Learning Center
Plans & pricing Sign in
Sign Out

Copy and Return to Teacher


									                                   Copy and Return to Teacher
                                    The Appendicular Skeleton
The Appendicular Skeleton
   126 bones
       o   Limbs (appendages)
       o   Pectoral girdle (attaches arm to the axial skeleton)
       o   Pelvic girdle (attaches leg to the axial skeleton)
The Pectoral (Shoulder) Girdle
   Composed of two bones
       o   Clavicle – collarbone
       o   Scapula – shoulder blade
   These bones are very light and allow the upper limb to have exceptionally free movement
                1. Each pectoral girdle attaches to axial skeleton at only 1 point =
                    sternoclavicular joint
                2. The loose attachment of the scapula allows it to slide back & forth against the
                3. The glenoid cavity is shallow & the shoulder joint is poorly reinforced by

   Consists of 2 bones:
       1. Clavicle (collar bone) = slender, double curved bone
                o   Attaches to manubrium of the sternum medially & to the scapula laterally
              o   Acts as a brace to hold the arm away from the thorax & helps prevent
                  shoulder dislocation
      2. Scapula (shoulder blade) = triangular & flare when we move our arms posteriorly
              o   Not directly attached to axial skeleton; held in place by trunk muscles
              o   Flattened body w/ 2 processes:
                     Acromion process = the enlarged end of the spine of the scapula
                             Connects w/ the clavicle @ the acromioclavicular joint
                     Coracoid process = beaklike
                             Points over the shoulder & anchors some of the arm muscles
              o   Suprascapular notch serves as a nerve passageway
              o   Scapula has 3 borders & 3 angles:
                     Superior
                     Medial (vertebral)     borders
                     Lateral (axillary)
                     Superior
                     Inferior      Angles
                     Lateral

Bones of the Upper Limb (30)
 The arm is formed by a single bone
   Humerus
      o   Rounded proximal end fits into glenoid cavity of scapula
      o   Opposite of the head – 2 bony processes = greater & lesser tubercles, sites of
          muscle attachment
      o   Midpoint of shaft – deltoid tuberosity where the deltoid m. attaches
    o   Radial groove runs obliquely down the posterior shaft
    o   Distal end – medial trochlea (looks like a spool) & lateral ball-like capitulum – both
        articulate w/ bones of forearm
    o   Above the trochlea anteriorly is a depression – coronoid fossa
    o   On posterior surface is the olecranon fossa
    o Both are flanked by medial & lateral epicondyles

   Forearm – consists of the radius & ulna
        o   Radius is lateral when the arm is in the anatomical position (on the thumb side) &
            the ulna is medial
        o   When the hand is rotated, the distal end of the radius crosses over & ends up
            medial to the ulna.
        o   Radius & ulna articulate @ small radioulnar joints
        o   They are connected along their entire length by a flexible interosseous
        o   Both have a styloid process @ their distal end
        o   Disc-shaped radial head forms a joint w/ the capitulum of the humerus.
        o   Below the head is the radial tuberosity where tendon of biceps m. attaches.
        o   On the ulna’s proximal end are the anterior coronoid process & the posterior
            olecranon process, which are separated by the trochlear notch.
                 These 2 processes grip the trochlea of the humerus in a pliers-like joint.

   Hand consists of carpals, metacarpals & phalanges
       o   8 carpals arranged in 2 irregular rows of 4 bones each form the part of the hand
           called the carpus (wrist)
                 Bound together by ligaments that restrict movements between them.
       o   Metacarpals form the palm
                 Numbered 1 to 5 from the thumb to the pinky
                 Clenched fist – heads of the metacarpals = knuckles
       o   Phalanges (14) are the finger bones (3 in each finger & 2 in the thumb)
Carpals starting Left to Right (pinky to thumb -
both rows):
Joe took a Hamate and hit poor Pete in the
Capitate, breaking it into a Trapezoid and
Trapezium. He did it b/c he was Pisiform(d)
Triquetral times. The Judge said he was
Lunate and sent him to the Scaphoid.

