the skeletal system final

8/3/2019 The Skeletal System Final

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THE SKELETAL SYSTEM

I. OBJECTIVE: To identify the parts of the human skeleton and their distinctivefeatures.

II. MATERIALS: Fresh beef bones sawed longitudinally, dissection instruments,

model of the human skeleton, models of various joints, coloredpencils.

III. PROCEDURE:

A. Examine the cut surface of a split beef bone and identify the following parts.

Structure of a Long Bone:

a. diaphysis- an elongated shaft

b. epiphyses- the expanded terminal portion of the shaft

c. epiphyseal disk- a plate of hyaline cartilage present at the junction of the

epiphyses and diaphysis during the growing yearsd. cancellous bone- the interior of the epiphyses and ends of the diaphysis

e. compact bone- forms the rigid tube of the diaphysis and is reduced in thickenesswhere it covers the underlying cancellous bone

f. medullary cavity- the hollow chamber in the diaphysis; lined with a thin

epithelial membrane, the endosteum

g. yellow marrow- fills the medullary cavity

h. red marrow- which forms the blood cells, occurs in cancellous bone in the

epiphyses of femur and humerus; most red marrow in adults is found in

cancellous bone of the ribs, sternum, pelvic girdle and vertebrae

i. periosteum- a tough, fibrous membrane covering that tightly adheres to the bone

surface except for the articular surfaces j. articular cartilage- covers the articular surfaces of the bone; reduces the frictionand protects the ends of the bone


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Identify the parts of a long bone

B. Using the model of the human skeleton identify the following parts.

Division of the Skeletal System

1. AXIAL SKELETON

A. Skull- composed of the cranial and facial bones; a firm covering or case of

the brain; contain numerous foramina for passage of cranial nerves and

blood vessels. Bones of the cranium begin to develop in early fetallife, ossification is gradual and not completed at birth, hence

membrane-filled bones are found between these spaces called

fontanels.

1.) Bones of the Cranium

a. frontal (1)- forms the anterior superior portion of the cranium, includingthe forehead, upper parts of the eye orbits, and roof of the nasal cavity.


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Above each eye orbit is a supraorbital foramen that is reduced in

some skulls to a supraorbital notch.

b. parietal bones (2)- form the roof and sides of the cranium posterior to thefrontal bone, to which they are joined by coronal sutures. The

parietal bones are joined to each other at the superior midline by the

sagittal suture. c. occipital bone (1)- the posterior inferior portion of the skull. It joins to the

parietal bones by the lambdoidal suture. The floor of the occipital

bone contains the large foramen magnum, which surrounds the brainstem. On each side of the foramen are the occipital condyles that

articulate with the atlas.

d. temporal bones (2)- located just below the parietal bones on each side of

the skull. Each joins to the parietal bone above it by a squamosal

suture and articulates posteriorly with the occipital bone by the

lambdoidal suture.

The ear components are located within the temporal bones. Theexternal auditory (acoustic) meatus, which leads inward toward the

middle ear, is located near the inferior margin. Just anterior to theauditory meatus is the mandibular fossa (depression). The

mandibular condyle fits into this fossa to form the

temporomandibular joint.

3 major processes on each temporal bone

1. zygomatic process- anterior extension that articulates with the

cheekbone (zygomatic)

2. styloid process- slender spinelike process that extends downward

below the auditory meatus; serves as an attachment site for some

tongue and pharyngeal muscles

3. mastoid process- rounded eminence inferior and posterior to the

auditory canal; attachment site for certain neck muscles

jugular foramina- located medial to the styloid processes at the junction of

the temporal and occipital bones; allow passage of the jugular veins

from the brain to the neck

carotid canals- located anterior to the jugular foramina; through which thecarotid arteries pass to the brain

e. sphenoid bone (1)- consists of a central body and two winglike structuresthat extend laterally; forms part of the floor of the cranium, the sides

of the cranium in the temple areas, and the posterior walls of the eye

orbits.

