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Joints and Articulations
Arthrology
Joints And Their Classification
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A joint, or articulation, is any point at
which two bones meet, regardless of
whether they are movable at that point
The science of joint structure, function,
and dysfunction is called arthrology
The study of musculoskeletal movement is
kinesiology
Joints And Their Classification
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Kinesiology is a branch of biomechanics,
which deals with a broad range of motions
and mechanical processes in the body,
including the physics of blood circulation,
respiration, and hearing.
About Joints
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Tendons
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Ligaments
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bind a muscle to bone
bind bone to bone
Both are dense regular connective tissue
About Muscles (acting at a joint)
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origin
insertion
action
Characterizing Joints
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What type of movement does the joint allow?
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No movement, limited movement, free movement
What tissue joins the bones?
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Fibrous Joints
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Fibrous connective tissue (suture, ligament, tooth)
Cartilaginous Joints
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Fibrocartilage (pubic symphysis)
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Hyaline cartilage (epiphyseal plate, costal cart)
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Synovial
Types of Movement
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Synarthrotic
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Amphiarthrotic
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immoveable, allows no movement
allows only limited movement
Diarthrotic
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freely moveable
Types of tissue between bones
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Suture (dense CT between bony plates)
Syndesmosis (ligament)
Gomphosis (tooth socket)
Symphysis (fibrocartilage)
Synchondrosis (hyaline cartilage)
Synovial (fluid filled joint)
Fibrous Joints
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A fibrous joint is two bones joined by
fibrous connective tissue.
It is immovable so it is categorized as a
synarthrotic joint.
No joint cavity
Fibrous Joints
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Sutures
Syndesmoses
Gomphoses
Suture
•In sutures and
gomphoses, the
fibers are very
short and allow
for little or no
movement
Syndesmosis
•In syndesmoses, the
fibers are longer and
the attached bones
are more movable:
ligament attaches!
Gomphosis
Peg in
socket
Cartilaginous Joints
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A cartilaginous joint is two bones joined by cartilage.
The cartilage is either fibrocartilage (a symphysis joint)
or hyaline cartilage (a synchondrosis).
Fibrocartilage joints (symphyses) are amphiarthrotic
(slightly moveable).
 Examples are intervertebral discs and the pubic
symphysis
Hyaline cartilage joints (synchondroses) are synarthrotic
(immovable).
 Examples are epiphyseal plates and costal cartilages
Symphysis
In a symphysis, two
bones are joined by
fibrocartilage (A symphysis
is amphiarthrotic: slightly
moveable)
Synchondrosis
A synchondrosis
is a joint in
which the bones
are bound by
hyaline cartilage
(A synchondrosis is
synarthrotic: not
moveable)
A synchondrosis
is a synarthrosis
Synovial Joints
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The most familiar type of joint and the most
common. It allows a wide range of motion so it
is functionally classified as a diarthrotic joint (a
diarthrosis)
Examples include the elbow, knee, knuckles, the
joints between the wrist and ankle bones
Synovial joints are the most structurally complex
type of joint, (having a joint cavity) and are the
most likely to develop uncomfortable and
crippling dysfunctions
Synovial Joints
Characteristics
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Enclosed chamber, flexible fibrous capsule
A cavity filled with fluid, synovial fluid
An inner membrane that produces
lubricating fluid, synovial membrane
Articular cartilages covering ends of bones
Reinforcing ligaments to stabilize
Innervated and vascular
Synovial Joint Structure
In synovial joints,
the facing surfaces
of the two bones
are covered with
articular cartilage,
a layer of hyaline
cartilage about 2
mm thick
These surfaces are
separated by a narrow
space, the joint (articular)
cavity, containing a slippery
lubricant called synovial
fluid. This fluid is rich in
albumin and hyaluronic
acid, which give it a viscous,
slippery texture. It nourishes
the articular cartilages,
removes their wastes, and
makes movements at
synovial joints almost
friction-free
Synovial Joint Structure
In several synovial
joints,
fibrocartilage
grows inward from
the joint capsule
and forms a pad
between the
articulating bones
When the pad
crosses the entire
joint capsule it is
called an articular
disc
Capsule
A connective tissue
membrane (articular
capsule) encloses the
cavity and retains the
fluid.
