Download The Appendicular Skeleton

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The Appendicular Skeleton
(Refer to Ch 8, Martini)
Appendicular Skeleton
o Consists of 126 bones of the upper and lower limbs and the shoulder (pectoral) girdle and pelvic girdle.
o Assist in locomotion and help us manipulate the environment.
o Each limb of the appendicular skeleton is composed of three major segments connected by movable
joints.
THE PECTORAL (SHOULDER) GIRDLE
The pectoral girdle is composed of the clavicle and the scapula.
Functions:



Attach the upper limbs to the axial skeleton
Provide attachment points for many of the muscles that move the upper limbs
Allows tremendous mobility of the upper limbs
The Clavicle (collar bone):
The clavicle is attached to the manubrium of
the sternum on one end and the scapula on
the other
 Sternal End – medial blunt end that
attaches to manubrium of sternum
 Acromion End – lateral elongated
end that attaches to acromion process
of scapula
 Shaft – body of the clavicle
Functions:


Provides attachment points
for many muscles
Act as braces to hold the
arms away from the thorax
(this function is very well
illustrated during a clavicle fracture in which the shoulder collapses medially)
The clavicle is extremely sensitive to muscle pull and as according to Wolff’s Law is noticeably larger in
individuals who lift weights or perform manual labor.
http://www.utsc.utoronto.ca/~sawchukl/web/images/bones_LOWres/clavicle2_labels.jpg
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Superior Border
The Scapula (shoulder blades):
acromion process - enlarged end of the spine of the
scapula that connects the clavicle as well as several
muscles
coracoid process - points over the top of the shoulder
and anchors the clavicle and some of the muscles of the
arm.
glenoid cavity - a shallow socket that receives the head
of the humerus.
(Vertebral)
(Axillary)
Scapular Spine – ridge along the posterior aspect of the
scapula
The pectoral girdle has exceptional range of motion due to only one attachment to the axial skeleton and a
shallow ball-and-socket joint that is poorly reinforced by ligaments. In comparison to the hip joint, the pectoral
girdle has exceptional flexibility but is very easily dislocated.
THE UPPER LIMBS
There are 30 bones per upper limb, humerus through the phalanges.
The Humerus (upper arm):
Characteristics of the humerus:
 The proximal end (head) of the
humerus fits into the shallow
glenoid cavity.

Greater tubercles and lesser
tubercles - sites of muscle
attachment on proximal end of
humerus

Deltoid tuberosity - point of
attachment for the deltoid muscle
along the midpoint of the shaft

The medial trochlea and the lateral
capitulum are located at the distal
end of the humerus and articulate
with the bones of the forearm.

Coronoid fossa and the olecranon fossa – found at the distal end of the humerus - allow the processes
of the ulna to move freely when the elbow is bent and extended.
Also know head, surgical neck, anatomical neck, intertubicular groove, medial epicondyle, lateral
epicondyle, and radial fossa
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The Radius and Ulna (forearm):
ULNA: forms elbow with the humerus and is
found on the little finger side of the wrist.
Coronoid process - on anterior proximal side
Olecranon process –posterior proximal side
o Together these processes grip trochlea
of the humerus in a pliers-like joint.
Trochlear (semilunar) notch – separates the
coronoid and olecranon processes; articulates
with the trochlea of humerus
Also know head, radial notch, distal
radialulnar joint, styloid process, and ulnar
tuberosity
RADIUS: the bone with the most
responsibility to carry the wrist.
head of radius: located on proximal end of
radius; articulates with capitulum of humerus
radial tuberosity –just below the head of the radius; where biceps tendon attaches.
Also know neck and styloid process
http://www2.ma.psu.edu/~pt/384fore1.gif
The Carpals, Metacarpals, and Phalanges (hand):
http://www2.ma.psu.edu/~pt/handbon.gif
There are 8 marble sized short bones
called the carpals, which are arranged in
two rows of four bones and form the
carpus (wrist). Each of these bones has an
individual name.
The 5 metacarpals form the palm if the
hand. These long bones are not named,
but are numbered 1 to 5 from the thumb to
the little finger. The heads of these bones
form your knuckles when you clench your
fist. Metacarpal #1 is associated with your
thumb and has the most flexibility and
even a different type of joint for
attachment. This allows your thumb to be
used in opposition (the opposing thumb) to
your other fingers.
There are 14 miniature long bones called
the phalanges that make up the human
fingers. Each finger has 3 phalanges,
except for the thumb (pollex) which has 2.
The names of the three phalanges are
proximal, middle, and distal. (Phalanx is
the singular term for phalanges.)
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THE PELVIC GIRDLE (HIP)
Functions:
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



