Post on 17-Jan-2016
Dr. Bruce Forciea
This presentation will examine the skeletal system. We will start by classifying bones.
Bones can be classified according to shape:
Long Bones
Short Bones
Irregular Bones
Sesamoid bones
Let’s look at the parts of a long bone.
Here is an example of a long bone (femur). The proximal and distal ends are known as epiphyses and the middle or shaft portion is the diaphysis. There are also processes protruding from the bone where muscles and ligaments attach.
epiphysis
epiphysis
diaphysis
epiphysis
diaphysis
epiphysis
process
Long bones have a long longitudinal axis and are tubular. At the ends of the bones are the epiphyses.
The epiphysis is covered with hyaline cartilage and forms a joint with another bone. It also contains the growth area known as the epiphyseal plate. If the plate is fractured it can hinder growth of the bone.
The epiphysis contains cancellous or spongy bone. This makes the epiphysis strong yet light in weight.
The diaphysis is hollow and contains the marrow. It also contains a type of bone known as compact bone which is very dense.
The hollow portion is called the medullary cavity.
Bones are covered by a fibrous vascular membrane called a periosteum. Blunt trauma to this area can cause a periosteal contusion or bone bruise that takes a long time to heal.
Spongy trabeculated bone
Compact bone
Forms medullary cavity (covered with endosteum and filled with marrow)
Compact bone is well organized. The structural units are called Haversian systems or osteons.
Here is an example of a Haversian system. There is a central canal containing blood vessels and nerve fibers. Bone deposits around the central canal in concentric rings called lamellae.
Central canal
Lamellae
The osteocytes wall themselves off in spaces called lacunae.
Osteocyte in lacunae
There is a communicating canal called a Volksmann’s canal between the central canal and other osteons.
Volksmann’s canal
The osteocytes are connected to the bony matrix via small canaliculi.
canaliculi
Haversian systems are oriented longitudinally in the long bones along the lines of force.
Spongy bone is organized a different way. Spongy bone is often called trabeculated bone. Osteocytes are located in trabeculae and get nutrients via diffusion.
Next we’ll look at how bone is formed. There are 2 basic processes. One for flat bones called intramembraneous bones and one for tubular bones called endochondral bones.
We’ll first look at intramembranous bone formation called:
Intramembraneous ossification.
Intramembraneous bones develop from sheet-like layers of connective tissue. The process is relatively simple in that bone forming cells called osteoblasts form bone in all directions. The ossification centers then connect to form the flat bone.
Once the osteoblast is finished it walls itself off in a lacuna. It is then called a mature osteocyte.
osteoblast
osteoblast
New bone formation in all directions
osteoblast
New bone formation in all directions
osteoblast
New bone formation in all directions
osteoblast
New bone formation in all directions
When osteoblast fully surrounded by matrix then it is called an osteocyte.
Endochondral bone formation is different from intramembraneous ossification.
In endochondral ossification bone grows from a cartilage model or template.
Hyaline cartilage model
Hyaline cartilage model
Periosteum develops
Hyaline cartilage model
Periosteum develops
Primary ossification center
Blood vessel
Hyaline cartilage model
Periosteum develops
Primary ossification center
Secondary ossification center
Medullary cavity
The epiphyseal plate is located between the epiphysis and diaphysis.
Contains 4 layers.◦ Resting layer (inactive)◦ Active cartilage forming layer◦ Older cell layer from second layer◦ Dead cell layer
Bone lengthens as long as cartilagenous cells of epiphyseal layer are active.
Bone growth stops when epiphyseal and diaphyseal ossification centers meet.
Nearly all bone growth stops at ages 23-25 years.
Bone growth requires a supply of nutrients. The following slides will examine some factors that affect bone growth.
Vit D deficiency◦ Rickets – children◦ Osteomalacia – adults◦ Vit D found in milk (fortified)◦ Vit D produced from UV rays from sun activating
dehydrocholesterol.
Vit A needed for the cells◦ Osteoblastic activity◦ Osteoclastic activity
Vit C◦ Collagen synthesis
Growth hormone◦ Stimulates division of cartilage cells in epiphyseal
plate.
Male and female sex hormones◦ Stimulate ossification of epiphyseal plates and
stop bone lengthening. Physical stress also affects bone growth as
bone grows along the lines of force to dissipate stress.
The following slide will present some information regarding the function of bones.
Support and Protection Body movement Formation of blood cells
◦ Red marrow Red and white blood cells and platelets
◦ Yellow marrow Contains fat (inactive in blood cell formation)
Storage of inorganic salts◦ Hydroxyapatite cyrstals (calcium phosphate)
Osteoclasts break down bone to release calcium salts into bloodstream.
Bone can become injured. A common kind of injury to bone is a fracture.
There are several general categories of fractures.
