Chapter 5 - Bone Development, Growth and Structure

Classification of Bones 
1. Long Bones
     These bones are long and slender as are many of the bones in the upper and lower limbs. Examples include the humerus, radius, ulna, tibia and fibula.
2. Short Bones
     Short bones are box-like in shape. Examples include the carpal bones of the wrist and the tarsal bones of the ankle. 
3. Flat Bones
     These bones have thin, roughly parallel layers of compact bone that sandwich a layer of spongy bone. Examples include the bones that form the roof of the skull, scapula, sternum and ribs.
4. Irregular Bones
     Irregular bones have complex shapes. These bones include vertebrae, ethmoid, sphenoid and temporal bones
5. Sesamoid Bones
     Sesamoid bones are typically small and round and develop within tendons. The patella (knee cap) is exceptional in being a large sesamoid bone. 
6. Sutural (Wormian) Bones
     These bones are small, flat, oddly shaped bones found between the flat bones of the skull along the suture. These bones are highly variable in presence, size and shape. They are never given individual names.
Bone Markings (Surface Features)
A. Elevations and Projections
1. Process -  general term for projection or bump
2. Ramus -  extension of a bone at an angle to rest of bone (body)
B. Process for Tendons and Ligaments
1. Trochanter - large, rough projection (Applies only to the proximal femur.)
2. Tuberosity - rough  projection
3. Tubercle - a round projection
4. Crest - prominent ridge
5. Line - low ridge
6. Spine - pointed process
C. Process for Articulations
1. Head - expanded articular end of epiphysis
2. Neck - narrow constriction below head
3. Condyle - smooth, round articular process
4. Trochlea - smooth, grooved articular process shaped like a pulley
5. Facet - small flat articular surface
D. Depressions
1. Fossa - shallow depression
2. Sulcus - narrow groove
E. Openings
1. Foramen - rounded passageway
2. Fissure - elongated cleft
3. Canal - passageway through bone
4. Sinus - chamber within bone normally filled with air

Chapter 7 – Appendicular Skeleton


      The appendicular skeleton includes the bones of the upper and lower limbs and their supporting elements, the pectoral girdle and pelvic girdle that attach them the axial skeleton.


