Skeletal System
Skeletal System includes:
-
Bones
Cartilages
Joints ( where two bones meet)
Ligaments (Bones to bones)
*BABY – 276
*ADULT – 206
*FUSION – decrease in no. of bones
*20% of weight
*EC Matrix – tendons, bones, cartilage, ligaments; has collagen, ground subs, org mol., fluid
*Collagen – ropelike CHON (makes cartilage tough)
*Proteoglycans – large molecules of polysaccharides
Functions
1. Support – bears weight; primary function
2. Protection – internal organs; 33 vertebras
3. Movements – contraction of skeletal muscles
4. Storage – Ca & P
5. Blood Cell Production – bone cavities -> bone marrow -> blood cells
Types accdg to SHAPE
1.
2.
3.
4.
Long bones – composed of COMPACT bones; upper and lower limbs
Short bones – composed of SPONGY BONES; cube-shaped; wrist and ankle
Flat bones – thin-flattened shape, curve; skull, ribs, scapulae and sternum
Irregular bones – include vertebrae & facial bones
Parts of the long bones (DP-EA)
1.
2.
3.
4.
5.
6.
7.
8.
9.
Diaphysis – central shaft
Epiphyses – ends of long bones
Periosteum – fibrous C.T that protects diaphysis
Articular Cartilage – covers epiphyses
Epiphyseal Plate – growth plate; site of growth; cartilages between E & D
Epiphyseal line – replaces E.P; spanning epiphysis
Sharpey’s Fiber – secure periosteum to underlying bone
Endosteum – lines medullary cavity
Medullary cavity - cavity within bone (diaphysis)
 Marrow
o Yellow Marrow - fats
o Red Marrow – blood forming cells; site for blood formation in an adult
Layers of Bones (cross-sectional)
1|Skeletal system
1. Periosteum - outermost
2. Bone substance – matrix & cells
3. Endosteum – innermost; lines medullary
2 BASIC TYPES OS BONE TISSUES
1. Compact bone- dense, looks smooth. Lamellae are organized into
Central /Harvesian Canal – sets of concentric ring contain blood vessels
Osteon/Harvesian System – central canal, lamellae and osteocytes
2. Spongy/Cancellous bone – consist of interconnecting rods or plates of bones
Trabeculae – resembles scaffoldings; add strength to the bone w/o weight
- has marrow and blood vessels; no central canal
- found in epiphyses of long bones
2 DIVISION OF SKELETAL SYSYTEM
I. Axial Skeleton (80 bones)
- Longitudinal axis
1.SKULL
-
22 Bones
2 sets of skull bones:
A. Cranium (braincase)
- bow ike structur composed of 8 bones
- covers & protects the fragile brain tissue
1. Frontal - forehead
2. Parietal – superior and lateral walls
3. Temporal – inferior to parietal
Bone markings:
* External Meatus Auditory – canal to eardrum
*Styloid process – needlike structure inferior to EMA
*Zygomatic process – bridge bone joins with cheekbone
*Mastoid process – rough projection posterior to EMA
4. Occipital - most posterior bone
*foramen magnum – large opening at occipital bone
- where spinal cord joins the brain
* occipital condyles - rest on the 1st vertebra
- where atlas could articulate
5. Sphenoid – butterfly-shaped; spans the width of skull; floor
*Sella Turcica - saddle-shaped at central region; pituitary gland
*Foramen ovale –allows the fiber of CRANIAL NERVE 5 (TRIGEMINAL NERVE)
2|Skeletal system
6. Ethmoid – irregularly shaped bones anterior to sphenoid
*Crista Galli – outermost covering of brain attaches to this bone
*Cribiform plate- allow fibers from OLFACTORY NERVES
B. Facial bones
- 14 bones (13 solidly connected; 1 mandible); 12 paired except vomer and
mandible
- holds facial muscles
- joined by SUTURES (interlocking, immovable joints)
1. Maxillae – upper jaw/teeth, main bones of face
2. Palatine Bones – posterior to maxillae
3. Zygomatic Bones –cheek bones
4. Lacrimal Bones – medial wall of each orbit
5. Nasal bones – bridge of the bone
6. Inferior nasal conchae – curved bones lateral to the nasal cavity
7. Vomer bone – median line of nasal cavity
8. Mandible – lower jaw; only freely movable
9. Sinuses - FEMS
10. Hyoid bone
- unpaired U-shape
- not part of skull
-tongue muscles; elevates larynx during speech & swallowing
2. VERTEBRAL COLUMN (Spine)
- central axis of the skeleton
- from skull to pelvis
5 Functions:
1. Supports the weight of head and trunk
2. Protects the SC
3. Allows spinal nerves to exit SC
4. Site for muscle attachment
5. Permits movement of head & trunk
*KYPHOSIS – posterior; thoracic hunchback
*LORDOSIS – anerior; lumbar swayback
*SCOLIOSIS –lateral curvature
PARTS OF A VERTEBRA:
1.Body/Centrum – disc-like weight bearing