Fractures heal by forming a blood clot called a hematoma.
The hematoma develops special granulated tissue that contains fibrin (an insoluble protein), inflammatory cells, fibroblasts and cartilage and bone-forming cells.
Osteoblasts (bone-forming cells) produce a bony callus that unites the damaged ends of the bone.
Blood forms hematoma Spongy bone forms in area of blood vessels
and fibrocartilage forms in distal to blood vessels.
Bony callus replaces cartilage Osteoclasts remove excess bony tissue and
restore structure.
Now that we have looked at bone formation and repair it is time to learn some of the bones and bony structures.
We will be learning the names of a number of bones as well as the names of some of the processes.
Bones contain a number of bumps, holes and grooves so that ligaments and tendons can attach and vessels and nerves can enter and exit a bone.
It is important to stick with learning the structures in your lab structure list.
We will come across a number of bony landmarks, but before we do here are some definitions:
Tubercle---a small, knoblike process Tuberosity—a knoblike process larger than a
tubercle Trochanter—a large process Styloid process—a pointed process Suture—an interlocking union between 2 bones Foramen—an opening in a bone (usually a
passageway for vessels) Sinus—a cavity within bone Condyle—a rounded process (usually articulates
with another bone)
The skeletal system is divided into the axial and appendicular skeletons. The axial skeleton consists of the skull, spinal column, ribs, sternum and sacrum. The appendicular skeleton consists of the upper and lower extremities.
Important features◦ Occipital bone
Foramen magnum (opening through which spinal cord passes).
◦ Temporal bones Contain external auditory meatus (ear passage). Mastoid process
Sphenoid◦ Sella turcica (pituitary gland)◦ Contains sphenoidal sinuses
Ethmoid bone◦ Cribriform plates (part of roof of nasal cavity)◦ Ethmoid sinuses◦ Crista galli (brain membrane attachment point)
Skull sutures◦ Coronal◦ Squamosal◦ lambdoidal
Maxillary Palatine Zygomatic Lacrimal Nasal Vomer Inferior, superior, middle nasal conchae Mandible
Maxillary bones◦ Maxillary sinuses
Palatine bones◦ Located behind maxilla◦ Form posterior portion of hard palate.
Zygomatic bones◦ Have a temporal process that connects with
zygomatic bone (zygomatic arch). Lacrimal bones
◦ Contain channel that carries tears. Mandible
◦ Mandibular condyle (TMJ)◦ Coronoid process◦ Mandibular foramen (blood vessels and nerve
that innervates lower teeth). ◦ Mental foramen (blood vessels and nerve that
supply chin and lower lip).
Frontal bone
Nasal bones
sphenoid
zygomatic
maxilla
mandible
lacrimal
Infraorbital foramen
Mental foramen
parietal
occipital
temporal
Mastoid process
TMJCoronoid process
frontal
sphenoid
Temporal part of zygomatic
maxilla
mandible
Mental foramen
Sagittal suture
Parietal bone
Lambdoidal suture
occiput
Fontanels –membranous areas that later form sutures. ◦ Posterior fontanel closes at 2 months.◦ Sphenoidal fontanel closes at 3 mos. ◦ Mastoidal fontanel closes at 1st yr. ◦ Anterior fontanel closes at middle to end of 2nd yr.
(as baby becomes more mobile)
Vertbra◦ 7 cervical (C1-7)◦ 12 thoracic (T1-12)◦ 5 lumbar (L1-5)◦ Sacrum (S1--)◦ coccyx
Curves◦ Cervical (lordosis)
secondary◦ Thoracic (kyphosis)
primary◦ Lumbar (lordosis)
secondary◦ Pelvic (kyphosis)
primary
cervical
cervical
thoracic
cervical
thoracic
lumbar
cervical
thoracic
lumbar
pelvic
Typical vertebra◦ Body◦ Pedicles◦ Lamina◦ Transverse processes◦ Spinous process◦ Facets
Learn more about the vertebral column at:
http://www.wisc-online.com/objects/index.asp?objID=AP12104
Cervical◦ Atlas (ringlike)◦ Axis (dens)◦ C2-7 has bifid spinous process◦ Transverse foramen (vertebral arteries)
Transverse foramen
Transverse process
Fovea dentis
Superior articular facet
Inferior articular facet
dens
Transverse process
lamina
Inferior articulating facet
Superior articulating facet
Bifid spinous process
Transverse process
Inferior articulating facet
body
Superior articulating facet
Transverse foramen
Spinous process
Spinous process
lamina
Transverse process
facet
pedicle
body
body
pedicle
Transverse process
facet
Vertebral foramen
Transverse
process
lamina
Spinous process
Ilium—ischium—pubis—sacrum Sacrum
◦ Sacroiliac joints (auricular surface + ilium)◦ Sacral promontory (body of first sacral vertebra)◦ Sacral canal –sacral hiatus (hollow section –
rudimentary spinal canal)◦ Sacral foramina (on ventral side)
Passageway for nerves and blood vessels
Coccyx◦ Rudimentary tailbone◦ 4 sacral vertebrae fused by age 25◦ Ligaments fuse to sacral hiatus
Pelvic Girdle◦ Coxae
Ilium—ischium—pubis Ilium
ASIS PSIS Iliac crest Greater sciatic notch
Pelvic Girdle◦ Coxae
Ilium—ischium—pubis Ischium
Ischial tuberosity (sit bones) Ischial spine
Pubis Symphysis pubis Obturator foramen
Iliac crest
Ischial tuberosity
Ischial spine
coccyx
PSIS
sacrum
Obturator foramen
ASIS
Pubic tubercle
Symphysis pubis
Iliac crest
Ischial tuberosity
pubis
Greater pelvis◦ Pelvic brim
From sacral promontory to symphysis pubis◦ Pelvic brim separates greater (false) pelvis from
lesser (true) pelvis. Infant passes through lesser pelvis at childbirth
Iliac bones more flared in female pelvis. Angle of pubic arch greater in female Greater distance between ischial spines and
ischial tuberosities. Sacral curvature shorter and flatter.
