Human Anatomy 205

Functions of Skeletal System
[Support, protection, movement, hemopoiesis, fat storage, mineral storage]

Four Basic Shapes of bones [long, short, flat, irregular]
Gross Anatomy of a long bone. See bone structure
- The tubular shaft is the diaphysis.
- On the distal and proximal end of the diaphysis is an epiphysis.
- Each epiphysis has an articular surface
- Both spongy bone and compact bone are found in most bones
- Red bone marrow in spongy bone contains hemopoietic tissue
- A periosteum of dense regular connective tissue is on the surface of bones
Histology
- Bone Cells [Osteoblast] [Osteocyte] [Osteoclast]
- Osteogenic cells = stem cells [within central canal]
- Matrix [area between cells containing collagen + minerals (Ca salts)]
- Marrow is soft tissue in bone cavity. [red marrow in spongy bone]
- Compact bone tissue shows a haversian pattern around central canal
- Spongy (cancellous) bone [lattice of spicules and trabeculae] microscopic view
Two Types of Bone Development
1. Endochondral ossification - skeletal component is first modeled in cartilage; then replaced by bone [most skeletal elements]
2. Intramembranous ossification bone forms directly in sheet-like fibrous connecitve tissue membranes. [skull bones in dermis]
3. Intramembranous also forms directly in tendons [sesmoid bones - patella]

Bones to Study & Organization of Skeletal System

AXIAL SKELETON

Skull - See Camelet's Bone List
- 8 cranial bones
  - Inferior cranial - ethmoid, sphenoid, occipital
  - Superior cranial - frontal, parietals
  - Lateral cranial - temporals
  - Sutural or Wormian Bone along lambdoidal suture
- 14 facial bones
  - Mandible, maxilla and palatine
  - Nasal, lacrimal, vomer, and zygomatic
The Lab Skulls [lateral view] [cranial cavity] [inferior view]
Interactive skull [lateral view] [lateral view] [frontal view]
Hyoid
Vertebral Column see interactive anatomy of spine
- 5 types: (7 cervical, 12 thoracic, 5 lumbar, and sacral,plus the coccygeal)
- Typical vertebrae
- Vertebrae from the anatomy lab
  - Compare cervical, thoracic, lumbar [superior view] [inferior view]
  - Cervical Vertebrae (1 & 2) [atlas & axis]
  - Thoracic [lateral view]
Sternum [manubrium, body, xiphoid process]
Ribs [head, neck, tubercle, body]
- True ribs (1-7)- costal cartilage attaches to sternum
- False ribs (8,9 & 10)- lack direct attachment to sternum
- Floating ribs (11 & 12)- no attachement to sternum

APPENDICULAR SKELETON

Pectoral Girdle [clavicle & scapula] see posterior view of shoulder
Pectoral Appendage
- Brachium - humerus [25]
- Antebrachium - ulna [27], radius [26]
- Hand - carpals, metacarpals, phalanges
Lab Skeleton
Pelvic Girdle [os coxae] and
Pelvic Appendage
- Thigh - femur
- Leg - tibia, fibula anterior view
- Foot - tarsals, metatarsals, phalanges
Lab Skeleton [distal leg & foot]

Click area on skeleton to view lab bones
map of human skeleton

[ Skeletal image map ]

Study & Tutorial Links for Skeletal System

Classification of Joints

By structure [fibrous, cartilage, synovial]
By movement [snyarthrotic (immoveable), amphiarthrotic (slightly), diathrotic (moveable)]
Fibrous Joints
- Sutures are synarthrotic (immoveable) skull joints * * See skull sutures
- Syndesmosis are amphiarthrotic [distal ends of radius & ulna; tibia & fibula]
- Gomphoses
Cartilagenous Joints
- Symphysis are amphiarthrotic [pubic symphysis and intervertebral discs]
- Synchondroses are synarthrotic [between epiphysis and diaphysis]
Synovial Joint has fluid between articulating bones. See Structure
- Fibrous capsule + synovial membrane
- Synovial cavity (joint cavity) contains a lubricating synovial fluid
- Articular cartilage cover the ends of the articulating bones
- Menisci are fibrocartilage pads between articulating bones in knee joint.
- Ligaments stabilize the joint [anterior knee] [posterior knee]
- Bursae are flattened sacs filled with synovial fluid which cushion friction points of joints
- See lab models of joints [Interactive shoulder] [hip] [knee]
Six types of synovial joints * See information with animations
1. Gliding [carpals]
2. Hinge [knee] [knee diagram]
3. Pivot [atlas to axis]
4. Condyloid [metacarpal to proximal phalynx]
5. Saddle [first metacarpal to carpal]
6. Ball-and-Socket [hip]

Movements at Synovial Joints.

Angular movements
- Flexion [decrease joint angle], extension [increase joint angle]
- Hyperextension [increase joint angle beyond 180^o]
- Adduction [movement of body part toward midline], abduction [movement of body part away from midline]
- Plantar flexion [extension of foot at ankle] and dorsiflexion [fexion of foot at ankle]
- Inversion [move sole of foot medially] and eversion [move sole of foot laterally]
Circular movements
- Rotation, circumduction
- Supination [rotation of forearm turns palm up or anterior], pronation [rotation of forearm turns palm down or posterior]
Muscles in Action - Shows movement at joints.
Biomechanics of body movement (Three classes of levers)

Lab skeletons and bones

Test yourself at these links

Human Anatomy On Line: link to skeletal system

Dynamic Human
at McGraw-Hill