The Skeleton Bones Joints Chapter 7 1 Bones

The Skeleton Bones & Joints Chapter 7 1

Bones o Main Functions: n Framework for the body n Protect delicate structures (such as the brain & spinal cord) n Work with attached muscles to provide movement n Store calcium which is reabsorbed into the blood when there is not enough calcium in the diet n Produce red blood cells (in the bone marrow) 2

Skeletal Structure o 206 bones o Skeleton is the complete bony framework of the body o Different shapes include: n FLAT – ribs & cranium (skull) n SHORT – wrist & ankles n IRREGULAR – face & vertebrae n LONG – arms & legs 3

Bone Tissue o Osseous Tissue (bone tissue) is made up of 2 types of tissue: n COMPACT BONE – hard & dense; makes up the main part of long bones and the outer layer of other bones n 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 4

Bone Marrow o Red Marrow – found at the ends of long bones & center of other bones; manufactures blood cells o Yellow Marrow – found mainly in the central cavities of the long bones & comprised primarily of fat 5

Bone Membranes o Periosteum – covers the outside ( except at the joints) of the bone n Osteoblasts make up the inner layer p Essential in bone formation, growth and repair o Endosteum – a thinner membrane that lines the marrow cavity n Contains cells that aid in the growth and repair of bone tissue 6

Bone Growth & Repair o In the embryo, bones are composed of cartilage. During the 2 nd & 3 rd months of embryonic life, bones start to OSSIFY n Osteoblasts become active o OSSIFICATION – is the hardening and strengthening of bone tissue (due to the addition of minerals, such as calcium and phosphorus) n Conversion of cartilage to bone **Long bones continue to grow into late teens 7

Bone Markings o Distinguishing features that include: n Raised areas or depressions that help form joints, attach muscles and/or allow passage of nerves & blood vessels 8

Projections o Head – is the rounded, knob-like end of a bone (as in the end of the humerus) o Process – large projection of bone (as in the elbow) o Crest – a distinct border or ridge (as in the hip) o Spine – sharp projection of bone (as in the scapula “shoulder blade”) o Condyle - a rounded projection 9

Depressions or Holes o Foramen – hole that allows a vessel or nerve to pass through or between bones o Sinus – is an air space (found in some skull bones) o Fossa – a depression found on bone surfaces o Meatus - a short channel or passageway, such as the channel in the temporal bone of the skull that leads to the inner ear 10

The Axial Skeleton One of two main division of the skeleton Contains 80 bones of the skull and trunk o Skull n Cranium - 8 n Facial Bones - 14 n Ear Bones - 3 plus 1 for the tongue o Trunk n Vertebrae p Spine - 26 in the adult n Thorax p Ribs - 12 pairs p Sternum – anterior bone of thorax 11

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The Appendicular Skeleton o Second division of the skeleton o Contains 126 bones of the extremities (limbs), shoulders and hips n n n 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 13

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Metabolic Bone Disorders o Osteoporosis is a lack of normal calcium and decrease in bone protein 21

Paget’s Disease o An abnormal calcium metabolism that causes bones to lose calcium followed by periods of excessive deposits of calcium which result in bone deformities 22

Rickets o Rare childhood disease o Caused by a deficiency of Vitamin D o Bones remain soft & become distorted because they cannot absorb calcium 23

Structural Bone Disorders o Scoliosis is a LATERAL curvature of the spine o Occurs during rapid growth periods o Occurs more often in girls than in boys 24

Kyphosis o An exaggeration of the THORACIC curve o Also referred to as “HUNCHBACK” 25

Lordosis o An excessive LUMBAR curve o Also referred to as “SWAYBACK” 26

Cleft Palate o A congenital deformity with an opening in the roof of the mouth 27

Flat Foot o Tendons & ligaments are weakened near the arch of the foot o Can be caused by: n n n Carrying excess weight Poor posture Heredity 28

The Joints o Areas of junction or union between two or more bones o Three types: n Fibrous n Cartilaginous n Synovial 29

Fibrous Joints o Bones in this type of joint are held together by fibrous connective tissue o An example would be the joints that hold the bones of the skull together o This type of joint is IMMOVABLE 30

Cartilaginous Joints o Bones in this type of joint are held together by cartilage o An example would be the joints between the bodies of the vertebrae o This type of joint is SLIGHTLY movable 31

Synovial Joints o Filled with a thick, colorless fluid called synovial fluid o Bones in this type of joint have space between them called a synovial cavity o This type if joint is FREELY movable 32

Movement at Synovial Joints o Flexion – bending motion that decreases the angle between bones o Extension – straightening motion that increases the angle between bones 33

o Abduction – movement away from the mid-line of the body o Adduction – movement towards the mid-line of the body 34

o Circumduction is a combination of flexion, extension, abduction & adduction o Rotation is the twisting or turning of a bone on it’s axis 35

o Supination is the act of turning the palm up o Pronation is the act of turning the palm down 36

o Inversion is the act of turning the sole inward o Eversion is the act of turning the sole outward 37

o Dorsiflexion is the act of pointing the toes upward, decreasing the angle between the lower leg and the top of the foot o Plantarflexion is the act of pointing the toes downward, increasing the angle between the lower leg and the top of the foot 38