Intercalated disks – separates the vertebral bodies
2. Vertebral arch – surrounds vertebral foramen

Vertebral Canal – where spinal cord is located; protects SC from injury
3|Skeletal system
*Each has 2 pedicles (transverse) and 2 Laminae (transverse spinous)
*Transverse process – 2 lateral projections; provides att. sites
*Spinous – single projection (posterior)
*Intervertebral foramina – where spinal nerves exit
*Articula process (superior-inferior) – vertebra articulate each other.. articular facet





Cervical Vertebrae – C1- C7
C1 – ATLAS; YES JOINT; CARRIES SKULL
C2 – AXIS; NO JOINT;
Odontoid process/DENS – axis fo cervical rotation
Thoracic Vertebra – T1-T2; apple-shaped
Lumbar – bears weight of axial skeleton; heavy transverse
Sacral
*sacral hiatus – caudal anesthetic
*sacral promontory – reference point; vaginal exam
Coccyx – tailbone
3. RIB CAGE
- Thoracic cage
Parts:
 Ribs – 12 ribs
 sternum - breastbone
 thoracic vertebrae
II. Appendicular skeleton
Bones of the limbs and girdles
126 bones
1. pectoral girdle
 scapula – shoulder blades
 glenoid cavity – head of humerus
 acromion – scapular spine form point of shoulder
 clavicle – spinal cord
 coracoid process – curves below clavicle
2. upper limb
 Arms – b/w shoulder and elbow
 Forearm
* Radius –thumbside of forearm
* Ulna – medial bone
 Wrist – 8 carpal bones
 Hand – 5 metacarpal
3. pelvic girdle – where lower limbs are attached to the body
4. lower limb
4|Skeletal system
2 BASIC TYPES OS BONE TISSUES (CS)
1. Compact bone
 Central /Harvesian Canal
 Osteon/Harvesian System
2. Spongy/Cancellous bone
 Trabeculae
PARTS OF A VERTEBRA:
1.Body/Centrum
2. Vertebral arch
Regional differences in Vertebrae
1. Lumbar
2. Sacral
3. Coccyx
4. Thoracic
5. Vertebra
6. Cervical
7. Vertebrae
Functions of Skeletal (SMPSB)
1. Support
2. Protection
3. Movements
4. Storage
5. Blood Cell Production
Type accdg to SHAPE (LIFS)
1.
2.
3.
4.
Long bones
Short bones
Flat bones
Irregular bones
Parts of the long bones (DEEPAE/MAPE-3D)
1.
2.
3.
4.
5.
6.
7.
Diaphysis
Epiphyses
Periosteum
Articular Cartilage
Epiphyseal Plate
Epiphyseal line
Medullary cavity
 Marrow
5|Skeletal system
o
o
Yellow Marrow
Red Marrow
Layers of Bones (PEB)
1. Periosteum
2. Bone substance
3. Endosteum
2 DIVISION OF SKELETAL SYSYTEM (AA)
1. Axial Skeleton (skull, vertebral column, rib cage)
2. Appendicular skeleton (pectoral girdle, upper limb, pelvic girdle, lower limb)
2 SETS OF SKULL BONES
1. Braincase/cranium
2. Facial bones
2 BASIC TYPES OS BONE TISSUES (CS)
3. Compact bone
 Central /Harvesian Canal
 Osteon/Harvesian System
4. Spongy/Cancellous bone
 Trabeculae
PARTS OF A VERTEBRA:
1.Body/Centrum
2. Vertebral arch
Regional differences in Vertebrae
1. Lumbar
2. Sacral
3. Coccyx
4. Thoracic
5. Vertebra
6. Cervical
7. Vertebrae
PELVIC GIRDLE
-
Where lower limbs attach to the body
2 coxal bones, sacrum, coccyx
6|Skeletal system
I. COXAL BONES (hip bones)
-
Join ach other anteriorly & sacrum posteriorly to form ring of bone (P.G)
3 bones:
1. Ilium - superior
2. Ischium – posterior, inferior, “sit-down bone”
3. Pubis – inferior, anterior








