BIO 223 Exam 2

Organs of the skeletal system 

Bones of the skeleton. Cartilage, ligaments, and other connective tissue that stabilizes or connect bones 

Functions of skeletal system

Support, storage of minerals, and lipids. Blood cell production, protection and leverage

Bones are classified by their

Shape and structure

Sutural bones 

Small, flat, oddly shaped bones found between flat bones of the skull 

Irregular bones

Complex shapes with short, flat, notched or ridged surfaces (vertebrae, pelvis)

Short bones 

Boxlike in appearance, (carpals and tarsals) 

Flat bones

Thin parallel surfaces, Flat bones for the roof of the skull, sternum, ribs, and the scapulae. Provides protection for underlying soft tissue

Long bones

Long and slender. Heaviest bone in the body

Sesamoid bones

Small, round, and flat. Found near joints of knees, hands, and feet. 

Structure of long bone - Diaphysis (Shaft)

Wall of compact bone. Central space called the medullary cavity (marrow cavity)

Structure of long bone - Epiphysis

Wide part of each end. Mostly spongy bone (trabecular bone)

Structure of long bone - Metaphysis

Where diaphysis and epiphysis meet

Structure of flat bone

Consist of spongy bone between 2 layers of compact bone.

Within the cranium, the layer of spongy bone is called the

Diploe

Characteristics of bone

Dense matrix due to deposits of calcium salts. Osteocytes within lacunae. Canaliculi and periosteum

Canaliculi

Narrow passageways that allow for exchange of nutrients, wastes, and gases 

Periosteum

Covers outer surfaces of bone. Consists of outer fibrous and inner cellular layers

Bone matrix

Composed of many collagens fibers interwoven with mineral crystals 

Calcium phosphate, Ca3(PO4)2 makes up almost ____ of bone mass

Two-thirds

Matrix proteins

About one-third of bone mass is collagen fibbers.

Bone cells

Make up only 2% of bone mass.

4 types of bone cells

Osteogenic cells, Osteoblasts, Osteocytes, and Osteoclasts 

Compact bone - Osteon

Functional unit of compact bone

Contains blood vessels

Central canal

Perforating canals

Perpendicular to surface of bone. Carry blood vessels into deep bone and marrow 

Lamellae

Layers of bone matrix

Arranged parallel to the long axis of a long bone. Makes bone very strong along this axis, Weaker along perpendicular axis

Osteons 

lacks osteons

Spongy bone

Spongy bone matrix

Forms an open network of trabeculae. Lacks capillaries and venules

Red bone marrow

Fills space between trabeculae. Forms blood cells, contains blood vessels that supply nutrients to osteocytes by diffusion 

Yellow bone marrow

Found in other sites of spongy bone. Stores fat

Periosteum

Membrane that covers outside of bones except within joint cavities, Outer, fibrous layer and inner, cellular layer, Fibers are interwoven with those of tendon. Perforating fibers incorporate into bone tissue with increase strength of attachments

Periosteum functions

Isolates bone from surrounding tissues, Provide a route for blood vessels and nerves and participates in bone growth and repair 

Endosteum

Incomplete cellular layer that lines medullary cavity. Active during bone growth, repair, and remodeling. Covers trabeculae of spongy bone. Lines central canals of compact bone. Consists of flattened layer of osteogenic cells 

Bone development - Ossification (osteogenesis) 

Bone formation. 

2 forms of ossification

Endochondral and intramembranous ossification

Bone development - Calcification

Depositions of calcium salts. Occurs during ossification

Endochondral ossification

How most bones form.

Primary ossification center

Develops inside diaphysis of hyaline cartilage model. Cartilage is gradually replaced by bone

Secondary ossification center

Develops inside epiphyses of hyaline cartilage model. Cartilage is gradually replaced by bone 

Appositional growth

Growth in width. Thickens and strengthens long bones. Layers of lamellae are added at out surface. During this process, osteoclasts slowly remove bone matrix at inner surface of bone, enlarging medullary cavity. 

Intermembranous ossification

Occurs when osteoblasts differentiate within a fibrous connective tissue. Also called dermal ossification (happens in deep layers of the dermis)

Produces dermal bones such as flat bones of skull, mandible (lower jaw), and clavicles (collarbones) 

Intermembranous ossificiation 

Bone remodeling

Occurs throughout life. Functions in bone maintenance, By recycling and renewing bone matrix. Involves osteocytes, osteoblasts, and osteoclasts.

Bone remodeling - effects of exercise on bone

Mineral recycling allows bone to adapt to stress. Heavily stressed bones become thicker and stronger. Exercise, particularly weight-bearing exercise, stimulates osteoblasts 

Bone degeneration

Bone degenerates quickly. Up to one-third of bon e mass can be lost in a few weeks of inactivity.

