Joints Fill In

I. Articulations (Joints)

Holds bones together
Allows skeletal system to be FLEXIBLE

CLASSIFICATION OF JOINTS:

Structural

Fibrous Joints: contain connective tissue fibers

Cartilaginous Joints: contain cartilage

Synovial Joints: contain a joint cavity with synovial fluid

2. Functional

Synarthroses: immovable joints (axial)

Amphiarthroses: slightly movable joints (axial)

Diarthroses: freely movable joints (mostly appendicular)

I. FIBROUS JOINTS: Bones are joined by fibrous tissue; there is no

joint cavity

Some of these joints are slightly moveable but most are immovable (synarthroses)

Two types of FIBROUS JOINTS

SUTURES : interlocking bones united by very short CT (skull)

SYNDESMOSES: LIGAMENTS connect articulating bones

Not interlocked, but only LITTLE MOVEMENT
Example is distal end of TIBIA / FIBULA (tibiofibular joint)

CARTILAGINOUS JOINTS: Bones are joined by pads of cartilage; there is no joint cavity

Most cartilaginous joints are SLIGHTLY MOVABLE (amphiarthroses)

Two types of CARTILAGINOUS JOINTS:

SYMPHYSES: connected by flat disc of FIBROCARTILAGE; Example: pubic symphysis

SYNCHONDROSES: connected by HYALINE cartilage

Example: costal cartilage of RIB 1 and sternum.

SYNOVIAL JOINTS: Bones are separated by a joint cavity

Cavity contains SYNOVIAL FLUID
ALL synovial joints are FREELY MOVABLE JOINTS (DIARTHROSES)
Some joints can only move in one plane while others can move in multiple planes

All Synovial joints are composed of:

ARTICULAR CAPSULE: 2-layered connective tissue sleeve covering joint
Synovial Membrane: inner layer, produces SYNOVIAL FLUID which reduces friction
Fibrous Capsule: thicker, outer layer – dense irregular connective tissue
ARTICULAR HYALINE CARTILAGE: covers articulating surfaces of bones
LIGAMENTS: present to reinforce ARTICULAR CAPSULE.
JOINT CAVITY : contains synovial fluid

TYPES OF SYNOVIAL JOINTS (Functional)

1.UNI-AXIAL: Joint only allows movement in one plane or one direction Example: elbow – FLEXION/EXTENSION (One plane of mo

vement)

2.BI-AXIAL: Joint allows for movement in 2 planes Example: Joints involving the fingers such as Carpals/Metacarpals FLEXION/EXTENSION, ADDUCTION/ABDUCTION, (2 planes of movement)

3.MULTI-AXIAL: Joint allows movement in all 3 planes Example: shoulder – ball-and-socket – ROTATION (all planes)

Types of Synovial Joints (Structural)

Plane / Gliding: flat surface

Hinge: rounded portion on one bone fits into concave depression of another bone

Pivot: round portion of one bone articulates with shallow depression of another bone

Condyloid: condyle of one bone fits into ellipsoidal depression

Saddle: one bone is concave and the other convex

Ball-and-Socket: head fits into rounded socket

IV. MAJOR JOINTS OF THE BODY

1. ELBOW JOINT: Hinge joint; 2 important ligaments restrict side-to-side movements ULNAR LIGAMENT – ulnar (medial) collateral ligament RADIAL LIGAMENT – radial (lateral) collateral ligament

2. SHOULDER JOINT: (Glenohumeral)Ball-and-socket joint; Head of humerus and glenoid cavity of scapula Great range of motion due to thin articular capsule

Anterior ligaments reinforce joint: CORACOHUMERAL LIGAMENT – coracoid process of scapulae to greater tubercle of humerus

GLENOHUMERAL LIGAMENTS : 3 weak ligaments reinforce capsule

TRANSVERSE HUMERAL LIGAMENT: greater tubercle to lesser tubercle of humerus

Muscles and tendons are the most important stabilizing elements

SITS Muscles – origins are on scapulae and insertion are on one of the humeral

tubercles:

SUBSCAPULARIS – lesser tubercle

SUPRASPINATUS – greater tubercle

INFRASPINATUS – greater tubercle

TERES MINOR – greater tubercle

3. HIP JOINT (Coxal) Ball-and-socket joint – thicker articular capsule; Head of femur and acetabulum of coxal bones; More stable than shoulder because of three strong ligaments:

Iliofemoral
Pubofemoral
Ischiofemoral

Other ligaments that do not contribute to joint stability:Ligamentum teres, Capitate Ligament

(These run from fovea capitis of femur to the lower lip of acetabulum)

SHOULDER JOINT— muscles/tendons are more important

than ligaments

HIP JOINT— ligaments are more important than muscle

s/tendons

4. KNEE JOINT: Hinge joint – allows flexion/extension and some rotation

Largest, most complex – 3 joints in one!
Femoropatellar joint
Tibiofemoral joints (lateral and medial)

PATELLAR LIGAMENTS: Patella covers anterior portion of the joint (patellar surface of femur)

Patellar ligaments – 3 strong ligaments that run from inferior patella to tibial tuberosity of tibia.

They are an extension of the quadriceps tendon which attaches to the superior patella.

EXTRACAPSULAR LIGAMENTS

1.LATERAL (FIBULAR) COLLATERAL LIGAMENT: Extends from lateral epicondyle of femur to head of fibula; Prevents lateral rotation when the knee is extended; Can see in anterior and posterior views

2.MEDIAL (TIBIAL) COLLATERAL LIGAMENT: Extends from medial epicondyle of femur to medial condyle of tibia; Prevents medial rotation when knee is extended; Can see in anterior view

3.ARCUATE POPLITEAL LIGAMENT: Extends from head of fibula and reinforces the joint capsule; It does not attach to the knee at all; Helps reinforce the knee and prevent side trauma and injury from the lateral side; Can see in posterior view

4.OBLIQUE POPLITEAL LIGAMENT; Extends from the lateral condyle of femur to head of tibia; Runs diagonally across the posterior of the knee; Reinforces the knee and prevents trauma from medial side

INTRACAPSULAR LIGAMENTS: These ligaments are named “cruciates” because they

cross each other; Can be seen within the joint capsule crossing between femoral condyles!

They are outside the synovial cavity

ANTERIOR CRUCIATE LIGAMENT (ACL): Extends from medial side of lateral condyle of femur to anterior portion of tibia; Prevents hyperextension of the knee and also prevents forward sliding of tibia on femur

POSTERIOR CRUCIATE LIGAMENT (PCL): Extends from lateral side of medial condyle of femur to posterior portion of tibia, Also prevents hyperextension of the knee and Prevents backward sliding of tibia on femur