ANAT 100 - Module 2

5 main functions of the skeletal system

SUPPORT

- the skeleton provides framework that anchors soft organs

MOVEMENT

- skeletal muscles use bones as levers

PROTECTION

- protects our internal organs

STORAGE

- bones are storage for minerals and fat

HEMATOPOESIS

(production of red blood cells)

- blood cell formation happens in the marrow of bones

2 types of bone marrow

YELLOW MARROW

- stores fat

RED MARROW

- important for hematopoiesis (production of red blood cells)

Basic Composition of Bone

OUTER CORTICAL LAYER

- made of compact bone, hard and strong

INNER CANCELLOUS LAYER

- made up of spongy bone, porous and sponge-like

medullary cavity

- where blood cells are produced, found in the inner cavity of the bone

Types of Bones

FLAT

- ex. bones of the skull

IREGULAR

- ex. vertebrae

LONG

- ex. femur (longer than they are wide)

SHORT

- ex. bones of the ankle and wrist (long as they are wide)

SESAMOID

- ex. patella (kneecap)

Structure of Long Bones

- most common bone in the body

EPIPHYSIS

- knobby enlarged region at the end that tendons and ligments attach on to

METAPHYSIS

- region between epiphysis and diaphysis (Middle)

DIAPHYSIS

-elongated cylindrical shaft

additional features of long bones: Articular cartilage

- covers the epiphysis

- reduces friction between joints and absorbs shock

- a hyaline cartilage because it lines the joint surface

additional features of long bones: periosteum

- a tough sheath of dense irregular connective tissue that covers the surface of bones

- protects the bone, and contains blood vessels and nerves that supply the bone

- it has cells responsible for forming new blood tissue

additional features of long bones: medullary cavity

- bone marrow that proceeds red blood cells (in the inner cancellous layer)

Axial Skeleton: Skull

2 sets of bones that make up the skull:

cranial bones

facial bones

Axial Skeleton: Skull: Cranial Bones

7 bones that form a roof (dome of the brain) and a floor (cranial base) creating the cranial cavity

- frontal

- temporal (2)

-sphenoid

- parietal (2)

- occipital

Cranial Bones: Frontal Bone

1 bone

- forms the forehead and roof of the orbits (eye sockets)

Cranial Bones: Temporal Bones

2 bones

features of the temporal bone:

- zygomatic process

- external auditory meatus (ear hole)

- mastoid process

Temporal Bones: zygomatic process

Temporal Bones: External auditory meatus

Temporal Bones: Mastoid process

Cranial Bones: sphenoid bone

1 bone

- "keystone" of the skill because it joints the facial and cranial bones by attaching to almost every bone in the skull

Cranial Bones: Parietal Bones

2 bones

- paired

- form the superior and lateral surfaces of skull (top and side)

Cranial Bones: Occipital Bone

- forms posterior wall and base of skull

features:

- foramen magnum

- occipital condyles

Occipital bone: foramen magnum

- allows the spinal chord to exit the cranial cavity

Occipital Bone: Occipital condyles

- articulate with the first bone in the neck

Sutures

- attachments between flat bones in the skull

coronal

sagittal

lambdoid

squamous

coronal suture

Junction between frontal and parietal bones

sagital suture

junction between 2 parietal bones

lambdoid suture

junction between occipital and parietal bones

squamous suture

junction between temporal bone and parietal bones

cranial vault

- formed by frontal, parietal, and occipital bones

cranial base

3 fossa:

- anterior cranial fossa

- middle cranial fossa

- posterior cranial fossa

fossa

a depression in a bone

Skull: facial bones

7 bones to know:

- maxillary (2)

- nasal (2)

- zygomatic (2)

- mandible (1)

Facial Bones: Maxillary Bones

- paired (2)

- upper jaw bones

Facial Bones: Nasal Bones

- paired (2)

- articulate with the frontal bone

- form the bridge of the nose

Facial Bones: Zygomatic Bones

- paired (2)

- form the cheekbones

feature:

