Anatomy Exam #2

What are the functions of the skeletal system?

1. Support of the entire body
2. Protection of organs
3. Movement/attachment of muscles
4. Hemopoiesis
5. Energy metabolism
6. Mineral reserves

Viscera

Organs

Hemopoiesis

Blood cell production

Where do bones meet?

Joints

Are bones considered organs?

Yes, bones are made up of multiple types of tissues so they are considered organs

Is the skeletal system internal or external?

Internal

How many bones are there in an adult human body?

206

Skeletal System Parts

1. Bones
2. Cartilages
3. Joints
4. Ligaments

Axial Skeleton

1. Skull
2. Vertebral column
3. Thoracic cage (sternum and ribs)
4. Hyoid bone
5. Sacrum
6. Coccyx
7. Includes 80 bones all together

Appendicular Skeleton

1. Pectoral girdle
2. Upper limbs
3. Pelvic girdle
4. Lower limbs
5. Includes 126 bones all together

Axial Skeleton Function

1. Supports head, neck, and trunk
2. Protects brain, spinal cord, and thoracic organs

Appendicular Skeleton Function

Supports the attachment and functions of the limbs of the human body

Foramen

1. AKA Foramina
2. A hole in a bone
- Typically for nerves or blood vessels
3. Examples; foramen magnum, infraorbital foramen

Fossa

1. AKA fossae
2. A depression in a bone
3. Examples; mandibular fossa, lacrimal fossa

Process Bone Marking

1. Projection from bone
2. Narrow or wide
3. Protrudes from surrounding bone
4. Examples; styloid or mastoid process

Meatus

1. A hole or tube-like structure
2. Passage or opening
3. Example; auditory meatus

Canal

1. A groove or tube-like structure
2. Example; optic canal

Bone

1. Strong and stiff
2. Mineral reservoir
3. Muscle attachment sites
4. Protection

Cartilage

1. Flexible
2. Resilient (mostly water)
3. Resists tension and compression

Cartilage Tissue Structure

1. Avascular
2. Cells are chondrocytes found in lacunae
3. Three types
- Hyaline
- Elastic
- Fibrocartilage

Avascular

No blood vessels

Cartilage Tissue Functions

1. Support soft tissues
2. Model for formation of bone
3. Gliding surface at articulations

Is cartilage soft bone?

NO

Hyaline Cartilage

1. Most common
2. Contains nearly invisible collagen fibers (fibrils)
3. Found in
- Ends of long bones
- Costal cartilages
- Articular joint cartilage
- Respiratory structures (larynx, trachea)
- Fetal/embryonic skeleton

Elastic Cartilage

1. Similar to hyaline cartilage
2. Contains lots of elastic fibers
3. VERY resilient and flexible
4. Tolerates repeated bending
5. Found in
- Pinna (outer ear)
- Epiglottis

Fibrocartilage

1. Contains little ground substance
2. Matrix has thick, dense collagen fibers
3. Resists strong compression
4. Found in
- Intervertebral disks
- Knee joint
- Pubic symphysis
- Meniscus

Cartilage Locations Diagram

Fibril

1. Very thin fibers
2. Found in hyaline cartilage

Bone Tissue

1. Very little fluid
2. Resists compression and tension; very strong
3. Well vascularized
- Heals/remodels easily
4. Organic and inorganic materials
5. Osteocytes in lacunae

Lacunae

Contains osteocytes

Osteocytes

1. Found in lacunae
2. Mature bone cells
3. Can also be osteoblasts and osteoclasts

What is the extracellular matrix of bones?

