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The Head and Neck.

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Presentation on theme: "The Head and Neck."— Presentation transcript:

1 The Head and Neck

2 Upper Respiratory Tract
Nasal Cavity Nostril Oral Cavity Larynx Pharynx

3 Nose Only portion of the RT that is externally visible Functions:
Provides airway for respiration Moistens and warms air Filters inhaled air Resonating chamber for speech Houses olfactory receptors 2 divisions: External nose Internal nasal cavity

4 Nasal Cavity Air enters here during breathing
Passes through the nares (nostrils) Divided into R and L by nasal septum Continuous with the nasopharynx through the internal nares

5 Nasal Cavity Boundries: Hard palate Soft palate
Roof – ethmoid bone (cribiform plate) Floor – maxilla (palatine process) palatine (horizontal plate) Lateral walls – nasal bones, superior and middle nasal conchae (ethmoid bone), inferior nasal conchae, maxilla, palatine bone Hard palate Palatine bones and maxillary bone Soft palate Muscular posterior portion

6 Nasal Cavity Vestibule Vibrissae Superior to nostrils Skin lined with:
Sebaceous glands Greasy secretion Collect dirt Lubricate Kill bacteria Sweat glands Acidic Slows growth of bacteria Hair follicles Trap small particles of dirt Vibrissae Nose hairs Filter large particles (insects)

7 Lining of the Nasal Cavity
Olfactory Mucosa Roof of nasal cavity Houses small receptors Respiratory Mucosa Pseudostratified ciliated columnar epithelium Goblet cells Lamina propria Mucous and serous cells Venous plexus Function is to filter and warm inhaled air

8 Nasal Conchae Project medially from each lateral wall 3 structures:
Superior of ethmoid bone Middle of ethmoid bone Inferior Functions: Filters air Heats air Moistens air Reclaim heat and moisture during exhalation

9 Paranasal Sinuses Air filled cavities that surround the nasal cavity
Lined by mucosa Perform same function as nasal cavity and lightens skull Located in Frontal, Ethmoid, Sphenoid, Maxilla bones

10 Pharynx Connects the nasal cavity and mouth to larynx and esophagus
Extends from base of skull to level of C6 vertebra Common passage for food and air (throat) Lined with skeletal muscle Divided into: Nasopharynx Oropharynx Laryngopharynx

11 Nasopharynx Location: ONLY an air passageway
Posterior to nasal cavity Inferior to sphenoid bone Superior to level of soft palate ONLY an air passageway Closed off during swallowing by the soft palates’ uvula Giggling! Ciliated pseudostratified epithelium Contain: Pharyngeal tonsils (adenoids) Tubal tonsils

12 Oropharynx Location: Swallowed food and inhaled air pass through here
Postreior to the oral cavity Extends inferiorly from level of the soft palate to level of the esophagus Swallowed food and inhaled air pass through here Stratified squamous epithelium Contain: Palatine tonsils Lingual tonsils

13 Tonsils Lymphoid organ Swellings of the mucosa lining the pharynx
Form ring around the entrance to the pharynx 4 groups: Palatine Lingual Pharyngeal Tubal Remove pathogens MALT

14 Laryngopharynx Location: Common passageway for food and air
Lies posterior to larynx Continuous with the esophagus and larynx Common passageway for food and air Stratified squamous epithelium

15 Larynx “Voice box” Extends from C4 to C6 Attachments:
Hyoid bone superiorly Continuous with trachea inferiorly Functions: Vocalization Provides open airway Switches to route air and food into proper channels Innervation: Vagus Superior part = stratified squamous epithelium Below vocal cords= ciliated pseudostratified columnar

16 Larynx Composed of 9 cartilages connected by membranes and ligaments:
1 Thyroid 1 Cricoid 1 Epiglottis 2 Arytenoid 2 Corniculate 2 Cuneiform

17 Laryngeal Cartilages Thyroid Cartilage Large Shield shaped
Formed by 2 plates Composed of laryngeal prominence Adam’s Apple!!

18 Laryngeal Cartilages Cricoid Inferior to thyroid cartilage
Forms a complete ring Perched on top of the trachea

19 Laryngeal Cartilages Epiglottis Composed of elastic cartilage
Covered by mucosa Projects upward from anterior wall of laryngeal inlet to level of base of tongue

20 Vocal Cords Located in the larynx
Mucosal folds formed by vocal ligaments Composed of elastic fibers Run from arytenoid cartilages to the thyroid cartilages Exhaled air passes over them and causes vibration Force of air = volume Length & tension of folds = pitch False vocal cords Vestibular folds (superior to true)

21 Thyroid Gland Location: 2 lateral lobes Butterfly shape
In anterior neck On trachea, inferior to larynx 2 lateral lobes Connected by the isthmus Butterfly shape Largest endocrine gland in body Produces TH Increases metabolic rate Calcitonin Depresses excess levels of Ca+ in blood

22 Thyroid Gland Internally, composed of follicles Blood supply
Follicular cells TH Parafollicular cells Calcitonin Blood supply Superior thyroid arteries Branches of external carotids Inferior thyroid arteries Branches of subclavians

23 Parathyroid Gland Two pairs
Located on the deep surface of the lateral lobes of the thyroid gland Produce parathyroid hormone Increases blood calcium levels

24 Hyoid Bone Location: Associated with the skull
Inferior to mandible In anterior neck Associated with the skull Only bone in skeleton that does not articulate directly to another bone!!! Attaches via ligaments to temporal bone, larynx Composed of: Body 2 pairs of horns Functions: Moveable base for tongue Points of attachment for larynx and neck muscles Sternohyoid, thyrohyoid,

25 Triangles of the Neck Neck subdivided into two triangles
Separated by the sternocleidomastoid muscle Anterior triangle Posterior triangle

