Skeletal System6th Period Mr. Morland

Human Anatomy & Physiology

Overview of Skeletal System

Skeletal System

BonesJoints

Cartilage

Ligaments (bone to bone)

Tendons (bone to muscle)

Learning Goals Part 1

1. Describe the functions of the skeletal system2. Differentiate between the 4 types of bones Give an example of each3. Explain how ossification works4. Compare the 3 types of bone cells5. Summarize how bone fractures are repaired

Function of the Skeletal System

l Support of the bodyl Protection of soft organsl Movement due to attached skeletal

musclesl Storage of minerals and fatsl Blood cell formation

Types of Bone Tissuel Compact Bone: Hard outer layer of bonel Spongy bone: Less dense, small needle-

like pieces of bone (trabeculae) with many open spaces

l Bone marrow: Soft tissue inside bone that produces blood cells

Classification of Bone

l Bones are classified according to shape

1. Long Bones

l Typically longer than wide

l Have a shaft with heads at both ends

l Contain mostly compact bone

l Examples: Femur, humerus

Classification of Bones Cont.

2. Short bones

l Generally cube-shape

l Contain mostly spongy bone

l Examples: Carpals, tarsals

3. Flat bones

l Thin and flattenedl Usually curvedl Thin layers of

compact bonearound a layer of spongy bone

l Examples: Skull, ribs, sternum

Classification of Bones Cont.

4. Irregular bones

l Irregular shapel Do not fit into other

bone classification categories

l Example: Vertebrae and hip

Gross Anatomy of Long Bonel Diaphysis

l Shaftl Composed of compact

bonel Location of yellow marrow

(fat)l Epiphysis

l Ends of the bonel Composed mostly of

spongy bonel Location of red marrow

(blood formation)

Gross Anatomy of Long Bone Cont.l Periosteum

l Outside covering of the diaphysis

l Fibrous connective tissue membrane

l Arteriesl Supply bone cells

with nutrients

l Articular cartilagel Covers the external

surface of the epiphysesl Made of hyaline cartilagel Decreases friction at joint

surfacesl Medullary cavity

l Cavity of the shaftl Contains yellow marrow

(mostly fat) in adultsl Contains red marrow (for

blood cell formation) in infants

Microscopic Anatomy of the Bonel Osteon (Haversian

System)l A unit of bone

l Central (Haversian) canall Opening in the center of

an osteonl Carries blood vessels

and nerves

l Lacunael Cavities containing bone

cells (osteocytes)l Arranged in concentric

ringsl Lamella

l Rings around the central canal

l Sites of lacunael Canaliculi

l Tiny canalsl Radiate from the central

canal to lacunael Form a transport system

Ossification: Bone Growthl Epiphyseal plates allow for growth of long

bone during childhoodl New cartilage is continuously formedl Older cartilage becomes ossified (changed to

bone)l Cartilage is broken downl Bone replaces cartilage

l Bones are remodeled and lengthened until growth stopsl Bones change shape somewhatl Bones grow in width

Types of Bone Cells

l Osteocytesl Mature bone cells

l Osteoblastsl Bone-forming cells for bone growth

l Osteoclastsl Bone-destroying cellsl Break down bone matrix for remodeling and

release of calciuml Bone remodeling is a process done by both

osteoblasts and osteoclasts

Bone Fracturesl A break in a bonel Types of bone fractures

l Closed (simple) fracture – break that does not penetrate the skin

l Open (compound) fracture – broken bone penetrates through the skin

l Bone fractures are treated by reduction and immobilizationl Realignment of the bone

Common Types of Fractures

Repair of Bone Fracturesl Hematoma (blood-filled swelling) is formedl Break is splinted (immobilized) by fibrocartilage

to form a callusl Fibrocartilage callus is replaced by a bony callusl Bony callus is remodeled to form a permanent

patch

Human Skeleton

Human Skeletonl 206 bones in the adult human bodyl Divided into 2 parts:

l Axial Skeleton

l Appendicular Skeleton

Skull

Vertebral column

Rib cage

Bones of arms and legs

Bones of shoulder

Pelvis

Learning Goals Part 21. Explain how the human skeleton is divided2. Summarize the parts of the Axial Skeleton3. summarize the parts of the Appendicular Skeleton4. Describe the function of the skull and vertebrae. What is different about the fetal skull?

