrid vein internal jugular vein c. Inferir thyrid vein external jugular vein / left/right brachicephalic Cverings

8 Head and Neck Lecture Ntes 1. Capsule 2. Pretracheal fascia and infrahyid muscles 3. Investing layer f deep cervical fascia 4. Superficial fascia and platysma 5. Skin Relatin f isthmus t tracheal rings trachetmy Relatin f external laryngeal nerve t superir thyrid artery thyridectmy Relatin f recurrent laryngeal nerve t inferir thyrid artery thyridectmy Remnant f thyrglssal duct may present as a midline cyst Relatin f parathyrid t thyrid explains hypparathyridism after thyridectmy SCALP, FACE, PAROTID REGION Scalp The scalp cnsists f five layers f sft issue that cver the calvaria, extending frm the superir nuchal line t the suprarbital margins. Laterally, it extends int the tempral fssae t the level f the zygmatic arches. Layers f the scalp nte that the scalp prper refers t the first three (fused) layers 1. Skin cvered in hair with many bld vessels and lymphatics. Thin in the elderly. Scalp laceratins bleed prfusely due t cmmunicating arteries (that d nt retract) untreated, infectin stemyelitis, extradural abscess r meningitis 2. Cnnective tissue thick subcutaneus layer, richly vascularized and innervated. a. Cllagen and elastin criss-crss attaching the skin t apneursis epicranialis b. Fat present as lbules between the cnnective fibres decreases with age 3. Apneursis epicranialis strng membranus sheet cvering the superir calvaria the membranus tendn f the epicranius muscles a. Epicranius muscle cnsists f ccipitfrntalis (CN VII) that cvers the scalp and has 2 ccipital and 2 frntal bellies cnnected by the apneursis. b. Epicranius apneursis is cntinuus laterally with the fascia cvering tempralis (attached t the zygmatic arch) The apneursis prevents superficial laceratins frm gaping hwever, deeper wunds gape widely due t the pull f epicranius (especially crnal plane) 4. Lse arelar tissue many ptential spaces, allws mvement f the scalp prper ver the pericranium Dangerus area f the scalp pus r bld can spread easily Infectin may pass t the cranial cavity via emissary veins (thrugh apertures in cranial bnes). It may als pass t the eyelids and rt f the nse, as frntalis muscle inserts int the skin and dense subcutaneus tissue Infectin will nt pass int the neck ccipitalis is attached t the superir nuchal line and the mastid parts f the tempral bne Infectin will nt pass laterally past the zygmatic arches, as the epicranius apneursis is cntinuus with the fascia f tempralis 5. Pericranium dense layer f specialised cnnective tissue with pr stegenic prperties a. Attached t the scalp by cnnective tissue fibres (Sharpey s fibres) b. Cntinuus with the endcranium in the cranial sutures Bleeding between the pericranium and the calvaria at birth cephalhematma Bne f the calvaria des nt regenerate in adults surgical bne flaps, metal r plastic plates required t repair trauma Cmpnents f the scalp: 1. Muscle a. Occipitfrntalis

9 Head and Neck Lecture Ntes 2. Nerves (sensry) a. Trigeminal (CN V) supplies the scalp anterir t the vertex i. Ophthalmic nerve (V 1 ) supratrchlear, suprarbital ii. Maxillary nerve (V 2 ) zygmatic-tempral iii. Mandibular nerve (V 3 ) auricultempral nerves b. C2 greater and lesser ccipital nerves supply the superir and psterir scalp 3. Arteries a. Internal cartid artery suprarbital, supratrchlear b. External cartid artery superficial tempral, psterir auricular, ccipital arteries 4. Veins a. Supratrchlear, suprarbital veins facial vein b. Superficial tempral vein maxillary vein retrmandibular vein c. Retrmandibular, psterir auricular vein external jugular vein d. Occipital vein subccipital venus plexus vertebral veins ( internal jugular) e. Emissary (valveless) veins pass t the intracranial venus sinuses 5. Lymph a. Abve the partid partid lymph ndes b. Abve the auricle retrauricular (mastid) lymph ndes c. Back f scalp and auricle ccipital lymph ndes at the apex f the psterir triangle Infectin f the scalp may spread t the intracranial venus sinuses via the emissary veins venus sinus thrmbsis Surgical pedicle flaps are made t preserve the bld supply and innervatin t the scalp (that enter inferirly) Face The face cvers the part f the head anterir t the external ears, and between the hairline and the tip f the chin. Cmpnents f the face: 1. Skin sweat and sebaceus glands, cnnected t bne by lse cnnective tissue 2. Superficial fascia muscles f facial expressin are embedded in this layer There is n deep fascia s laceratins gape widely 3. Nerves a. Sensry