Ribs—thoracic vert.—sternum—costal cartilages.
Ribs◦ Typically 12 pair◦ R1-R7 = true ribs
Articulate at thoracic vertebra to sternum via costal cartilage.
◦ R8-R12 = false ribs Do not articulate directly anteriorly with sternum
False ribs◦ Usually R8-R10 articulate anteriorly with
costosternal cartilage of R7.◦ R11-R12 are floating (no anterior articulation)
Sternum = 3 parts◦ Manubrium
Articulates with clavicles◦ Body◦ Xiphoid process
head
neck
tubercle
shaft
body
manubrium
xiphoid
True ribs
Clavicles◦ Articulate with manubrium of sternum
Scapulae◦ Acromion process◦ Coracoid process◦ Glenoid cavity (fossa)◦ Scapular notch◦ Spine of scapula
acromion
coracoid
glenoid
Lateral border
Medial border
acromion
Glenoid fossa
spine
spine
Humerus Radius Ulna Carpals Metacarpals Phalanges
Humerus◦ Head
Articulates with scapula at glenoid fossa◦ Greater tubercle
On lateral side◦ Lesser tubercle
On medial side◦ Intertubercular groove
Tendon of bicepts brachii passes through◦ Deltoid tuberosity
Attachment for deltoid muscle◦ Capitulum (lateral side)
Articulates with radius◦ Trochlea (medial side)
Articulates with ulna
Humerus◦ Coronoid fossa
Receives coronoid process of ulna when elbow bends.
◦ Olecranon fossa Receives olecranon process of ulna when elbow
bends.
head
Lesser tubercle
Medial epicondyle
trochlea
Greater tubercle
Intertubercular groove
Lateral epicondyle
capitulum
head
trochlea
Head◦ Articulates with capitulum of humerus
Radial tuberosity◦ Bicepts brachii muscle attachment
radiusulna
Radial head
Radial tuberosity
Styloid process
Trochlear notch
Coronoid process
Styloid process
Olecranon process of ulna
Radial head
Radial tuberosity
Carpals—metacarpals—phalanges Carpals
◦ Trapezium◦ Trapezoid◦ Capitate◦ Hamate◦ Scaphoid◦ Lunate◦ Triquetrum◦ pisiform
Carpals—metacarpals—phalanges Metacarpals
◦ Number = 5◦ Form the palm of the hand
Phalanges◦ Proximal◦ Middle ◦ distal
phalanges
metacarpals
carpals
hamate
pisiform
triquetrum
lunate
trapezium
trapezoid
capitate
scaphoid
Femur Tibia Fibula Tarsals—metatarsals--phalanges
Femur◦ Longest bone in body◦ Fovea capitus (lig attachment to hip)◦ Greater trochanter◦ Lesser trochanter◦ Linea aspera◦ Medial epicondyle◦ Lateral epicondyle
Tibia◦ Medial and lateral condyles◦ Tibial tuberosity (insertion of patellar tendon)◦ Medial malleolus
Fibula◦ Head◦ Lateral malleolus
headneck
Lesser trochanter
Medial condyle
Greater trochanter
Lateral condyle
Linea aspera
Fibula Tibia
head
Lateral
malleolus
Medial condyle
Tibial tuberosity
Medial malleolus
talus
navicular
Intermediate cunneiformMedial cunneiform
cuboid Lateral cunneiform
calcaneus
See more bones and landmarks at:
http://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/learnem/bones/main_bone.htm