Ch. 9 Joints

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Ch. 9 Joints
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• Articulation- A point of contact between two
  bones or between a bone and cartilage
• Can produce a wide variety of motions
• Arthrology The study of the structure of joints
• Arthrologist- help design joint replacements
• Kinesiology The study of the movement of joints
• Learn how a joint goes through a range of
  motions.
• The field of study for physical/occupational
  therapists.

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Functional Classifications of Joints

• This is the easy way to classify joints.
• Synarthroses
• The group of joints that produce no movement.
• Amphiarthroses
• Slightly moveable joints- little separation
  between bones
• Diarthroses
• Fully moveable joints

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Structural Classifications of Joints

• This is a more difficult way to classify joints.
• Fibrous joints lack a synovial cavity and the
  articulating bones are held together by a thin
  layer of dense irregular connective tissue.
• Bones are in direct contact with one another.
• Bones are joined in a way that no movement is
  produced.
• This is a type of synarthrosis
• Be careful on the on-line quiz- If the question
  asks for structural classification, then dont
  put the functional classification.

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Types of Fibrous Joints

• Suture joints fibrous joints in which the bones
  forming the joint are in direct contact.
• Found between bones of the cranium.
• Neighboring bones have saw-like projections to
  help lock the bones together producing a very
  strong joint.
• Joints are actually stronger than the bone
  itself!
• Synostosis A joint in which there is a complete
  fusion of the two separate bones into one bone.
• The saw-like projections completely ossify
• If this happens too quickly in the skull, it
  could affect brain development.

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Types of Fibrous Joints

• Syndesmoses fibrous joints in which there is a
  greater distance between the articulating
  surfaces and more dense iregular connective
  tissue than in a suture.
• Found between the bones of the forearm (radius
  and ulna) and the bones of the lower leg (tibia
  and fibula).
• Bones are held in place by the interosseus
  membrane which prevents bones from separating
  when weight is applied.

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Types of Fibrous Joints

• Gomphoses fibrous joints in which a cone-shaped
  peg fits into a socket.
• Hold the teeth in place
• A thin piece of connective tissue called the
  periodontal ligament helps secure the root of a
  tooth into the socket of the upper/lower jaw.

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Cartilaginous Joints

• Lack a synovial cavity and the articulating bones
  are tightly connected by either hyaline cartilage
  or by fibrocartilage.
• Two Types
• Synchondroses cartilaginous joints in which the
  connecting material is hyaline cartilage.
• Often found between the ends (epiphyses) and
  shaft (diaphysis) of a long bone.
• Epiphyseal plate
• Once it gets turned into bone, it could be
  considered a fibrous joint.
• Allow the ends of bones to shift slightly to
  compensate for muscle development.

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Cartilaginous Joints

• Symphyses cartilaginous joints in which the ends
  of the articulating bones are covered with
  hyaline cartilage but a broad, flat disc of
  fibrocartilage connects the bones.
• This is found between the bones of the spine and
  hip
• Allows bones to shift slightly during movement
• The hormone relaxin is secreted during childbirth
  to soften the connective tissue.

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Synovial Joints- have a synovial cavity

• This is the most complex of the 3 structural
  joints.
• These are forms of diarthroses.
• Synovial cavity a space between the articulating
  bones.
• Filled with synovial fluid
• This space allows joints to move freely.
• Synovial capsule surround a synovial joint,
  encloses a synovial joint and unites the
  articulating bones.
• Combination of fibrous connective tissue and the
  synovial membrane.

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Layers of the Synovial Capsule

• Fibrous capsule a layer of dense irregular
  connective tissue that attaches to the periosteum
  of the articulating bones.
• Functions to help hold the articulating bones
  together and limits the range of motion for that
  joint (to limit injury).
• Synovial membrane a layer of areolar connective
  tissue that contains elastic fibers.
• Functions to produce and secrete synovial fluid
  that acts as an additional shock absorber.
• Synovial fluid is slippery and viscous.

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6 Types of Synovial Joints

• Planar The articulating surfaces of the bones
  are flat or lightly curved.
• Also called a gliding joint.
• Found between carpal (wrist) and tarsal (ankle)
  bones.
• Sliding movement to even the distribution of
  forces to the arms and legs.

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6 Types of Synovial Joints

• Hinge The convex articulating surface of one
  bone fits into the concave articulating surface
  of another bone.
• Found at the elbow and knee.
• Opening and closing movements in 1 plane.
• Shape of the joint limits movement so this is the
  easiest synovial joint to damage.

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6 Types of Synovial Joints

• Pivot The rounded or pointed surface of one bone
  articulates with a ring formed partly by another
  bone and partly by a ligament.
• Found between the 1st 2 vertebrae (atlas and
  axis) and the bones of the forearm (radius and
  ulna)
• Moves by the rotation of 1 bones around its own
  long axis. (Rotation of the radius to turn the
  palm over)

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6 Types of Synovial Joints

• Condyloid The convex, oval-shaped projection of
  one bone fits into the oval-shaped depression of
  another bone.
• Found at the following
• Between the head and 1st vertebra
• Between the skull and lower jaw
• Between the forearm and wrist
• Between the palm and fingers
• Between the lower leg and ankle
• of the radius to turn the palm over)
• Moves front to back and side to side like in
  chewing

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6 Types of Synovial Joints

• Saddle the articular surface of one bone is
  saddle-shaped and the articular surface of the
  other bone fits into the saddle.
• Found at the base of each thumb
• Moves front to back, side to side, circular and
  opposing the pinky

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6 Types of Synovial Joints

• Ball and socket the ball-like articulating
  surface of one bone fits into the cup-like
  depression of another bone.
• Found at the shoulder and hip
• Provides the most versatile movement- front to
  back, side to side, circular, and rotating

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ACT-UP
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ACT-UP

• 1) What part of the body is being shown in the
  slide?
• 2) What is the structural classification of the
  joint shown?

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ACT-UP

• 3) What part of the body is being shown in the
  slide?.
• 4) What is the structural classification of the
  joint shown?

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ACT-UP

• 5) Which of the joints pictured offers the
  greatest range of motion and why?