i. Ophthalmic nerve (V 1 ) lacrimal, suprarbital, supratrchlear, infratrchlear, external nasal nerves ii. Maxillary nerve (V 2 ) infrarbital, zygmaticfacial, zygmatictempral nerves iii. Mandibular nerve (V 3 ) mental, buccal, auricultempral, inferir alvelar, lingual nerves iv. Great auricular (C2-3) area ver the partid and angle f the mandible An infrarbital nerve blck is used fr treating wunds f the upper lip, cheek r maxillary teeth nte prximity f cmpanin infrarbital vessels An inferir alvelar nerve blck is used when perfrming surgery n the mandibular teeth A lesin f the entire trigeminal nerve causes anaesthesia invlving the anterir half f the scalp, the face (aside frm an area near the angle f the mandible), the crnea and cnjunctiva, and mucus membranes f the nse, muth and tngue. b. Mtr i. Facial nerve tempral, zygmatic, buccal, mandibular, cervical branches

10 Head and Neck Lecture Ntes Bell s palsy unilateral paralysis f the facial nerve fr n bvius reasn. Mst cmmnly due t inflammatin f the facial nerve near the stylmastid framen. 4. Arteries a. External cartid artery facial artery submental, inferir labial, superir labial, lateral nasal arteries b. External cartid artery superficial tempral artery transverse facial artery c. Internal cartid artery branches f suprarbital, supratrchlear arteries supply the skin f the frehead via the phthalmic artery 5. Veins a. Suprarbital, supratrchlear veins unite at the medial eye facial vein b. Nte that the facial vein is cnnected t the cavernus sinus (via the suprarbital and superir phthalmic veins) dangerus area f the face c. Veins (crrespnding t branches f the facial artery) cmmn facial vein internal jugular vein. Nte that the deep facial vein als cnnect these with the pterygid venus plexus. 6. Lymphatics a. submandibular, partid, submental lymph ndes 7. Muscles all supplied by the facial nerve (CN VII) a. Eyelids rbicularis culi, levatr palpebrae superiris (dilatr), ccipitfrntalis (dilatr) b. Nstrils cmpressr naris, dilatr naris c. Lips rbicularis ris, dilatrs radiating ut frm the lips d. Cheek buccinatr muscle (cmpresses the cheek and lips n the teeth) Partid Gland and Regin The partid gland lies in the fssa psterir t the ramus f the mandible. It extends: Superir external auditry meatus Inferir upper part f the cartid triangle Medial stylid prcess (gland wraps arund the neck f the mandible) Psterir verlaps sterncleidmastid Anterir extends ver masseter The facial nerve divides it int superficial and deep parts the deep part may extend between the medial pterygid muscle and the ramus f the mandible (pterygid prcess). There may als be a detached accessry partid gland in the facial regin. Cmpnents f the partid gland: 1. Cverings a. Inner cnnective tissue capsule b. Outer dense fibrus capsule (frm investing layer) c. Stylmandibular ligament (frm investing layer) separates partid and submandibular glands 2. Partid duct 5am lng, passing 2 fingerbreadths inferir t the zygmatic arch a. Turns medially at the anterir brder f the masseter pierces buccinatr, enters the ral cavity adjacent t the upper secnd mlar tth 3. Structures within the gland facial nerve, retrmandibular vein, external cartid artery, lymph ndes 4. Arterial supply branches f the external cartid artery 5. Nerve supply a. Secretmtr parasympathetic glsspharyngeal (CN IX) via tic ganglin b. (Sympathetic pstganglinic plexus arund the external cartid artery) c. Sensry fibres branches f the great auricular and auricultempral nerves Facial nerve invlvement in lesins f the partid gland generally nly malignant lesins cause facial palsy Retrgrade bacterial infectin f the partid gland acute inflammatin Acute infectin via bld supply (mumps)

11 Head and Neck Lecture Ntes Swelling is painful due t the fascial capsule limiting expansin a swllen glenid prcess is respnsible fr pain during masticatin Sialgram radipaque material injected int the partid duct FUNCTIONAL AND CLINICAL ANATOMY OF THE EYE The eye (~2.5cm in diameter) is lcated within the rbit alng with the lacrimal sac/gland, cular muscles and tarsal plates making up the eyelids. The eyeball itself has a number f features: 1. Anterir Cmpartment a. Crnea (~0.5mm) respnsible fr ~2/3 f fcussing pwer i. In viv cnfcal micrscpe allws us t lk at the varius layers in the living crnea: 1. Epithelium (multiple cell layers, nerves) 2. Bwman s membrane (cllagen) 3. Strma (cells and fibrils) 4. Descemet s layer (cllagen) 5. Endthelium (single layer f hexagnal cells which d nt replicate). It functins t keep water ut f the strma