1 Lab 3 rev 7-11 SKELETAL SYSTEM Bone or Osseous Tissue –consists primarily of nonliving...

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Lab 3 rev 7-11

SKELETAL SYSTEM• Bone or Osseous Tissue

– consists primarily of nonliving extracellular crystals of calcium minerals

– contains several types of living bone cells, nerves, and blood vessels

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SKELETAL SYSTEMLab 3

Bones perform 5 important functions:• support-provides a hard framework that supports

the body, attaches the skeletal muscles and cradles the body’s organs

• movement-supports muscles to allow us to move• protection-because they are hard and surround

our internal organs, they protect our organs • formation of blood cells within the marrow cavity

• mineral storage-bones store minerals that are important to body metabolism and function

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Bones can be classified into 4 categories based on shape

• Long--bones of the limbs and fingers– are longer than they are wide– consist of a hollow, cylindrical shaft called the

diaphysis and– an enlarged knob at each end called the

epiphysis

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• Short--bones of the wrists – are approximately as wide as they are long

• Flat--including the cranial bones, sternum and ribs– are thin, flattened and sometimes curved, with a small

amount of spongy bone between 2 layers of compact bone

• Irregular--hip bones and vertebrae• include a variety of shapes that don’t fit into the

other categories

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• All bones contain 2 types of osseous tissue– a solid, compact tissue which forms the

external layer of bone– a spongy tissue

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• Periosteum covers the outer surface of all bones

• is a tough connective tissue consisting of 2 layers • the outermost layer is dense irregular connective

tissue– is richly supplied with nerve fibers, lymphatic

vessels and blood vessels which enter the bone through openings called nutrient foramen

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– provides insertion or anchoring points for the tendons and ligaments

– contains specialized bone forming cells– if the end of a long bone forms a movable joint,

the joint surface is covered by a thin layer of articular or hyaline cartilage that reduces friction, cushions the bone ends during joint movement, and absorbs mechanical stress

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• The internal part of the bone surface is covered by endosteum (a delicate connective tissue membrane)– this covers the trabeculae in the marrow

cavities of the spongy bone– lines the canals that pass through compact bone– contains osteoblasts (bone forming cells) and

osteoclasts (bone resorption cells)

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Long bones• Compact bone forms the external layer • central cavity of the shaft of long bones is called

the medullary cavity– this cavity is filled with red marrow in children

(for RBC production), and with yellow bone marrow in adults• yellow marrow is primarily fat which can be

utilized for energy• Compact bone consists of calcium phosphate laid

in a pattern around the central cavity

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• Structural Unit of Compact bone is the– Osteon (or Haversian system) this forms a

pattern of hollow tubes like the growth rings of a tree trunk

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• Parts of the Haversian system:– each ring of bone tissue in the hollow tube is

called a lamellae – Haversian or Central canal: middle cavity in

a Haversian system. Contains the blood vessels and nerve fibers

– lacunae: found at the junctions of the lamellae and is filled with bone cells called osteocytes

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• canaliculi: thin canals in bone tissue which connect the lacunae to each other and to the central canal– provide a path for nutrients to travel to the osteocytes

and for wastes to be removed

• Volkmann’s canals lie at right angles to the long axis of the bone and connect the blood and nerve supply of the periosteum to those in the central canals and the medullary cavity– this allows all osteocytes to get nutrients even

though they aren’t near a blood vessel

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Spongy bone

– Is found inside the epiphysis• spongy bone is less dense than compact bone

allowing the bones to be light but strong– this helps the bone to withstand mechanical stress

• spongy bone is a honeycomb of hard, strong pieces called trabeculae

– helps the bone to resist mechanical stress

– the open spaces of the trabeculae are filled with red or yellow bone marrow

• blood cell formation (hemopoiesis) takes place in the spongy bone

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– Contains the epiphyseal plate: line of cartilage where bone lengthening takes place in childhood

• When bone length growth is completed, the epiphyseal plate becomes ossified (hardened) and leaves an epiphyseal line

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SKELETAL SYSTEM

• Skeleton – provides support– protects internal organs– produces blood cells– stores minerals (calcium and phosphate)– stores energy– provides levers to make movement easier

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SKELETAL SYSTEM Lab 3

Skeletal system contains 3 types of connective tissue

• bone--hard elements of the skeleton• ligaments--dense fibrous connective tissue that

binds the bones to each other• cartilage--specialized connective tissue consisting

primarily of fibers of collagen and elastic in a gel-like fluid called ground substance

The Skeleton is organized into the (page 39)

• Axial skeleton and the Appendicular skeleton

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• Axial skeleton – forms the long axis of the body which supports

the head, neck and trunk– consists of the

– skull, **bones of the ear

– vertebral column, **hyoid bone (in the throat)

– ribs and

– sternum**these bones are also parts of the axial skeleton

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• The Skull (page 41) includes the bones of the face, the cranial bones and the jaws

• Frontal bone (forehead)

• Parietal bones (behind the frontal bone, on the top rear part of the skull)

• Occipital bone (forms the back of the skull) near the base of this bone is an opening called the

foramen magnum. This is where the vertebral column connects to the skull and the spinal cord enters the skull to communicate with the brain

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• Occipital condyles--2 rounded bumps at the base of the skull which pivot on the 1st vertebrae (as in nodding the head to say “yes”)

• Temporal bones (on the lateral [left and right side] of the skull under the parietal bone)

– each temporal bone has an opening into the ear canal which allows sound to travel to the eardrum

