anatomy ch 6-9

bones

• Organs along with the associated cartilages form the skeletal system 

• Made up of at least 2 types of tissue

Functions of Bones

1. Support

   • support the framework of the body

   • support viscera (ventral body cavity)

   • provide attachment points for tendons

2.  Protection

   • Protect internal organs from injury

3. Assistance in Movement

   • skeletal muscles attach to the bones by tendon

   • when skeletal muscles contract, they pull on the bones → produce movement

4. Mineral Storage and Release

   • Includes calcium and phosphate

5. Site of Blood Cell Formation = Hemopoiesis = Hematopoiesis

   • Production of blood cells in red bone marrow

Triglycerides Storage

Stored in the yellow bone marrow (a type of lipids/fats)

long bones

1. characteristics

   • has a shaft and 2 distinct ends

2. examples:

   • humerus

   • femur

   • tibia

short bones

1. characteristics

   • Equal in length, width and height

2. examples:

   • Carpals, tarsal

flat bones

1. characteristics

   • Thin, flat, curved → form a cavity

2. examples:

   • Sternum, front bone

irregular bones

1. characteristics

   • Not a long, short, or flat bone

2. examples:

   • Vertebra, sphenoid

sesamoid bones

1. characteristics

   • Small bones embedded in tendon

2. examples:

   • Patella (knee cap)

Diaphysis

1. Description = the long cylindrical, main portion of the bone

2. The shaft or the body of the bone

Epiphysis

end of the bone: proximal, distal

Metaphyses

1. The region between diaphysis and epiphysis 

2. Includes the epiphyseal plate → aka growth plate

3. Epiphyseal Plate= replaced by epiphyseal line when the bone stops lengthening

Articular Cartilage

1. Hyaline cartilage covering epiphysis to form joints

2. covers end of opposing bones

3. Function= reduce friction and absorb shock

Periosteum

1. A connective tissue sheath 

2. Composition (of 2 layers)= outer fibrous layer, inner osteogenic layer

3. Sharpey’s fibers = perforating fibers = attach the periosteum to the underlying bone

Medullary Cavity= Marrow Cavity

1. Description = long, cylindrical space within the diaphysis

2. Composition = contain yellow bone marrow and blood vessels

3. Function = reduce dene boney material

4. Long bone design maximize strength and minimize weight → run faster, stronger bones

Endosteum

1. Thin membrane that lines the medullary cavity

Blood Vessels

Structure of Other Types of Bones – outer plates of compact bone covering an inner core of spongy bone

Bone Surface Markings = Osseous Markings

1. structural features that adapt to specific function

2. 2 major types: (1) depressions and openings, (2) processes

3. Examples include= fissure, foramen, fossa, sulcus, meatus, and process

Histology of Bone Tissue

1. Bone = osseous tissue contains a matrix surrounding widely separated cells.

2. The matrix contains mineral salts (hydroxyapatite and calcium) deposited in a framework of collagen fibers.

3. Collagen fibers give bones flexibility and tensile strength.

4. Calcification of bone gives bone hardness.

Osteoblasts

1. Description = bone building cells

2. Function = produce tissue matrix

3. Location = not completely surrounded by matrix

Osteocytes

1. Description = mature bone cells

2. Function = maintain osseous tissue

3. Location = completely surrounded by matrix → found inside a lacuna

Osteoclasts

1. Description = made from the fusion of many monocytes

2. Function = break down bone matrix → called bone resorption

Compact = Cortical = Dense Bone Tissue

1. dense

2. has smaller spaces than spongy bone

Microscopic Structure of Compact Bone

1. composed of osteons = Haversian system – repeated structural units of columns of bone

2. central or Haversian canal – contains blood vessels, lymphatic vessels, and nerves

circumferential lamellae

arranged around entire outer or inner circumference of the shaft of the long bone

Canaliculi

1. slender, finger-like processes of osteocytes inside

2. small channels radiating in all directions from lacunae filled with interstitial fluid

perforating; Volkmann’s canal

canals that transverse through the periosteum

Spongy = Trabecular = Cancellous Bone Tissue

1. less dense than compact bone

2. have larger spaces than compact bone

3. contains bone marrow

Bone Growth and Development

1. bone formation involves ossification which begins around 6th week of embryonic life and continues throughout adulthood

2. ossification occurs via 2 processes in which preexisting connective tissue is replaced by bone tissue

