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The SkeletonBones & Joints

Chapter 7

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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)

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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

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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

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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

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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

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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

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Bone Markings

Distinguishing features that include: Raised areas or depressions that help form

joints, attach muscles and/or allow passage of nerves & blood vessels

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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

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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

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The Axial SkeletonOne of two main division of the skeletonContains 80 bones of the skull and trunk

Skull 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

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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

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Metabolic Bone Disorders

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

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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

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Rickets

Rare childhood disease

Caused by a deficiency of Vitamin D

Bones remain soft & become distorted because they cannot absorb calcium

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Structural Bone Disorders

Scoliosis is a LATERAL curvature of the spine

Occurs during rapid growth periods

Occurs more often in girls than in boys

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Kyphosis

An exaggeration of the THORACIC curve

Also referred to as “HUNCHBACK”

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Lordosis

An excessive LUMBAR curve

Also referred to as “SWAYBACK”

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Cleft Palate

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

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Flat Foot

Tendons & ligaments are weakened near the arch of the foot

Can be caused by: Carrying excess

weight Poor posture Heredity

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The Joints

Areas of junction or union between two or more bones

Three types: Fibrous

Cartilaginous

Synovial

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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

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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

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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

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Movement at Synovial Joints

Flexion – bending motion that decreases the angle between bones

Extension – straightening motion that increases the angle between bones

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

Adduction – movement towards the mid-line of the body

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Circumduction is a combination of flexion, extension, abduction & adduction

Rotation is the twisting or turning of a bone on it’s axis

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Supination is the act of turning the palm up

Pronation is the act of turning the palm down

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Inversion is the act of turning the sole inward

Eversion is the act of turning the sole outward

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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

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Joint Disorders

Dislocations are a derangement of the parts of the joint

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Arthritis

Inflammation of the joints

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Gout

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

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Backaches

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