l Axial Skeleton

l Appendicular Skeleton

l Divided into three partsl Skulll Vertebral columnl Rib Cage (bony

thorax)

The Axial Skeleton

The Skull

l Two sets of bonesl Craniuml Facial bones

l Skull bones are joined by suturesl Only the mandible is attached by a

freely movable joint

Bones of the Cranium (Skull)l Protects the brainl Bones are attached by immovable joints

called suturesl Made up of 8 flat bones

l 1 frontal bonel 2 parietal bonesl 1 occipital bonel 2 temporal bones

l Foramen Magnum – opening in the occipital bonel Area where spinal cord joins the brain

l Lateral View of Skull

l Superior View of Skull

l Inferior View of Skull

The Fetal Skulll Fontanelles –

fibrous membranes connecting the cranial bonesl Allow the brain

to growl Convert to bone

within 24 months after birth

Facial Bonesl Maxilla

l 2 bones that form the upper jawl Mandible

l Lower jawl Only movable bone of the skulll Contains tooth sockets for 16 teeth

l Nasal bonel Forms bridge of nose

l Zygomatic bonel 2 cheek bones

The Vertebral Columnl Vertebrae separated by

intervertebral discs (pads of fibrocartilage)

l The spine has 4 normal curvatures

l Each vertebrae is given a name according to its location

l Function: protect spinal cord, supports rib cage, attaches to pelvic

The Rib Cage (Bony Thorax)l Forms a cage to protect major organs

(heart, lungs)l Made-up of three parts:

1) Ribsl 12 ribs connected to the vertebrael True ribs:

l Ribs that connect directly to the sternuml False ribs:

l Ribs that attach to the sternum by a common cartilage

l Floating ribs:l Ribs that do not attach to the sternum

2) Sternuml Flat, blade-shaped bonel Composed of 3 bones: manubrium, body, xiphoid

processl Xiphoid process

l Inferior and smallest portion of sternuml Attachment site for diaphragm

3) Thoracic vertebrael 12 thoracic vertebrae

The Appendicular Skeleton

l Pectoral girdlel Limbs (appendages)l Pelvic girdle

Composed of:

The Pectoral (Shoulder) Girdle

l These bones allow the upper limbs to have exceptionally free movement

l Composed of 4 bones- 2 Clavicles – collarbonel Slender and s-shapedl Stabilizes shoulder but structurally weak (breaks

easily) L- 2 Scapulas – shoulder bladel Triangular shape

l Humerus (upper arm)l Radius and ulna

(forearm)l Carpals, metacarpals,

phalanges (hand)

Bones of the Upper Limb

l The upper arm is formed by a single bonel Humerus

Upper Arm Cont.

l The forearm has two bonesl Ulnal Radius

Hand Bones

l The handl Carpals – wristl Metacarpals –

palml Phalanges –

fingers

Bones of the Pelvic Girdlel Hip bonesl Composed of:

l 2 coxal bones (hipbones)l Sacruml Coccyx

l The total weight of the upper body rests on the pelvis

l Protects several organsl Reproductive organsl Urinary bladderl Part of the large intestine

l Coxal bone:- Ilium: largest part of coxal bonel Iliac crest: top of

the ilium- Ischium: most inferior part of the coxal bone- Pubis: anterior part of coxal bonel Pubic symphysis:

where the 2 pubic bones meet

Gender Differences of the Pelvisl Male:

l Not as wide or broadl Pelvic cavity is funnel-shapedl Bones are heavier & largerl Pubic arch more narrow

l Female:l Wider pelvis & broader hipsl Pelvic cavity is shallowl Bones are lighter & thinnerl Pubic arch is wider

