Bones and Joints, lecture presentation

Joints and Muscles

Joints (articulations)

• Where parts of skeleton meet
• Allows varying amounts of mobility
• Classified by structure or function
• Arthrology: study of joints

Classification of Joints

• Function:
• Synarthroses = no/little movement
• Amphiarthroses = slight movement
• Diarthroses = great movement

Joints by Functional Classification

Type	Movement	Example
Synarthrosis	None (minimal)	Sutures, Teeth, Epiphyseal plates, 1 st rib and costal cart.
Amphiarthrosis	Slight	Distal Tibia/fibula Intervertebral discs Pubic symphysis
Diarthrosis	Great	Glenohumeral joint Knee joint TMJ

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

Joints by Structural Classification

Structure	Type	Example
Cartilagenous	Synchondrosis Symphysis	Epiphyseal plates Intervertebral discs
Fibrous	Sutures Syndesmoses Gomphosis	Skull Distal Tibia/fibula Teeth in sockets
Synovial	6 Shapes	Glenohumeral joint Knee joint TMJ

Components of SYNOVIAL JOINTS:
(Structural Joint Classification continued)

• Articular cartilage: hyaline; covers ends of both bones articulating
• 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

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 Surface

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

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

Joint Shapes

• Saddle: articular surface both concave + convex
• side-to-side, back-forth movement
• Multiaxial movement
• (eg) carpometacarpal jt of thumb
• 
  
• Joint Shapes Ball + Socket: spherical head + round socket
• multiaxial movement
• (eg) shoulder, femur

!Muscles!

Function: 

1) movement
2) maintain posture
3) joint stability
4) generate heat

!Muscles!

• 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

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

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

Movements of Muscles

• Extension: increasing angle between body parts
• Flexion: decreasing angle between body parts
• Dorsiflexion vs. Plantarflexion
• Inversion vs. 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

Movements of Muscles

• 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

Functional Muscle Groups

• Agonist = primary mover of a muscle, major response produces particular movement
• (eg) biceps brachii is main flexor of forearm
• Antagonists = oppose/reverse particular movement, prevent overshooting agonistic motion
• (eg) triceps brachii is antagonist to biceps brachii

Functional Muscle Groups

• Synergists = muscles work together, adds extra force to agonistic movement, reduce undesirable extra movement
• (eg) muscles crossing 2 joints
• Fixators = a synergist that holds bone in place to provide stable base for movement
• (eg) joint stablilizers

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

  download lecture presentation Bones and Joints
source by  faculty.ccri.edu