The Skeleton: Bones & Joints

Chapter 7 Anatomy & Physiology I

Outline • BONES

– Main functions– Bone structure– Bone growth and repair– Bone markings

• BONES OF THE AXIAL SKELETON – Framework of the skull– Framework of the trunk

• BONES OF THE APPENDICULAR SKELETON – Upper division– Lower division

• DISORDERS OF BONE – Metabolic—osteoporosis, osteopenia, osteitis deformans, osteomalacia, rickets– Tumors– Infection—osteomyelitis, tuberculosis (in spine is called Pott disease)– Structural disorders—curvature of the spine, cleft palate, flat foot– Fractures—closed, open, greenstick, impacted, comminuted, spiral, transverse, oblique– Changes in aging—loss of calcium salts, decreased collagen production, thinning of intervertebral disks, loss of

flexibility• THE JOINTS (ARTICULATIONS)

– Kinds of joints– More about synovial joints– Disorders of Joints– Joint repair

Skeleton• Skeletal system is made up

of bones, joints, and supporting connective tissue

• Framework on which the body is constructed

• Must be strong enough to support & protect all body structures

• Most dense form of connective tissue in the body

• Consists of 206 bones, joints & supporting connective tissue

• Framework for entire body• Protection of delicate structures like brain &

spinal cord• Levers to assist muscles in providing

movement• Storehouse for Ca++ salts • Produce blood cells in red marrow

I. Bone Functions

• 206 bones• Axial skeleton – 80

bones -skull, facial bones, spine, ribcage

• Appendicular skeleton – 126 bones - pelvic bones, collarbones, extremity bones

II. Bone Structure

a. Long Bones

• Long bones– Diaphysis – long

narrow shaft– Medullary cavity –

middle of diaphysis, contains marrow

– Epiphysis – ends of long bone

b. Bone Tissue – Osseus Tissue

• Bones are alive. Bones are organs, with their own system of blood vessels, lymphatic vessels, and nerves.• 2 types of bone

– Compact– Spongy, aka Cancellous

Compact Bone

• Makes up main shaft in long bones & outer layer in other bones

• Haversian System – ring of bone tissue surrounding a canal for nerves blood vessels

• Haversian canals – canal through which nerves & blood vessels travel in bone

• Lacunae – space in which bones cells (osteocytes) live • Volkmann canals – tunnels for nerves and vessels that

lead to the outside of the bone

Compact Bone

Cancellous (Spongy) Bone• Spongy appearance

because it has more spaces than compact bone

• Filled with red bone marrow

• Found at the epiphyses (ends) of long bones & at the center of other bones

Checkpoint 7-1: A long bone has a long narrow shaft and two irregular ends. What are the scientific names for the shaft and the ends of a long bone?

Checkpoint 7-2: What are the two types of osseus (bone) tissue and where is each type found?

c. Bone Marrow

• Red marrow – in epiphyses of long bones & center of other bones

• Red bone marrow manufactures blood cells. • Yellow marrow – in central cavities of the long

bones– Composed mainly of fat

d. Bone Membranes

• Periosteum – Covering on the outside of bones– Inner layer made of osteoblasts (bone producing cells)– Rich blood and nerve supply to nourish bone

• Endosteum – very thin covering that lines the marrow cavity in a bone

e. Bone Growth & Repair

• Embryonic skeleton is mainly cartilaginous (parts of skull fibrous CT)

• Osteoblasts – bone producing cells – Become active between 8 &12 weeks– From stem cells in endosteum & periosteum

• Ossification – conversion of cartilage to bone– Osteoblasts form a matrix (the material between cells) mainly of

collagen– Enzymes help deposit Ca++ in the matrix– Osteoblasts remain enclosed in lacunae and are now called

osteocytes– Osteocytes – mature bone cells that do not produce new bone

Bone Growth & Repair

• Osteoclasts – responsible for breakdown or resorption of bone tissue– Develop from monocytes (WBC)

• Necessary for remodeling and repair of bone during growth & development, & after injury

• Bone tissue formation & resorption regulated by hormones

• Bone formation & resorption continues throughout life

Checkpoint 7-3: What are the three types of cells found in bone and what is the role of each?

