Posture, Spine, TMJ

kyphosis

convex is posterior

lordosis

convex is anterior

primary spinal curves

kyphosis (thoracic and sacral)

secondary spinal curves

lordosis (cervical and lumbar)

what happens at transitional regions

as you transition from one spinal region to another, the characteristics of the vertebrae begin to shift

scoliosis

spinal curve in the frontal plane

definition of posture

position of all the joints in the body at a given moment

optimal posture

posture that results in maximum physiological and biomechanical efficiency while minimizing stress and strain

sub-optimal posture

alters the stress and strain on tissues which affects the muscles, ligaments, and joints

characteristics of optimal posture from the sagittal view

line through the ear lobe, cervical vertebral bodies, acromion, trunk, lumbar bodies, greater trochanter and anterior to the knee joint and lateral malleolus

external moment of cervical spine created by gravity

anterior to axis → flexion torque → offset by cervical extensors

external moment of thoracic spine created by gravity

anterior to axis → flexion torque → offset by thoracic extensors

external moment of lumbar spine created by gravity

posterior to axis → extension torque → offset by abdominal muscles

external moment of hip created by gravity

posterior to axis → extension torque → offset by iliopsoas and iliofemoral ligament

external moment of knee created by gravity

anterior to axis → extension torque → offset by gastroc and posterior joint capsule

external moment of ankle created by gravity

anterior to axis → dorsiflexion torque → offset by gastroc and soleus

types of scoliosis

non-structural/non-fixed, structural/fixed

how is scoliosis labeled

based on the region of the vertebral column and convex side

how does scoliosis cause a rib hump

frontal plane misalignment causes transverse plane misalignment

types of sub-optimal postures

sway back, forward/rounded shoulders, forward head, iliac crest misalignment, genu varum/valgum, over pronation/supination

characteristics of sway back

lower back hyperextended, increased thoracic kyphosis, head forward, pelvis forward

characteristics of forward/rounded shoulders

scapula protraction, tight pectoral muscles, lengthened thoracic extensor muscles, glenohumeral internal rotation

characteristics of forward head posture

head protracted, tight SCM and rectus capitis posterior, upper body shifts backward

reasons against optimal posture

no single correct posture, differences in posture are a fact of life, posture reflects beliefs and moods, safe to adopt more comfortable postures

function of facet joints

orientation dictates the direction of motion, dorsal rami provide sensory input

relationship between IVDs and motion

the more thick the disc is the greater mobility there is

components of the nucleus pulposus

70-90% water, type 2 collagen

components of the annulus fibrosus

60-70% water, type 1 cartilage

components of the end plates of IVDs

hyaline, fibrocartilage, sharpey’s fibers

ligaments of the upper cervical spine

cruciform, alar, apical

muscles that stabilize the spine

multifidus, interspinalis, rotators, semispinalis

muscles that move the spine

iliocostalis, longissimus, spinalis, splenius, suboccipitals, SCM, scalenes

components of a spinal motion segment

2 vertebrae, disc, associated ligaments

types of spinal segment motions

3 rotations and 3 translations

cervical spine coupled motion

upper: contralateral directions, lower: ipsilateral directions

thoracic spine coupled motion

upper thoracic has ipsilateral coupled motion

when do IVFs open and close

open: superior-anterior slide, closed: inferior-posterior slide

function of special tests like cervical distraction and compression tests

impart additional forces to the impact it has on tissues

parts of the TMJ

mandibular fossa, articular eminence, mandibular condyle

types of cartilage on the articular eminence

articular and fibrocartilage

ligament that reinforces the TMJ capsule

lateral ligament

attachments of the articular disc in the TMJ

medial and lateral sides of the condylar head and neck junction, inner surface of the joint capsule, superior head of the lateral pterygoid, retrodiscal tissue

blood and nerve supply of the articular disc in the TMJ

blood supply: lateral pterygoid and retrodiscal tissue; nerve supply: retrodiscal tissue

components of the retrodiscal tissue

collagen/elastic fibers (laminae), fat, blood vessels, nerves

muscles of the TMJ

temporalis, masseter, lateral pterygoid, medial pterygoid

osteokinematic motions of the TMJ

depression, elevation, protrusion, retrusion, lateral excursion

TMJ arthrokinematics in the early phase of mouth opening

condylar head spins clockwise on the articular disc

TMJ arthrokinematics in the late phase of mouth opening

articular disc and condylar head slide together in an anterior-inferior motion from the fossa to the articular eminence

why is TMJ mouth opening split into two phases

the condylar head and articular disc are becoming optimally aligned to slide out of the fossa

TMJ arthrokinematics in the early phase of mouth closing

the condylar head and articular disc slide in a posterior-superior direction

TMJ arthrokinematics in the late phase of mouth closing

condylar head spins counter clockwise

TMJ arthrokinematics during lateral excursion (to the left)

left side spins counterclockwise, right side slides anterior and to the left

force coupling during lateral excursion of the TMJ

concentric contractions of the temporalis and pterygoids on contralateral sides

path of articular disc during anterior displacement with reduction

disc is anterior to condylar head → open mouth slightly and disc realigns → creates a click → moves through the motion → close mouth → disc goes back into misalignment → another click

dislocation of the TMJ

condylar head passes anterior to the articular eminence

causes of TMJ dislocation

non-traumatic (yawn, open mouth) or traumatic (dental procedures, blow to the chin)

how does a forward head posture affect the TMJ

sternohyoid, omohyoid, and suprahyoid muscles lengthen and generate a passive force in the posterior direction which causes the mandible to compress the retrodiscal tissue

ventilation

movement of air in and out of the body (inspiration and expiration)

types of ventilation

pulmonary and alveoli

respiration

gas exchange between the atmosphere, blood, and cells

external respiration

gas exchange between the lungs and blood (CO2 and O2)

internal respiration

gas exchange between the blood and cells (waste and O2)

how does the volume of the thoracic cavity change during ventilation

upper 6 ribs expand in an anterior-posterior direction, lower 6 ribs expand in a medial-lateral direction, diaphragm expands in a superior-inferior direction

how do the lungs stay inflated

negative interpleural pressure keeps the elastic fibers stretched

boyles law

the volume of gas varies inversely with the pressure of the gas

alveolar and atmospheric pressure at rest

equal (760 mmHg)

alveolar and atmospheric pressure during inhalation

volume of the thoracic cavity increases so alveolar pressure becomes less than the atmospheric pressure

alveolar and atmospheric pressure during exhalation

muscles relax and decrease the volume of the thoracic cavity causing the alveolar pressure to become more than the atmospheric pressure

what drives the muscles of ventilation

phrenic and intercostal nerves send signals driven by the oxygen feedback loop in the brain stem