Chapter 8
Joints
267
8
strength. In this joint, however, stability comes chiefly from
the deep socket that securely encloses the femoral head and the
strong capsular ligaments.
Temporomandibular Joint
Te
temporomandibular joint
(±MJ), or jaw joint, is a modified
hinge joint. It lies just anterior to the ear
(Figure 8.13)
. At this joint,
the condylar process of the mandible articulates with the inferior
surface of the squamous part of the temporal bone. Te mandible’s
condylar process is egg shaped, whereas the articular surface of the
temporal bone has a more complex shape. Posteriorly, it forms the
concave
mandibular fossa
; anteriorly it forms a dense knob called
the
articular tubercle
. Te lateral aspect of the loose articular cap-
sule that encloses the joint is thickened into a
lateral ligament
.
Within the capsule, an articular disc divides the synovial cavity into
superior and inferior compartments (Figure 8.13a, b).
Tese include the
iliofemoral ligament
(il
0
e-o-fem
9
o-ral), a strong
V-shaped ligament anteriorly; the
pubofemoral ligament
(pu
0
bo-
fem
9
o-ral), a triangular thickening of the inferior part of the capsule;
and the
ischiofemoral ligament
(is
0
ke-o-fem
9
o-ral), a spiraling
posterior ligament (Figure 8.12c, d). Tese ligaments are arranged
in such a way that they “screw” the femur head into the acetabulum
when a person stands up straight, thereby providing more stability.
Te
ligament of the head of the femur
, also called the
ligamen-
tum teres
, is a flat intracapsular band that runs from the femur head
to the lower lip of the acetabulum (Figure 8.12a, b). Tis ligament is
slack during most hip movements, so it is not important in stabiliz-
ing the joint. In fact, its mechanical function (if any) is unclear, but
it does contain an artery that helps supply the head of the femur.
Damage to this artery may lead to severe arthritis of the hip joint.
Muscle tendons that cross the joint and the bulky hip and
thigh muscles that surround it contribute to its stability and
Articular cartilage
Coxal (hip) bone
Ligament of the
head of the femur
(ligamentum teres)
Synovial cavity
Articular capsule
Acetabular labrum
Femur
(a) Frontal section through the right hip joint
Anterior inferior
iliac spine
Iliofemoral
ligament
Pubofemoral
ligament
Greater
trochanter
(d) Anterior view of right hip joint, capsule in place
(c) Posterior view of right hip joint, capsule in place
Ischium
Iliofemoral
ligament
Ischiofemoral
ligament
Greater
trochanter
of femur
Acetabular
labrum
Synovial
membrane
Ligament
of the head
of the femur
(ligamentum
teres)
Head
of femur
Articular
capsule (cut)
(b) Photo of the interior of the hip joint, lateral view
Figure 8.12
The hip joint.
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