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Appendicular Skeleton
The Skeletal System
• Major Divisions in the
skeletal system:
– Appendicular: consists of
appendages that attach
to the axial skeleton.
• Pectoral girdle, pelvic
girdle, limbs
Pectoral girdle
• Consists of two bones: Clavicle and Scapula
Clavicle
• Also known as the collar bone
• Is a slender, doubly curved bone
• It attaches to the arm away from the top of
the thorax and help prevent shoulder
dislocation
• When the clavicle is broken, the whole
shoulder region caves in medially
Scapulae
• Also known as the shoulder blades
• Are triangular
• Each scapula has a flattened body and two
important processes: The acromion and the
coracoid
Acromion
• The enlarged end of the spine of the scapula
• Connects with the clavicle laterally
Coracoid
• Points over the top of the
shoulder and anchors some
of the muscles of the arm
• The scapula is not directly
attached to the axial skeleton,
it is loosely held in place by
trunk muscles
Scapula Boarders and Angles
• The scapula has 3
boarders:
Superior, Vertebral
(medial) and Axillary
(lateral)
• The scapula also has 3
angles:
Superior, inferior and
lateral
The glenoid cavity, a
shallow socket that
receives the head of the
arm bone is in the
lateral angle
Lateral angle
Glenoid
cavity
Pectoral Girdle
• The shoulder girdle is very light
and allows the upper limb to
have exceptionally free
movement due to:
1. Each shoulder girdle attaches
to the axial skeleton at only one
point – the sternoclavicular joint
Pectoral Girdle
2. The loose attachment of the scapula allows it
to slide back and forth against the thorax as
muscles act
3. The glenoid cavity is shallow and the shoulder
joint is poorly reinforced by ligaments (bone to
bone)
Bone of the upper limbs
• 30 separate bones
form the skeletal
framework of each
upper limb
• They form the
foundation of the
arms, the forearms
and the hands
Arm
• The arm is
formed by a
single bone,
the humerus,
which is a
typical long
bone
Terminologies
• Tubercles: Roughly spherical structure
• Tuberosity: a projection or an elevation of a
bone
• Fossa: a depression
Processes of the humerus
• Greater or lesser
tubercles: sites of
muscle attachment
- The greater tubercle is
situated posteriorlateral to the lesser
tubercle
• Deltoid tuberosity:
where the large
deltoid muscle
(shoulder muscle)of
the shoulder attaches
Processes of the humerus
• Trochlea (Trok’le-ah) and
capitulum
(kah’pit’ulum): both
articulate with bones of
the forearm
• Coronoid and olecranon
(o-lek’rah-non) fossa:
these two depressions
allow the corresponding
processes of the ulna to
move freely when the
elbow is bent and
extended
Forearm
• Two bones, the radius and
the ulna, form the skeleton
of the forearm
• When the body is in the
anatomical position, the
radius is the lateral bone
- The radius is always on the
same side as the thumb
• Ulna: the median bone of
the forearm
Processes of the forearm
• Radial tuberosity: where
the tendon (muscle to
bone) of the bicep
muscle attaches
• Coronoid process and
Olecranon process are
separated by trochlear
notch
Hand
• The skeleton of the
hand consists of
the carpals, the
metacarpals, and
the phalanges
• Carpals: 8
• Metacarpals: 5
• Phalanges: 14
Bones of the Pelvic Girdle
• The pelvic girdle is
formed by 2 coxal
bones
• It is commonly
known as the hip
bone
• Together with the
sacrum and the
coccyx, the hip
bones form the
bony pelvis
Hip bone
• Each hip bone is formed by the fusion of 3
bones:
- Ilium (il’em)
- Ischium (is’ke-um)
- pubis
Ilium
• The ilium bone connects posteriorly with the
sacrum at the sacroiliac joint
• It is a large, flaring bone that forms most of
the hip bone
Ischium
• The ischium is the “sit down” bone
• The ischium tuberosity is a rough-ended area
that receives body weight when you are sitting
Pubis
• The pubis is the most
anterior part
• The pubic bones of each
hip bone fuse anteriorly
to form the acetabulum
(ase-tab’umlum)
• The acetabulum
receives the head of the
thigh bone
Pelvic inlet
• The pelvic inlet is a planar surface which is
typically used to define the boundary between
the pelvic cavity and the abdominal cavity
Male vs. Female
• The female inlet is larger
and more circular
• The female pelvis as a
whole is shallower and
the bones are lighter and
thinner
• The female ilia flare more
laterally
• The female sacrum is
shorter and less curved
• The female pubic arch is
more rounded
Bones of the lower limbs
• The lower limbs
carry our total body
weight
• They are much
thicker and stronger
than the
comparable bones
of the upper limbs
Thigh
• The femur, or thigh bone,
is the heaviest, strongest
bone in the body.
• Greater/Lesser
trochanter and gluteal
tuberosity: all serve as
sites for muscle
attachment
• The head of the femur
articulates with the
acetabulum
Leg
• The tibia and fibula
form the leg
• The tibia (shinbone) is
larger and more medial
-The patellar ligament
(the kneecap) attaches
to the tibial tuberosity
- The medial malleolus
process of the tibia
forms the inner bulge
of the ankle
Leg
• The fibula is thin and
stick-like
• The fibula has no part in
forming the knee joint
• The lateral malleolus
process of the fibula
forms the outer part of
the ankle
Foot
• The skeleton of the foot
consists of the tarsals,
the metatarsals, and the
phalanges
• Tarsals: 7
• Metatarsals: 5
• Phalanges: 14
• Body weight is mostly
carried by the two largest
tarsals: the calcaneus
(heel bone) and the talus