It has an outer fibrous
capsule, which acts like
a sleeve; it is
continuous with the
periosteum of the
adjoining bones, and
an inner, cellular
synovial membrane
Bursae
A bursa is a fibrous sac filled with synovial
fluid, located between adjacent muscles or
where a tendon passes over a bone.
Bursae cushion muscles, help tendons slide
more easily over the joints, and sometimes
enhance the mechanical effect of a muscle by
modifying the direction in which its tendon
pulls.
Bursae and Tendon Sheaths
The knee joint has at least 13 bursae
Figure 9.4a, b
Synovial Joint
Bursitis is
inflammation
of a bursa,
usually due to
overexertion of
a joint.
Tendinitis is a
form of bursitis
in which a
tendon sheath
is inflamed
Types of Synovial Joints
There are six types of synovial joints, characterized
by the motion allowed by the shapes of the bones.
1.
Plane
2.
Hinge
3.
Pivot
4.
Condyloid
5.
Saddle
6.
Ball and socket
Plane Joints
The carpal and
tarsal bones,
between the
articular processes
of the vertebrae,
and at the
sternoclavicular
joint
Hinge Joints
The elbow, knee,
and IPJ =
interphalangeal
(finger and toe)
joints
Pivot Joints
The atlantoaxial joint
between the first two
vertebrae and
proximal radioulnar
joint, where the
annular ligament on
the ulna encircles the
head of the radius
Condyloid Joints
Metacarpal-phalangeal
joints: these are
biaxial condyloid joints
Saddle Joints
At the base of the thumb
(between the trapezium
and metacarpal I) and
sternoclavicular joint
between the clavicle and
sternum.
Saddle joints are biaxial
joints; in primate anatomy,
allows for the opposable
thumb
Ball and Socket Joints
Shoulder and hip
joints are ball and
socket. This type
of joint is
multiaxial.
Three Important Synovial Joints
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Knee Joint
Hip Joint
Shoulder Joint
The Knee Joint
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Tibiofemoral joint and patellofemoral joint
The largest and most complex diarthrosis
of the body
Hinge joint, but has movements of gliding, rolling and
rotation
3 articulations: lateral and medial articulations of
femur and tibia; intermediate articulation of patella
and femur. Note: Fibula does not articulate with the
femur, only with the tibia.
Extracapsular ligaments
Patellar ligament (patellar tendon)
 Passes from the apex and margins of the patella distally to the
tibial tuberosity
Medial collateral ligament
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Extends from the medial epicondyle of the femur to the medial
condyle of the tibia
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At its midpoint, its fibers are attached to the medial meniscus,
Lateral collateral ligament
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Extends inferiorly from lateral epicondyle of femur to lateral
surface of the fibular head
Two ligaments lie outside the
joint capsule:
• tibial (medial) collateral
ligament.
•fibular (lateral) collateral
ligament
The two collateral ligaments
prevent the knee from rotating
when the joint is extended.
Cruciate ligaments
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There are two ligaments that lie inside
the joint capsule. They are deep within
the joint cavity, but they are not inside
the fluid-filled synovial cavity.
These ligaments cross each other in the
form of an X:
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the anterior cruciate ligament (ACL)
posterior cruciate ligament (PCL)
Intracapsular ligaments
Cruciate ligaments join proximal tibia with distal femur, crisscrossing in the
articular capsule
Anterior cruciate ligament (ACL)
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Weaker of the two cruciates
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Arises from anterior intercondylar area of tibia, attaches at the posteromedial
side of the femoral lateral condyle.
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Slack when knee is flexed, taut when fully extended
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Prevents posterior displacement of femur and hyperextension of knee joint
Posterior cruciate ligament (PCL)
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Arises from posterior intercondylar area of tibia, attaches to the anterolateral
surface of the medial condyle of femur.
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Taut during flexion, prevents anterior displacement of femur on the tibia
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Is the main stabilizing factor when weight-bearing during flexed knee position
(ie. Walking downhill.)
Menisci
Medial and Lateral Menisci
 Crescent (C-) shaped plates of fibrocartilage
located over the medial and lateral tibial
condyles
 Thicker laterally, thinner inside the joint
capsule
 Act like shock absorbers
 Thicker laterally, taper to thin unattached
edges at interior of the joint.
