anatomy #29. 2. bursae and tendon sheaths

bursae and tendon sheaths

Bags of synovial fluid that act as lubricating “ball bearing”

– Not strictly part of synovial joints, but closely associated

bursae

reduce friction where ligaments, muscles, skin, tendons, or bones rub together

Tendon sheaths:

elongated bursae wrapped completely around tendons subjected to friction

All muscles attach to bone or connective tissue at no fewer than

two points

-origin

-insertion

origin

attachment to immovable bone

insertion

attachment to movable bone

Muscle contraction causes

insertion to move toward origin

Movements occur along

transverse, frontal, or sagittal planes

Range of motion allowed by synovial joints

-nonaxial

-uniaxial

-blaxial

-multiaxial

nonaxial

slipping movements only

Uniaxial

movement in one plane

Biaxial

movement in two planes

Multiaxial

movement in or around all three planes

Three general types of movements

– Gliding

– Angular movements

– Rotation

Gliding movements

One flat bone surface glides or slips over another similar surface

examples of gilding movements

– Intercarpal joints

-Intertarsal joints

- Between articular processes of vertebrae

Angular movements

-Increase or decrease angle between two bones

– Movement along sagittal plane

Angular movements include:

-flexion

-extension

-hypertension

-abduction

-adduction

-circumduction

Flexion:

decreases the angle of the joint

Extension:

increases the angle of the joint

Hyperextension:

movement beyond the anatomical position

Abduction:

movement along frontal plane, away from the midline

Adduction:

movement along frontal plane, toward the midline

Circumduction

Involves flexion, abduction, extension, and adduction of limb

-Limb describes cone in space

rotation

turning of bone around its long axis, toward the midline or away from it

– Medial: rotation toward the midline

– Lateral: rotation away from the midline

Ex: Rotation between C1 and C2 vertebrae

-Rotation of humerus and femur

special movements

Supination and pronation: rotation of radius and ulna

supination

palms face anteriorly

– Radius and ulna are parallel

Pronation:

palms face posteriorly

– Radius rotates over ulna

Dorsiflexion and plantar

flexion of foot

dorsification

bending foot toward shin

planter

pointing toes

inversion

sole of foot faces medially

eversion

sole of foot faces laterally

protraction

mandible juts out

retraction

the mandible is pulled toward

elevation

lifting body parts superiorly

ex: shrugging shoulders

depression

lowering body part

-ex: opening jaw

opposition

movement of thumb

Ex: touching thumb to tips of other fingers on same hand or any grasping movement