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Articulations

Learning Objectives

Structure and purpose of joints
How degree of movement is determined at a joint
Structural and functional classifications of joints

Notes, Pictures & Videos

Slides introducing articulations	Slides for specific articulations

Flashcards to add to
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STRUCTURES:

Joint structure determines stability and mobility. The more mobile a joint is, the less stability it has. The more stable a joint is, the less movable it is. There are two ways to classify joints.

Structure: What it's made of
Function: Movement of the joint

I. by the type of connective tissue

Fibrous: (a), syndesmosis (tibiofibular), (b) suture, skull

Cartilaginous: (c) symphysis (vertebral bodies), (d) synchondrosis (first rib and sternum)

Synovial: (e) condyloid (wrist), (f) planar (intercarpals), (g) hinge or ginglymus (elbow), (h) ball and socket (hip), (i) saddle (carpometacarpal of thumb), (j) pivot (atlantoaxial)

II. by the amount of movement they allow.

Synarthrosis: immovable (sutures)

Amphiarthrosis: slightly movable (elbow)

Diarthrosis: freely movable (shoulder)

IN DEPTH VIEWS:

Fibrous Joints

Gomphoses: joins teeth to mandible and maxilla. Functional: synarthrosis
Sutures: joins bones in skull to each other. Irregular edges of the sutures provide increased strength and decreased number of fractures at the suture point. Functional: synarthrosis
Syndesmoses: joins articulating bones by long strands of dense, regular connective tissue. (radius/ulna and tibia/fibula) Functional: amphiarthrosis.

Cartilaginous Joints

Synchondroses: joined together by hyaline cartilage. Includes Epiphyseal growth plates and costochondral articulations (between ribs and sternum). Functional: synarthroses
Symphyses: have a pad of fibrocartilage between articulating bones. Includes the pubic symphyses and the intervertebral joints. Functional: amphiarthroses

Synovial Joints (selected joints)

Tempromanidbular Joint: the only movable joint in the skull. Actually two synovial joints. One between the temporal bone and the articular disc, and the sencond between the articular disc and the mandible. It is both a hinge joint and a gliding joint. Functional: diarthrotic
Glenohumeral: ball and socket joint. It is the most freely movable joint in the body, and as such is the least stable and subject to frequent dislocations. Functional: diarthrosis
Coxal joint (acetabulofemoral): articulation between head of the femur and the acetabulum. Not as freely moveable as the glenohumeral joint because the socket is deeper, but is capable of extension, flexion, abduction, rotation and circumduction. Functional: diarthrosis
Knee joint: primarily a hinge joint, but when flexed it can move laterally and have slight rotation. There are two articulations. Between the femur and patella and the femur and the tibia. There is no unified capsule in the knee, nor is there a common synovial capsule as seen in other synovial joints. Functional: amphiarthrosis
Talocrural joint: a highly modified hinge joint. Allows for inversion, eversion, plantarflexion and dorsiflexion of the foot. Subtalar facet asymmetry can cause problems with balance and coordination when playing sports. Functional: amphiarthrosis

Movements associated with Synovial Joints:

Gliding: a back and forth or side to side motion between two bones. The angle between the bones does not change
Angular motion: increases or decreases the angle between arcticulating bones
- Abduction - to move away from the midline of the body
- Adduction - to move towards the midline of the body (you are 'add'ing the body part back to the center of your body)
- Flexion: movement that decreases the angle between two bones (knee, elbow)
- Extension: movement that increases the angle between two bones, returning the bones to anatomical position.
- Hyperextension: extension of a joint more than 180 degrees.
- Circumduction: proximal portion of the joint remains fixed while the distal portion moves in a cone-like motion.
Rotational Motion: pivioting motion where a bone turns around its own axis. (atlanto-axial joint, pronation and supination)
Depression: inferior movement of a part of the body
Elevation: superior movement of a part of the body
Dorsiflexion: the ankle is bent so that the toes are moved towards the head. Only occurs at the ankle.
Plantarflexion: the ankle is extended so that the toes are pointed away from the head (think of a ballerina). Only occurs at the ankle.
Eversion: movement of the sole of the foot outward, or laterally.
Inversion: movement of the sole of the foot inward, or medially.
Pronation: medial rotation of the forearm, palm is directed posteriorly.
Supination: lateral rotation of the forearm, palm is directed anteriorly (anatomical position).
Protraction: movement anteriorly in a horizontal plane (chicken head movement #1, forward)
Retraction: movement posteriorly in a horizontal plane (chicken head movement #2, backward)
Opposition: movement of the thumb toward the fingertips, crossing the palm.