Which of these is a bone-building cell?

a. osteoblastb. osteoclastc. osteocyte

Formation of Long Bones

• Ossification begins at the center of the diaphysis during fetal development

• Epiphysial plates – bone forming centers at the ends of long bones that appear around birth

• Long bones grow in length from the epiphyseal plates throughout childhood

• Long bones grow wider in diaphysis as medullary cavity grows

• Calcification ends in late teens, early 20s and epiphyseal plate hardens

Ossification

Checkpoint 7-4: As the embryonic skeleton is converted from cartilage to bone, the intercellular matrix becomes hardened. What compounds are deposited in the matrix to harden it?

Checkpoint 7-5: After birth, long bones continue to grow in length at secondary centers. What are these centers called?

f. Bone Markings• Projections – “sticky-outy things”

– Head– Process– Condyle– Crest– Spine

• Depressions – dents or holes– Foramen– Sinus– Fossa– Meatus

Bony Projections

• Head – large knobby end attached to a bony neck (femur)

• Process – large projection of bone (styloid process radius & ulna) – for muscle attachment

• Condyle – rounded projection of bone – (humerus at elbow)

• Crest – distinct border or ridge – (pelvic bone has a crest)

• Spine – sharp projection from the surface of bone (spinous)

Bony Depressions

• Foramen – hole that acts as a tunnel for nerves, vessels– Foramena - holes

• Sinus – air space found in some skull bones• Fossa – depression on a bone surface

– Fossae - depressions• Meatus – short channel or passage, like ear

canal

• 80 bones of the head & trunk• Skull 28 bones

– Cranium – 8 bones– Facial bones – 14 bones– Ear bones (ossicles)- 6 ( 3 in each ear)

• Trunk – 52 bones– Hyoid – in throat, for muscle attachment– 26 vertebrae– 12 pair ribs (24 total)– Sternum

III. Bones of the Axial Skeleton

Cranium

• Encloses the brain• 8 bones• Frontal bone• 2 parietal bones• 2 temporal bones• Ethmoid bone• Sphenoid bone• Occipital bone

Cranium Continued

• Frontal bone – forehead bone– Frontal sinuses over eyes

• Parietal bones – top of the head & top sides of the head

• Temporal bones – sides of head around ears– Mastoid sinuses – Ear canal, eardrum– Mastoid process – behind external ear

Cranium Continued

• Ethmoid – between the eyes– Contains paranasal sinuses – Forms nasal septum– Superior & middle conchae – along walls of nasal cavity

• Sphenoid – forms part of eye socket, inside head – Sella turcica – depression that holds & protects pituitary

gland• Occiput – base of skull

– Foramen magnum – large hole for spinal cord to connect to brain

Cranial Sutures• Suture – flat, immovable joint that unites

cranial bones• Coronal suture –joins frontal bone with

parietal bones• Squamous suture – joins temporal bones with

parietal bones (on flat part of skull)• Lamboid suture – joins occipital bones with

parietal bones• Sagittal suture – joins the parietal bones

14 Facial Bones

• Mandible • 2 Maxillae• 2 Zygomatic bones• 2 Nasal bones• 2 Lacrimal bones• Vomer• 2 Palatine bones• 2 Inferior nasal conchae

Facial Bones

• Mandible – lower jaw bone; only moveable bone of the skull

• 2 maxillae – fuse to each other to form upper jaw bone, front of hard palate – Maxillary sinuses

• 2 zygomatic bones – cheek bones• 2 nasal bones –bridge of nose

Facial Bones

• 2 Lacrimal bones – corners of the eyes, size of fingernail

• Vomer – lower part of nasal septum• 2 Palatine bones – back of hard palate• 2 Inferior nasal conchae – along the lower

sides of the nasal cavity

Infant Skull

Vertebral Column

• 26 bones in vertebral column

• 7 cervical• 12 thoracic• 5 lumbar• 1 sacrum• 1 coccyx

Vertebrae

• Body – weight bearing – discs of cartilage that act as shock absorbers

between them • Spinous process – projects posteriorly• Transverse process – projects laterally • Bony arch which forms a foramen for spinal cord• Intervertebral foramina – between the

vertebrae for spinal nerves to pass through

Spinal Column

• Cervical – 7 neck bones– Atlas – first neck bone; to support head– Axis – second neck bone; to move head– Only 2 spinal bones without a body

