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GENERAL ANATOMY- 1 Reviewer Skeletal System For Dentistry FUNCTION OF BONES
- Support
- Protect
- Muscle Attachment
- Hemopoiesis (Red bone marrow)
- Storage of Minerals (Phosphorus, Calcium) HISTOLOGY OF BONES Components:
- Bone Cells
- Matrix o Collagenous fibers: give resilience to bones o Calcified ground substance: gives hardness to bones (Calcium phosphate, Calcium carbonate) Bone Cells:
- Osteoblasts: embryonic bone cells active in bone formation
- Osteocytes: mature osteoblasts
- Osteoclasts: bone resorption and remodeling Maintaining the Bone:
- Controlled by endocrine system
- Parathormone (PTH): released during hypocalcemia, causes calcium release from bone and increases blood calcium
- Calcitonin: released during hypercalcemia, promotes calcium deposition into bones and decreases blood calcium CLASSIFICATION OF BONES According to Structure:
- Compact (Dense)
- Spongy (Cancellous) According to Shape:
- Long
- Short
- Flat
- Irregular
- Sesamoid (develops within a tendon) According to Development:
- Endochondral (Cartilaginous): formed via endochondral ossification (cartilage → bone)
- Intramembranous: formed via intramembranous ossification (membrane → bone)
- Note: Clavicle is the first bone to start developing (5th week intrauterine) According to Location:
- Axial skeleton: 80 bones
- Appendicular skeleton: 126 bones AXIAL SKELETON Skull:
- Cranial bones (8): Frontal, Ethmoid, Sphenoid (unpaired), Occipital, Parietal (paired), Temporal (paired)
- Facial bones (14): Vomer (unpaired), Mandible, Nasal, Lacrimal, Zygomatic (paired), Maxillae (paired), Palatine (paired), Inferior nasal concha (paired) Others:
- Ossicles
- Hyoid
- Sternum
- Ribs
- Vertebrae Cranial Details:
- Calvarium: Frontal, Parietal, Temporal, Sphenoid, Occipital
- Pterion: H-shaped union of Frontal, Parietal, Sphenoid, Temporal bones Related to middle meningeal artery, common site of epidural hemorrhage
- Sutures: Coronal, Sagittal, Lambdoidal
- Fontanelles: Anterior (soft spot), Posterior STERNUM
- Parts: Manubrium, Body, Xiphoid process
APPENDICULAR SKELETON
Pectoral Girdle Humerus Radius / Ulna Carpals / Metacarpals / Phalanges Pelvic Girdle Tarsals / Metatarsals / Phalanges JOINTS / ARTICULAR SYSTEM According to Mobility:
- Synarthrosis (immovable)
- Amphiarthrosis (slightly movable)
- Diarthrosis (freely movable) According to Intervening Structure:
- Fibrous (sutures, gomphosis, schindylesis, syndesmosis)
- Cartilaginous (symphysis, synchondrosis)
- Synovial Synovial Joints: With a fibrous capsule around a synovial cavity between bones Types: a. Spheroid (Ball and socket): hip, shoulder b. Ginglymus (Hinge): elbow, ankle, knee c. Trochoid (Pivot): atlantoaxial, superior radio-ulnar d. Condyloid: metacarpophalangeal e. Ellipsoid: radiocarpal (condyloid and ellipsoid sometimes considered same) f. Sellar (Saddle): trapezium and metacarpal of thumb g. Plane: between carpal bones FLASHCARDS Q: What are the five main functions of bones? A: Support, protect, muscle attachment, hemopoiesis, and storage of minerals (phosphorus, calcium).
Q: Name the three main types of bone cells and their functions. A: Osteoblasts (bone formation), osteocytes (mature bone cells), osteoclasts (bone resorption and remodeling). Q: What is the difference between compact and spongy bone? A: Compact bone is dense and solid; spongy bone is porous and lighter. Q: List the five classifications of bones according to shape. A: Long, short, flat, irregular, sesamoid. Q: What type of ossification forms bones like the clavicle? A: Intramembranous ossification. Q: How many bones are in the axial skeleton? A: 80 bones. Q: Name the four bones forming the pterion. A: Frontal, parietal, sphenoid, temporal. Q: What are the three types of ribs based on attachment? A: True (vertebro-sternal), false (vertebro-chondral), floating (vertebral). Q: What vertebrae are considered atypical cervical vertebrae? A: C1 (Atlas), C2 (Axis), C7 (Vertebra prominens). Q: Name the three types of joints based on mobility. A: Synarthrosis (immovable), amphiarthrosis (slightly movable), diarthrosis (freely movable). Q: What are the seven types of synovial joints? A: Spheroid (ball and socket), ginglymus (hinge), trochoid (pivot), condyloid, ellipsoid, sellar (saddle), plane. Q: Explain the role of osteoclasts in bone maintenance. A: Osteoclasts break down bone tissue (resorption), which is important for bone remodeling and calcium regulation. Q: Why is the pterion clinically significant? A: It is the site of the middle meningeal artery underneath; trauma here can cause epidural hemorrhage. Q: What distinguishes sesamoid bones from other bone types? A: Sesamoid bones develop within tendons. Q: Describe the characteristics of a typical thoracic vertebra. A: Heart-shaped body, costal facets on body and transverse processes, long pointed spinous process angled downwards.