In the knee, two
fibrocartilages extend inward
from the left and right but do
not entirely cross the joint
Each is called a meniscus
Menisci absorb the shock of the
body weight jostling up and down
on the knee and prevent the femur
from rocking from side to side on
the tibia
Anterior View of Flexed Knee
Figure 9.14e, f
The ACL and PCL are named
according to whether they attach
to the anterior or posterior side of
the tibia, (not for their attachments
to the femur.)
When the knee is extended, the ACL
is pulled tight and prevents
hyperextension.
The PCL prevents the femur from
sliding off the front of the tibia and
prevents the tibia from being
displaced backward.
Knee Joint
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Be able to label the drawing with the
names of all of the structures of the
knee joint, including the bones,
ligaments, cartilage, membranes,
capsule, menisci, etc.
Know the movements allowed and the
movements prevented by the anatomy
of the knee.
10 pt Essay Question: Label this
(1/2 point each)
Essay Answer (a)
Essay Answer (b)
Quadriceps tendon
Lateral Collateral
ligament
Lateral Meniscus
Medial Collateral
ligament
Medial Meniscus
Patellar ligament
(patellar tendon)
Lateral Collateral
ligament
Lateral Meniscus
Medial Collateral
ligament
Medial Meniscus
Anterior Cruciate
ligament
Tibial tuberosity
Medial Collateral
ligament
Lateral Collateral
ligament
Lateral Meniscus
Medial Meniscus
Posterior Cruciate
ligament
Medial Collateral
ligament
Lateral Collateral
ligament
Lateral Meniscus
Medial Meniscus
Posterior Cruciate
ligament
Lateral
Meniscus
Medial
Meniscus
Anterior
Cruciate
ligament
Tibial
tuberosity
Hip Joint
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Strong, stable ball and socket joint,
most moveable of all joints
Transverse acetabular ligament (which
bridges the acetabular notch) holds
head in beyond its equator.
Hip Joint Ligaments
Iliofemoral ligament
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Y shaped; Attaches to ant infer iliac spine and acetabular rim
proximally and inferior intertrochanteric line distally
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Prevents hyperextension of the hip during standing
Pubofemoral ligament
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Runs from the superior ramus of the pubis and passes laterally and to
the intertrochanteric line (passing deep to the iliofemoral ligament.)
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Prevents overabduction of the hip joint
Ischiofemoral ligament
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Runs from ischial part of acetabular rim, to the neck of femur (best
seen from posterior view.)
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Prevents hyperextension of the hip by screwing the femoral head
deeper into the acetabulum
Ligament of the head of the femur (ligamentum teres)
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Weak, little importance in strengthening hip joint
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Runs from the transverse acetabular ligament and attaches to the pit
(fovea capitis) of head.
Hip Joint
Figure 9.13a, b
Posterior View of the Hip Joint
Figure 9.13c, d
Hip Ligaments
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Be able to label the drawing with the
names of the ligaments that attach to
the hip.
10 pt Essay Question: Label this
Essay Answer: 1 pt each
Anterior
Posterior
The Shoulder Joint
Diarthrotic, ball and socket joint:
Humeral head in glenoid cavity
Shoulder Joint (Glenohumeral Joint)
Ligaments:
Glenohumeral ligaments : 3 fibrous bands
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From the anterior glenoid labrum to the anatomical neck of humerus
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Reinforce the anterior part of the articular capsule (and are inside the
capsule, not visible from outside.)
Coracohumeral ligament
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From base of coracoid process to anterior aspect of greater tubercle of
humerus
Transverse humeral ligament
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Runs from greater to lesser tubercle of humerus
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Creates a channel , bridging over the intertubercular groove
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Site for tendon of long head of biceps brachii
Coracoacromial ligament
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From inferior aspect of acromion to coracoid process
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Forms a protective “arch” preventing superior displacement of the head
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Supraspinatus muscle passes under this arch.
Shoulder Ligaments
Shoulder:Glenohumeral Joint
Shoulder Ligaments
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Be able to label the drawing with the
names of the ligaments that attach the
clavicle to the scapula and to the head
of the humerus.
10 pt Essay Question: Label this
Essay Answer: ½ pt each
Ligaments of the Ankle Joint
Figure 9.17c
Ligaments of the Ankle Joint
Figure 9.17d