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The Joints A Study in Motion
The Joints
A Study in Motion
Joints
Joints are classified by structure and function.These can: Fibrous Joints
Joints
Joints are classified by structure and function.These can: Fibrous Joints Cartilaginous Joints
Joints
Joints are classified by structure and function.These can: Fibrous Joints Cartilaginous JointsSynovial Joints
Sutures(Fibrous Joints)
These can be found connecting the plates of the skull. As the plates fuse in the adult, the sutures are called synostoses and result in immovable joints.
Ligaments(Fibrous Joints)
These can be found where bones are connected by ligaments. These are called syndesmoses and result in amphiarthrotic joints (slightly moveable) joints or synarthrosis (not moveable).
Examples would be the distal ends of the fibula and tibia.
Gomphotic Joints(Fibrous Joints)
These are a peg and socket joint. The only example is the articulation of the tooth and its socket.
Cartilaginous Joints
These are joints where the articulating bones are united by cartilage. There is no joint cavity and mobility is limited.
Most common examples are the first rib and manubrium and epiphyseal plates of the long bones. This is classified as a synchondronsis.
Cartilaginous Joints
Cartilaginous Joints
Another example is in symphyses (growing together).This is seen with joints containing fibrocartilage the vertebral disks and pubic symphsis
Synovial Joints
The articulating bones are separated by a fluid containing cavity. These joints are diarthrotic (most motion) and provide the greatest movement. They have 6 distinguishing features.
6 distinguishing features.
1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.
6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.2. Synovial cavity that is a potential space containing a small amount of liquid.
6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers.
6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers. 4. Synovial fluid occupies the free space of the joint capsule.
6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers. 4. Synovial fluid occupies the free space of the joint capsule. 5. Reinforcing ligaments provide additional structure to the joints
6 distinguishing features. 1. Articular cartilage that is approximately 1 mm thick and composed of hyaline cartilage.2. Synovial cavity that is a potential space containing a small amount of liquid. 3. Articular capsule that is made of 2 layers. 4. Synovial fluid occupies the free space of the joint capsule. 5. Reinforcing ligaments provide additional structure to the joints 6. Nerve and blood vessels supply
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Figure 8.3 General structure of a synovial joint.
Periosteum
Ligament
FibrouscapsuleSynovialmembrane
Joint cavity(containssynovial fluid)Articular (hyaline)cartilage
Articularcapsule
Associated Structures
Other structures commonly associated with synovial joints include fat pads and articular discs of fibrocartilage. They work like “ball bearings” and reduce friction where ligaments, tendons and muscles rub against each other.
Associated Structures
Tendon Sheaths Bursae of the knee
Movement of Synovial Joints
All skeletal muscles attach to bone or connective tissue by at least 2 points.– The Origin is the muscle attachment to the less
movable bone– The Insertion is the muscle attachment to the
movable bone.
3 general types of movement
• Gliding• Angular• Rotational
Gliding motion is the simplest and consists of one bone sliding over another. This is seen with the intercarpal and intertarsal joints and between vertebrae
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Figure 8.5a Movements allowed by synovial joints.
Gliding
(a) Gliding movements at the wrist
Angular movements
increase or decrease the angle between 2 bones. Movements include:– Flexion– Extension– Hyperextension– Abduction– Adduction– Circumduction
a)Flexion is the bending along a sagittal plane; this decreases the angle of the joint and brings the bones closer together.
b) Extension is the straightening of bones resulting in the increase angle between bones.
c) Hyperextension is the bending of a joint beyond anatomical position.
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Figure 8.5b Movements allowed by synovial joints.
(b) Angular movements: flexion, extension, and hyperextension of the neck
Hyperextension Extension
Flexion
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Figure 8.5c Movements allowed by synovial joints.
Hyperextension Flexion
Extension
(c) Angular movements: flexion, extension, andhyperextension of the vertebral column
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Figure 8.5d Movements allowed by synovial joints.
Extension
Extension
Flexion
Flexion
(d) Angular movements: flexion and extension at theshoulder and knee
d) Abduction is moving away from the midline along the frontal plane.
e) Adduction is moving toward the midline.f) Circumduction is moving the limb to describe
a cone, for example the motion made by a pitcher. This motion involves the motions described above.
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Figure 8.5e Movements allowed by synovial joints.
Abduction
Adduction
(e) Angular movements: abduction, adduction, andcircumduction of the upper limb at the shoulder
Circumduction
Rotation
Is the turning of the bone along its axis. This is seen with the first and second vertebrae and the hip and shoulder joint
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Figure 8.5f Movements allowed by synovial joints.
LateralrotationMedialrotation
Rotation
(f) Rotation of the head, neck, and lower limb
Special Movements
Supination is the radius and ulna are parallel and the palms are facing forward. Pronation the radius and ulna form an X and the palms face posterior. (Think 3 P’s-pronation palms posterior).
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Figure 8.6a Special body movements.
Supination(radius and ulna are parallel)
(a) Pronation (P) and supination (S)
Pronation(radius rotatesover ulna)
Dorsi flexion and plantar flexion are seen with the bending of the foot up and down. Bending the foot towards the tibia is dorsi flexion. Pointing the toes away is plantar flexion. This latter motion is seen with ballet dancers.
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Figure 8.6b Special body movements.
Dorsiflexion
Plantar flexion
(b) Dorsiflexion and plantar flexion
Inversion/Eversion is medial and lateral movement of the ankle. Overextension or inversion is commonly seen with the sprained ankle.
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Figure 8.6c Special body movements.
EversionInversion
(c) Inversion and eversion
Protraction and Retraction are the anterior and posterior movement of the jaw. Protraction is the jutting out of the jaw.
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Figure 8.6d Special body movements.
Protractionof mandible
Retractionof mandible
(d) Protraction and retraction
Protraction and Retraction are the anterior and posterior movement of the jaw. Protraction is the jutting out of the jaw. Elevation and depression are the movement of the jaw in an inferior superior direction. (Opening and closing)
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Figure 8.6e Special body movements.
Elevationof mandible
Depressionof mandible
(e) Elevation and depression
Opposition is seen with touching of the thumb to the tips of the other phalanges.
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Figure 8.6f Special body movements.
(f) Opposition
Opposition
Questions?
