make up the wall of the articular capsule.
Bursae and tendon sheaths
help to reduce friction during joint movement.
Te muscle tendons
that cross the joint are typically the most important factor in stabilizing
Weeping lubrication helps keep the joint cartilages
nourished and “lubricates” the joint surfaces.
John’s hip joint was ﬂexed
and his knees extended and his thumb was in opposition (to his index ﬁn-
Te hinge and pivot joints are uniaxial joints.
Te knee and
temporomandibular joints have menisci. Te elbow and knee act mainly
as a uniaxial hinge. Te shoulder depends largely on muscle tendons for
Arthritis means inﬂammation of the joint.
produces pain, swelling, and joint deformations that tend to be bilateral
and crippling. OA patients tend to have pain, particularly on arising,
which is relieved by gentle exercise, and enlarged bone ends (due to spurs)
in aﬀected joints. Aﬀected joints may exhibit crepitus.
Lyme disease is
caused by spirochete bacteria and transmitted by a tick bite.
exercise strengthens joints and keeps them well nourished.
Review Questions 1.
(1)c, (2)a, (3)a, (4)b, (5)c, (6)b, (7)b, (8)a, (9)c;
Case Study 1.
Te hip joint would be structurally classiﬁed as a
and functionally classiﬁed as a
(freely movable) joint.
Te six distinguishing features that deﬁne a synovial joint are:
(1) articular cartilage, (2) joint (synovial) cavity, (3) articular capsule,
(4) synovial ﬂuid, (5) reinforcing ligaments, (6) nerves and blood vessels.
Te joint space in a synovial joint is normally ﬁlled with
Te acetabular labrum is a piece of ﬁbrocartilage that attaches to and
extends the rim of the acetabulum. Te diameter of the labrum is less than
the diameter of the head of the femur, and this helps stabilize the joint to
prevent it from dislocating.
Mrs. ±anner’s hip was bent (ﬂexed) and her
thigh was pulled toward the midline of her body (adducted) and turned in
toward this midline (medially rotated).
Mrs. ±anner suﬀered a poste-
rior dislocation of the hip. When the head of the femur comes away from
the acetabulum and then turns posteriorly, it causes the femur to rotate
counterclockwise. Tis can be determined from the fact that her thigh was
adducted and medially rotated.
Te hip movements include ﬂexion, ex-
tension, abduction, adduction, rotation, and circumduction of the thigh.
Check Your Understanding 1.
Striated means “with stripes.”
should respond “smooth muscle,” which ﬁts the description.
sium” literally translates to “outside the muscle” and this connective tis-
sue sheath is the outermost muscle sheath, enclosing the entire muscle.
Te thin myoﬁlaments have binding sites for calcium on the troponin
molecules forming part of those ﬁlaments.
In a resting muscle ﬁber,
the SR would have the highest concentration of calcium ions. Te mito-
chondrion provides the A±P needed for muscle activity.
nents of the neuromuscular junction are the axon terminal, the synaptic
cleF, and the junctional folds of the sarcolemma.
Te ﬁnal trigger for
contraction is a certain concentration of calcium ions in the cytosol. Te
initial trigger is depolarization of the sarcolemma.
Tere are always
some myosin cross bridges bound to the actin myoﬁlament during the
contraction phase. Tus, backward sliding of the actin ﬁlaments is pre-
Without A±P, rigor would occur because the myosin heads
could not detach.
A motor unit is an axon of a motor neuron and
all the muscle ﬁbers it innervates.
During the latent period, events of
excitation-contraction coupling are occurring.
Jay grabs the bar, his biceps muscles are contracting isometrically. As
his body moves upward toward the bar, they are contracting isotonically
and concentrically. As he lowers his body toward the mat, the biceps are
contracting isotonically and eccentrically.