1. Organic
- Fibers (lots of collagen)
- Ground substance
2. Inorganic
- 65% mineral salts
- Calcium phosphate

Osteoblast

1. A cell from which bone develops
2. Builds new bone

Osteoclast

1. Cells that breakdown and consume bone tissue
2. Break down or consume bone

Intramembranous Ossification

1. The process of forming bones within a membrane
2. Forms
- Flat bones
- Bones of the skull
- Clavicle
- Maxillae
- Zygomatic mandible

Endochondral Ossification

1. The process of forming bones most bones go through
2. Forms
- Long bones of the axial skeleton
- Appendicular skeleton

Endochondral Ossification Steps

1. Skeleton begins as hyaline cartilage model
2. Primary center of ossification appears in diaphysis and bone replaces cartilage
3. Secondary center of ossification form in epiphyses
4. Skeleton grows via division of cartilage (and bone) cells until maturity
5. Epiphyseal (growth) plates ossify

Primary Center for Ossification

1. Appears in diaphysis
2. Bone replaces cartilage

Secondary Center for Ossification

1. Forms in epiphyses
2. Skeleton continues to grow via division of cartilage (and bone)
cells until maturity

Spongy Bone (trabecular bone)

1. Internal (deep) portion of bones
2. Surrounded by marrow
3. Typically near joints
4. More air pockets than compact bone
5. Good shock absorption

Compact Bone (cortical bone)

1. External (superficial) portion of bones
2. Smooth
3. Dense
4. Strong
5. Rigid

Compact Bone Structure

Contain osteons

Osteon

1. Structural unit of compact bone
2. Made up of concentric tubes called lamellae
3. Oriented parallel to the long axis and main compression stresses
4. Haversian (central) canal runs through core

Haversian (central) Canal

1. Found in compact bone
2. Located inside osteons
3. Provides
- Blood supply
- Nutrients
- Nerves

Lamellae

1. Found in compact bone
2. Concentric tubes that make up osteons

What is the structure of a long bone?

1. Epiphysis
2. Epiphyseal line
3. Diaphysis
4. Compact bone
5. Spongy bone
6. Periosteum
7. Endosteum
8. Medullary cavity
9. Nutrient arteries
10. Articular cartilage

Epiphysis

End of a long bone

Epiphyseal Line/Plate

1. AKA Growth plate
2. Hyaline cartilage plate
3. Found in epiphysis at each end of a long bone
4. In people who have stopped growing, the plate is replaced by an epiphyseal line

Diaphysis

Shaft of long bone

Periosteum

1. Outer membrane on bone long bone
2. Well supplied with nerves and blood vessels
3. Provides a place for tendons and ligaments to attach to bone

Endosteum

1. Vascular membrane
2. Lines internal cavity of long bones

Medullary Cavity

1. Bone marrow
2. Lined by endosteum

What is the structure of flat, irregular and short bones?

1. Compact bone with periosteum on the outside
2. Spongy bone with endosteum on the inside
3. Contain marrow but DO NOT have a marrow cavity

Closure of Epiphyseal Plates

1. Cartilage is gradually replaced by bone tissue on both sides of
the epiphyseal plate (primary and secondary center of ossification)
2. Centers of ossification meet at the epiphyseal plate
3. Growth stops

Bony Callus

1. If injured, cells tend to overgrow at an injury site
2. Forms a bony callus from the overgrowth of the osteoblasts

How often do bones go through remodeling?

1. Bone continually undergoes remodeling
2. This is when cells break down/build bone

Osteoporosis

1. Results from an imbalance of bone remodeling
- More bone is broken down than new bone is built
2. Seen after menopause
- Women don’t absorb as much calcium so osteoclasts break bone down to release the calcium into the bloodstream
3. Common with compression fractures

What does bone development and growth look like BEFORE week 8 of life?

Skelton made of hyaline cartilage or mesenchyme

What does bone development and growth look like AFTER week 8 of life?

Bone tissue begins to replace most cartilage or mesenchyme

Pectoral Girdle

1. Appendicular skeleton
2. Left/right scapulae
3. Left/right clavicles

How are the scapulae attached to the axial skeleton?

1. Scapulae do NOT join to the axial skeleton at all
2. Their articulation with the clavicle is very loose
3. They are attached to the axial skeleton by way of associated muscles and ligaments
4. This provides a highly flexible system

Clavicle

1. Appendicular skeleton
2. Located in pectoral girdle
3. "Collarbone"
4. Provides muscle attachment
5. Acts as brace for the scapula and arms
6. S-shape makes it prone to fracturing near the curves

What does the acromial end of the clavicle attach too?