Which 2 hormones help stimulate bone growth

Growth hormone and thyroxine

Hormonal effects on bone growth - Sex hormones

Estrogen and testosterone stimulates osteoblasts and estrogen triggers epiphyseal closure faster than testosterone 

Which 2 hormones maintain calcium ion homeostasis

Parathyroid hormone and calcitonin  

4 steps for fracture repair

1. Fracture hematoma formation 

2. Callus formation 

3. Spongy bone formation 

4. Compact bone formation 

Fracture hematoma formation 

Production of large blood clot. establishes a fibrous network. Bone cells in the area die 

Callus formation

Cells of the endosteum and periosteum divide and migrate into fracture zone. Calluses stabilizes the break. Internal callus develops medullary cavity. External callus of cartilage and bone surrounds break

Spongy bone formation

Osteoblasts replace central cartilage of external callus with spongy bone

Compact bone formation

Repaired bone may be slightly thicker and stronger than normal

Joints (articulations)

Where two bones meet. Where body movement occurs

What trade off exist for joints

Between strength and mobility

Classification of Joints - Structural Anatomy

Fibrous, Cartilaginous, Bony, and Synovial

Classification of Joints - Functional range of motion

Synarthrosis, Ampiarthrosis, and Diathrosis.

Synarthrosis 

Immovable joint. Very strong, Edges of bones may touch or interlock. May be fibrous, cartilaginous, or bony.

4 types of synarthrotic joints 

Suture (fibrous), Gomphosis (fibrous), Synchondrosis (cartilaginous), and Synotosis (bony) 

Synarthrosis - Suture

Found only between bones of skull. Edges of bones interlock. Bound by dense fibrous connective tissue 

Synarthrosis - Gomphosis 

Binds teeth to bony sockets. Fibrous connections (periodontal ligament) 

Synarthrosis - Synchondrosis 

Rigid cartilaginous bridge between two bones. Found between vertebrosternal ribs and sternum. Also, epiphyseal cartilage of growing long bones

Synarthrosis - Syntosis 

Created when two bones fuse. 

Amphiarthrosis

Slightly moveable joint. More movable than a synarthrosis. Stronger than a diarthrosis. May be fibrous or cartilaginous. Two types of amphiarthroses. 

Amphiarthrosis - Syndemosis 

Bones connected by a ligament. Bones are joined by an interosseous membrane pr ligament. Radius with ulna, tibia with fibula

Amphiarthrosis - Symphysis 

Bones connected by fibrocartilage. Joint where bones are united by a fibrocartilage pad or plug. Best suited for regions of skeleton that must resist compression. Intervertebral joints and pubic symphysis 

Diarthrosis

Freely movable joint

Diarthrosis - Synovial joint 

Freely movable joint. At end of long bones. Surrounded by joint capsule (articular capsule). Contains synovial membrane. 

Diarthrosis - Articular cartilage 

Covers articulating surfaces. Prevents contact between bones 

Fibrous joints

Fastened together by dense regular connective tissue without a joint space between articulating bone

Cartilaginous joints

Fastened together with cartilage without a joint space

Bony joints

Form when fibrous or cartilaginous joints fully ossify

Synovial joints 

Joints have a layer of hyaline cartilage on articulating surface of each bone. Joint space is a fluid-filled cavity found between articulating bone. 

Synovial fluid

Has the consistency of egg yolk. Contains proteoglycans. Primary functions include lubrication, nutrient distribution and shock absorption

What accessory structure stabilizes synovial joints

Cartilages and fat pads. Ligaments, tendons, and bursae

Synovial joints - Cartilages (Meniscus)

Fibrocartilage pad between opposing bones

Synovial joints - Fat pads

Adipose tissue covered by synovial membrane. Protect articular cartilages

Synovial joints - Ligaments

Support and strengthen joints

Synovial joints - Tendons

Attach muscle around joint

Synovial joints - Bursae

Small pockets of synovial fluid. Cushion areas where tendons or ligaments rub against other tissues

Monaxial

1 Plane. Superior-inferior axis. (elbow)

Biaxial

2 planes. Superior-inferior and lateral-medial axis (wrist)

Triaxial

3 planes. Superior-inferior, lateral-medial, and anterior-posterior axes (shoulder)

Gliding movement (synovial joints)

When 2 flat surfaces slide past each other. (ex. between carpals, tarsals, clavicles with sternum) 

Flexion (angular movement)

Decrease angle between articulating bones

Extension (angular movement)

Increase angle between articulating bones

Hyperextension (angular movement)

Extension past anatomical position

Abduction (angular movement)

Movement away from longitudinal axis

Adduction (angular movement)

Movement towards longitudinal axis

Circumduction

A complete circular movement without rotation

Rotational movement

Rotation in reference to anatomical position. Limb rotation is relative to longitudinal axis of the body 

Medial rotation (rotational movements)

Internal rotation toward long axis 

Lateral rotation (rotational movements)

External rotation away from body

Pronation (rotational movements)

Rotates forearm so that radius rolls across ulna. Results in palm facing posteriorly

Supination (rotational movements)

Turns palms anteriorly. Forearm is supinated in anatomical position

Inversion (special movement)

Twists sole of foot medially

Eversion (special movement)

Twist sole of the foot laterally

Dorsiflexion (special movement)

Flexion at ankle (lifting toes)