foramen ovale- an oval opening on each side of the sphenoid bone; it is

where the mandibular nerve passes through


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sella turcica (Turks saddle)- the saddle-shaped structure of the central

body

deep hypophyseal fossa- located within the sella turcica is occupied by thehypophysis (pituitary gland) which hangs downward from the brain

optic foramina- passageways for the optic nerves; located on each side in

the anterior portion of the sella turcica superior orbital fissure- is the opening medial to the sphenoid

inferior orbital fissure- is located below the sphenoid

f. ethmoid bone (1)- forms part of the roof of the nasal cavity and part of the

medial surface of the orbit and closes the anterior portion of the

cranium.

cribriform plates- contain numerous olfactory foramina for the passage ofolfactory nerves from the brain to the nasal cavity

crista galli- projects upward into the cranial cavity between the cribriform

plates; membranes enclosing the brain are attached to the crista galli

2.) Bones of the face

a. maxillae (2)- upper jaw bones

alveolar process- portion of each maxillary bone containing teeth; together

these processes form the alveolar, ordental arch. Each tooth

occupies an alveolus (socket) in the dental arch.

b. palatine bones (2)- L-shaped, situated at the back of the nasal cavity.They help form the back potion of the roof of the mouth, part of the

floor and outer wall of the nasal cavity, and a small potion of the floor

of the orbit.

c. zygomatic bones (2)- cheekbones; form the prominences of the cheeks

and the lateral walls of the orbits

d. lacrimal bones (2)- located between the ethmoid and maxilla on themedial wall of each eye orbit. Each lacrimal bone has a small groove

for a tear duct that carries tears from the eye into the nasal cavity

e. nasal bones (2)- thin bones fused at the midline to form the bridge of thenose

f. vomer (1)- a thin, flat bone located on the midline of the nasal cavity;

forms part of the central septum

g. inferior nasal conchae (2)- scroll-like bones that extend from the lateralwalls of the nasal cavity inferior to the middle nasal conchae of the

ethmoid bone; support mucous membranes in the nasal cavity

h. mandible (1)- lower jaw bone consists of a horseshoe-shaped, horizontal

body with an upward-projecting ramus at each end; the posterior

inferior jumction of each ramus with the body is called the angle; the

strongest bone of the face. mandibular foramina- located on the medial surfaces of a rami; blood

vessels and nerves supplying the teeth enter these openings and later

emerge through the smallermental foramina, which are located on


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the anterolateral external surfaces of the mandibular body, to supply

the lips and chin.

Identify the bones of the skull.


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3.) The Paranasal Sinuses- cavities in some of the skull bones that reduce the

weight of the skull without appreciably weakening it. The sinuses are

lined with a mucous membrane and have passageways leading into thenasal cavity. They are named after the bones in which they are

located.

a. frontal sinuses- occur in the forehead above the eyes

b. maxillary sinuses- large sinuses below the eyes

c. sphenoidal sinuses- centrally located under the sella turcica d. ethmoidal sinuses- consist of a number of small, air-filled spaces

Identify the paranasal sinuses.


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4.) Fontanels- membranous areas at the junction of several cranial bones, allow

the compression of the skull during childbirth and growth of the brainafter birth; there are 6 fontanels

a. large anterior fontanel- lies on the midline at the junction of the parietaland occipital bones

b. smaller posterior fontanel- is on the midline at the junction of the

parietal and occipital bones c. anterolateral fontanel- occurs on each side of the skull at the junction of

the frontal, parietal, zygomatic, sphenoid and temporal bones

d. posterolateral fontanel- is on each side of the skull at the junction of the

temporal, parietal and occipital bones

Identify the fontanels.

B. Hyoid bone- horseshoe-shaped, consists of a central portion called the bodyand two projections on each side, the greater and lesser cornua

respectively. This can be felt in the neck, just above the Adams

apple. It supports the tongue and for muscles attachment.

C. Vertebral Column- forms a flexible but sturdy vertical axis extending fromthe skull to the pelvis. It is composed of 24 movable vertebrae, thesacrum and the coccyx. They are all abound together by ligaments and

muscles to form a unified structure; exhibits four defined spinal

curvatures the cervical, thoracic, lumbar and pelvic curvatures.