while allwing nutrients in. ii. Crneal dystrphies 1. Fuchs s endthelial dystrphy destructin f the crneal endthelium 2. Keratcnus nset arund puberty, develps prgressively. Cntact lenses may help, but the crnea can becme s distrted that a crneal graft is required. b. Lens respnsible fr ~1/3 f fcussing pwer i. Encased in a capsule, anterir surface has an epithelium lining ii. Fibres extend the length f the lens frming sutures as they meet iii. Banding pattern due t cell layers the central unbanded area is knwn as the nucleus and is the first t frm. iv. Cataracts (nuclear and crtical) lens becmes stiffer (mre cell layers), and nuclear cells degenerate and are replaced by prtein/crystals with age. c. Ciliary bdy i. The interactin f the circular ciliary muscle, the znules (suspensry ligaments cnstant tensin) and the lens allws accmmdatin i.e. cntractin f the ciliary muscle reduces tensin thicker lens ii. Ciliary epithelium prduces aqueus humur cntinuusly this is drained by the trabecular netwrk t the canal f Schlemm ( veins) 2. Psterir Cmpartment a. Vitreus humur i. Degeneratin can pull away part f the retina flaters b. Sclera fibrus tissue, helps t maintain shape and has bld supply t the anterir cmpartment c. Chrid (cntinuus with the ciliary bdy) has bld supply t the retina d. Retina i. Ophthalmscpic features 1. Optic disc/cup with ptic nerve n rds r cnes 2. Macula with fvea high presence f cnes in this area 3. Retinal arteries ii. Nte that light passes thrugh a number f cell layers befre reaching the rds and cnes 3. Nerves and Muscles a. Extracular muscles SO 4 (LR 6 ) 3 fr innervatin i. Superir, medial, lateral, inferir rectus muscles

12 Head and Neck Lecture Ntes ii. Inferir (supermedial mvement) and superir blique (inferlateral mvement) muscles [check this] b. Orbicularis culi muscle (CN VII) c. Levatr palpebrae superiris 4. Glands and the tear film a. Cnsists f three layers i. Mucus gblet cells ii. Aqueus lacrimal gland iii. Oil Meibmian glands b. Helps t prevent reflectin prblems with the tear film lead t visual distrtin/blurriness and pain (nervus stimulatin) CRANIAL FOSSAE, MENINGES, CAVERNOUS SINUS Cranial Fssae The anterir cranial fssa is the shallwest f the three fssae and cntains the inferir and anterir parts f the frntal lbes. 1. Bundaries a. Anterir inner surface f the frntal bne b. Psterir lesser wing f the sphenid bne c. Flr rbital plates f the frntal bne, cribrifrm plate and crista galli f the ethmid, jugum and lesser wing f the sphenid 2. Features crista galli (attaches t the falx cerebri), anterir clinid prcesses (attaches t the tentrium cerebelli) 3. Framina a. Framina f the cribrifrm plate axns f lfactry cells ( CN I) b. Nasal slit anterir and psterir ethmidal nerves and arteries c. Framen caecum nasal emissary vein between nasal cavity and superir sagittal sinus (1% f peple) The middle cranial fssa cntains the anterir and ½ f the inferir parts f the tempral lbes. It is separated frm the psterir cranial fssa by the drsum sellae. 1. Bundaries a. Anterir lesser wing f the sphenid bne b. Psterir superir brders f petrus part f the tempral bne c. Flr bdy and greater wings f the sphenid, squamus and petrus parts f the tempral bne 2. Features a. Sella turcica tuberculum sella, hypphyseal fssa, drsum sellae b. Psterir clinid prcesses c. Sulcus chiasma, grve fr internal cartid artery, grve fr middle meningeal vessels, impressin fr the trigeminal ganglin 3. Framina a. Optic canal ptic nerve (CN II) and phthalmic arteries b. Crescent f framina in the greater wing i. Superir rbital fissure phthalmic veins, CN V 1 (phthalmic), II, IV, VI and sympathetic fibres ii. Framen rtundum CN V 2 (maxillary) iii. Framen vale CN V 3 (mandibular), accessry meningeal artery iv. Framen spinsum middle meningeal artery and vein, meningeal branch f CN V 3 c. Framen lacerum internal cartid artery, sympathetic and venus plexuses d. Hiatus f greater petrsal nerve greater petrsal nerve, petrsal branch f middle meningeal artery e. Hiatus f lesser petrsal nerve usually t small t be seen (if present)