Pectoral Girdle
     The pectoral girdle, or shoulder girdle, consists of the clavicle and scapula. The pectoral girdle positions the shoulder joint and provides a base for arm movement. The only direct connection between the girdle and the axial skeleton is the articulation of the clavicle with the sternum. Only skeletal muscles support and position the scapula.
  The clavicle connects the pectoral girdle to the axial skeleton. Features include:
  Sternal end – roughly pyramidal attachment to the sternum.
  Acromial end – flatter and broader attachment to the acromion of the scapula.
  The superior surface directly underneath the skin is smooth. The inferior surface has attachment sites for ligaments these are:
  Conoid tubercle – at acromial end.
  Costal tuberosity – at sternal end.
  The body of the scapula forms a broad triangle. The three sides of the triangle are places where muscles attach and are:
  1. Superior border
  2. Medial (vertebral) border
  3. Lateral (axillary) border
  The corners of the triangle are:
  1. Superior angle (medial end of superior border).
  2. Inferior angle
  3. Lateral angle
  The lateral angle forms a broad process that supports the cup-shaped glenoid cavity (fossa). The lateral angle is also called the head of the scapula and is connected to the body of the scapula by a rounded neck.
  Two large processes extend over the glenoid cavity. These processes attach to ligaments and tendons of the shoulder joint.
  Coracoid process – smaller anterior projection. The suprascapular notch is an indentation medial to the base of the coracoid process.
  Acromion – larger posterior process. The acromion is continuous with the scapular spine a ridge that extends to the medial border.
  The broad flat surfaces on the scapula are called fossa and include:
  Subscapular fossa – the concave anterior surface on the body of the scapula.
  Supraspinous fossa – the flat surface superior to the scapular spine.
  Infraspinous fossa – the flat surface inferior to the scapular spine.
Upper Limb
  Head – smooth and round, superior and medial portion of the epiphysis that articulates with the glenoid cavity.
  Greater tubercle – large projection lateral to the head.
  Lesser tubercle – smaller projection on the anterior and medial surface of the epiphysis.
  Intertubercular groove – groove separating the greater and lesser tubercles.
  Anatomical neck – constriction distal to the head of the humerus.
  Surgical neck – constriction distal to tubercles and head of humerus. Frequent site of fractures.
  Deltoid tuberosity -  elevated, roughened surface on the lateral side of the shaft. Deltoid muscle attaches here.
  Diaphysis (Shaft) – The proximal shaft is cylindrical. The distal shaft flares to form a flatter triangular portion.
  Medial and lateral epicondyles – the flared distal ends of the humerus on either side of the articular surface. Muscles attach here.
  Condyle – The inferior articular surface of the humerus that articulates with the ulna and the radius. The articular condylar surface is divided into:
  Trochlea (pulley) – spool-shaped medial portion that articulates with the ulna.
  Capitulum – rounded lateral portion that articulates with the head of the radius.
    Depressions above the condyle accommodate proximal parts of the radius and ulna when the elbow joint is fully flexed and extended. These include:
  Coronoid fossa – accepts coronoid process on the anterior surface during flexion.
  Olecranon fossa – accepts olecranon of ulna during extension.
  Radial fossa – accepts head of radius during flexion.
  The ulna is the medial bone of the forearm. The proximal end of the ulna articulates with the humerus and has the following features:
  Olecranon – superior and posterior portion of the epiphysis that forms the point of the elbow.
  Trochlear (semilunar) notch – anterior portion that interlocks with the groove of the trochlea.
  Coronoid process – forms the inferior lip of the trochlear notch.
  Radial notch – lateral to the coronoid process, this notch accommodates the radial head.
  The distal end of the ulna narrows and shows the following features:
  Ulnar head – disc-shaped distal part.
  Styloid process – short process posterior to the ulnar head.
  The radius is the lateral bone of the forearm. The proximal radius has:
  Radial head – disc-shaped head articulates with the capitulum of the humerus.
  Radial tuberosity – the attachment site for the biceps brachii muscle.
  The distal radius widens to the:
  Distal extremity – distal portion of the radius that forms the proximal side of the wrist joint. Features found here are:
  Styloid process – process on lateral side of distal extremity stabilizes the wrist joint.
  Ulnar notch of radius – notch on medial side articulates with the ulnar head.
  Carpal Bones
  There are eight carpal (wrist) bones, four proximal and four distal. The bones are connected by moveable joints that permit them to slide and twist.
  Proximal carpal bones
  From lateral to medial:
  Scaphoid (boat-like) bone – adjacent to styloid process of radius.
  Lunate (moon-like) bone – articulate with radius along with the scaphoid.
  Triquetrum (triangular) bone – shaped like a pyramid.
  Pisiform (pea-shaped) bone – small bone that lies anterior to the triquetrum.
  Distal carpal bones
  From lateral to medial:
  Trapezium – forms a proximal articulation with the scaphoid.
  Trapezoid bone – wedge-shaped bone that also has a proximal articulation with the scaphoid.
  Capitate (having a head) bone – largest carpal bone.
  Hamate (hooked) bone – hook-shaped bone.
  Metacarpal Bones
  The metacarpal bones are bones that support the palm and articulate with the distal carpal bones. They are numbered with the Roman numerals (I – V) from lateral to medial. Each has a wide proximal base, a middle body,  and a distal head.
  There are 14 finger bones with three in each finger (proximal, middle and distal) with the exception of the thumb, also called the pollex, which has only two (proximal and distal).
The Pelvic Girdle
     The pelvic girdle is more massive than the pectoral girdle because of the greater stresses involved in weight bearing and locomotion. The pelvic girdle also supports and protects the lower viscera.
     The pelvic girdle consists of the sacrum and coccyx and the two ossa coxa (sing. os coxae).
  Os coxae
  The ossa coxae result from the fusion of the ilium, ischium and pubis. At the place where the three bones meet there is the:
  Acetabulum – curved surface that articulates with the head of the femur. Within the acetabulum are found:
  Lunate surface – smooth curved, c-shaped surface. An anterior and inferior gap in this surface is called the acetabular notch.
  Acetabular fossa – the dished-out space enclosed by the lunate surface.
  The anterior and medial portions of the ossa coxae are connected by a pad of fibrocartilage called the pubic symphysis.
  The three bones that form the ossa coxae are:
  The largest of the three bones contributes to the superior two-fifths of the acetabulum. Features of the ilium include:
  Arcuate line – line on the medial side marks the beginning of the broad superior expansion.
  Going around the border of the ilium:
  Inferior iliac notch – notch inferior to anterior inferior iliac spine.
  Anterior  inferior iliac spine (AIIS) – process on anterior border of ilium.
  Anterior superior iliac spine (ASIS) – process on anterior border of ilium.
  Iliac crest – curving superior border of ilium.
  Posterior superior iliac spine (PSIS) – process at the end of the iliac crest.
  Posterior inferior iliac spine (PIIS) – rounded inferior process on posterior border of ilium.
  Greater sciatic notch – notch through which the sciatic nerve passes.
  On the inner or medial side of the ilium:
  Iliac fossa – concave medial surface of ilium.
  Auricular surface – ear-shaped roughened surface that contributes to the sacroiliac joint.
  Iliac tuberosity – roughened process superior to the auricular surface where the ligaments that stabilize the sacroiliac joint attaches.
  The posterior bone that contributes to the posterior two-fifths of the acetabulum. Features of the ischium include:
  Ischial spine – process below greater sciatic notch.
  Lesser sciatic notch – inferior to ischial spine.
  Ischial tuberosity – roughened projection on which the body weight is borne when seated.
  Ischial ramus – narrow branch that fuses with the inferior branch of the pubis.
  The anterior bone that contributes to the anterior one-fifth of the acetabulum. The two bones are joined anteriorly by a fibrocartilage pad called the pubic symphysis. Features of the pubis include:
  Inferior ramus – branch that fuses with the ischial ramus.
  Superior ramus – contributes to the acetabulum. Features on the superior ramus include:
  Pubic tubercle – process on anterior and superior part.
  Pectineal line – line that extends from pubic tubercle to arcuate line.
  Pubic crest – roughened ridge that extends medially from pubic tubercle.
  Obturator foramen – “opening” surrounded by ischial and pubic rami and closed by connective tissue in the living person.
  Obturator groove – groove on superior ramus that permits passage of blood vessels and nerves.
     The pelvis consists of a ring of bones that include the two ossa coxae, the sacrum and the coccyx. The pelvis is divided into:
  False (greater) pelvis – the superior part bounded by the expanded, blade-like portions of each ilium superior to the arcuate line. Encloses organs of the inferior abdominal cavity.
  True (lesser) pelvis – inferior to iliopectinial line and bounded by both pubic bones, both ischium, the sacrum and coccyx. The boundaries of the true pelvis are:
  Pelvic inlet – superior boundary of true pelvis bounded by the pelvic brim which includes the base of the sacrum, ileopectineal line, and superior margin of the pubic symphysis.
  Pelvic outlet – inferior opening bounded by coccyx, ischial tuberosities and inferior border of pubic symphysis.


