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Appendicular Skeleton
Appendicular Skeleton
• Contains 126 bones between 4 groups:
– Pectoral girdle (4)
– Arms (60)
– Legs (60)
– Pelvic girdle (2)
Pectoral Girdle: attaches the
upper appendage to the thorax
Pectoral Girdle
• Includes 2 bones (on each side)- clavicle
and scapula.
• Weaker girdle than the pelvic girdle
– Not designed to be weight bearing
– Small point of attachment with the axial
skeleton (at the sternoclavicular joint)
– Most of the girdle is supported by back
muscles.
Clavicle: the anterior bone of
the pectoral girdle
• S-shaped
• Collarbone
• Articulates with the manubrium of the
sternum (sternoclavicular joint). This is a
diarthroses (gliding joint).
Clavicular Landmarks
• Sternal end: the thickened medial end of
the clavicle that articualtes with the
manubrium of the sternum.
• Acromial end: the thinner lateral end of the
clavicle that articulates with the acromion of
the scapula.
• Conoid tubercle: a small projection found on
the inferior surface of the lateral end of the
clavicle.
– This can help determine if it is the left/right
clavicle.
Scapula: the posterior bone of
the pectoral girdle.
• Larger than the clavicle
• Triangular shaped
• Attached to the axial skeleton through the
joint it forms with the clavicle
(acromioclavicular joint).
• Held in place by the larger muscles of the
back.
Anterior Scapular Landmarks
• Superior angle: the highest point on the
scapula.
• Superior border: the superior edge of the
scapula.
• Inferior angle: the lowest point on the
scapula.
• Medial (vertebral) border: a thin ridge of bone
found close to the vertebral column.
• Lateral (axillary) border: a thick ridge of bone
found close to the humerus and inferior to the
Glenoid fossa.
Anterior Scapular Landmarks cont…
• Scapular notch: a small “cut out” in the
superior border of the scapula, medial to the
coracoid process.
– Allows blood vessels to pass over the superior
border in order to feed and drain the arm. This
notch protects the vessels.
• Subscapular fossa: a large shallow
depression found on the anterior surface of
the scapula.
– In this case, “sub” means “underneath”.
Anterior Scapular Landmarks cont…
• Coracoid process: a long, tube-like
projection found medial to the Glenoid fossa.
– Where the pectoralis minor and biceps brachii
attach.
Posterior Scapular Landmarks
• Spine: a prominent ridge of bone found on
the posterior surface of the scapula.
• Acromion: a wide flat projection found on the
lateral end of the spine.
– Angled 90° anterior to the spine.
– Articulates with the acromial end of the clavicle at
the acromioclavicular joint.
• Supraspinous fossa: a shallow depression
found superior to the spine of the scapula.
– PFMA.
Posterior Scapular Landmarks
• Infraspinous fossa: a large shallow
depression found inferior to the spine of the
scapula.
– PFMA
• Glenoid (cavity) fossa: a shallow depression
found superior to the lateral (axillary) border.
– Articulates with the head of the humerus to form
the shoulder joint. This helps form the socket of
the “ball and socket”. This joint is not a tight fit
which allows a range of motion.
The Upper Appendages
• 30 bones in each arm
• Proximal  Distal:
Humerus Radius Ulna Carpals (8)
Metacarpals (5) Phalanges (14)
• Humerus: single bone of the upper arm.
– Largest bone of the arm
Proximal Humeral Landmarks
• Head: the rounded proximal end of the
humerus.
– Articulates with the glenoid fossa (not tightly
which allows for a wide range of motion)
• Anatomical neck: a small line found just
distal to the head of the humerus.
– Site of the epiphyseal line (where the growth
plate has completely ossified).
• Greater tubercle: a large blunt projection
found on the proximal end of the humerus,
lateral to the head.
Proximal Humeral Landmarks cont..
• Lesser tubercle: a small blunt projection
found on the proximal end of the humerus on
the anterior surface.
– This helps determine if it is the right/left humerus
because it is only on the anterior surface.
• Intertubercular (sulcus) groove: an elongated
channel (groove) found between the greater
and lesser tubercles.
– Allows the tendon of the biceps brachii muscle to
pass over the head on its way to the scapulawithout being bent.
Proximal Humeral Landmarks cont..
• Surgical neck: the constricted region found
inferior to the intertubercular sulcus.
– This is a term created by doctors.
– Most commonly fractured region of the humerus.
– Where the compact bone of the diaphysis thins
to transition to spongy bone of the epiphyses.
• Deltoid tuberosity: a large slightly rounded
projection found on the lateral surface of the
diaphysis.
– Point for the deltoid muscle attachment.
Distal Humeral Landmarks
• Capitulum: the rounded lateral condyle of
the humerus.
– Articulates with the head of the radius to help
stabalize the elbow joint.
• Trochlea: the pulley-shaped medial
condyle of the humerus.
– Articulates with the ulna to form the
“functional” part of the elbow that allows it to
be a hinge joint.
* Most condyles are specifically named but
these 2 are shaped so differently!
Distal Humeral Landmarks cont..
• Medial epicondyle: a large projection
found proximal to the trochlea.
– PFMA
– This region is called the “funny bone”. The
sensation that you feel when you hit this is
actually due to the pressure put on the ulnar
nerve that runs posteriorly to this.
• Lateral epicondyle: a small projection
found proximal to the capitulum.
– PFMA
Distal Humeral Landmarks cont..
• Coronoid fossa: a small projection found
proximal to the capitulum.
– It accepts the coronoid process of the ulna when
the elbow is bent.
– If we didn’t have this, we wouldn’t be able to
bend the joint so far.
• Olecranon fossa: a large shallow depression
found proximal to the trochlea on the distal
posterior surface of the humerus.
– This accepts the olecranon of the ulna and allows
the elbow to straighten.
Radius
• The lateral bone of the forearm.
– On the thumb side
– Helps to stabilize the elbow joint.
• Head: the flattened proximal end of the
radius.
– Articulates with the capitulum of the humerus.
• Radial tuberosity: a small round projection
found on the anterior surface just distal to the
head.
– Where the biceps brachii attaches and pulls on
the radius.
Radius continued…
• Styloid process: a small triangular projection
found on the distal lateral surface.
– PFMA
– Can be felt as a bump on the distal, lateral
surface.
Ulna
• The medial bone of the forearm.
– On the pinky side
• Trochlear notch: a “C” shaped notch found on
the proximal anterior surface.
– Articulates with the trochlea to form the functional
part of the elbow. This is the pivot point for the
hinge joint.
• Coronoid process: a small triangular process
found on the anterior surface of the trochlear
notch.
– Fits into the coronoid fossa of the humerus when
the elbow is bent.
Ulna continued…
• Olecranon (process): a large blunt projection
found on the proximal posterior surface.
– PFMA
– The part of the elbow that “sticks out” when it is
bent.
• Head: the smaller distal end.
– The only bone that has the head at the distal end.
• Styloid process: a small triangular projection
on the distal medial surface.