13 Head and Neck Lecture Ntes The psterir cranial fssa is the largest and deepest fssa, and cntains the cerebellum, pns and medulla. Nte that the ccipital lbes lie n the tentrium cerebelli, superir t the psterir cranial fssa. 1. Bundaries a. Anterir superir brder f petrus part f the tempral bne b. Psterir internal surface f the ccipital bne c. Flr ccipital bne, mastid bne 2. Features a. Internal ccipital crest internal ccipital prtuberance divides the fssa int tw cerebellar fssae (superir and psterir) b. Grve fr transverse sinus sigmid grve c. Clivus anterir t the pns and medulla 3. Framina a. Framen magnum medulla and meninges, spinal rts f CN XI, vertebral arteries, anterir and psterir spinal arteries, dural veins b. Jugular framen CN IX, X, XI, superir bulb f internal jugular vein, inferir petrsal and sigmid sinuses, meningeal branches f ascending pharyngeal and ccipital arteries c. Hypglssal canal CN XII d. Cndylar canal emissary vein between sigmid sinus and vertebral veins e. Mastid framen mastid emissary vein between sigmid sinus and meningeal branch f ccipital artery Meninges and Dural Venus Sinuses The dura mater cnsists f cllagenus cnnective tissue. While it cnsists f ne layer, it is described as a tw-layered membrane as it adheres s clsely t the internal peristeum (endcranium) except fr where there are dural venus sinuses. 1. Dural septa (reflectins f the dura) divide the cranial cavity int ne subtentrial and tw supratentrial cmpartments a. Falx cerebri attached t the internal surface f the calvaria frm crista galli t internal ccipital prtuberance (als the midline f tentrium cerebelli) b. Tentrium cerebelli i. Anterir superir edges f petrmastid part f the tempral bnes, anterir and psterir clinid prcesses ii. Psterir ccipital bne alng the grves fr transverse sinuses c. Falx cerebelli d. Diaphragma sellae rf fr the hypphyseal fssa with a central aperture fr hypphyseal veins and the hypphyseal stalk (infundibulum) 2. Nerve supply mainly via the three divisins f CN V (particularly pththalmic), althugh CNX and the superir three cervical nerves (accmpanying CN XII) als cntribute. Mre numerus adjacent t the superir sagittal sinus, tentrium cerebelli and arteries and veins. 3. Arterial supply middle meningeal artery (framen spinsum greater wing f sphenid bne anterir/frntal and psterir/parietal branches) 4. Venus drainage middle meningeal veins framen spinsum and vale pterygid plexus The arachnid mater is cmpsed f weblike tissue and is separated frm the dural by a ptential subdural space. It des nt dip int the sulci and fissures f the brain, and is separated frm the pia mater by the subarachnid space. The pia mater cnsists f highly vascularized lse cnnective tissue and is adherent clsely t the surface f the brain. Nte that the perivascular spaces are cntinuus with the subarachnid space. Meningitis inflammatin f the pia and/r arachnid mater Tentrial herniatin f the tempral lbe laceratin and damage t CN III Expansin f a pituitary tumur bulging f diaphragma sella (visual disturbances) Extradural haemrrhage - fracture in the pterin regin middle meningeal vessel Subdural haemrrhage tearing f superir cerebral vein in the sagittal sinus

14 Head and Neck Lecture Ntes Subarachnid haemrrhage rupture f a berry aneurysm Dural venus sinuses (underline between dura layers, italics between layers f dural flds): 1. Superir sagittal sinus upper attached margin f falx cerebri 2. Transverse sinuses attached margin f the tentrium cerebelli 3. Sigmid sinuses grve in the ccipital and mastid parts f the tempral bne 4. Cavernus sinuses either side f the bdy f the sphenid bne a. Superir and inferir petrsal sinuses between sigmid and cavernus i. Basilar plexus basilar part f ccipital bne between inferir petrsal sinuses, cmmunicates with internal vertebral venus plexus b. Sphenparietal sinuses cavernus sinus lesser wing f the sphenid c. Intercavernus sinuses 5. Inferir sagittal sinus lwer free margin f falx cerebri a. Straight sinus inferir sagittal sinus cnfluence f sinuses 6. Occipital sinus attached margin f falx cerebelli Cnfluence f the sinuses superir sagittal, straight, ccipital and transverse sinuses Basilar and ccipital sinuses cmmunicate with the internal vertebral plexuses (via framen magnum) these are valveless bi-directinal bld/tumur spread Scalp infectins can pass t the venus sinuses via emissary veins Cavernus Sinus The cavernus sinuses are 1.5mL sinuses lcated n each side f the sella turcica and the bdy f the sphenid bne. Each extends frm the superir rbital fissure t the apex f the petrus part f the tempral bne. 1. Receives bld frm: a. Superir and inferir phthalmic veins (rbit) b. Central retinal vein (retina) c. Superir middle cerebral vein (brain) d. Sphenparietal dural venus sinus (skull) e. Intercavernus sinuses 2. Drains bld t: a. Superir and inferir petrus sinuses b. Pterygid venus plexus 3. Relatins a. Extended i. Anterir apex f the rbit ii. Psterir brainstem iii. Medial bdy f sphenid and pituitary fssa iv. Lateral medial surface f tempral lbe v. Superir internal cartid artery and uncus f the tempral lbe vi. Inferir greater wing f the sphenid b. Immediate i. Lateral wall CN III, IV, V 1 and V 2 (NOT V 3 ) ii. Internal internal cartid artery, CN VI Fractures f the base f the skull tearing f internal cartid artery arterivenus fistula engrgement f veins (especially phthalmic) pulsing exphthalms Spread f infectin via the phthalmic veins t the cavernus sinus (dangerus area) ORBIT AND ITS CONTENTS

