Skeletal System A&P Week 11

Skeletal System A&P Week 11

Bones 206 bones in the body Smallest are in the middle ear cavity Malleus, incus, stapes

Functions of Bone Framework and support Protection Contains/protects red bone marrow Storage site for calcium

Types of Bone Tissue Osteocytes Osteoblast osteoclast Bone matrix Compact bone Osteons (Haversian systems) Haversian canals Spongy Bone Red bone marrow

Classification based on Shape Four groups 1) Long bones longer than wide, shaft with heads at both ends, mostly compact bone, all bones of limbs except patella, wrist, ankle 2) Short bones cube shaped, mostly spongy, wrist, ankle, sesamoid bones 3) Flat bones thin, flattened, usually curved, outer layers of compact bone sandwich spongy, skull, ribs, sternum http://www.aclasta.co.nz/osteoporosis/index.htm 4) Irregular bones don t fit previous categories, hip bones, vertebrae

Long Bones

Structure of a Long Bone Medullary cavity 1) adults - yellow marrow 2) infants red marrow - in adults red marrow confined to spongy bone of flat bones and epiphyses of some long bones Bone Markings Table 5.1 projections vs depressions ex. Trochanter, Foramen http://www.curehandpain.com/images/bone/long_bone.gif

Short Bones Nearly cube shaped Smaller, more complex movements

Flat Bones Thin, flattened May curve sternum, scapulae, ribs, and most of the skull bones

Irregular Bones Facial bones Spine

Sesamoid Bones Small bones Held within tendons

Yellow bone marrow is mostly what tissue? What does an osteon consist of? What does the periosteum anchor and where do these come from?

Bone Growth Embryonic skeleton is cartilage and fibrous connective tissue Bone matrix produced by osteoblasts Ossification begins in a center of ossification in each bone at 3 months gestation Ossification not complete at birth but continues through childhood. In long bones, growth occurs in the epiphyseal discs.

Bone Growth

What cells form the marrow cavity? What hormones promote closure of the epiphyseal discs? Besides growth, when else are oeteoblasts important?

How are the fontanels important during birth? How are the fontanels important after birth?

Factors Affecting Bone Growth and Repair Heredity Nutrition Hormones Chemical communication from other tissues Exercise

Bone Fractures Occur less often in youth, requires exceptional trauma twists or smashes Two types simple or compound Comminuted many fragments Compression crushed Depressed broken bone portion pressed inward (skull) Impacted broken ends forced into each other Spiral ragged break due to twisting Greenstick incomplete break http://www.hivandhepatitis.com/2008icr/ddw/docs/060308_b.html http://www.itim.nsw.gov.au/index.cfm?objectid=2a54ae6d-1321-1c29-707811d2028cc580

Bone Repair Reduction closed or open, immobilization to all healing 1) Hematoma forms blood vessels broken, blood filled swelling 2) Fibrocartilage callus formation mass of repair tissue cartilage matrix, bony matrix, and collagen fibers, act as splint 3) Bony Callus forms osteoblasts and osteoclasts migrate to break, spongy bone callus forms 4) Bone Remodeling permanent patch due to stresses

Repair Dependent on adequate blood supply Stability

Which bones are considered long bones? Which bones are short? Flat? What to flat and irregular bones contain?

Divisions of the Skeleton Axial Skeleton Skull Vertebral column Rib cage Appendicular Skeleton Arms Legs Shoulder girdle Pelvic girdle Ligaments Join bones to one another

The Axial Skeleton Eighty bones segregated into three regions Skull Vertebral column Bony thorax

Thoracic Cage Also known as bony thorax Protects organs in thoracic cavity Made up of sternum, ribs, and thoracic vertebrae What kind of bones are these? http://academic.kellogg.cc.mi.us/herbrandsonc/bio201_mckinley/skeletal.htm

Ribs 12 pair True Ribs 1 st 7 pair Attach to sternum via costal cartilages False Ribs last 5 pair Indirectly or not attached to sternum Floating Ribs last 2 pair Lack sternal attachment Intercostal space filled with intercostal muscle

The Skull The skull, the body s most complex bony structure, is formed by the cranium and facial bones Cranium protects the brain and is the site of attachment for head and neck muscles Facial bones Supply the framework of the face, the sense organs, and the teeth Provide openings for the passage of air and food Anchor the facial muscles of expression

The Brain Case Frontal Parietal Temporal Occipital Sphenoid Ethmoid

Skull: Anterior View Figure 7.2a

Temporal Bone Protects sense organs of hearing Contains auditory meatus: the external ear canal

Occipital Bone Forms most of skull s posterior wall and base Contains the foramen magnum through which the medulla oblongata passes Figure 7.2b

Sphenoid Bone Bat shaped bone that spans the width of the middle cranial fossa Forms the central wedge that articulates with all other cranial bones Consists of a central body, greater wings, lesser wings, and pterygoid processes Major markings: the sella turcica, hypophyseal fossa, and the pterygoid processes Major openings include the foramina rotundum, ovale, and spinosum; the optic canals; and the superior orbital fissure

Sphenoid Bone Figure 7.6a, b

Ethmoid Bone Figure 7.7

What do the maxilla and mandible have in common? In which bones are the structures of the ear? Which bone is the cheekbone? What shape is a fossa?

