Biology 322 Human Anatomy I Joints

Previously: Defined bones as organs of skeletal system Also organs: joints (one or more types of tissues, all serving a common function)

Joints: Classified two ways: 1. What type of tissue connects the bones at the joint 2. How much motion the joint allows Ordinary connective tissue = Fibrous joint Hyaline or fibrous cartilage = Cartilagenous joint Fluid-filled capsule (synovium) = Synovial joint No motion = Synarthrosis Limited motion = Amphiarthrosis Freely movable = Diarthrosis

Fibrous Joints: Bones connected by dense regular or dense irregular connective tissue with many collagen fibers. No joint cavity. Depending on length of collagen fibers, may be synarthrotic (no motion) or amphiarthrotic (limited motion)

Fibrous Joints: Three subtypes: 1. Suture: Collagen fibers very short Always synarthrotic Only in skull

Collagen fibers longer Amphiarthrotic (some motion) Fibrous Joints: Three subtypes: (1. Suture: Collagen fibers very short, synarthrotic, only in skull) 2. Syndesmosis Collagen fibers longer Amphiarthrotic (some motion)

Collagen fibers very short Synarthrotic (no motion) Fibrous Joints: Three subtypes: (1. Suture: Collagen fibers very short, synarthrotic, only in skull) (2. Syndesmosis: Collagen fibers longer, amphiarthrotic) 3. Gomphosis: Collagen fibers very short Synarthrotic (no motion) Teeth in mandible or maxilla

Cartilagenous Joints: Bones connected by some form of cartilage No joint cavity. Depending on length of collagen fibers, may be synarthrotic (no motion) or amphiarthrotic (limited motion)

Cartilagenous Joints: Two subtypes: 1. Synchondrosis: Bones connected by hyaline cartilage Synarthrotic or amphiarthrotic Costosternal; Epiphyseal plates

Cartilagenous Joints: Two subtypes: (1. Synchondrosis: Bones connected by hyaline cartilage Synarthrotic or amphiarthrotic; Costosternal; Epiphyseal plates) 2. Symphysis: Bones connected by fibrous cartilage Amphiarthrotic or synarthotic Intervertebral disks; Pubic symphysis

Synovial Joints: Bones separated by synovial joint cavity, connected by ligaments of dense regular connective tissue Most synovial joints are diarthrotic Some synovial joints are amphiarthrotic

Synovial Joints: Components: Proximal bone with articular cartilage Distal bone with articular cartilage Articular capsule with: Fibrous capsule Synovial membrane surrounding Synovial cavity Ligaments of dense irregular connective tissue Intrinsic = thickenings of fibrous capsule Extracapsular = outside fibrous capsule Intracapsular = inside synovial cavity

Proximal bone with articular cartilage Synovial Joints: Proximal bone with articular cartilage Distal bone with articular cartilage Articular capsule with Fibrous capsule, Synovial membrane surrounding Synovial cavity Intrinsic ligament = thickenings of fibrous capsule Extracapsular ligament = outside of fibrous capsule Intracapsular ligament = inside synovial cavity In knee, sternoclavicular, acromioclavicular, distal radioulnar, and temporomandibular joints: Also articular disk or meniscus of fibrous cartilage

Synovial Joints: Six types based on structure and type of motion:

Synovial Joints: Six types 1. Plane or Gliding Gliding motion along flat articular surfaces. Amphiarthrotic

Synovial Joints: Six types 2. Hinge joint Motion around single axis which is perpendicular to long axis of the bones. Often convex articular surface on one bone and concave articular surface on other bone. Diarthrotic

Synovial Joints: Six types 3. Pivot joint Motion around single axis which is parallel to long axis of the bones. Often convex articular surface on one bone and concave articular surface on other bone. Diarthrotic

Synovial Joints: Six types 4. Condyloid joint Motion around two axes. Articular surfaces of both bones round or oval. One shallowly convex One shallowly concave Diarthrotic

Synovial Joints: Six types 5. Saddle joint Motion around two axes. Articular surfaces of both bones are: Convex one direction Concave other direction Diarthrotic

Synovial Joints: Six types 6. Ball & Socket joint Motion around all three axes. Articular surfaces of one bone forms "ball" which fits into "socket" on other bone. Diarthrotic

We’ve noted that Synovial joints are stabilized by Shapes of the articular surfaces of bones Ligaments Menisci They are also stabilized by muscles and tendons which cross over the joint

Synovial joints often cushioned by a fluid-filled sac called a bursa which separates the joint from overlying muscles, tendons, or ligaments.

The following six specific synovial joints are described in your textbook: Jaw (Temporomandibular) Shoulder (Glenohumoral or Humeroscapular) Elbow (Humeroulnar, Humeroradial, and Radioulnar) Hip (Femorocoxal or Coxal) Knee (Tibiofemoral) Ankle (Talotibial, Talofibular) On exams, you should be able to briefly but accurately describe the structure of each of these joints, including all major ligaments; and you should be able to describe the actions for each

Movements of synovial diarthrotic joints: Flexion and Extension

Movements of synovial diarthrotic joints: Abduction and Adduction

Movements of synovial diarthrotic joints: Rotation and Circumduction

Movements of synovial diarthrotic joints: Protraction and Retraction

Movements of synovial diarthrotic joints: Elevation and Depression

Movements of synovial diarthrotic joints: Pronation and Supination

Movements of synovial diarthrotic joints: Opposition (and Reposition)

Movements of synovial diarthrotic joints: Movement of the foot at ankle joint Inversion, Eversion In the foot: Pronation is used for: dorsiflexion + abduction + eversion Supination is used for: plantar flexion + adduction + inversion Dorsiflexion, Plantar flexion