Iliac Crest – seen along superior margin of ilium; INJECTIONS
Anterior Superior Iliac Spine – anterior of iliac crest
Iliac fossa - medial
Greater Sciatic Notch - posterior
Pubic Symphysis – where coxal bones join anteriorly
Acetabulum – socket that receives the head of femur
Sacroliac Joints- join sacrum posteriorly
Obturator Foramen – large hole in coxal bone
*Male pelvis – larger
*Female pelvis – broader
II. LOWER LIMBS
1. Thigh

Femur - only bone in thigh; heaviest & strongest
PARTS:
1.
2.
3.
4.
Head
Condyles
Epicondyles
Greater Trochanters
2. Leg

Tibia
- shinbone
- larger and more medial
- medial malleolus

Fibula
- thin and sticklike that forms the lateral side of the leg
- lateral malleolus
7|Skeletal system
* Broken hip – break in femoral neck
* Patella - kneecap
3.
Ankle
- 7 tarsal bones







Calcaneus – ankle bone
Talus – heel bone
Cuboid
Navicular
Medial Cuneiform
Lateral Cuneiform
Intermediate Cuneiform
4. Foot
- base, shaft, head
- 14 phalanges
III. JOINTS
-
Where two bones come in contact
Functional Classification
1. Synarthrosis – immovable
2. Amphiarthrosis – Slight
3. Diarthrosis – movable
Structural Classification
1. Fibrous
- synarthrosis
a. Sutures- skull bones
b. fontanels – soft spots; anterior, posterior
c. syndesmosomes – bones are separated; held by ligaments (radius, ulna)
d. gomphoses – pegs fitted into sockets (tooth)
8|Skeletal system
2. Cartilaginous
- bone ends
- amphiarthrosis
e.g. epiphyseal plaes, fibrocartlilage
3. Synovial
– diarthrosis; contains synovial fluid surrounds end of articular joints
a. articulating cartilage – cover articulating surfaces
b. joint cavity – filled with synovial fluid
c. joint capsule - encloses cavity;
d. Synovial Membrane-lines the cavity everywhere except over the articular cartilage
e. Synovial fluid-produced by the synovial membrane
-made up of polysacc,CHONs,lipids and cells
f.Bursa
-pocket or sac that is an extension of the synovial membrane
-located b/w structures that rub together,such as where a tendon crosses a bone
-reduce friction causing BURSITIS
Types of Synovial Joints
1. Plane/Gliding Joints – two opposed flat surfaces that glide over each other
2. Saddle Joints – consists of 2 saddle-shaped surfaces oriented to each other.
3. Hinge Joints – consists of a convex cylinder of one bone applied to the other
concave side of the other bone
4. Pivot Joints – consists of a cylindrical bony process that rotates within a ring
composed partly of bone and partly ligament
5. Ball-and-socket Joint – consists of a ball in one end and a socket in the adjacent
bone in which part of the ball fits
6. Condyloid/Ellipsoid Joint – elongated ball-and-socket joint
TYPES OF MOVEMENT
 Flexion/Extension
 Abduction/Adduction
 Pronation/Supination
 Eversion/Inversion
 Rotation
 Protraction/Retraction
 Elevation/Depression
 Excursion
 Opposition/Reposition
 Circumduction
PARTS OF THIGH (HECG)
1.
2.
3.
4.
Head
Condyles
Epicondyles
Greater Trochanters
9|Skeletal system
COXAL BONES
1. Ilium
2. Ischium
3. Pubis
7 TARSAL BONES OF ANKLE
1.
2.
3.
4.
5.
6.
7.
Calcaneus
Talus
Cuboid
Navicular
Medial Cuneiform
Lateral Cuneiform
Intermediate Cuneiform
PROXIMAL – NTC
DISTAL – MILC
FOOT
1. Metatarsal
2. Phalanges
10 | S k e l e t a l s y s t e m
11 | S k e l e t a l s y s t e m