FACT: The radiocarpal is made up of three proximal carpal bones and the distal articular surface of the radius. The Ulna is separated from the radiocarpal joint by a fibrocartilaginous articualr disc.

FACT: "Locking" the knee for a long period of time can make an individual faint.

FACT: Some people develop hyper-mobile joints by stretching their tendons and muscles. Check out the Contortionists page for some videos!

COMMON INJURIES:

Shoulder Separation: Dislocation of the Acromioclavicular joint. Symptoms will include pain, tenderness and edema in the area, and acromion will be very prominent and appear more prominent.

Dislocations: Glenohumeral Joint. Symptoms include the shoulder appearing more flattened due to the humeral head tearing through the inferior part of the articular capsule.

Sublaxations: Radial head being pulled out of annular ligament. Most common in children, due to parents pulling to hard on the childs arm while child is being resistant. Symptoms include pain on the lateral side of elbow where a prominent lump is seen.

LIGAMENTS:

What is a ligament?

A ligament is a band composed of dense regular connective tissue. They help to connect bone to bone and strengthen/reinforce most synovial joints. Extrinsic ligaments are those that are found on the outside of the joint capsule and physically separate from the capsule. Intrinsic ligaments represents thickenings of the articular capsule.

TENDONS:

What is a tendon?

A tendon like a ligament is composed of dense regular connective tissue and it connects bone to muscle. Tendons help to stabilize joints in that they pass across or around a joint to provide mechanical support; however they can limit the range of movement in a joint.

Case Study

In the News

Association between Bruxism and TMD

Glossary

articulation: place of contact between bones, bones and cartilage or bones and teeth.
arthrology: scientific study of joints
Interosseous membrane: broad ligmentous sheet that binds articulating bones side by side (ie, radius and ulna, tibia and fibula). Provides a pivot point where these bones can rotate against one another.
synostoses: complete fusion of bone across the suture line

Connections to other body systems

Articulations are the determining factors in the movements of the skeleton system.

Review Questions

1. The _____________ are those that form a thin layer in osseous grooves through which tendons of muscles will glide?
*a.The Stratiform fibro-cartilages
b. Inter Osseous fibro-cartilages
c. Circumferential fibro-cartilages
d. Inter Articular fibro-cartilages

2. Which of the following is an example of an amphiarthrotic joint?
a. between the femur and pelvis
*b. between the metacarpals and phalanges
c. between the teeth and their sockets
d. between the intervertebral disks

3. The ___________ often contains bundles of dense, irregular, connective tissue called ligaments.
a. Synovial Membrane
*b. Fibrous Capsule
c. Articulate Capsule
d. Synovial Cavity

4. Between the Atlas (C1) and Axis (C2) of the vertebrae which functional class is it classified in?
a. Amphiarthotic
b. Synarthrosis
*c. Diarthrosis
d. Synovial

5. Where in the body is the largest and most extensive Synovial joint located?
a. Shoulder joint
*b. Knee joint
c. Hip joint
d. Elbow joint

6. The ankle joint is limited to what two movements?
*a. Extension and Flexion
b. Lateral and Flexion
c. Protraction and Extension
d. Pronation and Lateral

7. 'The unhappy triangle' refers to what?
a. carpal tunnel
b. tendinitis
c. a torn ACL, PCL and MCL
d. a torn ACL, MCL and middle mencius*

8. The ligament teres attaches
a. to the fibula
b. to the humerus
c. the radius to the ulnar
d. to the fovea capitis

9.
a.
b.
c.
d.

10.
a.
b.
c.
d.
Here is an x-ray of a patellar tendon rupture. This happened to my knee 2 years ago. This is also the injury that ended Alonzo Mourning's basketball career. Articulations - The Anatomy Wiki

borderline	Latest page update: made by borderline , Feb 19 2009, 5:01 PM EST (about this update About This Update Edited by borderline 28 words added 1 image added view changes - complete history)
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