Joints

Question 1

What is a joint?

Answer 1

A joint is the physical point of connection between 2 bones.

Question 2

What is the function of joints?

Answer 2

Joints are constructed to allow movement (articulation) and provide mechanical support (stability).

Question 3

What are joints named according to? Give an example.

Answer 3

Joints are named according to bones they connect e.g. temporal bone & mandible = temporomandibular joint

Question 4

Functional classification looks at whether or not the joint moves. There are 3 classifications within this:

1. ______ - non-movable
2. _________ - slightly movable
3. ________ - freely movable

Answer 4

Functional classification looks at whether or not the joint moves. There are 3 classifications within this:

1. SYNARTHROSIS - non-movable
2. AMPHIARTHOSIS - slightly movable
3. DIARTHROSIS - freely movable

Question 5

Structural joint classification looks at the way bones ______, and is a more precise way of classifying joints. Again, there are 3 classifications within this:

1. _____ – joined by dense fibrous connective tissue
2. _________ – joined by cartilage
3. ______ – not directly joined, instead the bones have a synovial cavity & are united by a capsule, which allows movement

Answer 5

Structural joint classification looks at the way bones CONNECT, and is a more precise way of classifying joints. There are 3 classifications within this:

1. FIBROUS – joined by dense fibrous connective tissue
2. CARTILAGINOUS – joined by cartilage
3. SYNOVIAL – not directly joined, instead the bones have a synovial cavity & are united by a capsule, which allows movement

Question 6

Fibrous joints are within _______ classification. Bones joined by fibrous _______ tissue. There is minimal or no ________. Fibrous joints can be further classified:

a) ______ = bones often interdigitate, e.g. _____
b) _______ = bones further apart, joined by ligaments, e.g. ______ and _____
c) _______ = pegs in sockets, held in place by connective tissue, e.g. _____

Answer 6

Fibrous joints are within STRUCTURAL classification. Bones joined by fibrous CONNECTIVE tissue. There is minimal or no MOVEMENT. Fibrous joints can be further classified:

a) SUTURES = bones often interdigitate, e.g. SKULL
b) SYNDESMOSES = bones further apart, joined by ligaments, e.g. TIBIA and FIBIA
c) GOMPHOSES = pegs in sockets, held in place by connective tissue, e.g. TEETH

Question 7

Describe sutures (structural > fibrous > sutures).

Answer 7

Sutures are where opposing bones integrate. They are strong. They are non-movable joints (synarthrosis). They are found in the skull. In adults, sutures often completely ossify.

Question 8

Describe frontanels.

Hint: think sutures!!

Answer 8

Fontanels are the membranous areas between skull bones in baby, which allow change in head shape for birth & rapid growth after birth

Question 9

Describe syndesmoses (structural > fibrous > syndesmoses)

Answer 9

The bones are farther apart than suture. It is a slightly movable joint (amphiaryhrosis). The bones are joined by fibrous ligaments E.g radioulnar

Question 10

Describe gomphoses (structural > fibrous > gomphoses)

Answer 10

They are non-movable joints (Synarthrosis). these are specialized joints, e.g. teeth. They are like pegs fit into sockets.
Periodontal ligaments: hold teeth in place

Question 11

What is periodontal disease?

Answer 11

Periodontal disease is when plaque & bacteria accumulate, causing inflammation and destroying periodontal ligaments & bone – loose teeth

Question 12

Describe cartilaginous joints.

Answer 12

The bones are joined by cartilage (often strengthen by ligaments). These allow limited movement.

They can be further classified into 2 groups:

a) Symphyses = fibrocartilage
b) Synchondrosis = hyaline cartilage

Question 13

Describe the 3 types of elastic cartilage (elastic, fibrocartilage, hyaline) and give examples of each type.

Answer 13

Elastic: elastic fibres + collagen & proteoglycans, rigid but elastic properties e.g. External ears

Fibrocartilage – more collagen than proteoglycans (strongest), Thicker bundles of collagen fibres, Slightly compressible, deals with pressure points e.g. intervertebral disks.

Hyaline – equal collagen + proteoglycans (weakest), Collagen fibres evenly dispersed, smooth, translucent, Abundant, strong support but flexible e.g. shoulder, Covers surface of bones to reduce friction & shock

Question 14

Describe symphyses (structual > cartilaginous > symphyses) and give examples.

Answer 14

It is fibrocartilage uniting two bones. It is slightly movable (Amphiarthrosis)

E.g. symphysis pubis, between manubrium & body of the sternum, intervertebral disks.

Question 15

Describe syndochroses (structual > cartilaginous > syndochroses)

Answer 15

Bones are joined by hyaline cartilage. The joints are unmovable (Synarthrosis)

Some are temporary & replaced by suture, e.g. Epiphyseal plate connecting epiphysis & diaphysis of growing bone, while some are permanent

Question 16

Describe synovial joints.

