Basicranium and Pharynx

By Laura Flores,2014-05-08 20:49
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Basicranium and Pharynx

    Basicranium and Pharynx

    I. Basicranium

    a. Bones

    i. Occipital, temporals, sphenoid, vomer, palatines, & maxillae

    ii. Also parts of parietals and zygomatics are visible

    b. Foramina & Structures Passing through them

    i. Incisive foramennasopalatine n., sphenopalatine a.

    ii. Palatine Foraminagreater/lesser palatine nn. & vessels iii. Foramen OvaleCN V3 (and sometimes lesser petrosal n.) iv. Foramen Lacerumcovered w/ cartilage; int. carotid passes superiorly;

    jxn of occipital, sphenoid, and temporal bones

    v. Foramen Spinosummiddle meningeal vessels; meningeal br. of CN V3 vi. Carotid Canalinternal carotids; carotid plexus (sympathetic) vii. Jugular ForamenCNs IX, X, XI, internal jugular veins

    viii. Stylomastoid ForamenCN VII

    ix. Foramen Magnumspinal cord, vertebral aa., spinal accessory nn.

    x. Hypoglossal Canal (foramen)CN XII

    xi. Condylar Canal (fossa)emissary vv. From sigmoid sinus; meningeal br.

    of occipital a.; holes are variable

    xii. Mastoid Foraminaemissary v. from sigmoid sinus; holes are variable

    c. Other structures

    i. Choanemark boundary between nasal cavity and nasopharynx

    ii. Medial/lateral pterygoid plates of sphenoidinsertion for pterygoid mm.

    & tensor veli palatine

    iii. Hamulus of medial ptergoid platepulley for tensor veli palatine iv. Articular tubercle & mandibular fossaform TMJ

    v. Pharyngeal Tuberclewhere pharynx attaches to occipital bone ant. to

    foramen magnum

    vi. Styloid process3 muscles & 2 ligaments attach here

    vii. Auditory tube & EAM

    viii. Mastoid Processeshollow and full of air cells

    ix. Occipital condyles

    x. External Occipital Protuberanceinion

    II. Pharynx

    a. Definition: a fibromuscular tube running from base of skull to inferior border of

    cricoid cartilage

    i. Common route for food and air

    ii. Five layers: mucosa, submucosa, fibrous fascia (pharyngofacial fascia),

    muscular layer, loose connective fascia (buccopharyngeal fascia)

    b. Divisions

    i. Nasopharynxposterior extension of nasal cavity superior to soft palate;

    1. extends from choanae (internal nares) to soft palate

    2. contains pharyngeal tonsils (adenoids) & opening to auditory

    tubes (pharygotympanic)

    ii. Oropharynxcontinuous with oral cavity

    1. extends from soft palate to epiglottis

    2. contains palatoglossal & palatopharyngeal arches & palatine


    iii. Laryngopharynxposterior to larynx

    1. extends from epiglottis to the lower border of the cricoid cartilage

    2. contains aditus (inlet) of larynx & piriform recesses

    3. continuous with esophagus

    c. Muscles

    i. External: three constrictors (sphincters); all insert into median raphe;

    have gaps laterally but overlap slightly on posterior aspect

    1. Superior Constrictorfrom pterygomandibular raphe

    &pterygoid hamulus to median raphe and pharyngeal tubercle

    2. Middle constrictorfrom hyoid bone & inf. end of stylohyoid lig.

    To median raphe

    3. Inferior Constrictorfrom thyroid and cricoid cartilages to

    median raphe

    ii. Internal (longintudinal)

    1. Stylopharyngeusfrom styloid process to thyroid cartilage (starts

    externally but becomes internal)

    2. Palatopharyngeusfrom palate to thyroid cartilage & side of


    3. Salpingopharyngeusfrom auditory tube to pharynx

    d. Innervation

    i. Pharyngeal Plexussupplies most innervation to pharynx; composed of

    CN IX (sensory), CN X (motor) & sympathetics from superior cervical


    ii. Exceptions

    1. Stylopharyngeusmotor innervation by CN IX (only muscle inn) 22. Nasopharynxsensory supplied by CN V instead of CN IX

    e. Structures Passing between Pharyngeal Muscles

    i. Between skull & superior constrictorlevator veli palatine & auditory


    ii. Between superior & middle constrictorsstylopharyngeus m, CN IX, &

    stylohyoid ligament

    iii. Between middle & inferior constrictorsinternal laryngeal n & superior

    laryngeal vessels

    iv. Below inferior constrictorinferior laryngeal a & recurrent laryngeal n.