15 Head and Neck Lecture Ntes Bnes f the Orbit Bundaries f the rbit: 1. Superir frntal bne 2. Inferir zygmatic and maxillary bnes 3. Medial frntal and maxillary bnes 4. Lateral zygmatic and frntal bnes Walls f the rbit: 1. Medial wall a. Bnes maxilla, lacrimal, ethmid, sphenid (bdy) b. Features naslacrimal canal, anterir and psterir ethmid framens 2. Lateral wall a. Bnes greater wing f sphenid (anterir surface), zygmatic (rbital part) b. Features zygmatic canal fr zygmatic nerve (branch f maxillary) 3. Rf a. Bnes frntal, lesser wing f sphenid b. Features lacrimal fssa, ptic framen, trchlear fssa 4. Flr a. Bnes maxilla, zygmatic, palatine b. Features infrarbital grve and canal Superir rbital fissure separates the lateral wall frm the rf f the rbit; lies between the greater and lesser wings f the sphenid. It cnnects the rbit with the middle cranial fssa and transmits CN III, IV, VI, branches f VI and phthalmic veins. Inferir rbital fissure separates the flr f the rbit frm the lateral wall; lies between the greater wing, maxilla and zygmatic. It cnnects the rbit with the pterygpalatine and infratempral fssae, and transmits the maxillary and zygmatic nerves, and infrarbital vessels. Blw t the eye blw-ut fracture f the rbit due t increase in infrarbital pressure (and relative thinness f medial and inferir walls) Prefrntal lbtmy was previusly perfrmed thrugh the rf f the rbit Freign bdies - rf frntal sinus, flr maxillary sinus Tumurs in the sphenidal r psterir ethmidal sinuses may cmpress the ptic nerve and rbit cntents Cntents f the Orbit Muscle Origin Insertin Innervatin Actin Levatr palpebrae superiris Lesser wing f sphenid Skin f eyelid CN III Elevates upper eyelid Superir tarsal muscle Cntinuatin f LPS Tarsal plate Cervical symp. trunk, int. cartid Elevates upper eyelid plexus Superir rectus Cmmn tendinus ring Psterir t sclercrneal junctin CN III Elevatin, medial rtatin Inferir rectus Cmmn tendinus ring Psterir t sclercrneal junctin CN III Depressin, lateral rtatin Medial rectus Cmmn Psterir t sclercrneal CNIII Adductin tendinus ring junctin Lateral rectus Cmmn Psterir t sclercrneal CN VI Abductin tendinus ring junctin Superir blique Bdy f Pstersuperir CN IV Medial rtatin, Inferir blique sphenid Maxilla (rbital flr) lateral rbit Psterinferir lateral rbit CN III depressin Lateral rtatin, elevatin

16 Head and Neck Lecture Ntes A fascial sheath surrunds the eyeball (except the crnea) and is attached t the sclera, clse t the ptic nerve and at the sclercrneal junctin. It is pierced by the tendns f the muscles that rtate the eyeball, and blends with their fasciae. 1. Ptential space between sheath and eyeball allws fr mvement 2. Ligaments prevent excessive mvement medial and lateral expansins f the fascial sheaths f the medial and lateral rectus muscles 3. Suspensry ligament f the eye thickening f inferir fascial sheath, attached t anterir medial and lateral walls f the rbit Nerves f the rbit: 1. Inside the cmmn tendinus ring a. Optic nerve (CN II) b. Oculmtr nerve (CN III) c. Nasciliary nerve (branch f CN V 1 ) i. Ciliary ganglin ( shrt ciliary nerves), lng ciliary nerves, anterir ethmid nerve, infratrchlear nerve d. Abducens nerve (CN VI) 2. Outside the cmmn tendinus ring a. Trchlear nerve (CN IV) b. Lacrimal nerve (branch f CN V 1 ) c. Frntal nerve (branch f CN V 1 ) i. Supratrchlear nerve, suprarbital nerves Bld vessels f the rbit: 1. Ophthalmic artery a. Central artery f the retina b. Ciliary arteries c. Lacrimal artery nte that the recurrent meningeal branch anastmses with the middle meningeal artery d. Muscular branches anterir ciliary arteries e. Suprarbital, supratrchlear, drsal nasal arteries exit the rbit 2. Veins a. Superir and inferir phthalmic veins cmmunicate with the facial vein and cavernus sinus. The receive tributaries frm the chridal veins and cmmunicate with the pterygid plexus. CN III palsy levatr palpebrae superiris affected ptsis CN VII damage rbicularis culi paralysis inability t clse the eye Extracular muscle paralysis diplpia. Exam superlaterally (SR), inferlaterally (IR), supermedially (IO), infermedially (SO), medially (MR), laterally (LR) Retinal artery is an end artery bstructin instant and ttal blindness Thrmbphlebitis f a facial vein cavernus sinus retinal vein thrmbsis NOSE AND NASAL CAVITY, PARANASAL SINUSES Nse Functins f the nse: 1. Prtectin, especially t the eyes ruptured rbits 2. Csmetic nte that shape is largely defined by the shadws arund the nse 3. Ventilatin The variatins in shape f the external nse are mstly due t differences in cartilage. 