246
UNIT 2
Covering, Support, and Movement of the Body
Chapter Summary
7
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1.
Te axial skeleton forms the longitudinal axis of the body. Its
principal subdivisions are the skull, vertebral column, and
thoracic cage. It provides support and protection (by enclosure).
2.
Te appendicular skeleton consists of the bones of the
pectoral and pelvic girdles and the limbs. It allows mobility for
manipulation and locomotion.
PART 1
The Axial Skeleton
The Skull
(pp. 201–217)
1.
Te skull is formed by 22 bones. Te cranium forms the vault
and base of the skull, which protect the brain. Te facial skeleton
provides openings for the respiratory and digestive passages and
attachment points for facial muscles.
2.
Except for the temporomandibular joints, all bones of the adult
skull are joined by immovable sutures.
3.
Cranium.
Te eight bones of the cranium include the paired
parietal and temporal bones and the single frontal, occipital,
ethmoid, and sphenoid bones (see ±able 7.1, pp. 216–217).
4.
Facial bones.
Te 14 bones of the face include the paired maxillae,
zygomatics, nasals, lacrimals, palatines, and inferior nasal conchae
and the single mandible and vomer bones (±able 7.1).
5.
Orbits and nasal cavity.
Both the orbits and the nasal cavities are
complicated bony regions formed of several bones.
6.
Paranasal sinuses.
Paranasal sinuses occur in the frontal,
ethmoid, sphenoid, and maxillary bones.
7.
Hyoid bone.
Te hyoid bone, supported in the neck by
ligaments, serves as an attachment point for tongue and neck
muscles.
The Vertebral Column
(pp. 218–224)
1.
General characteristics.
Te vertebral column includes 24
movable vertebrae (7 cervical, 12 thoracic, and 5 lumbar) and the
sacrum and coccyx.
2.
Te fibrocartilage intervertebral discs act as shock absorbers and
provide flexibility to the vertebral column.
3.
Te primary curvatures of the vertebral column are the thoracic
and sacral; the secondary curvatures are the cervical and lumbar.
Curvatures increase spine flexibility.
4.
General structure of vertebrae.
With the exception of C
1
and C
2
,
all vertebrae have a body, two transverse processes, two superior
and two inferior articular processes, a spinous process, and a
vertebral arch.
5.
Regional vertebral characteristics.
Special features distinguish
the regional vertebrae (see ±able 7.2, p. 223).
The Thoracic Cage
(pp. 224–227)
1.
Te bones of the thoracic cage include the 12 rib pairs, the
sternum, and the thoracic vertebrae. Te thoracic cage protects
the organs of the thoracic cavity.
2.
Sternum.
Te sternum consists of the fused manubrium, body,
and xiphoid process.
3.
Ribs.
Te first seven rib pairs are called true ribs; the rest are
called false ribs. Ribs 11 and 12 are floating ribs.
PART 2
The Appendicular Skeleton
The Pectoral (Shoulder) Girdle*
(pp. 227–228)
1.
Each pectoral girdle consists of one clavicle and one scapula. Te
pectoral girdles attach the upper limbs to the axial skeleton.
2.
Clavicles.
Te clavicles hold the scapulae laterally away from the
thorax. Te sternoclavicular joints are the only attachment points
of the pectoral girdle to the axial skeleton.
3.
Scapulae.
Te scapulae articulate with the clavicles and with the
humerus bones of the arms.
The Upper Limb*
(pp. 228–234)
1.
Each upper limb consists of 30 bones and is specialized for mobility.
2.
Arm/forearm/hand.
Te skeleton of the arm is composed solely
of the humerus; the skeleton of the forearm is composed of the
radius and ulna; and the skeleton of the hand consists of the
carpals, metacarpals, and phalanges.
The Pelvic (Hip) Girdle*
(pp. 234–238)
1.
Te pelvic girdle, a heavy structure specialized for weight bearing,
is composed of two hip bones and the sacrum. It secures the
lower limbs to the axial skeleton.
2.
Each hip bone consists of three fused bones: ilium, ischium, and
pubis. Te acetabulum occurs at the point of fusion.
3.
Ilium/ischium/pubis.
Te ilium is the superior flaring portion
of the hip bone. Each ilium forms a secure joint with the sacrum
posteriorly. Te ischium is a curved bar of bone; we sit on
the ischial tuberosities. Te V-shaped pubic bones articulate
anteriorly at the pubic symphysis.
4.
Pelvic structure and childbearing.
Te pelvis is the deep,
basinlike structure formed by the hip bones, sacrum, and coccyx.
Te male pelvis is deep and narrow with larger, heavier bones
than those of the female. Te female pelvis, which forms the birth
canal, is shallow and wide.
The Lower Limb*
(pp. 238–243)
1.
Each lower limb consists of the thigh, leg, and foot and is
specialized for weight bearing and locomotion.
2.
Tigh.
Te femur is the only bone of the thigh. Its ball-shaped
head articulates with the acetabulum.
3.
Leg.
Te bones of the leg are the tibia, which participates in
forming both the knee and ankle joints, and the fibula.
4.
Foot.
Te bones of the foot include the tarsals, metatarsals, and
phalanges. Te most important tarsals are the calcaneus (heel
bone) and the talus, which articulates with the tibia superiorly.
5.
Te foot is supported by three arches (lateral, medial, and
transverse) that distribute body weight to the heel and ball of
the foot.
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