The Lower Limb
     The lower limb is designed to transfer weight from the body to the ground.
  The femur is the longest and heaviest bone in the body. Its features include:
  Head – proximal, rounded articulation with the acetabulum.
  Fovea – depression in head where a stabilizing ligament attaches.
  Neck – constriction distal to the head.
  Greater trochanter – process that projects laterally from the junction of the neck with the shaft.
  Lesser trochanter – process on posterior, medial surface of femur.
  Intertrochanteric line – anterior line between greater and lesser trochanter.
  Intertrochanteric crest – more prominent ridge on the posterior surface.
  Gluteal tuberosity – inferior to intertrochanteric crest on lateral side.
  Linea aspera – prominent rough elevation on posterior side of femoral shaft. Divides inferiorly into
  Medial and lateral  supracondylar ridges with a flattened, triangular
  Popliteal surface in between.
  The medial and lateral supracondylar ridges terminate in medial and lateral epicondyles with a rough projection called the adductor tubercle on the medial epicondyle.
  The distal articular surface has smooth and round medial and lateral condyles. The condyles fuse anteriorly to form the patellar surface but remain separate posteriorly where there is an intercondylar fossa.
  The patella is a large sesamoid bone that forms in the tendon of the quadriceps femoris tendons. Featues include:
  Base – broad superior attachment for quadriceps tendon.
  Apex – inferior somewhat broad point.
  The large medial bone of the leg. The proximal end has:
  Medial and lateral  condyles – round expanded processes with flat articular surfaces.
  Intercondylar eminence – ridge between  the medial and lateral condyles.
  Tibial tuberosity – roughened prominence on anterior surface for attachment of patella ligament.
  The shaft has a:
  Anterior margin – a prominent ridge that begins at the tibial tuberosity and extends distally.
  The distal tibia has a
  Medial malleolus – a large medial process that helps stabilize the ankle joint medially.
  Slender bone parallel to lateral border of tibia. The features include:
  Head – articulates inferior and slightly posterior to the lateral tibial condyle.
  Lateral malleolus – distal epiphysis provides stability to the ankle joint by preventing medial sliding of tibia across the talus.
  Tarsal Bones
  The tarsus (ankle) has seven bones:
  Talus – transmits weight from tibia to foot. Its articulation with the tibia is the smooth superior surface, the trochlea.
  Calcaneus – largest tarsal bone forms the heel. Transmits most of the weight while standing.
  Cuboid bone – articulates with anterior surface of calcaneus.
  Navicular bone – articulates with anterior surface of talus.
  Cuneiform bones – three wedge-shaped bones, medial cuneiform, intermediate cuneiform and lateral cuneiform, articulate with anterior surface of navicular bone.
  Metatarsal bones
  Five bones numbered with Roman numerals I – V proceeding from medial to lateral.
  As in the hand, there are 14 phalanges in the five digits with three phalanges (proximal, middle and distal) in all except the great toe, hallux, which has only two (proximal and distal).