<< Chapter < Page Chapter >> Page >
Illustration shows a synovial joint between two bones. An I-beam–shaped synovial cavity exists between the bones, and articular cartilage wraps around the tips of the bones. Ligaments connect the two bones together.
Synovial joints are the only joints that have a space or “synovial cavity” in the joint.

Classification of joints on the basis of function

The functional classification divides joints into three categories: synarthroses, amphiarthroses, and diarthroses. A synarthrosis    is a joint that is immovable. This includes sutures, gomphoses, and synchondroses. Amphiarthroses are joints that allow slight movement, including syndesmoses and symphyses. Diarthroses are joints that allow for free movement of the joint, as in synovial joints.

Movement at synovial joints

The wide range of movement allowed by synovial joints produces different types of movements. The movement of synovial joints can be classified as one of four different types: gliding, angular, rotational, or special movement.

Gliding movement

Gliding movements occur as relatively flat bone surfaces move past each other. Gliding movements produce very little rotation or angular movement of the bones. The joints of the carpal and tarsal bones are examples of joints that produce gliding movements.

Angular movement

Angular movements are produced when the angle between the bones of a joint changes. There are several different types of angular movements, including flexion, extension, hyperextension, abduction, adduction, and circumduction. Flexion , or bending, occurs when the angle between the bones decreases. Moving the forearm upward at the elbow or moving the wrist to move the hand toward the forearm are examples of flexion. Extension is the opposite of flexion in that the angle between the bones of a joint increases. Straightening a limb after flexion is an example of extension. Extension past the regular anatomical position is referred to as hyperextension    . This includes moving the neck back to look upward, or bending the wrist so that the hand moves away from the forearm.

Abduction occurs when a bone moves away from the midline of the body. Examples of abduction are moving the arms or legs laterally to lift them straight out to the side. Adduction is the movement of a bone toward the midline of the body. Movement of the limbs inward after abduction is an example of adduction. Circumduction is the movement of a limb in a circular motion, as in moving the arm in a circular motion.

Rotational movement

Rotational movement is the movement of a bone as it rotates around its longitudinal axis. Rotation can be toward the midline of the body, which is referred to as medial rotation    , or away from the midline of the body, which is referred to as lateral rotation    . Movement of the head from side to side is an example of rotation.

Special movements

Some movements that cannot be classified as gliding, angular, or rotational are called special movements. Inversion involves the soles of the feet moving inward, toward the midline of the body. Eversion is the opposite of inversion, movement of the sole of the foot outward, away from the midline of the body. Protraction is the anterior movement of a bone in the horizontal plane. Retraction occurs as a joint moves back into position after protraction. Protraction and retraction can be seen in the movement of the mandible as the jaw is thrust outwards and then back inwards. Elevation is the movement of a bone upward, such as when the shoulders are shrugged, lifting the scapulae. Depression is the opposite of elevation—movement downward of a bone, such as after the shoulders are shrugged and the scapulae return to their normal position from an elevated position. Dorsiflexion is a bending at the ankle such that the toes are lifted toward the knee. Plantar flexion is a bending at the ankle when the heel is lifted, such as when standing on the toes. Supination is the movement of the radius and ulna bones of the forearm so that the palm faces forward. Pronation is the opposite movement, in which the palm faces backward. Opposition is the movement of the thumb toward the fingers of the same hand, making it possible to grasp and hold objects.

Questions & Answers

what is cell
Prince Reply
synthesis of 1 molecules of glucose requires
Purvesh Reply
what is the chemical composition of water
Abigail Reply
h20
Rita
Oh, how's is it going..
Brian Reply
not too good
Monique
hy
Adeola
hi
Imamkasim
hi
Veronica
Any one else taking Bio 1406 with Stephanie Martin?
Veronica
where is it ?
ShAmy
am here Veronica
iyota
Part of compound microscope
Bakish Reply
a. body b. stage clip c. adjacent knob d. arm e. eye piece
Kpodo
E
Rita
How do u know when you want to urinate
Akpo Reply
how do you know when you want to urinate
Akpo
I don't know please explain
Coded
As the bladder fills up .. the signals are sent to the brain specifying that its filling up and should be emptied and the fuller it gets, the more signals/ alerts are sent to brain ...leading to the urge to urinate .... to go pee
Khalida
OK thank you
Coded
hello
Issiya
hi
Abigail
I want the this ecologycal terms
Catherine Reply
what are enzymes
Alvin Reply
enzymes are organic catalysts which speed the rate of chemical reaction but it's self is not used up in the process
Azeezah
what is fertilization
Ofosu Reply
fusion of male and famele gametes
Biology
fusion of female and male gametes.
Biology
form zygote to eggs
Ahmad
also known as syngamy
RESHMA
why is water called a polar molecule
Jabari Reply
enzyme that not found in mitochondria
Mukesh Reply
Internal carotid arteries
Anjola Reply
A closed circulatory system is a closed-loop system, in which blood is not free in a cavity. Blood is separate from the bodily interstitial fluid and contained within blood vessels. In this type of system, blood circulates unidirectionally from the heart around the systemic circulatory route, and th
Peter Reply
food
Ramatulai
Is DNA a proteins or genetic materials ?
Bisallah
what is meiosis
Ram Reply
meiosis is a reduction Division in which four hapliod off springs are produced
Nandanee
what is electrochemical gradient?
Joneth Reply

Get the best Biology course in your pocket!





Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Biology' conversation and receive update notifications?

Ask