• Thoracic – 12 bones – Ribs attach to these vertebrae

Atlas & Axis

Spinal Column

• Lumbar – 5 lower back bones– Large & heavy

• Sacrum – form part of pelvic girdle• Coccyx –tailbone

Spinal Column

• Has 4 curves corresponding to groups of vertebrae which develop through childhood

• Fetus – curled up & this is first curve• Infant – lifts head, develops 2nd curve• Toddler – develops 3rd & 4th curve as learns to

walk

Development of Spinal Curves

Thorax

• Sternum – aka breastbone– Manubrium – superior aspect, joins with collarbone– Sternal angle – where manubrium joins body– Body – long & bladelike & joins with rib pairs 2-7– Xiphoid process – tip at inferior aspect

• Ribs – 12 pair attached to thoracic spine posteriorly– Rib pairs 1-7 – “true ribs” – attach to sternum– Rib pairs 8-12 – “false ribs”

• 8-10 attach to cartilage• 11-12 – floating ribs with no anterior attachment

• 126 bones of the shoulders, hips & extremities• Upper division of appendicular skeleton

– Shoulder girdle– Upper extremity

• Lower division of appendicular skeleton– Pelvis– Lower extremity

IV. Bones of the Appendicular Skeleton

Shoulder Girdle

• Clavicle aka collarbone– Most frequently fractured bone in body– Connects to sternum & scapula

• Scapula aka shoulder blade– Spine – posterior ridge – Supraspinous fossa – above spine– Infraspionous fossa – below spine– Acromian – attaches to clavicle– Glenoid cavity – forms arm socket– Coracoid process – for muscle attachment

Shoulder Girdle Anterior & Posterior

Scapular Anatomy

Upper Extremity

• Humerus – arm– Head – fits into scapula

glenoid fossa– Medial & lateral

epicondyle – for tendon attachment

– Trochlea – part of elbow joint

• Forearm– Radius– Ulna

Humerus

Forearm

• Ulna – medial side– Olecranon – point of elbow– Trochlear notch – indention into which trochlea of

humerus fits, which allows hinge action of elbow– Styloid process at distal end visible when arm is supine

• Radius – on lateral (thumb side)– Forearm bones are parallel in anatomical position

(prone)– When arm is supine, bones are crossed

Elbow Joint

Movement of Forearm

Wrist & Hand

• Wrist - 8 carpal bones • Palm bones – 5 metacarpal bones• Finger bones – 14 phalanges

– Each finger has 3 phalanges– Thumb has only 2 phalanges

Lower Appendicular Skeleton Hip Bones

• Hip bone – os coxae• Innominate bone

– Acetabulum – socket that holds head of femur

– Obturator foramen – largest foramen in body

Innominate Bone• Os coxae begins as 3 bones that

later fuse– Ilium

• Iliac spine - top ridge of ilium• Anterior superior iliac spine (ASIS) –

bump in front of body– Ischium – strongest part of pelvic

girdle• Ischial spine – point of reference

during childbirth• Ischial tuberosity – supports body

weight while sitting– Pubis – anterior part of pelvic

girdle• Pubic symphysis – joint formed by

union of two hip bones

Pelvic Girdle

• Pelvis – strong bony girdle made of os coxae, sacrum & coccyx

• Supports trunk• Protects organs of lower abdomen• Female pelvis is

– Lighter– Wider – Larger opening

Lower Extremity• Femur – thigh

– Longest & strongest bone in body

– Head – ball of the hip joint– Greater trochanter & lesser

trochanter – near head– Linea aspera – along side of

femur for muscle attachment• Leg

– Tibia– Fibula

• Patella - kneecap

Lower Extremity• Patella – kneecap

– Sesamoid bone – bone that develops within a tendon

• Tibia – shin bone– Weight bearing bone – Medial malleolus – distal

end, medial “ankle bone”• Fibula

– Not weight bearing– Lateral malleolus – lateral

“ankle bone”