- the temporal process (which articulate with the zygomatic process of the temporal bone to form the zygomatic arch)

temporal process

Facial Bones: Mandible Bone

- 1 bone

- forms the Lower jaw

- parts of the mantle: body, ramus, angle

labelled mandible bone

Axial Skeleton: Vertebral Column

- made up of 26 bones:

24 vertebrae

1 sacrum

1 coccyx

divisions of vertebral column

- cervical (7 vertebrae)

- thoracic (12 vertebrae)

- lumber (5 vertebrae)

- sacrum (5 fused vertebrae)

- coccyx (4 fused vertebrae)

Basic Structure of vertebrae

BODY (anterior)

VERTEBRAL ARCH (posterior)

- extends into spinous and transverse processes

VERTEBRAL FORAMEN

- they all stack together to form the vertebral canal, which protects the spinal chord

spinous process

extending posteriorly

transverse process

- paired, extending laterally

Vertebra that aren't the same (Atypical)

C1

C2

C1

- 1st cervical

2 features important for its articulation with other bones

ANTERIOR ARCH

- surface for articulation with the dens (C2)

LATERAL MASSES

- surface for articulation with the occipital condyles of the occipital bone

C2

- main feature:

DENS

- rests within the anterior arch of C1

Movement of C1 and C2

- the occipital condyles rest on the lateral masses of C1, allowing for "yes" movement of head

- the dens of C2 articulates with the anterior arch of C1, allowing for the "no" movement of the head

Vertebral articulations

INTRAVERTEBRAL DISC

- jelly between 2 vertebra

- acts as a shock absorber

- fibrocartilage: they resist compression of the bones

INTRAVERTABLE FORAMEN

- openings between vertebrae to allow for the passage of spinal nerves

intravertebral discs

intravertebral foramen

Sacrum

5 fused vertebrae

Coccyx

4 fused vertebrae

axial skeleton: ribs

We have 12 ribs

TRUE RIBS

- pairs 1-7

- attaches directly to the sternum

FALSE RIBS

- pairs 8-10

- they dont attach directly to the sternum, they attach to rib 7 and the sternum by cartilage

FLOATING RIBS

- pairs 11-12

- dont attach to the sternum

Structure of a rib

- head

- tubercle

- shaft (body)

- angle (where the shaft is bent)

- costal groove

Axial Skeleton: Sternum

- makes up the anterior portion of the thoracic cage

3 parts:

MANUBRIUM

- articulation with rib 1

BODY

- articulation with rib 2-7

THE XIPHOID PROCESS

- tip

Thoracic cage

- made up of thoracic vertebrae, ribs, and sternum

Appendicular Sketelon: Upper Limb

contains 30 bones

Upper Limb: Pectoral Girdle

- connects the upper limb to the axial skeleton

Formed by:

- clavicle

- scapula

pectoral girdle: Clavical

- s-shaped bone (collar bone)

- it joins with the manubrium of the sternum (proximally) and the scapula (distally)

pectoral girdle: Scapula

- triangle shape

ANTERIOR SURFACE

- corticoid process

POSTERIOR SURFACE

- acromion

- spine

LATERAL SURFACE

-glenoid fossa

coracoid process

(with the acromion, the corticoid helps stabilize the shoulder joint)

LOOK AT PICTURE IN BOOK

acromion

Spine (Pectoral Girdle)

glenoid fossa

- articulates with the head of the humerus to contribute to the shoulder joint

Arm- Humerus

- articulates with the glenoid fossa to form the shoulder joint, and distally with the radius and ulna to form the elbow joint

features of the humerus

- head, neck, shaft

ANTERIORLY

- lateral epicondyle

- medial epicondyle

- capitulum

- trochlea

POSTERIORLY

- olecranon fossa

lateral and medial epicondyles

(lateral away from body)

(medial towards body)

capitulum

trochlea

olecrannon fossa

Forearm

RADIUS

ULNA

forearm: Radius

- in anatomical position, the radius is on the thumb side

features:

HEAD (PROXIMAL END)