Facial bones 14 bones Only mandible and vomer are unpaired Only the mandible is moveable Maxillae Nasal bones Lacrimal bones Zygomatic bones Palatine bones

Mandible and Its Markings Figure 7.8a

Sinuses Air cavities Paranasal Open into nasal cavities Lined with ciliated epithelium Mastiod Mastoid process of the temporal bone Mastoiditis

What are the functions of the paranasal sinuses? Into what do these sinuses open?

Vertebral Column Individual bones: vertebrae 7 cervical 12 thoracic 5 lumbar 5 sacral fused to form 1 sacrum 4 to 5 coccygeal fused to form coccyx

Rib Cage 12 pairs of ribs Sternum Manubrium Central body Xiphoid process

Appendicular Skeleton Parts of the appendicular skeleton consist of: a. the skull and vertebral column b. the sternum and rib cage c. arms, legs, hands and feet d. the pectoral and pelvic girdles

Upper Limbs 30 bones Arm Humerus Which type of bone? Forearm Radius, Ulna Hand Carpal (8) wrist Metacarpals (1->5) Phalanges (14) http://commons.wikimedia.org/wiki/file:human_arm_bones_diagram.svg

Shoulders and Arms Shoulder girdles attach arms to axial skeleton Consist of: Scapula Ball and socket joint

Humerus Long bone of the upper arm Deltoid muscle is anchored at the deltoid tuberosity Ball and socket joint with the scapula Hinge joint with the ulna

Forearm Ulna Radius Semilunar notch of ulna is part of the hinge joint Radius and ulna articulate to form a pivot joint permitting pronation and supination of the hand

Wrist and Hand Carpals: 8 small bones in the wrist Gliding joints Metacarpals: 5 bones of the palm Saddle joints permit thumb to cross over the palm Phalanges: finger bones Hinge joints Two phalanges in each thumb, three in each finger

Hip and Leg Pelvic Girdle: AKA Pelvic bone Two hip bones Ilium Ischium Pubis Articulate with axial skeleton at the sacrum

Pelvic Girdle Large and heavy bones Attached to axial skeleton Bearing weight most important function Houses reproductive organs, urinary bladder, part of large intestines http://classes.midlandstech.com/bio112/figure7.23pelvic%20girdle%20and%20hip%20bone.htm

Hip and Leg Acetabulum Ball and socket joint Femural head

Lower Limbs Thigh Femur heaviest, strongest bone in body Leg Tibia, Fibula Foot Tarsals (7) Metatarsals (5) Phalanges (14) Supports weight, level to propel bodies http://www.nlm.nih.gov/medlineplus/ency/imagepages/8844.htm

Leg Femur Tibia Fibula Patella

Foot Tarsals bones of the ankle Calcaneus heel bone Talus Metatarsals phalanges

Joints Where 2 bones meet; articulate Three classifications Synarthrosis: an immoveable joint Amphiarthrosis: Slightly moveable Diarthrosis: Freely moveable

Synarthrosis Immoveable joints Cranial sutures Tooth sockets Joints of the skull

Amphiarthrosis Boney surfaces are joined by a broad, flattened disk of fibrocartilage Symphysis: Between vertebrae Symphysis pubis

Diarthrosis Freely moveable All are synovial joints Contiguous bony surfaces are covered with articular cartilage Connected by ligaments lined by synovial membrane Hinge Ball and socket Saddle Pivot Gliding joint

Synovial Joints Each joint surface covered with articular cartilage Joint enclosed in the strong sheath of the joint capsule Joint capsule is made of fibrous connective tissue Synovial membranes line the capsule Synovial membranes secrete synovial fluid Bursae: sacs of synovial fluid that permit tendons to slide easily

Hinge Joints Knee Elbow Phalanges A convex projection on one bone fits into a concave depression in another permitting only flexion and extension as in the elbow joints

Saddle Joints This type of joint occurs when the touching surfaces of two bones have both concave and convex regions with the shapes of the two bones complementing one other and allowing a wide range of movement. The only saddle joint in the body is in the thumb.

Ball and Socket Joints The ball-shaped end of one bone fits into a cup shaped socket on the other bone allowing the widest range of motion including rotation. Examples include the shoulder and hip.

Pivot Joint Rounded or conical surfaces of one bone fit into a ring of one or tendon allowing rotation. An example is the joint between the axis and atlas in the neck.

Tendons and Ligaments Tendons Connect muscle to bone Tough flexible bands of fibrous tissue Ligaments Long stringy collagen fiber Connect bone to bone Stabilize joints Slightly elastic Double jointed refers to people with more elastic ligaments

Aging and the Skeletal System Bone loses more Calcium than is replaced Matrix becomes thinner Erosion of articular cartilage, esp weight bearing joints, small active joints Prevention: Weight bearing exercise, vit D