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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:

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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
Only point of attachment between the upper appendicular skeleton and the axial skeleton
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

Conoid Tubercle – located on the
posterior side of lateral end of
clavicle. Attachment of
stabilizing ligaments from
coracoid process of scapula

Sternoclavicular Joint – joint
between clavicle and sternum
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.
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The Scapula (shoulder blades):

Acromion Process - larger more posterior process located on the end of the spine of the scapula that
connects the clavicle as well as several muscles and ligaments

Coracoid Process - smaller more anterior process that points over the top of the shoulder and anchors
the clavicle and some of the muscles and ligaments of the arm.

Glenoid Cavity/Fossa - a shallow socket that receives the head of the humerus.

Scapular Spine – ridge along the posterior aspect of the scapula
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Supraspinous Fossa – depression above the scapular spine

Infraspinous Fossa – depression below the scapular spine
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Subscapular Fossa – depression on anterior scapula

Acromioclavicular Joint – joint between acromion process of scapula and clavicle

Glenohumeral Joint – joint between glenoid cavity and humerus
Be able to also locate the following:
Superior angle, inferior angle, lateral angle (head), body, superior border, medial (vertebral) border, and
lateral (Axillary) border
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.
Superior Border
(Axillary)
(Vertebral)
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THE UPPER LIMBS
There are 30 bones per upper limb, humerus through the phalanges.
The Humerus (upper arm):

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

Intertubercular Groove – located between the tubercles; houses a tendon of the shoulder
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Deltoid tuberosity - point of attachment for the deltoid muscle along the midpoint of the shaft

The condyle is composed of the medial trochlea and the lateral capitulum. Located at the distal end of
the humerus and articulate with the bones of the forearm. Trochlea with ulna and capitulum with radius

Coronoid fossa (anterior) and the olecranon fossa (posterior) – found at the distal end of the humerus allow the processes of the ulna to move freely when the elbow is bent and extended.

Anatomical Neck – narrow area at the edge of the articular surface

Surgical Neck – common place for fractures and therefore surgery (open reduction)

Radial Groove – located on posterior humerus; passage of radial nerve to triceps to extend elbow

Medial Epicondyle – (epi = above) place of muscle attachment on distal medial humerus
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Lateral Epicondyle – place of muscle attachment on distal lateral humerus

Radial Fossa – depression that accommodates the radial head when the arm is flexed
Funny Bone – a blow at the
posteromedial surface of elbow strikes
ulnar nerve creating numbness in the
anterior forearm
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The Radius and Ulna (forearm):
ULNA: forms elbow with the humerus and is found on the little finger (medial) 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

Ulnar Head – located on distal end of ulna

Radial Notch – depression that accommodates the head of the radius on the proximal end of the ulna
(forms Proximal Radioulnar Joint)

Styloid Process of Ulna – located on medial aspect of distal ulna; works with styloid process of radius
to enclose proximal carpal bones

Ulnar Tuberosity – roughened area of anterior proximal ulna; point of muscle attachment
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.

Radial Neck – narrow area just distal to the radial head

Styloid Process of Radius - located on lateral aspect of distal radius; works with styloid process of ulna
to enclose proximal carpal bones

Ulnar Notch – depression within the distal radius that embraces the distal ulna (forms Distal
Radioulnar Joint)

