Anatomy Chapter 5

bones

4 Parts of the Skeleton System

Bones, Joints, Cartilages, Ligaments

Two Subdivisions of the Skeleton

Axial Skeleton and Appendicular Skeleton

What are the functions of bones? (5)

Support, Protection, Allows Movement, Stores Minerals and Fats, and Blood Cell Formation

How many bones does an adult skeleton have?

206 Bones

Two Basic Types of Bone Tissue

Compact Bone and Spongy Bone

Describe Compact Bone

Homogeneous

Describe Spongy Bone

Small needle-like pieces of bone, has open spaces

Bones are classified as...

Long, Short, Flat, or Irregular

Classification of Long Bones

• Typically Longer than they are wide

• Shaft with heads situated at both ends

• Contain mostly compact bone

• All of the bones of the limbs (except wrist, ankle, and kneecap bones)

• Example: Femur and Humerus

Classification of Short Bones

• Generally cube-shaped

• Contain mostly spongy bone

• Includes bones of the wrist and ankle

• Sesamoid bones are a type of short bone which form within tendons (patella)

• Example: Carpals and Tarsals

Classification of Flat Bones

• Thin, flattened, and usually curved

• Two thin layers of compact bone surround a layer spongy bone

• Example: Skull, Ribs, and Sternum

Classification of Irregular Bones

• Irregular shape

• Does not fit into other bone classification categories

• Example: Vertebrae and Hip Bones

Anatomy of a Long Bone (2)

- Diaphysis and Epiphysis

What is Diaphysis?

Shaft and composed of compact bone

What is Epiphysis?

Ends of the bone and composed of mostly spongy bone

Anatomy of a Long Bone (7)

• Periosteum

• Perforating (Sharpey's) Fibers

• Arteries

• Articular Cartilage

• Epiphyseal Plate

• Epiphyseal Line

• Marrow (Medullary) Cavity

What is Periosteum?

• Outside covering of the diaphysis

• Fibrous connective tissue membrane

What are Perforating (Sharpey's) Fibers?

Secure periosteum to underlying bone

What do Arteries do?

Supply bone cells with nutrients

What is Articular Cartilage and what does it do?

• Covers the external surface of the epiphyses

• Made of hyaline cartilage

• Decreases friction at joint surfaces

What is Epiphyseal Plate?

Flat plate of hyaline cartilage seen in young, growing bone

What is Epiphyseal Line?

• Remnant of the epiphyseal plate

• Seen in adult bones

What is Marrow (Medullary) Cavity?

• Cavity inside of the shaft

• Contains yellow marrow (mostly fat) in adults

• Contains red marrow for blood cell formation

Bone Markings

Surface features of the bones

What are the two categories of bone markings?

• Projections/Processes: grow out from the bone surface

• Depressions/Cavities: indentations

Bone markings are sites of attachments for? (3)

Muscles, Tendons, and Ligaments

Bone markings are also passages for nerves and blood vessels. (T/F)

TRUE

3 Parts of the Microscopic Anatomy of Compact Bone

Osteon (Haversian system), Central (Haversian) canal, and Perforating (Volkmann's) canal

Describe the Osteon (Haversian system)

A unit of bone containing central canal and matrix rings

Describe the Central (Haversian) canal

• Opening in the center of an osteon

• Carries blood vessels and nerves

Describe the Perforating (Volkmann's) canal

• Canal perpendicular to the central canal

• Carries blood vessels and nerves

3 Parts of the Microscopic Anatomy of Bone

Lacunae, Lamallae, and Canaliculi

Describe Lacunae

• Cavities containing bone cells (osteocytes)

• Arranged in concentric rings called lamellae

Describe Lamallae

• Rings around the central canal

• Sites of lacunae

Describe Canaliculi

• Tiny canals

• Radiate from the central canal to lacunae

• Form a transport system connecting all bone cells to a nutrient supply

In embryos, the skeleton is primarily \_______?

Hyaline cartilage

During development, bone is replaced by cartilage. (T/F)

FALSE. During development, much of hyaline cartilage is replaced by bone.

Cartilage remains in isolated as ...

• Bridge of a nose

• Parts of ribs

• Joints

What does bone growth (Ossification) allow?

Epiphyseal plates allow for lengthwise growth of long bone during childhood

How does the bone growth happen?

• Older cartilage ossified

• Cartilage is broken

• Enclosed cartilage is digested away, opening up a medullary cavity

• Bone replaces cartilage through the action osteoblasts

• Bones are remodeled and lengthened until growth stops

Bones are remodeled in response of two factors, what are they?

• Blood calcium levels

• Pull of gravity and muscles on the skeleton

What is Appositional Growth?

Bones grow in width

Types of Bone Cells

• Osteocytes: mature bone cells

• Osteoblasts: bone forming cells

• Osteoclasts: giant bone destroying cells (break down bone matrix for remodeling and release of calcium in response to parathyroid hormone)

Which two types of cells perform in bone remodeling?

Osteoblasts and Osteoclasts

What is a Fracture?