• Sphenoid bone which forms the back of the eye sockets

• Ethmoid bone which helps support the nose and part of the eye socket

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• Facial bones and jaws-comprise the front of the skull

– zygomatic bones form the cheeks and the outer part of the eye sockets

– nasal bones (including the ethmoid) underlie only the upper bridge of the nose (the rest of the nose is made up of cartilage and other connective tissue)

– lacrimal bones are the inner part of the eye sockets

» each is pierced by a tiny opening through which the tear ducts drain

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– maxillary bones form part of the eye sockets, anchors the upper row of teeth, and forms part of the upper palate

» upper, immovable, jaw bone is called the maxilla

– Mandible or lower jaw anchors the lower teeth

• Hyoid bone: not really part of the skull; lies inferiorly to the mandible in the anterior neck

– is the only bone in the body which doesn’t articulate with another bone

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• Ear bones– present in the middle ear and move when air vibrations

bend the eardrum inward

» called the malleus (hammer), incus (anvil) and stapes (stirrup)

– Several of the cranial and facial bones contain air spaces which form the sinuses and make the skull lighter

• Vertebral column or spine– supports the head, protects the spinal cord and serves as

the attachment for each of our arms and legs and the body’s muscles

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– Is a column of 33 vertebrae (irregular bones) which extends from the skull to the pelvis

– is classified into 5 anatomical regions• cervical (neck)-7 vertebrae

• thoracic (chest or thorax)- 12 vertebrae

• lumbar (lower back)-5 vertebrae

• sacral (sacrum/upper pelvic region)- 5 vertebrae which have fused

• coccygeal (coccyx or tailbone)- 4 fused vertebrae

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– The first cervical vertebrae is called the Atlas• it articulates with the occipital condyles

– The second cervical vertebrae is called the Axis• you need to know these names

– vertebrae share 2 points of contact called articulations

• The spinal cord passes through a canal between the articulations

– vertebral bodies are separated from each other by intervertebral disks which serve as shock absorbers and permit a limited amount of movement

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• Ribs and sternum (breastbone)– protect the chest cavity– we have 12 pairs of ribs

• the upper 7 pairs, called “true” ribs, attach via cartilage to the sternum

• “False ribs:– pairs 8-10 are joined to the 7th rib by cartilage and are

thus indirectly attached to the sternum

– pairs 11 and 12 are called floating ribs because they don’t attach to the sternum at all.

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• Appendicular skeleton• bones which help get us from place to place (locomotion)

and enable us to manipulate our environment

– includes the:– Pectoral Girdle is a supportive frame for the

upper limbs• consists of the clavicles and scapulas

– Arms (the humerus, ulna, radius, wrist bones, the palm [metacarpal bones], and the fingers [the phalanges])

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– The Pelvic Girdle consists of the 2 pelvic (hip) bones and the sacrum and coccyx of the vertebral column

• they meet in front at the pubic symphysis where cartilage joins the 2 bones

• primary purpose is to support the weight of the upper body against the force of gravity

• in adult women, the pelvic girdle is

– broader and shallower than in men and

– the pelvic opening is wider/rounder--to allow for childbirth

– the sacrum is flatter

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– The leg bones:• Femur

• Patella

• Tibia

• Fibula

• Tarsals

• Metatarsals

• Phalanges (toes)

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• Joints or Articulations– are sites where 2 or more bones meet– give our skeleton mobility– hold the skeleton together– are the weakest parts of the skeleton

• ligaments and tendons are connective tissues that stabilize each joint

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• Joint types– freely movable, diarthrosis, or synovial --

bones are separated by a thin fluid filled synovial cavity (this type joint is seen in the limbs)

– Types of synovial joints:• ball and socket--the ball end of one bone fits into

the socket of another bone: shoulder and hip joints

• ovoid--an egg shaped surface of bone fits into a matching shaped surface on another bone: wrist joint and forearm bones

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• Hinge--freely movable: knee and elbow joint

• Pivot--joint spins around an axis: between the atlas and axis (vertebrae)

• Gliding--nearly flat bone surfaces allow side to side and back and forth motion: carpals of the wrist and the tarsals of the ankle

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• Slightly Movable, Cartilaginous or Amphiarthrosis Joint --has no synovial cavity and permit only slight movement (this type joint is mainly found in the axial skeleton)

– have a pad of fibrocartilage between 2 bones• Pubic Symphysis (is only moveable during childbirth)• intervertebral discs• sacroiliac• joint connecting the lower ribs to the sternum

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• Immovable, Synarthrosis or Fibrous Joints – flat bones in a baby’s skull

• at birth these bones are separated by space filled with fibrous connective tissue. These “soft spots” are called fontanels

– allow the baby’s head to squeeze through the birth canal

– allow for brain growth and development

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REMINDER, page 1 of 2:

1. Learn the major bones of the human skeleton(in bold print in your lab manual and identified in the diagram, except for the middle ear bones).– Use the large models as well as those on your

lab desks

2. Look at the adult and infant skull– You need know what a fontanelle is but you

don’t need to know the individual names

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REMINDER, page 2 of 2:3. Learn the parts of a typical long bone

– study the long bone model which is cut in half

4. Study the male and female pelvis and know their differences

5. Learn the basic joints on page 45 of your lab manual.

6. Learn the microscopic structures of bone from the models not the microscope slides

1 Lab 3 rev 7-11 SKELETAL SYSTEM Bone or Osseous Tissue –consists primarily of nonliving...

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