26 Triangles of the Neck: Posterior
Boundries: Anterior - sternocleidomastoid Posterior - trapezius Inferior – clavicle Contents: Nerves: accessory nerve, cranial plexus, phrenic nerve, brachial plexus Artery: Subclavian Vein: External jugular

27 Triangles of the Neck: Anterior
Boundries: Anterior - midline Posterior - sternocleidomastoid Superior – inferior margin of the mandible Contents: Glands: Submandibular Muscles: Suprahyoid and infrahyoid muscles Artery: Carotid Vein: Internal jugular, External jugular Nerve: Acccessory

28 Mouth and Associated Organs
Tongue Salivary glands Teeth

29 Mouth - Oral Cavity Food enters alimentary canal through here
Mucosa-lined Thick stratified squamous epithelium, with keratinization in some areas Boundaries: Lips anteriorly Cheeks laterally Palate superiorly Tongue inferiorly Oropharynx posteriorly Mouth divided into 2 parts: Vestibule Oral cavity proper

30 Mouth Lips (labia) and Cheeks Palate: forms the roof of the mouth
Keep food inside mouth during chewing Composed of skeletal muscle surrounded by skin Lips formed by orbicularis oris muscle Cheeks; Muscles of Mastication (pg ) Temporalis & Masseter (elevate mandible, close mouth) Buccinator (chewing) Digastric (lower mandible against resistance, opens mouth) Pterygoids (lateral movements) Palate: forms the roof of the mouth Soft palate (posterior) rises to close off nasopharynx during swallowing; made of smooth muscle Hard palate (anterior) provides surface for tongue to force food against during chewing

31 Tongue Functions Creates floor of mouth
Grips and moves food between teeth during chewing Mixes food with saliva = BOLUS Moves bolus down pharynx Speech production Houses taste buds (= gustation) Creates floor of mouth Attachments: hyoid, mandible, styloid process, soft palate Made of Skeletal muscle with a CT septum Intrinsic muscles (change shape; rolling) Extrinsic muscles (movement; protrude, retract) Motor = Hypoglossal (CN XII) Sensory = Mandibular (CN V3), Facial (CN VII), Glossopharyngeal (CN IX)

32 Swallowing Voluntarily initiated (pharynx) Peristalsis = propulsion
Involuntary Alternate waves of contraction and relaxation of muscles in organ walls (e.g. esophagus) Squeezes food from one organ to next Some mixing

33 Salivary Glands Compound tubuloalveolar glands
Intrinsic salivary glands In mucosa of tongue, palate, lips and cheeks Keeps mouth moist at all times Extrinsic salivary glands Lie external to mouth Connected by ducts Secrete only during eating or prior to (“mouth watering”) 3 paired glands: Parotid Submandibular sublingual

34 Salivary Glands Produce saliva
Mixture of water, ions, mucus and enzymes Moistens mouth Dissolves food for taste Binds food into a bolus Enzymes digest starch Bicarbonate buffer neutralizes acids Kill microorganisms Contains proteins to promote growth of beneficial bacteria

35 Teeth – From Eruption to Edentate
Lie in sockets (alveoli) in gum-covered margins in mandible and maxilla Have 2 sets of teeth (dentitions) Primary dentition / deciduous (milk) teeth Permanent dentition Incisors: rip, cut Canines: tear and pierce Premolars: grinding Molars: grinding

36 Teeth Function: Ingestion and mechanical breakdown of food Periodontal ligaments (collagen fibers) anchor tooth in bony socket Gomphosis - form of immovable articulation; a peglike part fits into a cavity Continous with gingiva (gum)

37 Teeth Regions: Pulp cavity Crown Neck (gumline) Root Center of tooth
Covered with enamel Area above gingiva Neck (gumline) Root Area below neck in alveolus Pulp cavity Center of tooth Loose CT with vessels and nerves Supplies nutrients to hard tissues

38 Teeth Root Canal Apical foramen Blood supply Innervation
Portion of the pulp cavity in the root Apical foramen Opening into the root canal at the tip of each root Blood supply Superior/Inferior Alveolar artery, branches of External Carotid artery Innervation Maxilla = Superior Alveolar Nerves Mandible = Inferior Alveolar Nerves

39 Teeth Substances Enamel Dentin Cementum Made of calcium salts
Avascular, acellular Not renewed or replaced HARDEST substance in body!!!! Dentin Underlines enamel Forms bulk of tooth Made of minerals and collagen Maintained during life Harder than bone Cementum Calcified external surface Attaches tooth to periodontal ligament

40 Teeth at Birth Number of erupted teeth = 0
Jaws covered by gingiva (gums) Lots of drooling!!!

41 First Teeth – 6 Months Lower central incisors first to appear
8 Incisors = 6-10 months 4 Canines = months 4 1st Molars = months 4 2nd Molars = months 20 deciduous teeth emerge by age 2 Dental formula Describes the number and position of classes of teeth (half of the mouth) 2I, 1C, 2M Deciduous teeth dental formula: X 2 = 20 ****No premolars!

42 Adolescence – Adult Permanent teeth enlarge and develop
Roots of deciduous teeth reabsorbed Teeth loosen and fall out Begin to erupt from 7-13 years of age Third molars (wisdom teeth) emerge from years May be absent!! Adult dental formula: 2I, 1C, 2P, 3M X 2 = 32

43 Tooth Troubles Cavities (caries)
Demineralization of enamel by bacteria In severe cases, erodes the dentin of tooth Most severe cases erosion penetrates pulp cavity

44 Tooth Troubles Gingivitis Periodontitis
Inflammation of the gingiva caused by plaque accumulation Leads to……. Periodontitis Infection of periodontal ligament leading to its destruction along with the bone around the teeth Leads to……………

45 Toothlessness!!!!!!


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