1. Parts rt, apex, nares, drsum nasi, ala nasi a. Anterir nares (nstrils) are bunded laterally by the ala b. Psterir nares pen t the naspharynx c. Nasal septum perpendicular plate f ethmid, vmer and septal cartilage 2. Skeletal framewrk

17 Head and Neck Lecture Ntes a. Superir bny part (nasal bnes, frntal prcesses f maxillae, nasal part f frntal bne) b. Cartilaginus part 5 parts jined by peristeum and perichndrium i. U-shaped alar cartilages are mbile and dilate/cnstrict nares Fractures (transverse) are cmmn as the perpendicular plate f the ethmid and the vmer are thin bnes cribrifrm plate can becme fractured with a direct blw Deviatin f the nasal septum may be due t trauma, birth injury, r cngenital malfrmatin surgery is required if it cmes int cntact with the lateral walls The nasal cavity cnsists f the lateral wall, septum, flr, rf, nasal apertures & vestibule 1. Flr palatine prcesses f maxillae and hrizntal plates f palatine bne 2. Rf frntnasal, ethmidal, sphenidal parts 3. Medial wall (septum) vmer, perpendicular plate f ethmid, septal cartilage, fibrfatty tissue f the mbile septum 4. Lateral wall: a. Skeletal framewrk nasal bne, frntal prcess f maxilla, lacrimal, ethmid labyrinth, perpendicular plate f palatine bne, medial pterygid plate b. Cnchae shelf-like bny prjectins cvered in mucus membrane (superir, middle and inferir) c. Meatuses crrespnd t the cnchae (superir, middle and inferir) i. Sphenethmidal recess is superir t the superir meatus ii. Bulla ethmidalis runded elevatin in the middle meatus due t the middle ethmid air cell grup iii. Hiatus semilunaris curved grve in the middle meatus between the bulla and uncinate prcess f ethmid bne d. Openings in the lateral wall: i. Sphenethmidal recess pening f the sphenidal sinuses ii. Superir meatus pening f the psterir ethmid cell grup iii. Middle meatus frntal sinus, anterir ethmid cell grup, maxillary sinus iv. Inferir meatus naslacrimal duct 5. Linings f the nasal cavity: a. Vestibule skin with vibrissae b. Rf, adjining septum and lateral wall lfactry mucsa c. Rest f the nasal cavity respiratry mucsa (rich venus plexuses) d. Nte that the nasal mucsa is cntinuus with that in the paranasal sinuses Nerves, arteries and lymphatics: 1. Nerves a. CN I (lfactry nerve) lfactry area b. CN V 1 (phthalmic nerve) anterir ethmidal nerve c. CN V 2 (maxillary nerve) naspalatine and greater palatine nerves 2. Arterial supply a. Ophthalmic artery ethmidal branches b. Maxillary artery sphenpalatine and greater palatine branches c. Facial artery superir labial, ascending palatine, lateral nasal branches 3. Lymphatics a. Drainage submandibular, retrpharyngeal and upper deep cervical ndes CSF rhinrrhea due t fracture f the cribrifrm plate and tearing f the meninges Ansmia (lss f smell) may be due t cnditins affecting the lfactry receptr cells, the secndary lfactry neurns in the lfactry bulb, r their cnnectins Infectins may spread t the anterir cranial fssa (via the cribrifrm plate), the naspharynx, middle ear (via the auditry tube), the paranasal sinuses r the lacrimal apparatus and cnjunctiva Epistaxis is generally due t trauma, but may be assciated with hypertensin r infectin. Severe bleeding may be treated by clamping the external cartid arteries

18 Head and Neck Lecture Ntes Paranasal Air Sinuses The paranasal air sinuses are air-filled cavities within the frntal, maxillary, ethmid and sphenid bnes f the skull. They are lined with respiratry mucsa but that which is thin, less vascular and lsely attached t peristeum. 