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Joints and Muscles
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Joints (articulations)
Where parts of skeleton meet
Allows varying amounts of mobility
Classified by structure or function Arthrology: study of joints
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Classification of Joints
Function:
Synarthroses = no/little movement Amphiarthroses = slight movement
Diarthroses = great movement
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Joints by Functional Classification
Type Movement Example
Synarthrosis None
(minimal)
Sutures, Teeth,
Epiphyseal plates,
1st rib and costal cart.
Amphiarthrosis Slight Distal Tibia/fibula
Intervertebral discs
Pubic symphysisDiarthrosis Great Glenohumeral joint
Knee joint
TMJ
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Joint Classification
Structure
Cartilagenous
Synchondrosis: connected by hyaline cartilage
Symphysis: connected by fibrocartilage
Fibrous
Sutures: connected by short strands of dense CT
Syndesmoses: connected by ligaments
Gomphosis: peg in socket w/short ligament
Synovial
Page 20 & 23
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Joints by Structural Classification
Structure Type Example
Cartilagenous Synchondrosis
Symphysis
Epiphyseal plates
Intervertebral discs
Fibrous SuturesSyndesmoses
Gomphosis
SkullDistal Tibia/fibula
Teeth in sockets
Synovial 6 Shapes Glenohumeral jointKnee joint
TMJ
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Components of SYNOVIAL JOINTS:
(Structural Joint Classification continued)
Articular cartilage: hyaline; covers ends of both bonesarticulating
Synovial (joint) cavity: space holding synovial fluid
Articular capsule: Made of 2 layers
Fibrous: external, dense CT for strength
Synovial membrane: internal, produces synovial fluid
Synovial fluid: viscous; lubricates and nourishes;
contained in capsule and articular cartilages Reinforcing ligaments: extracapsular/intracapsular
Nerves + vessels: Highly innervated, Highly vascular
Meniscus (some): fibrocartilage; improves the fit of 2 bones
to increase stability pg 21
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Bursae & Tendon Sheaths
Bursae: flat, fibrous sac w/synovial
membrane lining
Tendon Sheaths: elongated bursae that
wraps around tendons
3 Factors in Joint Stability:
Muscle Tone Ligaments
Fit of Articular Surfacepg 671
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Shapes of Synovial Joints
Hinge: cylindrical end of 1 bone fits into
trough shape of other
Uniaxial movement
(eg) elbow, ankle, interphalangeal Plane: articular surface in flat plane
Short gliding movement
(eg) intertarsal, articular processes of vertebrae
Pg 715
Pg 725
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Joint Shapes
Condyloid: egg-shape articular surface +oval concavity
Multiaxial movement
(eg) metacarpophalangeal (knuckle)
Pivot: round end fits into ring of bone +ligament
Uniaxial movement rotation on long axis
(eg) prox. radius/ulna, atlas/dens
pg 753
pg 725
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Joint Shapes
Saddle: articular surface both
concave + convex
side-to-side, back-forth movement Multiaxial movement
(eg) carpometacarpal jt of thumb
Pg 664, 753
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Ball + Socket: spherical head +
round socket
multiaxial movement (eg) shoulder, femur
pg 534
Joint Shapes
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!Muscles!
Function: 1) movement
2) maintain posture
3) joint stability4) generate heat
!Muscles!
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Muscle Basics to Remember
3 Types: Skeletal, Cardiac, Smooth
Origin vs. Insertion
Direct vs. Indirect Attachments direct = right onto bone
indirect = via tendon/aponeurosis
more common leave bony markings = tubercle, crest, ridge, etc.
Sometimes attach to skin
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Special Features of Muscle
Contractibility= cells generate pulling force
Excitibility = nervous impulses travel through
muscle plasma membrane to stimulate
contraction
Extensibility = after contraction, muscle can be
stretched back to original length by opposing
muscle action
Elasticity = after being stretched, muscle
passively recoils to resume its resting length
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Muscle System: uses levers to move objects
How it works: A rigid bar moves on fixed point
when a force is applied to it, to move object
Lever = rigid bar = bone Fulcrum = fixed point = joint
Effort = force applied = muscle contraction
Load = object being moved = bone
www.biologyreference.com/.../biol_03_img0301.jpg
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Movements of Muscles
Extension: increasing angle between body parts
Flexion: decreasing angle between body parts
Dorsiflexionvs.Plantarflexion Inversionvs.Eversion
Abduction: moving away from the median plane
Adduction: moving towards the median plane Rotation: moving around the long axis
Circumduction: moving around in circles
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Elevation: lifting body part superiorly
Depression: moving body part inferiorly
Protraction: Anterior movement Retraction: Posterior movement
Supination: rotating forearm laterally
Pronation: rotating forearm medially
Opposition: movement of thumb against other
fingers
Movements of Muscles
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Functional Muscle Groups
Agonist = primary mover of a muscle, majorresponse produces particular movement
(eg) biceps brachii is main flexor of forearm
Antagonists = oppose/reverse particularmovement, prevent overshooting agonistic
motion (eg) triceps brachii is antagonist to biceps brachii
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Functional Muscle Groups
Synergists = muscles work together, adds extraforce to agonistic movement, reduce undesirableextra movement
(eg) muscles crossing 2 joints
Fixators = a synergist that holds bone in place to
provide stable base for movement (eg) joint stablilizers
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Naming Muscles
Location: (eg) brachialis = arm
Shape: (eg) deltoid = triangle
Relative Size: (eg) minimus, maximus, longus Direction of Fascicles: (eg) oblique, rectus
Location of Attachment: (eg) brachioradialis
Number of Origins: (eg) biceps, quadriceps
Action: (eg) flexor, adductor, extensor
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