Articulations is just another word for a bone that connects with another bone. With articulations, the movement is inversely proportional with stability. Hence, the higher the mobility, the lower the stability and vice versa.
From descending order of mobility:
a. Glenohumeral joint (shoulder)
b. Hip joint
c. Humeroulnar joint (elbow)
d. Intervertebral joint
e. Sutures
The joints can be differentiated based on Structure or Function. Structure is based on what type of connective tissue the joint is made up of while Function is just another word for movement or degree of mobility.
Functions.
There are three types of functions (movements):
a. Synarthrosis - no movement
b. Amphiarthrosis - slight movement
c. Diarthrosis - move all you want
A good way I remember this is through the word SAD.
Structures.
There are three types of structures (what type of connective tissue):
a. Fibrous - dense regular connective tissue
b. Cartilaginous - cartilage is..... cartilage.
c. Synovial - synovial fluid, joint capsule and ligaments for stabilization
Fibrous.
a. Gomphosis - in the mandible and maxilla, synarthrosis. A good way to remember is by the word "Gom" -- it sounds just like where it is, in the gums!
b. Sutures - in the cranial skeleton, synarthrosis. If you remember from the last post, it is only with adults that the sutures are synarthrosis. They used to be the fontanelles.
c. Syndesmosis - also known as the interosseous membrane between the radius and the ulna in the middle and distally, amphiarthrosis.
Cartilaginous.
a. Synchondroses - Look at the word "chondroses", also synonymous to "chondrocytes" found in cartilage, specifically, hyaline cartilage. These are synarthrosis and are found in the epiphyseal plate of growing children and in costochondral joints of the ribs.
b. Symphyses - Guess where? In the pubic symphysis! What's interesting about them is that the body releases a hormone for the expansion of the pelvis when giving birth. Symphyses are also found in the intervertebral disc of the vertebrae and are made up of fibrocartilage as a shock absorber. They are amphiarthrosis.
Synovial.
Starting from the outermost layer of the synovial joint is the fibrous layer. The fibrous layer is made up of dense connective tissue layer. The inner layer is called the synovial membrane that secretes the synovial fluid filling the synovial cavity to supply nourishment and to absorb shock. The bones are capped by articular cartilages, particularly by hyaline cartilage.
Nerves are also present in the synovial joint to allow stimulus for pain. Minimal blood vessels are present. This is why joints takes time to heal!
Seen above are ligaments present in and around the synovial joint. The rope like drawings are the ligaments that connect a bone to another bone. The capsular ligament is around the joint capsule, the intracapsular joint are inside the capsule and the extracapsular joint are outside the joint capsule.
Types of Synovial Joints.
Movements of bones include uniaxial (one plane), biaxial (two planes) and multiaxial (more than two planes).
From the lowest mobility to the highest mobility, silly as it sounds, I like to remember the sentence "Peter Pan Hugged Some Cute Bear" to remember the hierarchy.
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| http://images.mocpages.com/user_images/48287/1366754888m_SPLASH.jpg REMEMBER! "Peter Pan Hugged Some Cute Bear" |
Ready? Let's get to the meat!
a. Planar (gliding) - is uniaxial, the least movable of all, are flat in shape and can only move from side to side. Examples include intercarpal joints, intertarsal joints, acromioclavicular joint and vertebrocostal joints.
b. Pivot - is also uniaxial, consists of a peg and a hole with ligament and a bone. Moves in a transverse plane. Some examples are the atlas, axis and proximal radioulnar joint. How I remember this is by picturing a pivotal handle on a radio.
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| engineersgarage.com |
c. Hinge - is also uniaxial, consist of a convex and a concave shape. Moves in a sagittal plane. An example is the humero-ulnar joint also known as the elbow.
d. Saddle - is biaxial, consists of a convex and a concave shape. Movements are in frontal and oblique planes. How I remember this is I picture a horse's oblique muscles. Saddle and horses and oblique planes....
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| http://classconnection.s3.amazonaws.com/583/flashcards/651583/jpg/abdominalobliques1328643963804.jpg
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e. Condyle - is also biaxial, consists of a concave and a convex, oval/egg shaped, moves in frontal and sagittal planes. A great example of the condyle is the metacarpophalangeal joint.
f. Bear.... or oops... the Ball and Socket (don't do that on the exam ok) - is triaxial, is the most movable of all, consists of a ball shape and a cup like shaped bone. The glenohumeral or the shoulder joint is a great example of the Ball and Socket joint.
Now on to the injuries. Ouch! Most injuries are seen in the shoulder and knee joint because they are the most mobile joints. Unfortunately, they sacrifice stability in exchange for their mobility. It's like a give and take relationship.
Dislocation is what it sounds like, the bones are completely knocked out of alignment.
Subluxation is partial dislocation. Subluxation is a term mostly used for the vertebrae.
Sprains are caused by stretching or tearing of the ligaments. The first degree is by stretching only. The second degree is partial stretching and partial tearing. The third degree is by tearing and only tearing.
Sprains take a while to heal because they are not vascularized like bones are.
These sprains can be classified as either a high ankle sprain or a low ankle sprain.
The high ankle sprain is the result of a divorce between the married tibia and fibula. They got divorced because they were always high, it sprained their relationship... wonk wonk wonk. Man, I am such a dork. This is also known as the syndesmotic sprain, usually a result of overinversion which causes bruising and swelling.
The low ankle sprain, sprains the talocrural (ankle) joint and also causes bruising and swelling.
Arthritis.
This is my simple mathematical equation that I invented.
Arthritis = inflammation
Pretty simple, right?
There are several types you have to remember -- osteoarthritis, rheumatoid arthritis and gout.
Osteoarthritis is the cause of wear and tear of the articulating cartilage.
Rheumatoid arthritis is an autoimmune disease where the body is attacking its own joint tissues.
Gout is seen in patients with kidney issues as a result of the deposition of uric acid where the body is unable to get rid of urea. These build up crystals that causes rubbing and tearing.
Now it's just pure memorization time
Sagittal plane - flexion, extension, hyperextension, dorsiflexion and plantarflexion
Frontal plane - Abduction, Adduction, Lateral flexion
Transverse plane - Medial and lateral rotation, rotation right and left, supination and pronation (shout out to runners/joggers out there... I used to jog a lot until I gained 1000 pounds. That was called a hyperbole)
Special movements (aplanar or multiplanar) - inversion, eversion, protraction, retraction, elevation, depression and circumduction.
a. Shoulder (glenohumeral) - ball and socket; flexion, extension, hyperextension, abduction, adduction, medial and lateral rotation and circumduction
b. Elbow (humeroulnar) - hinge; Easy! Just plain ol' flexion and extension!
c. Wrist (radiocarpal) -saddle; flexion, extension, abduction, adduction and circumduction.
d. Knuckles (metacarpophalangeal) - condylar; same as the wrist.
e. Finger and toes (interphalangeal) - hinge; flexion and extension
f. Hip - Lateral flexion, flexion, extension, abduction, adduction, medial rotation, lateral rotation and circumduction
g. Knee - hinge; flexion, extension, medial and lateral rotation
h. Ankle (talocrural) - hinge; dorsiflexion and plantarflexion
i. Intertarsal (talonavicular) - Inversion and eversion
j. Atlanto occipital - condyle; flexion and extension
k. Atlanto axial - head rotation
The Shoulder.
These are ligaments you have to remember. Look at my sucky illustration below.
The Knee.
Again with the sucky illustrations!
Have a great day,
M
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