Anatomi Sendi dan Arah Gerak
Channel: M. Rifki Al Ikhsan, MD
Date: 28/11/2020

Joints are flexible connections (junctures) between cartilaginous
and/or bony skeletal elements. They allow movements and a transfer
of forces without reaching critical values of load in the bones,
which could lead to a fracture.
Joint connections (junctures)
The adjacent bones of the skeletal system can be connected continuously
or articulate intermittently, and therefore two types of joints
exist:
• ‘false’ joints (synarthroses, as continuous connections)
• ‘true’ joints (diarthroses, as discontinuous connections)
‘False’ joints are immobile articulations characterised by filling tissue
between the skeletal elements; there is no joint space; they are
referred to as symphysis, junctures, syndesmosis or synchondrosis.
In contrast, true joints have a joint space between the articulating
skeletal elements.
False joints
Synarthroses (› Table 1.7 , › Fig. 1.18 ) differ according to the
type of filling tissue which can consist of connective tissue, cartilage
or bone. Normally synarthroses allow only a low-grade to
moderate mobility (connective or cartilaginous tissue) or no movement
at all (bony tissue) between the skeletal elements. The freedom
of movement also depends on the type and amount of the
filling
tissue, which in turn develops in the sense of a functional
adaptation depending on the mechanical stresses to which the synarthrosis
is exposed. In this way syndesmoses are loaded by
traction;
in synchondroses, depending on the type of loading, hyaline
cartilage (compressive stress) or fibrous cartilage (shear stress)
may occur. One example is the pubic symphysis (› Fig. 1.19 ). It is
reinforced above and below by 2 ligaments (Ligg. pubica superius
and inferius), which absorb traction forces; the hyaline cartilage in
the gap of the pubic symphysis absorbs compressive forces and the
fibrous cartilage absorbs shear stresses.
Syndesmosis [ligamentous juncture, Junctura fibrosa]
The adjacent bones of ligamentous articulations or junctures are
connected by: • Collagen tissue fibres – e. g. Membrana interossea radioulnaris
• Elastic tissue fibres – e. g. Ligg. flava between adjacent vertebral
arches
If two bones of an existing joint become fused, e. g. after a
joint infection or due to immobilisation, this is defined as
ankylosis.
True joints
Characteristic features of diarthroses are (› Fig. 1.20 ):
• articulating skeletal elements
• a joint space
• joint surfaces (Facies articulares) covered with cartilage
• a joint cavity (Cavitas articularis)
• a surrounding joint capsule (Capsula articularis)
• ligaments reinforcing the joint capsule
• and muscles that move and stabilise the joint
Syndesmoses include the Membrana interossea cruris, and the
Syndesmosis tibiofibularis as well as the cranial sutures and fontanelles.
The cranial sutures are bridged by connective tissue, that
has developed from embryonic tissue and that shortly after birth,
has covered even larger areas between the developing cranial bones
in the form of fontanelles (› Chap. 9.1.3). According to the form
of sutures, a distinction is made between:
• Sutura serrata (serrate suture): a toothed connection, very solid
(e. g. Sutura lambdoidea)
• Sutura squamosa (squamous suture): a scale-like bevelled bone
surface (e. g. Squama ossis temporalis or Os parietale)
• Sutura plana (plane suture): with almost even, smooth and parallel
bone edges (e. g. Sutura palatina mediana)
• Schindylesis (‘tongue and groove’ suture): a bony crest sunken
into a slit-like deepening (e. g. the vomer in the Os sphenoidale)
• Gomphosis (pouring in): as the dental root ‘plugged’ in the
alveolar
bone
Synchondrosis [cartilaginous articulation or juncture, Junctura
cartilaginea]
The adjacent bones of a synchondrosis are connected by hyaline cartilage.
These junctures include the costal cartilage between ribs and
sternum, the epiphyses (growth zones) and also the Synchondrosis
sphenooccipitalis of the skull. A symphysis (fused) like the Symphysis
pubica represents a special form. Fibrous cartilage occurs here
as well as in the intervertebral discs (Disci intervertebrales).
Synostosis [osseous juncture or union, Junctura ossea]
Two bones are secondarily fused by bony tissue, e. g. the Os sacrum
and hip bones. Anatomical terms of movement.
Region Term Movement
Extremities Extension Elongation
Flexion Bending
Abduction Pulling away from the body
Adduction Pulling towards the body
Elevation Raising of the arm/shoulder above the horizontal plane
Depression Lowering the arm/shoulder from above the horizontal plane
Inner rotation Inward rotation
Outer rotation Outward rotation
Pronation Rotation movement of hand/foot with hand turned inwards or sole of foot turned outwards
Supination Rotation movement of hand/foot with palm of hand turned outwards or sole of foot turned inwards
Radial abduction Swivelling hand/fingers towards the radius