F. Anatomy 4 mastic. & vent.

Inspiratory reserve volume

Amount of air that can be taken into lungs on forced inspiration

Protrusion

Anterior translation of mandible Important for widely opening mouth

Scalenes

Anterior, middle, and posterior ______attach between cervical spine and upper two ribs assist with inspiration by elevating upper ribs and attached sternum Excessive hypertrophy of these muscles may be symptom of respiratory disorder

Supporting Structures of the TMJ:

Articular Disc Capsule

Mandibular fossa

Articulates with mandibular condyle, forming TMJ Articular eminence and postglenoid tubercle Small tuberosities on anterior and posterior aspects of mandibular fossa (respectively)

External Intercostals

Assists inspiration by elevating ribs and expanding thorax

Internal Intercostals

Assists with forced expiration by depressing ribs

Retrusion

Posterior translation of mandible Important for closing widely opened mouth

Quiet expiration

Primarily a passive process not dependent on muscular activation Driven by recoil of lungs, thorax, and connective tissues of stretched inspiratory muscles

Lateral Excursion

Primary component of mastication, as food is ground between teeth Primarily involves contraction of masseter and temporalis on same side as lateral motion and activation of contralateral medial and lateral pterygoid muscles

Diaphragm

Primary muscle of inspiration

Opening the mouth

Suprahyoid muscles and gravity assist Mandible depresses and mandibular condyle translates forward Lateral pterygoid muscle primarily controls anterior translation, while suprahyoid muscles produce depression of mandible

Capsule

TMJ surrounded by fibrous capsule with medial and lateral thickenings that form collateral ligaments These structures provide medial and lateral stability of TMJ; often required during chewing motions

Coronoid process

Thin triangular projection of bone arising from anterior aspect of ramus

Vital capacity

Total volume of air that can be moved in and out of lungs on maximal forced inspiration and maximal forced expiration

Hyoid Bone

U-shaped bone located at base of throat, just anterior to third cervical vertebra Suspended primarily by stylohyoid ligaments Serves as attachment for several tongue muscles that are active during speaking and swallowing

Tidal volume

Volume of air moved in and out of lungs during each ventilation cycle

Depression of mandible

________ opens mouth Opening mouth requires anterior translation of each mandibular condyle relative to its mandibular fossa

Role of Articular Disc

__________ is important in smoothness of opening or closing mouth Attachments of lateral collateral ligaments and lateral pterygoid to _______ guide proper motion and alignment of TMJ Asynchronized motions between disc and TMJ can cause clicking or even locking of jaw

Forced ventilation

_______occurs during activities requiring rapid and large exchanges of air, such as exercise, or as result of respiratory diseases

Elevation of mandible

_____closes mouth Disc is "re-seated" into joint as mandible is elevated during mouth closure

Muscles of Forced Expiration

include four abdominal muscles and internal intercostales

Temporomandibular Joint

joint that consists of articulation between mandibular condyle and mandibular fossa of temporal bone Any jaw movement such as chewing, speaking, and swallowing requires movement of TMJ joints

Expiratory reserve volume

Amount of air that can be pushed out of lungs on forced expiration

Medial Pterygoid

Actions: Elevation of mandible (closing mouth) Lateral excursion to opposite side

Lateral Pterygoid

Actions: depression of mandible (opening mouth), protrusion of mandible, lateral excursion to opposite side

Parts of the Mandible

Body Ramus Mandibular condyle Pterygoid fossa Coronoid process Mandibular notch

Zygomatic Bone

Compose cheek regions and lateral orbit of eyes Temporal process forms anterior half of _______ arch

Mandibular condyle

Convex portion of bone arising from superior aspect of each ramus; articulates with mandibular fossa of temporal bone, forming TMJ

Articular Disc

Covers inferior border of mandibular fossa Consists of dense fibrous connective tissue Provides joint stability, reduces contact pressure, and helps guide condyle of mandible during jaw movements

Muscles of Inspiration:

Diaphragm External Intercostals Internal Intercostals Scalenes

Suprahyoid muscles

Digastric, geniohyoid, mylohyoid, stylohyoid Firm base to assist with mandible depression

Mandibular notch

Extends between coronoid process and mandibular condyle

External auditory meatus

External opening for ear, posterior to mandibular fossa

Closing mouth

Forcefully_________, such as when biting or chewing, involves activation of masseter, medial pterygoid, and temporalis muscles ________ involves mandibular elevation and retrusion

Zygomatic arch

Formed by zygomatic process of temporal bone and temporal process of zygomatic bone Serves as proximal attachment for masseter muscle Forms part of a bony tunnel occupied by temporalis muscle

Body

Horizontal portion of mandible that has sockets for lower 16 adult teeth

Forced expiration

Involves active contraction of expiratory muscles, such as abdominals during actions like sneezing or blowing out candles

Parts of the Temporal Bone

Mandibular fossa External auditory meatus Zygomatic process Zygomatic arch

Ventilation

Mechanical process by which air is inhaled and exhaled through lungs Persists 12-20 times per minute at rest Mechanics are based on an interaction between muscles and joints of axial skeleton

Muscles of Temporomandibular Joint:

Medial Pterygoid Lateral Pterygoid

Infrahyoid muscles

Omohyoid, sternhyoid, sternothyroid, thyrohyoid Stabilize hyoid bone

Zygomatic process

Projects anteriorly from temporal bone forming posterior half of zygomatic arch

Ramus

Projects vertically from body of mandible; angle of each ____ provides attachment for masseter and medial pterygoid muscles

Maxillae

Right and left ______ unite to form upper jaw Maxilla is fused to adjacent facial bones including sphenoid, nasal, and zygomatic bones Inferior aspects of ______ contain sockets for upper teeth

Sphenoid Bone

Single, deep bone that runs transversely across cranium Greater wings are located on either side of cranium, just anterior to temporal bone Medial and lateral pterygoid plates provide proximal attachment for medial and lateral pterygoid muscles

Pterygoid fossa

Small depression on inferior-medial aspect of mandibular condyle, marking attachment of lateral pterygoid muscle

Lateral excursion

___ of mandible occurs as mandible translates side to side Motion is used to grind food between teeth

Quiet ventilation

_______ occurs during relatively sedentary activities

Boyle's law

volume and pressure exerted by a gas are inversely proportional