Foot

• Stronger & less mobile than hand• 7 tarsal bones (ankle)• 5 metatarsal bones – heads of these form ball

of the foot• 14 phalanges

– 3 phalanges in each toe– 2 phalanges in great toe

• Osteoporosis• Osteitis deformans• Osteomalacia• Tumors• Osteomyelitis • Scoliosis• Cleft palate• Fractures

V. Bone Disorders

Metabolic Disorders

• Osteoporosis – lack of normal ca++ deposits, increased bone breakdown with no increase in bone production

Osteoporosis

Metabolic Disorders

• Osteitis deformans – • Aka Paget’s disease • Periods of ca++ loss

followed by excessive ca++ deposits causing bone deformities

Metabolic Disorders

• Osteomalacia – softening of bone due to no ca++ deposits forming

• Aka Ricketts

Tumors & Infection• Tumors from

other sites often metastasize to bones, particularly the spine

• Osteomyelitis – bone infection – can be difficult to treat

Structural Disorders

• Scoliosis – curvature of the spine, begins in teens and is generally idiopathic

Structural Disorders

• Cleft palate – congenital deformity in which there is faulty union of maxillary bones resulting in opening at the roof of the mouth

Fractures• Closed – simple fracture with no open wound• Open – broken bone protrudes through skin• Greenstick – one side broken, other side bent;

common in children• Impacted – broken ends are jammed together• Comminuted – bone is shattered• Spiral – bone has been twisted • Transverse – fracture in straight line across bone• Oblique – fracture occurs at an angle across bone

V. Joint

• Aka articulation• An area of junction

between 2 or more bones

• Classified based on material between joints & on the type of movement at the joint

3 Types of Joints

• Fibrous – held together by fibrous connective tissue– Sutures of the skull– Immovable joint so also termed synarthrodial

• Cartilaginous – connected by cartilage– Pubic symphsys – Vertebral bodies– Slightly moveable so also termed amphiarthrodial

• Synovial – have a joint cavity filled with synovial fluid– Most joints are synovial– Freely moveable so termed diarthrodial

Fibrous Joint

Cartilaginous Joints

Synovial Joints

Synovial Joint Structure• Ligaments – fibrous bands

that connect bone to bone– Reinforce & stabilize the

joints during movement• Joint capsule – connective

tissue joint enclosure• Articular cartilage – smooth

layer of hyaline cartilage that lines the bones

• Bursae – small synovial fluid filled sacs surrounding some joints to reduce stress

Types of Synovial Joints

• Gliding• Hinge• Pivot• Condyloid/Ellipsoidal• Saddle• Ball & socket

Synovial Joint Movement• Flexion• Extension• Abduction• Adduction• Circumduction • Rotation• Supination• Pronation• Inversion• Eversion• Dorsiflexion• Plantarflexion

Synovial Joint Movement• Flexion – bending to decrease the angle between bones• Extenion – straightening to increase angle between bones• Abduction – moving away from the midline of the body• Adduction – moving toward the midline of the body• Circumduction – combining angular movements to allow for free

movement in many directions

Rotation & Circumduction

Synovial Joint Movements

• Rotation – twisting or turning a bone on its own axis

• Supination – turning the palm upwards• Pronation – turning the palm downwards• Inversion – turning the foot inward• Eversion – turning the foot outward• Dorsiflexion – pointing the toes upward• Plantarflexion – pointing the toes downward

Supination & Pronation

Foot Movements

Joint Disorders

• Dislocation – the bones of a joint separate from each other– Ball & socket joints most likely to dislocate

• Sprain – rupture or tearing of ligaments supporting a joint

• Herniated disk – the disk between vertebra ruptures and the gel-like fluid leaks out, putting pressure on the spinal nerves

• Backache – 2nd only to common cold as a reason for missing work

Shoulder Dislocation

Herniated Disk

Arthritis

• Osteoarthritis – “wear & tear” arthritis – Aka degenerative joint disease– Degeneration of cartilage lining of bone, increased

bone growth in the joint space– Most common type of arthritis– Not systemic – selectively affects joints

• Rheumatoid arthritis – systemic autoimmune disease– Inflammation and overgrowth of synovial membranes

Osteoarthritis