Parts of a typical vertebra


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1. body or centrum- anterior structural mass, that is the major load-bearing

contact between adjacent vertebrae

2. pedicles- two processes projecting posteriorly from each side of thevertebral body

3. laminae- processes connecting the pedicles below and meet mid-dorsally

to form the neural arch4. neural arch- encloses the spinal foramen

5. spinal foramen- located at the center of neural arch; the spinal cord

descends through this where it is protected by the surrounding neuralarches of the vertebrae

intervertebral foramina- small openings between pedicles of adjacent

vertebrae where spinal nerves emerging from the spinal cord exit

6. seven processes

a. 2 articular processes to connect with the bone above

b. 2 articular processes to connect with the bone below

c. 2 transverse processes where the lamina and pedicles join

d. 1 spinous process projecting dorsally from the junction of thelamina

Regions of the Vertebral Column

1. Cervical or neck region- composed of 7 vertebrae; the first- the atlas, the

second- the axis

transverse foramen- occurs in each transverse process only in cervical

vertebrae; serve as passageways for the vertebral arteries and

veins

2. Thoracic region- 12 vertebrae below the cervical vertebrae

3. Lumbar region (in the loins)- the next 5 vertebrae; they have a larger

body than other vertebrae because of the greater stress that occurs in this

region of the vertebral column

4. Sacral region (pelvis)- composes the posterior wall of the pelvic cavity;

it consists of 5 fused vertebrae

dorsal sacral foramina- one row on each side of the sacrum; throughwhich blood vessels and nerves pass

sacral canal- form from the neural arches of the fused vertebrae which

continues to an inferior opening the sacral hiatus

sacral superior articular surfaces- articulate with the inferior articular

surfaces of the fifth lumbar vertebra

5. Coccygeal region (lower pelvis)- composed of 4 or 5 rudimentary

vertebrae fused together to form the coccyx, of tailbone


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Identify the parts of a typical vertebra, a sacral vertebra and the vertebral

column.


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D. The Thoracic Cage- the thoracic vertebrae, ribs, costal cartilages and

sternum form the skeleton (rib cage) of the thorax. It protects the heat and

lungs and provides support of the pectoral (shoulder) girdles.

1. Sternum or breastbone- is notched along the sides where the costal

cartilages attach. It consists of three parts: an uppermanubrium, amiddle body orgladiolus and a lowerxiphoid process

2. Ribs- there are 12 pairs attached to the thoracic vertebrae

Kinds of Ribs as to Attachment

a. vertebrosternal or true ribs- the first seven pairs of ribs attach

directly fo the sternum by costal cartilages

b. false ribs- the remaining 5 pairs of ribs, subdivided into:

1. vertebrochondral- the cartilage of the first 3 pairs of false ribs

are fused to the costal cartilages of ribs above them

2. vertebral or floating ribs- last 2 pairs of false ribs are notattached anteriorly

Parts of a Rib

a. head- articulates with the vertebral column via two articular facets

b. tubercle- consists of an articular portion and a nonarticular

portion

c. neck - the short segment between the head and tubercle

d. body- the flattened, curved remainder of the rib

Identify the parts of the thoracic cage.


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Identify the parts of a rib.

B. APPENDICULAR SKELETON

1. The Pectoral Girdle or Shoulder Girdle- it supports the upper limbs and

permits great freedom of movement.

a. Clavicle or collar bone (2)- a slender S-shaped bone. Its lateral end

articulates with the acromion process of a shoulder blade, and its

medial end articulates with the superiolateral margin of the sternum.

In the female, the clavicle is generally less curved, smoother, shorter

and more slender than in male.

b. Scapula or shoulder blade (2)- is a flat, triangular bone that does not

articulate directly with the axial skeleton. Instead, it is held in place

by muscles thus giving greater mobility to the shoulder. On itsaxillary margin is the shallow glenoid cavity which articulates with

the head of the humerus.

2 large processes above the glenoid cavity

1. coracoid process- projects anteriorly under the clavicle

2. acromion process- projects posteriorly and articulates with theclavicle

scapular spine- is a slender process on the scapulas posterior surface that

runs diagonally from the medial vertebral margin to the acromionprocess

scapular notch- occurs on the superior margin at the base of the coracoid


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Identify the parts of the pectoral girdle.