Eric was breathing heav-
ily because it takes some time for his heart rate and overall metabolism
to return to the resting state aFer exercise. Moreover, he had likely
incurred an oxygen debt that required he take in extra oxygen for the
because the only freely movable joints of the skull are the temporoman-
dibular joints of the jaw.
Te maxillae are the keystone bones of the
Te sphenoid, ethmoid, frontal, and maxillary bones
contain paranasal sinuses.
Te cribriform plates of the ethmoid bone
form the roof of the nasal cavity.
Te maxillae form the bulk of the
orbit ﬂoor. Te eye is housed in the orbit.
Te ﬁve major regions of
the vertebral column are the cervical, thoracic, lumbar, sacral, and coccy-
Te cervical and lumbar regions are concave posteriorly.
Te ﬁbrocartilage discs contribute to the ﬂexibility of the vertebral
Tere are 7 cervical and 12 thoracic vertebrae.
is the axis on which the atlas rotates. If it’s broken, movements of the
atlas would be less controllable.
A lumbar vertebra is heavier and
its massive body is kidney shaped. Its spinous processes are short and
project directly back. A thoracic vertebral body is generally heart shaped,
its spinous process is long, sharp, and points downward, and its trans-
verse processes have facets for articulating with the ribs.
A true rib
connects to the sternum by its own costal cartilage. A false rib connects
to the sternum via costal cartilages of other ribs or not at all.
nal angle is a ridge across the front of the sternum where the manubrium
joins the sternal body. It acts as a hinge allowing the sternum to swing
anteriorly when we inhale. Because it is aligned with the second rib, it
is a handy cue for ﬁnding that rib and then counting the ribs during a
Te thoracic vertebrae also contribute to the thoracic
Each pectoral girdle is formed by a scapula and a clavicle.
Te pectoral girdle attaches to the sternal manubrium of the axial skel-
eton via the medial end of its clavicle.
A consequence of its ﬂexibility
is that it is easily dislocated.
±ogether the ulna and humerus form
the elbow joint.
Te ulna and the radius each have a styloid process
Carpals are found in the proximal region of the palm. Tey
are short bones.
Te third bone of the os coxae is the ischium.
Te pelvic girdle receives the weight of the upper body (trunk, head,
and upper limbs) and transmits that weight to the lower limbs.
female pelvis is wider and has a shorter sacrum and a more movable coc-
Te tibia is the second largest bone in the body.
malleolus is located on the distalmost medial aspect of the tibia.
lateral condyles are not sites of muscle attachment, they are articular sur-
Because of their springiness, the foot arches save energy during
Te two largest tarsals are the talus and the calcaneus,
which forms the heel.
Te enlargement of the facial skeleton between
ages 6 and 13 is due to the enlargement of the nose and paranasal sinuses
and the development of the permanent teeth.
Te lumbar curvature
develops when the baby begins to walk.
Review Questions 1.
(1)b, g; (2)h; (3)d; (4)d, f; (5)e; (6)c; (7)a, b, d, h;
(1)g, (2)f, (3)b, (4)a, (5)b, (6)c, (7)d, (8)e;
(1)b, (2)c, (3)e, (4)a,
(5)h, (6)e, (7)f
Case Study 1.
Te hemispherical socket at the point where her femur at-
taches is called the
Te structure on the femur that forms
the “ball” that ﬁts into the “socket” named in question 1 is called the
of the femur.
Te three bones in the pelvic girdle that fuse together at a
point within the structure identiﬁed in question 1 are the
If you were asked to rest your hands on your hips, your
hands would be resting on the
Te structures on the femur
where the large muscles of the buttocks and thigh attach are the
Te structure of the pelvis that the
sciatic nerve passes through as it travels into the upper thigh is the
Check Your Understanding 1.
Joint and articulation are synonyms.
Te synarthroses are the least mobile of the joint types.
and synchondroses are cartilaginous joints.
In general, the more stable a
joint, the less mobile it is.
Te ﬁbrous layer and the synovial membrane