1. Relatins t rbit a. Superir frntal sinus b. Inferir maxillary sinus c. Medial ethmidal sinus d. Psterir sphenidal sinus 2. Frntal sinus in the frntal bnes beneath the medial 1/3 f the superciliary arch a. Between the inner and uter tables f the frntal bne b. Opens t the middle meatus (frntnasal duct infundibulum hiatus semilunaris) c. Innervated by branches f CN V 1 (suprarbital nerve) 3. Maxillary sinus in the maxilla a. Pyramidal shape (apex faces zygma) b. Relatins skin, pterygpalatine fssa, eye, teeth, nse c. Opens t the infundibulum f the frntnasal duct near the rf f the sinus (hence the sinus must fill befre it can drain) d. Innervated by CN V 2 (alvelar nerve) e. Bld supply frm the maxillary artery 4. Ethmidal air cells in the labyrinthine part f the ethmid bne a. Numerus, divided int three grups i. Anterir ethmid air cell grup middle meatus ii. Middle ethmid air cell grup (beneath the bulla ethmidalis) middle f the bulla in the middle meatus iii. Psterir ethmid air cell grup superir meatus 5. Sphenidal sinus in the bdy f sphenid bne a. Divided by a septum (nt usually midline) b. Opens int the sphenethmidal recess c. Clsely related t the cavernus sinus, internal cartid arteries, pituitary fssa, basilar artery, midbrain Arteries, nerves and lymphatics: 1. Arteries branches f phthalmic, maxillary and facial arteries 2. Nerves branches f the trigeminal nerve 3. Lymphatics a. Frntal, anterir/middle ethmidal, and maxillary submandibular ndes b. Psterir ethmidal and sphenidal sinuses retrpharyngeal ndes Grwth f the paranasal sinuses (particular frntal and sphenidal) is imprtant in determining the shape f the face, and adding resnance t the vice Maxillary sinus is prly drained Shddy remval f the mdal teeth belw the maxillary sinus may allw cmmunicatin t the ral cavity spread f infectin Infectin f the ethmidal sinus infectin/pus cllectin in the rbit Sinusitis (pansinusitis) may result in blckage f ne r mre penings int the nasal cavity. This is assciated with tthache as the superir alvelar nerves supply the maxillary teeth and the mucus membrane f the maxillary sinus Blwing the nse after fractures f the frntal, ethmidal, maxillary r nasal bne may intrduce air int subcutaneus tissues r the cranium MOUTH, TONGUE, PALATE, SUBMANDIBULAR REGION Muth

19 Head and Neck Lecture Ntes The muth is cmprised f three parts the ral cavity, lips and cheeks: 1. Oral cavity divided int vestibule (between teeth and lips) and the muth prper a. The palate (hard and sft) frms the rf, while the palatglssal arches/flds are lateral b. Cmmunicates psterirly pharynx via rpharyngeal isthmus (f fauces) 2. Lips a. Cvered externally by skin, internally by submucus cat and mucus membrane, and cntains part f the rbicularis ris muscle b. Attached t the gums by the frenulum; meet at the angles (labial cmmissures) f the muth c. Mistened by mucus labial salivary glands in the vestibule d. Features: i. Znes cutaneus, vermilin brder, transitinal and mucsal znes ii. Nerves infrarbital (V 2 ), mental (V 3 ) iii. Arteries labial arteries (branches f the facial artery) iv. Lymph submandibular ndes 1. Exceptin central lwer lip submental lymph ndes Pustules/infectin f the lip superir labial vein angular vein suprarbital vein cavernus sinus Cleft lip may be limited t the vermilin brder, r extend t the palate Carcinma f the lip mre cmmn in the lwer lip and in males 3. Cheeks cntinuus with the lips (same general structure) a. Buccinatr frms the muscle layer, deep t the buccal fat pad b. Partid duct pens n a small papilla ppsite the crwn f 2 nd upper mlar c. Features: i. Nerves branches f CN V 2 and V 3 Tngue The tngue is a mbile muscular rgan that cnsists f three parts a rt, bdy and tip. At rest it fills mst f the muth prper and functins t squeeze fd int the pharynx, and frming wrds during speaking. 1. Subdivisins separated by the sulcus terminalis a. Oral part (bdy) anterir 2/3 b. Pharyngeal part psterir 1/3 c. Subdivisin has an embrylgical basis framen caecum at the apex f the sulcus terminalis is the remnant f the thyrglssal duct 2. Surfaces a. Drsum (upper) i. Vallate, fungifrm and filifrm papillae ii. Lingual tnsil in psterir 1/3 b. Ventrum (lwer) i. Frenulum linguae nte the deep lingual vein and penings f the submandibular glands n either side c. Related features f the rpharynx: i. Between the psterir 1/3 f the tngue and the epiglttis: 1. Median glssepiglttic fld 2. Lateral glssepiglttic flds 3. Valleculae f the epiglttis ii. Between the palatglssal fld and palatpharyngeal fld: 1. Palatine tnsil d. The median grve is the line f fusin f the embrynic tngue buds Ankylglssia (tngue-tie) frenulum linguae extends t the tip f the tngue 3. Musculature a. Extrinsic muscles geniglssus, hyglssus, stylglssus, palatglssus b. Intrinsic muscles superir/inferir lngitudinal, transverse, vertical muscles 4. Other features: a. Nerves