    III. Nasal Cavity & Paranasal Sinuses

    a. Function:

    i. Transmit, warm, filter, & humidify air

    ii. Olfaction via CN I

    iii. Resonating chambersnose and paranasal sinuses affect voice sound


    b. Innervation 1+2i. SensoryCN V (mucosa)

    ii. ParasympatheticCN VII (mucosal secretions via paranasal sinuses &

    nasolacrimal duct)

    iii. OlfactionCN I

    c. Nasal Septum (medial wall)

i. Midline structure dividing nasal cavities

    ii. Composition: septal cartilage & bone (vomer & perp. plate of ethmoid)

    d. Lateral Wall

    i. Composed of superior, middle, inferior conchae (turbinates) ii. Superior & middle conchaepart of ethmoid, relatively small

    iii. Inferior Conchaseparate bone; largest of the three

    iv. Meatusspaces between and lateral to the conchae (sup/mid/inf meatus)

    e. Paranasal Sinuses

    i. Air spaces w/in bones of skull; communicate w/ nasal cavity thru meatus

    ii. Inflammation may => closure & inability to drain fluid (possibly leads to

    an infection)

    iii. Frontal sinusconnects via frontonasal duct in middle meatus iv. Maxillary Sinuslargest sinus; connects via histus semilunaris into

    middle meatus

    v. Ethmoidal Sinusopens into middle meatus (ant/mid air cells) &

    superior meatus (post. ethmoidal air cells)

    vi. Sphenoidal Sinusopens into superior meatus

    IV. Palate & Tongue

    a. Definition

    b. Hard Palate

    i. Roof of mouth & floor of nasal cavity

    ii. Anterior 2/3 of palate; composed of bone (maxillae & palatines)

    c. Soft Palate

    i. Definition: posterior 1/3 of palate; mobile & fibromuscular ii. Muscles

    1. Levator veli palatineelevates palate

    2. Tensor veli palatinetenses palate & helps open auditory tube

    3. Palatoglossusforms palatoglossal arch; pulls back of tongue &

    soft palate together

    4. Palatopharyngeusforms palatopharyngeal arch; tenses palate;

    pulls pharynx up, forward, & medially during swallowing

    5. Musculus Uvulaepulls uvula superiorly to close nasopharynx

    during swallowing

    iii. Innervation

    1. CN Xinnervates almost all mm. 32. Tensor Veli PalatiniCN V

    d. Tongue

    i. Function

    1. highly mobile, muscular organ covered by mucosal membrane

    2. necessary for mastication, speech, and swallowing

    3. Sulcus terminalis: divides tongue into oral (anterior 2/3) and

    pharyngeal (posterior 1/3 of tongue) parts

    4. Foramen Cecumremnant of thyroglossal duct in middle of

    sulcus terminalis

    ii. Muscles

    1. Extrinisic (four)

    a. Genioglossus(largest); depresses & protrudes tongue,

    attached to mental spine of mandible & hyoid bone

    b. Hyoglossusdepresses & retracts tongue; attached to


    c. Syloglossusretracts & curls tongue; attached to styloid


    d. Palatoglossus; elevates posterior of tongue; attached to

    palatine aponeurosis

    2. Intrinsic

    a. Superior/inferior longintudinal mm

    b. Transverse mnarrows & thickens tongue

    c. Vertical mbroadens & flattens tongue

    iii. Innervation

    1. Motor to almost all tongue mm.CN XII (hypoglossal)

    2. Motor to palatoglossusCN X 33. General SensoryAnterior: CN V; Posterior: CN IX

    4. Special Sensory (taste)Anterior: CN VII; Posterior: CN IX

    V. Mastication

    a. Definition: process of preparing food for deflutition (swallowing); involves

    complex vertical, anterioposterior and mediolateral movements

    b. Temporomandibular Joint (TMJ)

    i. Hinge-type synovial joint

    ii. Divided into superior & inferior compartments by articular disc

    iii. Mandibular condyle (mandible) articulates w/ mandibular fossa &

    articular tubercle (skull)

    iv. Temporomandibular ligamentlateral thickening of loose fibrous

    articular capsule

    c. Muscles

    i. Elevation: temporalis, masseter, medial/lateral pterygoids ii. Depression: digastric, infrahyoid, gravity

    iii. Protrusion: masseter pterygoids

    iv. Retraction: temporalis (posterior fibers) masseter (deep fibers) v. Mediolateral motion: pterygoids

    d. Innervation 3i. CN Vall but the depressors (digastric & infrahyoid)

    e. Mastication

    i. Two movements: anterior gliding and hinge-like motions ii. Chew on one side of mouth at a time => have “working side” &

    “balancing side”

    1. balancing side”—slides onto articular tubercle (anterior gliding


    2. working side”—condyle rotates in the mandibular fossa (hinge


    * lateral pterygoids are active during opening and closing b/c they

    reposition mandible during opening stroke

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