2. The Upper Limb- consists of the upper arm, forearm and hand

a. Humerus (2)- is the bone of the upper arm. The rounded head of thehumerus fits into the glenoid cavity of the scapula.

2 processes inferior to the head

1. greater tubercle- on the lateral surface2. lesser tubercle- on the anterior surface

surgical neck- inferior to the tubercles and is so named because of the

frequency of fractures in this area

deltoid tuberosity- is a rough, raised area near the midpoint of the lateral

surface of the shaft to which the deltoid muscle attaches

2 condyles at the distal end of the humerus

1. capitulum- the lateral condyle articulating with the radius

2. trochlea- the medial condyle, which articulates with the ulna

lateral and medial epicondyles- located superior to the 2 condyles

coronoid fossa- the depression on the anterior surface just superior to the

trochleaolecranon fossa- is in similar location on the posterior surface of the

humerus

b. Radius (2)- found at the lateral side of the ulna; is shorter and smaller

than the ulna. The disklike head articulates with the capitulum of the

humerus and enables the head to rotate when the position of the handis changed from palm up to palm down.


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radial tuberosity- a short distance below the head; the attachment site for

the biceps brachii muscle, a major flexor of the arm

neck- located between the head and the tuberosity

styloid process- present at the distal end of the radius, at the articulation

with the hand

c. Ulna (2)- elbow bone, the largest bone of the forearm, located at the

medial side of the radius

olecranon process- proximal posterior prominence of the ulna, forms thepoint of the elbow and fits into the olecranon fossa when the arm is

extended

semilunar notch- a depression that articulates with the trochlea of the

humerus

coronoid process- a small eminence at the anterior margin of the trochlear

notch

head- knoblike, located at the distal end of ulna that articulates with the

radius and a fibrocartilaginous disk that separates it from the hand.Styloid process- is the distal medial prominence

d. Carpus or wrist (16)- composed of 8 small bones united by ligaments:

arranged in two rows and closely joined together, yet they allow

certain amount of motion

e. Metacarpus or body of the hand (10)- composed of five bones curved

longitudinally, behind, concave in front. They articulate at their bases

with second row of carpal bones, and with the first row of phalanges.

f. Phalanges (28)- bones of the fingers; 14 in number, 3 for each finger and

2 for its thumb


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Identify the parts of the upper limbs.

3. The Pelvic Girdle or Pelvis- is formed by two coxal bones (hipbones), thesacrum and the coccyx.

Parts of a coxal bone- consists of 3 separate parts in children

1. ilium- broad upper bone whose superior margin forms the iliac crest, theridgelike prominence of the hip. The iliac crest extends between the

anterior superior spine and the posterior superior spine. Just inferior to

each of these prominences are smaller iliac spines: the anterior inferior

spine and the posterior inferior spine.

2. ischium- is the lower posterior portion

3. pubis- the lower anterior part


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symphysis pubis- anterior articulation of coxal bones articulate with each

other

sacroiliac joints- posterior articulation of the coxal bones with the sacrum

acetabulum- a large cup-shaped fossa is located at the junction of the ilium,

ischium and pubis on the lateral surface of each coxal bone; receives the

head of the femurgreater sciatic notch- between the posterior inferior spine and the ischial

spine

lesser sciatic notch- is just inferior to the ischial spine

tuberosity of ischium- located at the posterior inferior angle of the ischium

obturator foramen- the large opening surrounded by the ischium and pubis

Identify the parts of the pelvic girdle.

4. The Lower Limb

a. femur (2)- the bone of the upper leg; longest bone in the body; its

rounded head fits into the acetabulum of a coxal bone.