The Bony Pelvis vs. the Pelvic Girdle
      Bony Pelvis
           o   Composed of:
                      Sacrum
                      Coccyx
                      Coxal bones (coxae) or ossa coxae (Hip bones)

      Pelvic Girdle
           o   Coxae are composed of three pair of fused bones
                      Ilium
                      Ischium
                      Pubic bone
The Pelvic Girdle: Right Coxal Bone

      Coxae are large, heavy & attached securely to the axial skeleton.
      Sockets that receive the femur are deep & heavily reinforced w/ ligaments.
      Function = bearing weight; total wt. of upper body rests on pelvis.
      Reproductive organs, bladder & part of large intestine lie within & are protected by
      Each coxa is formed by the fusion of 3 bones:
                 1. Ilium (Large flaring bone - forms most of the coxa)
                         Connects posteriorly w/ sacrum @ the sacroiliac joint.
                         Alae - winglike portions of the ilia.
                         Iliac crest – upper edge of alae that ends anteriorly in the anterior
                            superior iliac spine & posteriorly in the posterior superior iliac spine w/
                            small inferior spines located below these.
                 2. Ischium (“sit down bone”)
                         Most inferior part of coxa.
                         Ischial tuberosity, a roughened area, receives body wt. when sitting.
                        Ischial spine, superior to the tuberosity, narrows the outlet through
                             which the baby passes during childbirth.
                        Greater sciatic notch allows blood vessels & the large sciatic nerve to
                             pass from the pelvis posteriorly into the thigh.
              3. Pubis or pubic bone
                        Most anterior part of the coxa.
                        Fusion of the rami of the pubis anteriorly & the ischium posteriorly
                             forms a bar of bone enclosing the obturator foramen, an opening
                             through which blood vessels & nerves pass into the anterior part of
                             the thigh.
                        Pubic bones fuse anteriorly to form a cartilaginous joint called the
                             pubic symphysis.
      The ilium, ischium, & pubis fuse @ the deep socket called the acetabulum (“vinegar
       cup”); it receives the head of the femur.
The Bony Pelvis

         Male pelvis                                                Female pelvis

      Bony pelvis is divided into 2 regions:
          o   False pelvis, superior to the true pelvis, is the area medial to the flaring portions
              of the ilia.
          o   True pelvis lies inferior to the flaring parts of the ilia & the pelvic brim.
          o   Dimensions of the true pelvis are important for childbirth – must be large enough
              for the head to pass.
                      Outlet is the inferior opening of the pelvis.
                      Inlet is the superior opening.
Differing characteristics between the male & female pelvis
      Female inlet is larger & more circular.
      Female pelvis as a whole is shallower & the bones are lighter & thinner.
      Female ilia flare more laterally.
      Female sacrum is shorter & less curved.
      Female Ischial spines are shorter & farther apart; thus the outlet is larger.
      Female pubic arch is more rounded because the angle of the pubic arch is greater.
Bones of the Lower Limbs
      Carry our total body weight when standing = thicker & stronger.
      The thigh has one bone – femur (thigh bone)
      Femur (thigh bone)
          o   Heaviest, strongest bone in the body.
          o   Proximal end has ball-like head, neck and greater & lesser trochanters.
              Trochanters are separated anteriorly by intertrochanteric line and posteriorly by
              intertrochanteric crest.
          o   Trochanters, inter.-crest & gluteal tuberosity are sites for muscle attachment.
          o   Slants medially as it runs downward to bring knees in line w/ body’s center of
              gravity. (more noticeable in females b/c of wider pelvis)
          o   Distally are the lateral & medial condyles – articulate w/ tibia. (condyles
              separated by condylar fossa)
          o   Anteriorly on distal end is the patellar surface – forms a joint w/ patella (kneecap)
   Lower leg has 2 bones – Tibia & Fibula
       o     Connected by interosseous membrane.
   Tibia (shinbone)
       o     Larger & more medial
       o     At proximal end – medial & lateral
             condyles (separated by intercondylar
             eminence) articlulate w/ distal end of
             femur to form knee joint.
       o     Patellar ligament attaches to tibial
             tuberosity (anter.)
       o     Distally, a process called medial malleolus
             forms inner bulge of ankle.
       o     Anterior surface has sharp ridge – anterior
             border (unprotected by muscle – so you
             can feel this)
   Fibula
       o     Thin & sticklike
       o     Distally - lateral malleolus forms outer
             part of ankle.
   Foot – composed of tarsals, metatarsals &
       o     Two important functions: supports
             body weight & serves as a lever
             allowing us to propel body forward
             when walking,etc.
       o     7 Tarsals
                    Weight carried by the 2
                     largest tarsals:
                          calcaneus
                              (heelbone) &
                          talus (lies b/n tibia &
       o     5 metatarsals form the sole
       o     14 phalanges form the toes (each
             toe has 3, except the big toe)
       o     Bones are arranged to form 3 strong arches:
   2 longitudinal (medial & lateral), 1 transverse
     Ligaments bind foot bones together
     Tendons of the foot muscles help to hold bones in arched position
       but allow for “springiness” – weak arches are referred to as “fallen
       arches” or “flat feet”

To top