The Joints

Objectives

*to identify the four main synovial joints and structures of each joint.

*to know the type of each joint and its movement.

     The joint is defined as the point connecting between two different bones, bone and cartilage and bone and teeth. Since the bones can't bend without being damaged, there must be connective tissue that permits the flexibility of movement and connection strongly like the regular dense connective tissue as ligament and tendon.

    

     The joints can be classified structurally into:

*fibrous joint: the fibrous connective tissue exists without synovial cavity.

*cartilaginous joint: cartilage is the connector and no synovial cavity.

*synovial joint: synovial cavity is found and surrounded by articular capsule to connect the involved bones. The extracapsular ligaments are found for further connection.

    

The joints are also classified functionally into:

*synarthrosis: immovable joint.

*amphiarthrosis: slightly movable joint.

*diarthrosis: several different types of movement.

Four main synovial  joints will be discussed in this lab.:

1. The shoulder joint

bones involved: the scapula ( glenoid cavity and coracoid process) and the humerous ( greater and lesser tubercles).

The humerous and the scapula are connected together by an articular capsule and a group of extracapsular ligaments.

Type of joint movement: flexion, extention, adduction, abduction, medial and lateral rotation and circumduction.

list of extracapsular ligaments:

·        The coracohumeral ligament: between the coracoid process and the humerous bone at the greater tubercle.

·        The glenohumeral ligament: between the coracoid process and the humerous bone at the lesser tubercle.

While the clavicle and the scapula  are connected by:

·        The acromioclavicular ligament; between the clavicle and the acromion of the scapula.

·        The coracoacromial ligament; between the cocacoid process of the scapula and the acromion of the scapula.

·        The coracoclavicular ligament; is divided into two portions:

The trapezoid ligament: between the coracoid process and the clavicle     anteriorly.

The conoid ligament: between the coracoid process and the clavicle at the conoid tubercle posteriorly.

     

The scapular notch is covered by the suprascapular transverse       ligament.

    No intracapsular ligaments and discs are found.

2. The elbow joint

bones involved: the hemerous ( the distal end), the ulna( olecranon and coronoid process) and the radius ( head).

Type of joint movement: flexion and extention of forearm.

The three bones are connected together by the articular capsule and a group of extracapsular ligaments; which are:

·        The ulnar collateral ligament: between the humerous and ulna medially.

·        The radial collateral ligament: between the humerous and radius laterally.

·        The radial annular ligament: between the humerous and radius in circular pattern.

The ulna and radius are connected together by the interosseous membrane.

The biceps tendon can be seen at the radial tuberosity.

No intracapsular ligaments and discs are found.

3. The hip joint

bones involved: the hip bone ( the ilium( anterior inferior iliac spine), the ischium( ischial wwall of acetabulum) and the pubis( pubic part of acetabulum) ) and the femur ( head and femur).

Type of joint movement: flexion, extention, adduction, abduction, medial and lateral rotation and circumduction of thigh.

The articular capsule is formed from two portions: the circular fibers are    known as zona orbicularis and the longitudinal fibers are reinforced by the following group of extracapsular ligaments:

-         the iliofemoral ligament: between the ilium and the femur.

-         the ischiofemoral ligament: between the ischium and the femur.

-         the pubifemoral ligament: between the pubis and the femur.

Two intracapsular ligaments are found in the hip joint to strengthen and fix the joint; which are:

-the trasverse ligament: closes the acetabular notch which will deepen the      acetabulum to hold the head of the femur.

-the ligament of the head of the femur: extends from the fovea capitis to the acetabulum for further fixation of the head of the femur.

4. The Knee joint

bones involved: the femur(the medial and lateral epicondyles), the tibia    ( medial and lateral condyles).

Type of joint movement: flexion, extention and slight medial and lateral rotationof leg.

two groups of ligaments are found:

A. the extracapsular ligament:

-the patellar ligament: starts as quadriceps muscle tendon from the femur to the anterior surface of the          patella. It             continues as patellar ligament  to the tibial tuberosity

-the collateral tibial ligament: between the medial condyles of both the     femur and the tibia.

-the collateral fibular ligament: between the lateral condyle of the femur to the lateral side of the fibula.

B. the intracapsular ligament:

-the anterior cuciate ligament: from the intercondylar area of the tibia  anteriorly to the lateral condyle of  the femur posterorly.

    -the posterior cruciate ligament: from the intercondylar area of the tibia    posteriorly to the medial condyle of the femur.

    -the trasverse ligaments: between the lateral and medial menisci.

two articular discs are found:

-the medial meniscus: between the medial condyles of femur and tibia.

-the lateral meniscus: between the lateral condyles of femur and tibia.