Biology: Knee and Synovial Joints Essay

Submitted By kathira6
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Pages: 7

Biology 1103/09 – Week 6
Support II
Human Skeleton Lab II

Human Skeleton Lab II
• Part A: articulations
– Examining different types of joints and the movement allowed due to the nature of the joints

• Part B:
– Understanding different types of levers (time to brush up on your physics!)


• A union point between two bones
• In the skeletal system, joints exists between all bones
• The movement (from none to free) of a joint is referred to as “articulation”
• Generally classified by function and structure

Joint classification by function
• functional classification refers to the degree of allowed movement
1. Synarthrotic: not movable
2. Amphiarthrotic: slightly movable
3. Diarthrotic: freely movable

Joint classification by structure
• The physical structure of a joint
• Different structures allows for different types of movement
1. Fibrous joints
2. Cartilaginous joints
3. Synovial joints

Fibrous joints
• Held by dense connective tissue
• No cavity between joints, and therefore little or no movement
• Three types:
a) Suture
b) Syndesmosis
c) Gomphosis

a) Sutures
• Immovable
• Jagged ends interlock like a jigsaw puzzle
• Thin layer of dense fibrous connective tissue unites bones of the skull Coronal suture

Figure 9.1, pg 290

b) Syndesmosis

Figure 9.1, pg 291

• Bones are held rightly together by dense fibrous tissue
• Bones are farther apart than sutures so some movement is possible (amphiarthortic)
• E.g., distal end of the tibia and fibula

c) Gomphosis

Figure 9.1, pg 291

• Special type of syndesmosis; teeth in the sockets of the mandible and maxilla are held together by a ligament
• Generally immovable (synarthrotic)

Cartilaginous joints
• Bones are held together by cartilage
• Little or no movement between bones
• Two types:
– Synchondrosis
– symphysis

a) Synchondrosis

Figure 9.2, pg 292

• Connecting material is hyaline cartilage
• Immovable (synarthrosis)
• Epiphyseal plate or joints between ribs and sternum

b) Symphysis

• Fibrocartilage is connecting material
• Slightly movable
• Intervertebral discs and pubic symphysis Figure 9.2, pg 292

Synovial joint
• Freely movable joints (diarthrotic)
• Contain a space/cavity between the bones
• Found in most of the joints in the appendicular skeleton

Parts of a synovial joint
Frontal plane

Articulating bone Articulating bone (a) Frontal section


Parts of a synovial joint
• Joint capsule: sleeve-like layer of fibrous connective tissue; attached to the perosteum of the articulating bones • Synovial membrane: lines the inner surface of the joint capsule, but not the articular cartilage
• Synovial cavity: the space between the two articulating joints • Synovial fluid: slippery fluid that lubricates joints and also supplies nutrients to the articular cartilage
• Articular cartilage: the ends of articulating bones in synovial joints; reduces friction and absorbs shock

Parts of a synovial joint
Tendon of quadriceps femoris muscle



Articular cartilage


Infrapatellar fat pad



(c) Sagittal section

Figure 9.15, pg 317

Parts of a synovial joint
• Ligaments: bands of fiber external to the joint and holds articulating bones together
• Meniscus: a cartilage pad which acts as a pad between the two joints to prevent the bones from smashing into one another
• Bursa: strategically located sac of fluid to reduce friction during joint movement

Possible movements of synovial joints • Note that not all synovial joints can make all of the following movements
• The allowable movements depends on the muscles surrounding the bones as well as the type of synovial joints