Interosseous Membrane – fibrous sheet that connects the ulna to the radius
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The Carpals, Metacarpals, and Phalanges (hand):
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.
Proximal Carpal Bones: Scaphoid, Lunate, Triquetrum, Pisiform
Distal Carpal Bones: Trapezium, Trapezoid, Capitate, Hamate
Sam likes to push the toy car hard; some like to ponder that this class hard
The 5 metacarpals form the palm of the hand. These long bones are not named, but are numbered I to V 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:
 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: superior section of the coxal bone
The ilium is the largest bone of the pelvis; Attachment of muscles, tendons, and ligaments
Sacroiliac Joint – where the sacrum and ilium join
Iliac Crest.- superior edge of the ilium
Anterior Superior Iliac Spine & Anterior Inferior Iliac Spine
Posterior Superior Iliac Spine & Posterior Inferior Iliac Spine – projections of bone on the edges of the
ilium that serves as an attachment point for muscles and some ligaments
Anterior, Posterior and Inferior Gluteal Lines– attachment of large hip muscles on the lateral side
Auricular Surface – (of ilium) – attaches to the auricular surface of the sacrum to form sacroiliac joint
Iliac Tuberosity – roughened area superior to the auricular surface, stabilizes sacroiliac joint
Iliac Fossa – shallow depression on the medial side of ilium – holds organs of abdomen
Arcuate Line (ilium) – continuation of pectineal line; attachment of muscles and ligaments
Greater Sciatic Notch - allows blood vessels and the sciatic nerve to pass through the pelvis into the thigh.
The Ischium: forms posterior, inferior coxal bone
The ischium (is’ke-um) forms the most inferior part of the coxal bone.
Ischial Tuberosity - receives the body weight when sitting.
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Ischial Spine - a protrusion that narrows the outlet of the pelvis where the baby must pass during child birth
Lesser Sciatic Notch – notch that is inferior to and smaller than the greater sciatic notch of the ilium; vessels
and nerves pass
Ischial Ramus – section of bone between the body of the ischium and the pubis bone
The Pubis: forms anterior, inferior coxal bone
The pubis fuses with the ischium to form a bar of bone enclosing the obturator foramen.
Obturator Foramen - spaced closed by sheet of collagen fiber; provides firm attachment for hip muscles
Pubic Symphysis – fibrous cartilage joint formed where the bones of the pelvis fuse
The ilium, ischium, and pubis fuse at the Acetabulum, the deep socket that receives the head of the femur.
Lunate Surface of Acetabulum – articular surface of the acetabulum
Pubic Tubercle – small elevated area anterior lateral to the pubic symphysis
Superior and Inferior Pubic Ramus - sections of bone between the body of pubis bone and the ischium
inferiorly and the ilium superiorly
Pectineal Line – ridge superior to pubic tubercle; attachment of muscles and ligaments
Pubic Arch (Pubic Angle) – anterior inferior upside down“V” or “U” shaped notch at the junction of the pelvic
bones
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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 – includes the outside of coxal bones
Pelvic Girdle – includes the two coxal bones
Pelvis – includes the two coxal bones, the sacrum, and the coccyx
Pelvic Brim – inner edge of the true pelvis
Pelvis Inlet – superior enclosed space or superior opening of the true pelvis
Pelvis Outlet – inferior opening bounded by the coccyx, ischial spines, and the inferior border of the pubic
symphysis
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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 and thigh muscle tendons
Intertrochanteric Crest – located on the posterior surface of the femur; separates the greater and lesser
trochanters
Intertrochanteric Line – located on the anterior surface of the femur; separates the 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
Shaft of Femur – diaphysis
Patellar Surface – anterior distal femur surface; smooth articular surface over which the patella glides
Linea Aspera – line or ridge that runs parallel to the diaphysis on the posterior aspect of the femur and divides
into the medial and lateral supracondylar ridges; attachment of powerful hip muscles
Popliteal Surface – posterior distal femur surface; back of knee
Medial and Lateral Supracondylar Ridges – increased surface area for muscle attachment
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The Patella (knee):
Patella – A sesamoid bone enclosed in the quadriceps femoris
tendon that secures the thigh muscles and the tibia
The patellae are cartilaginous at birth. Ossification begins at age
2-3 and ends roughly by the time of puberty
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 Margin (also known as the Anterior Crest or Border) – sharp ridge along the anterior aspect of the
tibia (shin); easily felt through the skin
Inferior Articular Surface of the Tibia - articulates with the trochlea of talus
Malleolar Articular Surface of the Tibia – articulates with the side of talus
Superior Tibiofibular Joint – location where the tibia and fibula articulate near the knee
Inferior Tibiofibular Joint – location where the tibia and fibula articulate near the ankle
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FIBULA:
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.
Fibular Head – proximal part of the fibula
Neck – connects the fibular head to the shaft
Lateral Malleolus - located on the distal end of the fibula; forms the outer bulge of the ankle.
Interosseous Membrane – supporting membrane located between the tibia and fibula
Malleolar Articular Surface of the Fibula – articulates with the side of talus
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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 tarsus (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).
Trochlea of Talus – articulates with Tibia
Talus, Calcaneous, Cuboid, Navicular,
Medial Cuneiform, Intermediate Cuneiform, and Lateral Cuneiform
The metatarsals are composed of 5 small long bones. They are not named, but are numbered using Roman
Numerals I-V beginning with the big toe side of the foot. #1 is the shortest and thickest metatarsal.
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.
Hallux – Great Toe
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.