Attaches the lower limbs to the lower
end of the axial skeleton
Transmits the weight of the upper body
to the lower limbs
Provides a surface for muscles to
attach
Supports the visceral (internal) organs
of the pelvis
Firmly holds the head of the femur,
using a deep socket and some of the
strongest ligaments in the body
A pair of irregularly shaped hipbones called the
coxal bones forms the pelvic girdle.
During childhood the coxal bones consist of
three individual bones that fuse by adulthood.
The three individual bones are the ilium,
ischium, and pubis.
The Ilium:
The ilium is the largest bone of the pelvis.
sacroiliac joint – where the sacrum and ilium join
iliac crest.- superior edge of the ilium
anterior superior iliac crest
The Ischium:
The ischium (is’ke-um) forms the most
inferior part of the coxal bone.
ischial tuberosity - receives the body
weight when sitting.
ischial spine - a protrusion that narrows
the outlet of the pelvis where the baby
must pass during child birth
greater sciatic notch - allows blood
vessels and the sciatic nerve to pass
through the pelvis into the thigh.
The Pubis:
The pubis fuses with the ischium to form a
bar of bone enclosing the obturator
foramen.
obturator foramen - allows blood vessels
and nerves to pass into the anterior part of
the thigh.
pubic symphysis – cartilage joint formed
where bones of the pelvis fuse
The ilium, ischium, and pubis fuse at the acetabulum, the deep socket that receives the head of the femur.
Also know pubic crest, pubic ramus, ischial ramus, anterior superior iliac spine, and pubic arch
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The pelvis provides an easy way to distinguish between
the skeletons of a male and a female. The female pelvis
reflects modifications for childbearing.
In comparison to the male pelvis, the female pelvis:
 Wider
 Rounder
 Shallower
 Lighter
In addition, the inlet and outlet of the female are larger
and more circular and the sacrum is shorter/less curved.
True Pelvis – opening inside of coxal bones
False Pelvis – outside of coxal bones
THE LOWER LIMBS
Functions:
 Carry the weight of the entire upper body
 Provides attachment for the muscles of the legs
The Femur (thigh): Largest, longest, & strongest bone in the body (length is roughly ¼ of a person’s height)
 head – proximal end that fits in
acetabulum of coxal bone
 fovea capitis – small pit in the center of
the femoral head (ligament attaches to
acetabulum)
 neck - supports head – weakest area of
the femur
 greater trochanter - attachment for
buttocks & thigh muscles
 lesser trochanter - attachment for
buttocks & thigh muscles
 intertrochanteric crest – separates
greater and lesser trochanters
 lateral epicondyles – located on lateral
distal end of femur; attachment for
large muscles
 medial epicondyles - located on medial
distal end of femur; attachment for
large muscles
 lateral condyles - lateral distal femur;
articulates with tibia
 medial condyles - located on medial
distal end of femur; articulates with
tibia
 gluteal tuberosity – located on
diaphysis; attachment for gluteal
muscles
 intercondylar fossa –
depression between condyles
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The Patella (knee):
A sesamoid bone enclosed in the quadriceps tendon that secures
the thigh muscles to the tibia.
The Tibia and Fibula ( lower leg):
The tibia and fibula are much less flexible yet more stable than the ulna and radius of the forearm.
The tibia (shinbone) forms the knee joint with the femur, and also forms the ankle joint with the bones of he
foot. The tibia can be felt through the thin layer of skin for the entire length of the lower leg. It is only
second to the femur in strength and size.

lateral condyles – located
at the lateral proximal end
of the tibia; articulates
with the femur

medial condyles - located
at the medial proximal
end of the tibia;
articulates with the femur

intercondylar eminence –
separates the medial and
lateral condyles of the
tibia

tibial tuberosity – located
on the anterior tibial
surface; anchor point for
the patellar ligament

medial malleolus – forms
the inner bulge of the
ankle

anterior crest – sharp
ridge along the anterior crest of the tibia (shin)
The fibula only provides support for the ankle and does not assist in the joint of the knee. The fibula does not
bear weight, but does have many muscles attached to it.
Lateral malleolus - located on the distal end of the fibula; forms the outer bulge of the ankle.
Also know inferior articular surface of tibia, malleolar articular surface of tibia and fibula, and head and
neck of fibula
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The Tarsals, Metatarsals, and Phalanges (foot):
Functions of the Foot:
 Supports our body weight
 Acts as a lever to propel our body forward as
we walk or run
If we had only one bone in our foot, we could still
propel our body in the same fashion, however, we
would not be able to adapt so well to uneven ground.
The tarsas (ankle) is composed of 7 tarsals that are
more irregular shaped than the carpals, and there are
more size differences among them. (Refer to page
141) Most of the body weight is carried on the largest
two tarsals, the calcaneus (heel bone) and the talus
(lies between tibia and calcaneus).
The metatarsals are composed of 5 small long bones.
They are not named, but are numbered 1 to 5 beginning
with the big toe side of the foot. #1 is the shortest and
thickest metatarsal.
http://www.icbmedical.com/__data/page/104
/Foot-Bone-Structure3.gif
The 14 phalanges of the toes are much smaller than those of the fingers. There are three phalanges within each
toe except the big toe. The phalanges of each toe are proximal, middle, and distal, with the big toe missing the
middle phalanx.
Arches
The bones in the foot are arranged to form
three arches; two longitudinal (medial and
lateral) and one transverse (Refer to Figure
5.24). The ligaments and tendons of the foot
hold the bones in place and allow a certain
amount of give to maintain the arches.
http://www.slackbooks.com/excerpts/34914/10-3.gif