Skeletal System

Articulations

Articulations

• Articulation (joint): a point of contact between bones.

• Some allow movement, others are immovable (sutures).

• Most joints allow considerable movement as a result of muscle contractions.

Classification of Joints

• Categories– Structural (by connective tissue or fluid)

• Fibrous• Cartilaginous• Synovial

– Functional• Synarthrosas• Amphiarthrosis• diarthrosis

Table 9-1 pg 256 classifies Each joint. Refer to it

Often.

Fibrous Joints (Synarthroses)

• Fibrous joints fit close.

• Connective tissue permit limited movement; most joints are fixed (immovable.)

• 2 sub types– Syndesmoses– Sutures– Gomphoses

Syndesmoses

• Joints in which fibrous tissue connect two bones.

• Some movement possible because of ligament flexibility.– Example: Distal ends of radius and ulna

Sutures

• Found only in skull.

• Thin layer of fibrous tissue between bones.

• Immovable.

Gomphoses

• Unique joints between root of teeth and mandible or maxilla.

Cartilaginous Joints (Amphiarthrosis)

• Bones joined by hyaline or fibrocartilage.

• Hyaline joints- Synchondroses

• Fibrocartilage joints- symphyses

• Joints are slightly movable in certain circumstances.

Synchondroses

• Hyaline cartilage between articulating bones

• Examples: Articulation between first rib and sternum.

Symphyses• Fibrocartilage pads bones

• Slight movement possible when pressure is applied.

• Example: Symphysis pubis opens pelvis during childbirth.

• Other examples of symphysis joints: vertebrae.

Synovial Joints (diarthroses)• Freely movable.

• A majority of joints are synovial.

• Ex: knee, hip

• Subcatagories:– Uniaxial– Biaxial– Muliaxial

Flashcards: Will be used during first dissection• Requirements:

– Front of card• Name of the joint

type.– Back of card

• Definition of joint• Example of the

joint.• Picture of the joint

• Required Cards:– Synarthroses: Syndesmoses– Synarthroses: Sutures– Synarthroses: Gomphoses– Amphiarthrosis: Synchondroses– Amphiarthrosis: symphyses– Diarthroses

DiarthrosesThese joints are freelyMovable.

Examples: Hip & knee

Types of Synovial Joints (Diarthroses)

• 3 main groups:– Uniaxial

• Hinge• Pivot

– Biaxial• Saddle• Condyloid

– Multiaxial• Ball and socket• Gliding

Uniaxial Joints

• Synovial joints that permit movement around one axis and in one plane.

• Hinge: Hinge shape; only back and force movement.– Example: Knee; ulna & humerus

• Pivot: Projection articulates with a ring or notch of another bone.– Example: 2nd & 1st cervical vertibrae.

Biaxial Joints

• Movement around 2 perpendicular axes in two perpendicular planes.

• Saddle: Joint resembles a saddle.– Example: Thumbs are the only 2 saddle joints

in the body.

• Condyloid: Where a condyle (rounded projection) fits into a socket.– Example: Occipital condyles & cervical

vertebrae; Distal end of radius into carpal bones.

Saddle

Condyloid Condyle

Multiaxial Joint

• Joints that allow movement around multiple axes & around multiple planes.

• Ball & socket: Most moveable joint; ball shaped head fits into circular depression.– Example: Should; hip

• Gliding joints: Flat articulating surfaces that allow limited gliding along various axes; least moveable synovial joint.– Example: Vertebrae; carpals & tarsals.

Gliding

Ball & Socket

Flashcards: Will be used during first dissection• Requirements:

– Front of card• Name of the joint

type.– Back of card

• Definition of joint• Example of the

joint.• Picture of the joint

• Required Cards:– Uniaxial: Hinge– Uniaxial: Pivot– Biaxial: Saddle– Biaxial: Condyloid– Multiaxial: Ball & socket– Multiaxial: Gliding

Uniaxial: HingeOnly back and forcemovement

Examples: knee

Structure of synovial joints

• Joint capsule

• Synovial Membrane

• Articular cartilage

• Joint cavity

• Menisci (articular Disks)

• Ligaments

• Bursae

Joint Capsule

• Sleeve-like extension of periosteum (bone membrane)

• Forms a casing around ends of bones, binding them.

Synovial Membrane

• Membrane that lines joint capsule and attaches to margins of articular cartilage.

• Secretes synovial fluid.

Articular Cartilage

• Thin layer of hyaline cartilage.

• Cushions articular (connecting) ends of bone.

Joint cavity

• Space between articulating bones.

• More space More movement.

Menisci (articulating disks)

• Pads of fibrocartilage between articulating ends of some diarthroses.

• Usually divide joint cavity into two separate spaces.

• Knee joint has 2 menisci.

Ligaments

• Strong cords of dense fibrous tissue.

• Keep bones together.

Bursae• Closed pillow like

structure.

• Filled with synovial fluid.

• Cushion joint and facilitate movement of tendons.

• Bursitis- Inflammation of bursae.

Disorders of the Joints• Osteoarthritis: Degenerative joint disease; wear

& tear of articular cartilage. Cartilage thins, bony spurs form at articulations, ligaments calcify. Symptoms: stiffness, pain, limited mobility.

Disorders of the Joints• Traumatic Injuries:

– Dislocations- damages nerve & blood vessels.– Damage to cartilage- tears produce edema, pain,

instability, & limited motion.– Sprain- injury to ligaments surrounding a joint,

disrupting synovial membrane. Bruising and swelling may result from ruptured blood vessels.

Disorders of the Joints• Arthritis: inflammatory joint disease.

Inflammation of synovial membrane, destruction of cartilage, erosion of bone. Can be crippling and cause deformities.– Juvenile arthritis: Onset during childhood.– Gouty arthritis: Arthritis caused by a metabolic

disorder- excess uric acid deposit into synovial fluid.