The Skeleton Bones & Joints Chapter 7

Bones Main Functions: Framework for the body Protect delicate structures (such as the brain & spinal cord) Work with attached muscles to provide movement Store calcium which is reabsorbed into the blood when there is not enough calcium in the diet Produce red blood cells (in the bone marrow)

Skeletal Structure 206 bones Skeleton is the complete bony framework of the body Different shapes include: FLAT – ribs & cranium (skull) SHORT – wrist & ankles IRREGULAR – face & vertebrae LONG – arms & legs

Bone Tissue Osseous Tissue (bone tissue) is made up of 2 types of tissue: COMPACT BONE – hard & dense; makes up the main part of long bones and the outer layer of other bones SPONGY BONE (cancellous bone) – has more spaces than compact bone & is made of a meshwork of small, bony plates filled with red marrow; found at the center of bones & ends of long bones

Bone Marrow Red Marrow – found at the ends of long bones & center of other bones; manufactures blood cells Yellow Marrow – found mainly in the central cavities of the long bones & comprised primarily of fat

Bone Membranes Periosteum – covers the outside ( except at the joints) of the bone Osteoblasts make up the inner layer Essential in bone formation, growth and repair Endosteum – a thinner membrane that lines the marrow cavity Contains cells that aid in the growth and repair of bone tissue

Bone Growth & Repair In the embryo, bones are composed of cartilage. During the 2nd & 3rd months of embryonic life, bones start to OSSIFY Osteoblasts become active OSSIFICATION – is the hardening and strengthening of bone tissue (due to the addition of minerals, such as calcium and phosphorus) Conversion of cartilage to bone **Long bones continue to grow into late teens

Bone Markings Distinguishing features that include: Raised areas or depressions that help form joints, attach muscles and/or allow passage of nerves & blood vessels

Projections Head – is the rounded, knob-like end of a bone (as in the end of the humerus) Process – large projection of bone (as in the elbow) Crest – a distinct border or ridge (as in the hip) Spine – sharp projection of bone (as in the scapula “shoulder blade”) Condyle - a rounded projection

Depressions or Holes Foramen – hole that allows a vessel or nerve to pass through or between bones Sinus – is an air space (found in some skull bones) Fossa – a depression found on bone surfaces Meatus - a short channel or passageway, such as the channel in the temporal bone of the skull that leads to the inner ear

The Axial Skeleton One of two main division of the skeleton Contains 80 bones of the skull and trunk Cranium - 8 Facial Bones - 14 Ear Bones - 3 plus 1 for the tongue Trunk Vertebrae Spine - 26 in the adult Thorax Ribs - 12 pairs Sternum – anterior bone of thorax

The Appendicular Skeleton Second division of the skeleton Contains 126 bones of the extremities (limbs), shoulders and hips Clavicle & scapula > shoulder Humerus, ulna & radius > arm Carpals > wrist Metacarpals > palm Phalanges > fingers Os Coxae > pelvis Femur > thigh bone Patella > knee cap Tibia & Fibula > bones of the lower leg Tarsals > ankle Metatarsals > foot Phalanges > toes

Metabolic Bone Disorders Osteoporosis is a lack of normal calcium and decrease in bone protein

Paget’s Disease An abnormal calcium metabolism that causes bones to lose calcium followed by periods of excessive deposits of calcium which result in bone deformities

Rickets Rare childhood disease Caused by a deficiency of Vitamin D Bones remain soft & become distorted because they cannot absorb calcium

Structural Bone Disorders Scoliosis is a LATERAL curvature of the spine Occurs during rapid growth periods Occurs more often in girls than in boys

Kyphosis An exaggeration of the THORACIC curve Also referred to as “HUNCHBACK”

Lordosis An excessive LUMBAR curve Also referred to as “SWAYBACK”

Cleft Palate A congenital deformity with an opening in the roof of the mouth

Flat Foot Tendons & ligaments are weakened near the arch of the foot Can be caused by: Carrying excess weight Poor posture Heredity

The Joints Areas of junction or union between two or more bones Three types: Fibrous Cartilaginous Synovial

Fibrous Joints Bones in this type of joint are held together by fibrous connective tissue An example would be the joints that hold the bones of the skull together This type of joint is IMMOVABLE

Cartilaginous Joints Bones in this type of joint are held together by cartilage An example would be the joints between the bodies of the vertebrae This type of joint is SLIGHTLY movable

Synovial Joints Filled with a thick, colorless fluid called synovial fluid Bones in this type of joint have space between them called a synovial cavity This type if joint is FREELY movable

Movement at Synovial Joints Flexion – bending motion that decreases the angle between bones Extension – straightening motion that increases the angle between bones

Abduction – movement away from the mid-line of the body Adduction – movement towards the mid-line of the body

Circumduction is a combination of flexion, extension, abduction & adduction Rotation is the twisting or turning of a bone on it’s axis

Supination is the act of turning the palm up Pronation is the act of turning the palm down

Inversion is the act of turning the sole inward Eversion is the act of turning the sole outward

Dorsiflexion is the act of pointing the toes upward, decreasing the angle between the lower leg and the top of the foot Plantarflexion is the act of pointing the toes downward, increasing the angle between the lower leg and the top of the foot

Joint Disorders Dislocations are a derangement of the parts of the joint

Arthritis Inflammation of the joints

Gout Overproduction of uric acid (a waste product in the blood) that causes crystals to form and settle around the joints

Backaches Causes can include: Infections Tumors Disk problems Abnormal vertebral structure Organ disease (especially the kidney) Strains