Biology 1103/09 – Week 6
Support II
Biomechanics
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!)
JOINTS
Joints
• 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
(synarthrotic)
• 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
(amphiarthroses)
• 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
Periosteum
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
Sagittal plane SUPRAPATELLAR BURSA
Femur
Patella
Articular cartilage
LATERAL
MENISCUS
PREPATELLAR BURSA
Infrapatellar fat pad
Tibia
INFRAPATELLAR BURSA
PATELLAR LIGAMENT
(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