2 large processes occur at the base of the neck

1. greater trochanter- lateral process

2. lesser trochanter- medial process

lateral and medial condyles- enlarged lower terminal end of the femur,

which have lateral and medial epicondyles just above them


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b. patella or kneecap (2)- a small, flat triangular bone located in front of the

knee joint, articulates with the femur and is surrounded by a large fluid-

filled bursa

c. tibia or shinbone (2)- lies at the front and medial side of the leg; it

articulates with the talus or ankle bone and with both ends of the fibula.lateral and medial condyles- consists the upper end of tibia that articulate

with the corresponding condyles of the femur

tibial tuberosity- located on the anterior surface just inferior to thecondyles

anterior crest- a sharp ridge evident on the shaft

medial malleolus- a process at the distal end of the tibia which forms the

medial prominence of the ankle

d. fibula or calfbone (2)- lies at the lateral side of tibia and parallel with it,

smaller than the tibia and most slender of all the long bones in

proportion to its length. The lower extremity articulates with the tibiaand the talus.

e. tarsus or ankle (14)- there are 7 tarsal bone, the most prominent are the

talus, which articulates with the tibia and fibula and the calcaneus orheelbone.

f. metatarsus (10)- is formed by 5 sole bones which articulates with the

tarsus and first row of phalanges. The tarsal and metatarsal bones form

2 distinct rows of arches, that running from heel to toes of the medialside is the longitudinal arch, the other running across the foot in the

metatarsal region, the transverse arch.

g. phalanges (28)- 14 in number, 2 in the great toe and 3 in each of the other

toes.


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Identify the parts of the lower limbs.

Questions:

1. Clench your fist. What bones form the raised knobs of your knuckles?

2. Flex your arm. What bones form the elbow? What is a funny bone?


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3. Use your left hand to hold your right forearm near the elbow. Now rotate your

right wrist from palm up to palm down. What bone is stationary?

Label the parts of the human skeleton and color red the axial skeleton and

yellow the appendicular skeleton.

C. Examine the joint models and the major structures of each.

The Basic Functional Types

1. Synarthrotic joints- are immovable because the bones forming the joint are

tightly bonded to each other by fibrous connective tissue or cartilage


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2 types of immovable joints

1. sutures- are irregular joints between immovable bones of the skull. The

bones are bonded together by fibrous connective tissue that iscontinuous with the periosteum on the outer surface of the bones and

with the dura mater on the inner surface of the bones.

2. sychondroses- have cartilage as the bonding tissue e.g. the bonding of theepiphyses to the diaphysis by the epiphyseal cartilages in the long

bones of children

2. Amphiarthrotic joints- are slightly movable; also bound by fibrous connective

tissue or cartilage but not as tightly as in immovable joints.

2 types of slightly movable joints

1. symphyses- have a cushioning pad of fibrocartilage between the bones e.g.

symphysis pubis and intervertebral disc; adjacent to the cartilaginous

pads, the articular surfaces of the bones are covered with articular

cartilages that reduce friction in the joint. The joint is wrapped in afibrous capsule formed ofligaments.2. sydesmoses- lack fibrocartilage, but the bones are held together by fibrous

connective tissue forming interosseous ligaments e.g. attachment of

the fibula to the tibia

3. Diarthrotic- are freely movable; bones are bound together by a fibrous articularcapsule formed of ligaments. A synovial membrane lines the inside of the

capsule and secretes synovial fluid that lubricates the joint. The articular surfaces

of the bones are covered by protective, friction-reducing articular cartilages.These joints may also contain bursae, sacs of synovial fluid that reduce friction.

6 kinds of synovial joints

1. gliding joints- occur between small bones with flat or slightly convex

surfaces e.g. carpal and tarsal bones.

2. hinge joints- allow movement in only one plane e.g. elbow and knee

3. condyloid joints- allow movement in two planes; they are formed by a

rounded condyle articulating with an elliptical depression e.g. between

carpus and radius

4. saddle joints- occur where the ends of both bones are saddle-shaped, convexin one direction and concave in the other e.g. the joint between the

trapezium (a carpal bone) and the metacarpal bone of the thumb,

which permits a variety of movements

5. pivot joints- allow rotational movement around a pivot point e.g. atlas around

the odontoid process of the axis

6. ball-and-socket joints- allow angular movement in all directions e.g.shoulder and hip joints


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Identify the types of joints and label the parts.

Identify the parts of a shoulder joint.

the skeletal system final

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