Break in a bone

Two Types of Bone Fractures

• Closed (simple) fracture: break that does not penetrate the skin

• Open (compound) fracture: broken bone penetrates through the skin

How are bone fractures treated?

Reduction and Immobilization

Comminuted Fracture

bone breaks into many fragments

* Compression Fracture

bone is crushed

Depressed Fracture

broken bone portion is pressed inward

Impacted Fracture

broken bone ends are forced into each other

Spiral Fracture

ragged break occurs when excessive twisting forces are applied to a bone

Greenstick Fracture

bone breaks incompletely

The Axial Skeleton does what?

Forms the longitudinal axis of the body

What are the three parts of the Axial Skeleton?

Skull, Vertebral Column, and Bony Thorax

What are the two sets of bones in the skull?

Cranium and Facial Bones

Bones are joined by \______?

Sutures

(T/F) Only the mandible is attached by a restricted movable joint

FALSE, Only the mandible is attached by a freely movable joint

What types of bones surround the nasal cavity?

Hollow portions of bones

What are the functions of paranasal sinuses? (2)

• Lighten bone

• Give resonance/amplification to voice

What bone is the only bone that does not articulate with another bone?

The hyoid bone

What are the functions of the hyoid bone? (2)

• Serves as a moveable base for the tongue

• Aids in swallowing and speech

An infant's fetal skull is \____ body length compared to an adult skull which is \____ body length.

1/4, 1/8

What are fontanels?

Fibrous membranes connecting to the cranial bones

What are the functions of the fontanels? (3)

• Allow skull compression during birth

• Allow the brain to grow during later pregnancy and infancy

• Convert to bone within 24 months after birth

There are \___ single vertebral bones separated by intervertebral discs

24

Seven \______ vertebrae are in the neck

Cervical

Twelve \_____ vertebrae are in the chest region

Thoracic

Five \_____ vertebrae are associated with the lower back

Lumbar

Nine vertebrae fuse to form two composite bones, which are?

Sacrum and Coccyx

Where are the primary curvatures located? (spinal curvatures)

Thoracic and Sacral regions

(T/F) Curvatures are present from birth

TRUE

What shape are primary curvatures in newborns?

C-shaped

Secondary curvatures are located where? (spinal curvatures)

Cervical and Lumbar regions

(T/F) Secondary curvatures develop before birth.

FALSE, they develop after birth

What shape are secondary curvatures on adults?

S-shaped

The sacrum is formed by the fusion/blend of how many vertebrae?

5

It is formed from the fusion/blend of 3-5 vertebrae.

Coccyx

Coccyx is the fancy word for?

Tailbone (or remnant of a tail that other vertebrates have)

A typical vertebrae has what? (6)

• Body

• Vertebral Arch (pedicle and lamina)

• Vertebral Foramen

• Transverse Processes

• Spinous Process

• Superior and Inferior Articular Processes

What does the body thorax do for the body?

Forms a cage to protect major organs

3 Parts That Make Up the Body Thorax

Sternum, Ribs, and Thoracic Vertebrae

How many pairs do true ribs have?

1-7 pairs

How many pairs do false ribs have?

8-12 pairs

How many pairs do floating ribs have?

11-12 pairs

(T/F) The appendicular skeleton is composed of 100 bones.

FALSE, 126 bones

What are three things that make up the appendicular skeleton?

• Limbs (appendages)

• Pectoral Girdle

• Pelvic Girdle

The clavicle (collarbone) and scapula (shoulder blade) compose what?

The Pectoral (Shoulder) Girdle

How does the clavicle fit in the body? (how is it placed?)

Articulates with the sternum medially and with the scapula laterally.

How is the scapula placed?

Articulates with the clavicle at the acromiclavicular joint and articulates with the arm bone at the glenoid cavity.

What does the clavicle and scapula do for the body?

These bones allow the upper limb to have free movement.

Bones of the Upper Limbs (3)

• Humerus

• Forearm (Ulna/Radius)

• Hand

Explain the Humerus (4)

• Forms the arm

• Single bone

• Proximal end articulation (head articulates with the glenoid cavity of the scapula)

• Distal end articulation (trochlea and capitulum articulate with the bones of the forearm)

Explain the Forearm (Ulna and Radius)

ULNA: (the thinner bone, outside)

• Medial bone in anatomical position

• Proximal end articulation (coronoid process and olecranon articulate with the humerus)

RADIUS:

• Lateral bone in anatomical position

• Proximal end articulation (head articulates with the capitulum of the humerus)

What are the three parts that make up the hand?

• Carpals

• Metacarpals

• Phalanges

Explain each part of the hand (3)

CARPALS (wrist): 8 bones arranged in 2 rows of 4 bones in each hand

METACARPALS (palm): 5 per hand

PHALANGES (fingers and thumb): 14 phalanges in each hand, 3 bones each finger, 2 bones in thumb

What is formed by two coxal (ossa coxae) bones?

Pelvic Girdle

The Pelvic Girdle is composed of three pairs of fused bones, what are they?

• Illium

• Ischium

• Pubis

A pelvic girdle contains...

2 coxal bones and a sacrum

A bony pelvis contains...

2 coxal bones, sacrum, and coccyx