- round shape that articulates with the humerus and the ulna

SHAFT

NECK

DISTAL END

- articulates with the carpal (wrist) bones

- styloid process

styloid process of radius

forearm: Ulna

- in anatomical position, it is on the pinky side

features:

PROXIMAL END

- articulates with the distal end of the humerus

- olecranon

- trochlear notch

SHAFT

NECK

HEAD (DISTAL END)

- styloid process

IMPORTANT TO NOTICE THAT UNLIKE THE RADIUS, THE HEAD IS DISTAL

olecranon

fits into the olecranon fossa of the humerus

trochlear notch

C shaped interlocks with the trochlea of the humerus

styloid process of ulna

Tiny bulb at bottom of Ulna

Wrist and Hand

Wrist

- 8 carpal bones (short bones)

Palm

- 5 metacarpal bones (long bones)

FIngers

- 14 phalanges (long bones) 3 each except the thumb has 2

Appendicular Skeleton: Lower Limb

contains 30 bones +inanimate bone

Lower Limb: pelvic girdle

- attaches the lower limb to the axial skeleton

formed by:

ILIUM

ISCHIUM

PUBIS

Pelvic Girdle: Ilium

- largest bone of the pelvic girdle

features:

- iliac crest

- anterior superior iliac spine

- anterior inferior iliac spine

- posterior superior iliac spine

- posterior inferior iliac spine

LOOK IN NOTE FOR A PICTURE

Pelvic Girdle: Pubis

- fuses with the ilium and the ischium

- fuses with the other pubic bone at the pubic symphysis (made of fibrocartilage)

2 structures of the pelvic girdle

ACETABULUM

- deep depression for articulation with the head of the femur

- made up by the ilium, ischium, and pubis

OBTURATOR FORAMEN

- large opening in the anterior of each pelvic girdle which is a passage for verse and blood vessels

- made up of the ischium and pubis

Acetabulum

obturator foramen

Also on the pelvis:

GREATER SCIATIC NOTCH

- located between the posterior inferior iliac spine

- allows the passage of major nerves and blood vessels from the pelvic cavity into the posterior region

LESSER SCIATIC NOTCH

- located between the posterior inferior iliac spine and the ischial tuberosity

- allows for the passage of structures from the pelvic cavity to the genital region

Thigh- Femur

- biggest bone in the body

features:

- head, neck, shaft

Proximal End of femur

- head articulates with the acetabulum of the pelvic girdle forming the hip joint

- bumps and ridges for muscle attachment

Distal End of the Femur

- articulates with the tibia and patella (knee cap)

- medial and lateral condyles

- patellar surface

medial and lateral condyles (on the femur)

- 2 bumps on the end

patellar surface

- surface which forms a groove for the patella

Leg

tibia and fibula

Leg: Tibia

- weight bearing bone of the leg

features

PROXIMAL END

- medial and lateral condyles (which articulate with the medial and lateral condyles of the femur)

- tibial tuberosity

SHAFT

DISTAL END

- medial malleolus

tibial tuberosity

medial malleolus

Fibula

- the lateral malleolus (the distal tip of the fibula) provides stability to the ankle joint

features:

PROXIMAL END

- medial head which articulates with the tibia

NECK

SHAFT

DISTAL END

- lateral malleolus

lateral malleolus

Ankle and foot

ankle

- 7 tarsal bones (short bones)

foot

- 5 metatarsal bones (long bones)

toes

- 14 phalanges (long bones)

articulation

- where bones meet other bone, cartilage, or teeth

the most mobile joints are unstable

the least mobile joints are stable

Classification of joints

Structural Classification

- based on the type of materials that unite the articulating bones

Functional Classification

- based on the extend of movement they permit

Synovial joints

- articulating bones are enclosed by a joint capsule with a fluid filled cavity

movements of synovial joints

- gliding

- angular

- rotation

- special movements

movements of synovial joints: Gliding

the motion of bones sliding on one another

movements of synovial joints: angular

Flexion

- decreasing angle between articulating bones (bending)

Extension

- increasing angle between articulating bones (extending)

Abduction

- movement away from the midline of the body

Adduction

- movement towards the midline of the body