Intramembranous Ossification

1. Occurs within fibrous connective membranes

2. Involves 4 steps:

   • ossification center development

   • calcification

   • trabecular formation

   • periosteal formation

Endochondral Ossification

1. Occurs within a hyaline cartilage model

2. Cartilage grows by interstitial and appositional growth

Primary Ossification Center

1. Forms in the diaphysis before birth 

2. The medullary cavity forms

3. Bone grows in diameter by the osteogenic periosteum via appositional growth (a process in which osteoblasts from the periosteum add new bone to the outer surface)

4. Forms the articular cartilage and epiphyseal plate

Secondary Ossification Center

1. Forms in the epiphyses after birth

2. Strengthens the epiphyses for walking

3. The growth end of the long bone retain a strip of cartilage called the epiphyseal disc to allow the bone to grow in length

Bone Remodeling

1. New bone tissue is continuously deposited and resorbed in response to hormonal and mechanical stimuli

2. Osteoclasts break down bone tissue by secreting digestive enzymes and acids onto bone surfaces.  This process releases calcium and phosphate into the blood

3. Osteoid is secreted by osteoblasts at areas of bone deposits.  Calcium salt is then deposited in the osteoid (Bone Deposition)

4. Compressive forces and growth acting on the skeleton help maintain bone strength because bones thicken at sites of stress

Aging

1.   demineralization of bone matrix (loss of Ca2+ is a major factor in development of osteoporosis)

2.   decrease rate of protein (mainly collagen) synthesis results in loss of tensile strength, making bones more brittle and susceptible to fractures

Osteosarcoma

most common form of bone cancer primarily in teenagers during their growth spurt

Osteomyelitis

an infection of bone characterized by high fever, sweating, chills, pain, and nausea.  It is usually caused by Staphylococcus aureus

Osteopenia

reduced bone mass due to various causes

Osteoporosis

1. bone resorption outpaces bone deposition

2. occurs often in women after menopause

3. in the elderly, the neck of the femur has low bone mass and breaks; then the person falls

4. hip fractures!

Ostealgia

pain in a bone

Boney Spur

1. an abnormal projection on a bone due to bone overgrowth

2. common in aging bones

concentric lamellae

circular plates of mineralized extracellular matrix of increasing diameter

interstitial lamellae

fragments of older osteons partially destroyed during bone rebuilding or growth

lacunae

small spaces between concentric lamellae containing osteocytes

overview of skeleton

1. consists of bones, joints, cartilage, and ligaments

2. composed of 206-208 named bones in the adult skeleton grouped into 2 major divisions

   • axial skeleton

   • appendicular skeleton

axial skeleton

• 80-82 bones

• located around the longitudinal axis of the body

• includes the skull, vertebral column, ribcage, auditory ossicles & hyoid

skull

• composed of 22 bones

• cranial bones= 8 cranial bones to form cranial cavity to protect the brain

• facial bones= 14 facial bones to form the face

ribcage

sternum, costae, thoracic vert

vertebral column

• cervical, thoracic & lumbar vertebrae, sacrum, coccyx

• strong, flexible rod with functions; protects the spinal cord (nervous tissue)

• supports the head

auditory ossicles

malleus, incus, stapes

appendicular skeleton

• 126 bones

• includes the pectoral girdle, brachium, anterbrachium, manus

• includes the pelvic girdle, femoral region, leg, pedus

cranial bones

• inner surfaces= attach to membranes

• outer surface= provides attachments for muscles

• formation= form cavities for sense organs: hearing, equilibrium

frontal bone

1 bone

pariteal bone

2 bones

occipital bone

1 bone

temporal bone

2 bones

sphenoid bone

1 bone

ethmoid bone

1 bone

facial bones

• 14 bones

• function= provides support, protect entrance of digestive and respiratory tract

• formation= forms the cavity for sense organs for vision, smell, and taste

• provides attachment for facial bones

nasal septum

• formed by the vomer, septal cartilage, perpendicular plate of ethmoid bone

• divides the nasal cavity into right and left compartments

orbital cavity

• formed by frontal, sphenoid, zygomatic, maxillary, palatine, lacrimal, and ethmoid bones

• houses the eyeballs, eye muscles, and lacrimal glands

sutures

• immovable joints between skull bones

• point of attachment for 2 cranial bones

• appears irregular and saw-tooth

coronal suture

frontal & parietal bones

sagittal suture

2 parietal bones

squamous suture

parietal & temporal bones

lambdoid suture

parietal and occipital bones

paranasal sinuses

• paired cavities located in certain skull bones

• lined w/ mucosa that are continuous w/ lining of the nasal cavity

• function= produce mucus & serve as resonating chambers of sound

• located in maxillary, frontal, sphenoid, and ethmoid bones

fontanel

• fibrous connective tissue membrane= filled spaces between cranial bones

• point of attachment for 3 cranial bones

• function= fetus modify skull through birth & permits rapid growth of the brain during infancy