20 Head and Neck Lecture Ntes i. Sensry 1. General anterir 2/3 by lingual nerve, psterir 1/3 by glsspharyngeal nerve 2. Special (taste) anterir 2/3 by chrda tympani (branch f facial), psterir 1/3 by glsspharyngeal ii. Mtr 1. Hypglssal nerve all muscles except palatglssus 2. Palatglssus is supplied by vagus via pharyngeal plexus b. Arteries i. Lingual artery majr artery ii. Facial artery tnsillar and ascending palatine branches iii. Ascending pharyngeal artery c. Veins lingual vein n each side internal jugular r facial veins d. Lymphatics i. Tip submental lymph ndes ii. Anterir 2/3 submandibular lymph ndes, central bth sides iii. Psterir 1/3 deep cervical lymph ndes Glssitis usually accmpanies stmatitis marked edema due t lymphatics and lse arelar tissue in he tngue Atrphy f filifrm papillae in sme frms f anaemia and vitamin deficiencies Lesin f CN XII paralysis/atrphy (tngue deviates twards affected side) Psterir part f the tngue can bstruct the larynx in uncnscius patients Carcinma f the psterir part f the tngue has pr prgnsis (bilateral spread) Flr f the muth allws access t deep lingual veins drug administratin Palate Hard palate 1. Skeletn palatine prcesses f maxilla, hrizntal plates f palatine bnes 2. Alvelar margin teeth and gum 3. Psterir margin sft palate 4. Oral surfaces stratified squamus keratinised epithelium, transverse palatine flds, prminent mucsal glands Sft palate 1. Bundaries a. Anterir (base) hard palate b. Psterir free brder, uvula in the midline i. Palatglssal and palatpharyngeal flds arise frm the undersurface c. Lateral cntinuus with the walls f the pharynx d. Oral and pharyngeal surfaces 2. Structure a. Oral surface (and adjining pharyngeal surface) ral mucsa b. Rest f pharyngeal surface respiratry mucsa c. Cre cntains palatine apneursis i. Upper surface levatr palati muscle ii. Lwer surface palatpharyngeus and palatglssus 3. Muscles tensr & levatr palati, musculus uvulae, palatglssus, palatpharyngeus 4. Other features: a. Nerves i. Sensry greater palatine, lesser palatine, naspalatine nerves ii. Mtr CN XI fibres pharyngeal plexus (via vagus and pharyngeal branches) 1. Tensr palati is supplied by mandibular nerve b. Arteries greater and lesser palatine arteries (branches f maxillary) c. Veins pterygid plexus d. Lymphatics submandibular, retrpharyngeal, deep cervical lymph ndes

21 Head and Neck Lecture Ntes Submandibular Regin The submandibular regin lies between the bdy f the mandible and the hyid bne. Its superficial part includes the submental and digastric triangles, while the deep part includes the rt f the tngue and flr f the muth. 1. Imprtant structures a. Digastric muscle tw bellies cnnected by an intermediate tendn i. Anterir belly nerve t mylhyid ii. Psterir belly facial nerve b. Stylhyid muscle clsely related t the psterir belly f digastric i. Innervated by facial nerve c. Mylhyid muscle frms the muscular flr f the muth between the mylhyid line f the mandible t the hyid bne i. ¾ interdigitates with the ppsite side t frm the median raphe d. Hyglssus thin quadrangular muscle between the hyid bne and the side/inferir aspect f the tngue 2. Other structures: a. Lingual nerve b. Hypglssal nerve c. Lingual artery The submandibular gland is a mixed serus and mucus acinus gland (mucus predminates). 1. The U-shaped gland has superficial and deep parts, separated by mylhyid a. Superficial part in the digastric triangle, reaching up under the bdy f the mandible. Separated frm the partid gland by the stylmandibular ligament. b. Deep part extends frwards between mylhyid and hyglssus and gives rise t the duct. i. Psterir end is cntinuus with the superficial part f the gland; anterir extends t the sublingual gland. 2. Cverings inner cnnective tissue capsule, uter fibrus capsule (derived frm investing layer f deep cervical fascia) 3. Submandibular duct runs between mylhyid and hyglssus a. Opens n a small sublingual papilla n the flr f the muth adjacent t the lingual frenulum b. Nte that the duct is crssed by the lingual nerve 4. Other features: a. Nerves derived frm the submandibular ganglin i. Parasympathetic fibres frm chrda tympani (branch f facial) ii. Lingual branch f mandibular nerve iii. Sympathetic trunk b. Arteries branches f facial and lingual arteries c. Veins fllw the arteries Cmmn site fr calculus frmatin seen as a tense swelling belw the bdy f the mandible, largest befre and during a meal. In mumps swelling f the submandibular gland is an vid enlargement that extends anterinferirly frm the angle f the mandible. Pain due t tight fibrus cverings. INFRATEMPORAL REGION, TEMPOROMANDIBULAR JOINT Infratempral Regin The infratempral regin lies beneath the base f the skull, between the pharynx and ramus f the mandible. 1. Bundaries a. Anterir maxilla