Appendicular Skeleton

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Appendicular Skeleton
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Appendicular Skeleton

• Contains 126 bones between 4 groups
• Pectoral girdle (4)
• Arms (60)
• Legs (60)
• Pelvic girdle (2)

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Pectoral Girdle attaches the upper appendage to
the thorax
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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.

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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).

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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

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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.

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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
  scapula-without being bent.

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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.

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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!

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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

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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 didnt have this, we wouldnt 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.

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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.

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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.

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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.

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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.

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