• includes= anterior fontanel, posterior fontanel, sphenoid fontanel, mastoid fontanel

hyoid bones

• “U” shaped bone

• location= in the superior neck, inferior to the mandible

• does not articular with any other bone

• function= supports the lengua

• attachment site= for lingual, cervical, pharyngeal muscles

cervical vertebrae

• named C1-C7

  • C1= atlas

  • C2= axis

thoracic vertebrae

• named T1-T12

• attached to costae= ribs

lumbar vertebrae

named L1-L5

sacrum

fusion of 5 sacral vertebrae

coccyx

fusion of 3-5 coccygeal vertebrae

primary curvature (concave)

• retains original curvature of embryonic vertebral column

• thoracic curve

• sacral curve

secondary curvature (convex)

• begins to form later, several months after birth

• may be progressively lost in old age

• cervical curve= obtained when baby lifts up its head by 2 months

• lumbar curve obtained when baby sits up between 5-7 months

intervertebral discs

• located between neighboring vertebrae frm C2 down to sacrum

• composed of fibrocartilage

• functions:

  • form strong joints

  • permits various movement of the spine

  • absorb vertical shock

thoracic cage

• sternum, thoracic vertebrae, costae

• function= protect the organs of the thoracic cavity (lungs, heart, trachea, esophagus, aorta)

• supports the pectoral girdle and upper extremities

sternum

• flat bone composed of 3 major regions:

  • manubrium

  • body

  • xiphoid process

• includes sternal angle and xiphosternal angle or joint

ribs= costae

• 12 pairs of ribs

• all ribs are attached posteriorly to the thoracic vertebrae

• anteriorly, the superior 7 pairs of ribs attach directly to the sternum via costal cartilages and are called true ribs= vertebrosternal ribs

• the inferior 5 ribs called false ribs are attached to the sternum indirectly or not at all

• pairs 8-10, are also called vertebrochondral ribs= vertebral ribs

• the last 2 of the 5 inferior ribs (ribs 11 & 12) aka floating ribs because they have not anterior attachments

• intercostal spaces are spaces between neighboring ribs

orthopedists= orthopedic surgeon

a physician who specializes in restoring lost function or repairing damages to bones and joints

chiropractic

holistic health-care discipline that focuses on nerves, muscles, and bones

chiropractor

a doctor who practices chiropractic

cleft plate

the right and left halves of the palate fail to join medially

whiplash injury

an injury to the neck region caused by rapid sequence of hyperextension (backward tilting) followed by hyperflexion (forward tilting) of the neck

scoliosis

abnormal lateral curvature of the thoracic region of the spine (S shaped spine)

kyphosis

• hunchback

• exaggerated thoracic curvature

lordosis

• “swayback” or “hollow back”

• accentuated lumbar curvature

pectoral girdle= shoulder girdle

• attached the bones of the free upper extremities to the axial skeleton

• includes 3 bones= (1) clavicle, (2) scapula, (3) humerus

fractures of the clavicles

results from a blow to the superior part of the anterior thorax

upper limb= upper extremity

composition= includes arm, forearm, and hand

hand

composed of carpals= 8 carpal bones in the wrist

5 metacarpal bones

found in the palm of the hand; I, II, III, IV

phalanges

14 bones, located in the digits

• proximal

• medial

• distal

boxer’s fracture

fracture of the metacarpal V, usually near the head of the bone

carpal tunnel syndrome

• compression of the median nerve due to the repeated flexing of the fingers an wrists

• seen commonly in people who use computers all day long

pelvic girdle= hip girdle

• connects the bone of the free lower extremities to the axial skeleton

• composed of the paired hip bones called os coxae or pelvic bone

• each os coxae is composed of 3 fused bones:

  • ilium

  • ischium

  • pubis

• pubic bones united anteriorly by the pubic symphysis composed of fibrocartilage

• sacrum articulates with the os coxae posteriorly at the sacroiliac joint

• the deep, basin-like structure formed by the os coxae, sacrum, and coccyx= bony pelvis

false pelvis

superior to the pelvic brim

true pelvis

inferior to the pelvic brim

female pelvis

adapted for childbearing

lower limb= lower extremity

includes the thigh, leg, and foot