Answer 16

Synovial joints are one of the structural classifications. Bones don’t directly join. Bones are enclosed in a cavity surrounded by a capsule, which holds bones together. It contains synovial fluid.
Articulating bone surfaces are covered in hyaline/articular cartilage
Movement limited by shape of articular surfaces and arrangement of ligaments E.g. Joints in limbs (Diarthrosis).

Question 17

Describe bursae. What is bursitis?

Answer 17

This is a synovial membrane which extends as a pocket away from rest of joint cavity, and contain synovial fluid.
They are found in areas of friction to cushion between structures in certain synovial joints (e.g. knee, shoulder)
Bursitis = inflammation of a bursa, causes considerable pain around the joint and restrict movement

Question 18

Describe the 6 groups synovial joints can be further classified into (plane joint, hinge joint, ball and socket joint, saddle joint, pivot joint, ellipsoid joint) and give an example for each type.

Answer 18

Plane joint: between flat bone, sliding, uniaxial, e.g. articular processes between vertebrae

Hinge joint: uniaxial, flexion/extension, e.g. knee

Ball and socket joint: multiaxial, free movement, flexion, extension and rotation, e.g. hip

Saddle joint: biaxial, flexion/extension, e.g. carpo-metacarpal thumb

Pivot joint: uniaxial rotation, e.g. radio-ulnar joint

Ellipsoid joint: biaxial, flexion/extension, modified ball & socket, AKA Chondyloid, e.g. atlantoocipital joint (very top of spine and base of skull)

Question 19

Describe ligaments and tendons.

Answer 19

Ligaments connect bone to bone. They are a tough, flexible, fibrous connective tissue.

Tendons connect muscle to bone. They are a flexible but inelastic cord of strong fibrous collagen tissue.

Question 20

Describe the following movements:

Extension
Flexion
Abduction
Adduction
Rotation
Pronation
Supination
Circumduction

Answer 20

Extension: posterior to coronal plane

Flexion: anterior to coronal plane

Abduction: away from medial plane

Adduction: toward medial plane

Rotation: turning on it’s axis, medial and lateral rotation

Pronation: unique rotation of forearm with palms facing posteriorly

Supination: unique rotation of forearm with palms facing anteriorly

Circumduction: combination of flexion, extension, abduction and auction.

Question 21

Describe the following “special” movements:

Elevation
Depression
Protraction 
Retraction
Opposition 
Reposition

Answer 21

Elevation: moves a structure superior
Depression: moves a structure inferior
Protraction: gliding motion anteriorly
Retraction: moves structure back to anatomic position or even back further posteriorly
Opposition: movement of them and finger towards each other
Reposition: return fingers to anatomical position

Question 22

Amount of mobility at a given joint influenced by;

• Shape of _____ surfaces forming joint
• Amount & shape of ______ covering surfaces
• Strength & location of ______ & ______
• Location of_____ associated with joint
• Amount of _____ in and around joint
• Amount of __/_____ of joint
• Amount of ___ in and around joint

Answer 22

Amount of mobility at a given joint influenced by;

• Shape of ARTICULAR surfaces forming joint
• Amount & shape of CARTILAGE covering surfaces
• Strength & location of LIGAMENTS & TENDONS
• Location of MUSCLES associated with joint
• Amount of FLUID in and around joint
• Amount of USE/DISUSE of joint
• Amount of PAIN in and around joint

Question 23

Describe the effects of waging on joints.

Answer 23

Tissue repair slows; new blood vessel development decreases
Articular cartilages wear down
Production of synovial fluid declines
Ligaments & tendons shorter & less flexible
Muscles around joints weaken
A decrease in activity causes less flexibility

Question 24

Describe osteoporosis.

Answer 24

It results in“porous bone” due to loss of bone matrix which weakens bone, making them more prone to bending & fracture
Causes; decreased estrogen, poor diet (Ca), lack of exercise.
2.5x more common in women

Question 25

Describe arthritis. Also describe osteoarthritis and rheumatoid arthritis.

Answer 25

Arthritis is an inflammation of joints, leading to pain & stiffness. There are over 100 causes including infectious agents, metabolic disorders, trauma and immune disorders.

Osteoarthritis = Degenerative, most common; affects 85% of Americans >70yrs; gradual degeneration of a joint with advancing age; delayed with exercise

Rheumatoid arthritis = General connective tissue autoimmune disorder that predominantly affects joints.

Question 26

What is tenditis?

Answer 26

Inflammation of tendon sheaths, often from overuse, e.g. tennis elbow

Question 27

Describe dislocations.

Answer 27

Movement of bones out of correct alignment at a joint; partial dislocation=subluxation

Question 28

What is a sprain?

Answer 28

Stretching or tearing of ligaments supporting a joint