Bones of the Lower Limbl Femur (thigh)l Patella (kneecap)l Tibia & Fibula (leg)l Tarsals, metatarsals,

phalanges (foot)

l Femurl Thigh bonel Strongest and

longest bone in the body

l Patellal Triangular bone

that protects the knee joint

Lower Limbs

Lower Limb Cont.l Tibia

l Shinbonel Medial (towards the

middle) to the fibulal Thicker – bears

weight of femurl Fibula

l Lateral (away from midline) to the tibia

l Stabilize ankle

The footl Tarsal bones

l Anklel Supports weight of

bodyl Metatarsals

l Sole or instepl Phalanges

l Toes

Jointsl Articulations

(attachments) of bones

l Functions of jointsl Hold bones togetherl Allow for mobility

l Joints are classifiedby the amount of movement allowed

Fibrous Joint

Structural Classification of Joints

l Fibrous jointsl Generally immovablel Fibrous connective tissue

join bone to bonel Example: cranium bones

Joints

l Cartilaginous jointsl Immovable or slightly

moveablel Fibrocartilage found

between bonesl Example:

ribs/sternum, vertebrae, pelvis

l Synovial Joints:l Freely movable

jointsl Bones do not

come in contact with each other

l 6 Types

Joint Vocabularyl Ligaments

l Connective tissue that connects bone to bonel Tendons

l Connect bone to muscles to further stabilize jointl Synovial fluid

l Lubricating fluid found between bones to reduce friction

l Bursael Fluid-filled sacs that cushion joint (ex. knee)

l Meniscusl Cartilaginous pads of tissue between the tibia and

femur in knee joint

Knee Injuries1. Torn Meniscus

§ The menisci absorb shock by compressing and spreading the weight evenly within the knee.

§ The menisci are attached to the tibia and joint and ligaments, allowing the menisci to pivotfreely.

§ One of the most common knee injuries. § Grow weaker with age, and tear as a result of

minor injuries or movements. § The most common injury occurs when the knee

joint is bent and the knee is then twisted.

§ A damaged meniscus can cause it to become caught between the bones of the joint (femur and tibia).

§ Symptoms: Knee then becomes swollen, painful, popping or clicking with the knee, and difficult to move.

§ Treatment: Surgery to repair tear by trimming a portion of the meniscus (meniscectomy).

Knee Injuries Cont.2. Torn ACL (Anterior Cruciate Ligament)

l ACL provides stability to the jointl Common injury in athletes in contact sportsl Occurs when the knee is locked with the foot

planted and the knee is twisted quickly. l The bones are more likely to rub against each

other (chronic ACL deficiency). l Can also damage the cartilage that covers the

ends of the bones and can trap and tear the menisci.

l Left untreated it can lead to osteoarthritis.

Disorders of the Skeletal Systeml Osteoporosis

l Most common bone diseasel 1 in 5 women in USA over 50

have osteoporosisl Men over 70 are at riskl During menopause, estrogen levels drop l Body stops making new bone due to lack of

calcium, resulting in brittle bones and fractures

Osteoporosis

Arthritisl Inflammation of one or more jointsl Breakdown of cartilage causes bones to

rub together, leading to pain, inflammation, and stiffness

l There are many different types of arthritis

Arthritisl Osteoarthritis (OA)

l Most common type of arthritisl Caused by ‘wear and tear’ on jointl Cartilage breaks down and bony spurs may

developl Runs in families

Arthritisl Rheumatoid arthritis (RA)

l Autoimmune diseasel Body mistakenly attacks

healthy tissues, breaking down cartilage

l Common in middle aged people

l Women get RA more than men

Arthritisl Gout

l Type of arthritis that occurs when uric acid builds up in the blood, causing crystals to form in the joint

l Leads to major inflammation

l More common in men, women after menopause, and those who drink alcohol

Rickets

l Uncommonl Caused by a lack of

Vitamin D, calcium, or phosphate, leading to a weakening and deformation of bones

l Vitamin D deficiency caused by lack of sunlight or rare genetic X-linked dominant trait