1. Lateral
2. The acromial end articulates with the acromion process of the
scapula

What does the sternal end of the clavicle attach too?

1. Medial
2. The sternal end attaches to the manubrium of the sternum

Scapula

1. Appendicular skeleton
2. Located in pectoral girdle
3. Located on the posterior surface of the rib cage
4. Scapular spine is on posterior side of the scapula
5. Contains
- Gelnoid cavity
- Supraspinous/infraspinous fossae
- Subscapular fossa
- Coracoid process
- Acromion

Glenoid Cavity

1. AKA glenoid fossa
2. Appendicular skeleton
3. Located in pectoral girdle on scapula
4. Where the humerus articulates
5. Forms shoulder joint

Supraspinous/infraspinous Fossae

1. Appendicular skeleton
2. Located in pectoral girdle on scapula
3. Attachment sites for muscles

Subscapular Fossa

1. Appendicular skeleton
2. Located in pectoral girdle on scapula
3. Anterior site for muscle attachment

Coracoid Process

1. Appendicular skeleton
2. Located in pectoral girdle on scapula
3. Attachment point of the biceps muscle
4. Located anteriorly

Acromion

1. Appendicular skeleton
2. Located in pectoral girdle on scapula
3. Articulates with the acromial end of clavicle
4. Located posteriorly

Upper Limb

1. Appendicular skeleton
2. 30 bones
3. Arm
4. Forearm
5. Hand

Arm

1. AKA Brachium
2. Upper arm
3. One bone
- Humerus

Forearm

1. AKA antebrachium
2. Lower arm
3. Two bones
- Radius
- Ulna

Hand

1. Includes the wrist
2. 27 bones
- Carpal bones
- Metacarpals
- Phalanges

Humerus

1. Appendicular skeleton
2. Found in arm of upper limb
3. Head articulates with scapula at the glenoid cavity
4. Distal end articulates with radius and ulna (elbow)
5. Greater and lesser tubercles are sites of muscle attachment
- Deltoid tuberosity is attachment for deltoid muscle
6. Most frequently fractures at the surgical neck

What are common fractures of the humerus?

1. Surgical neck (1)
2. Midshaft spiral fractures (2)
3. Nerves (in yellow) pass along the bone and can be damaged by these two fractures
4. MAY lead to permanent upper limb dysfunction

Distal Humerus

1. Appendicular skeleton
2. Found in arm of upper limb
3. Articulates with the radius and ulna
4. Capitulum

Trochlea (Upper Limb)

1. Appendicular skeleton
2. Found in arm of upper limb
3. Trochlea of the humerus articulates with trochlear notch of ulna
4. Trochlear notch fits over trochlea to create a hinge

Coronoid (Upper Limb)

1. Appendicular skeleton
2. Found in arm of upper limb
3. Coronoid process of ulna fits into coronoid fossa when forearm bends

Olecranon Process (Upper Limb)

1. Appendicular skeleton
2. Found in arm of upper limb
3. Olecranon process of ulna fits into the olecranon fossa of the humerus when forearm extends
4. Sharp edge of elbow

Lateral/Medial Epicondyles (Upper Limb)

1. Appendicular skeleton
2. Found in arm of upper limb
3. Lateral and medial epicondyles on humerus are attachment sites for forearm muscles

Capitulum

1. Appendicular skeleton
2. Found in arm of upper limb
3. Distal humerus
4. Articulates with head of the radius

What is the major articulation at the elbow?

Radial head articulates with the radial notch of the ulna (proximal
radioulnar joint) to form a pivot joint

Ulna

1. Appendicular skeleton
2. Found in forearm
3. Medial
4. Connected to the radius by interosseous membrane to keep bones a fixed distance and allow rotation
5. Radial head articulates with radial notch on ulna (proximal)
6. Has a styloid process (distal)

Radius

1. Appendicular skeleton
2. Found in forearm
3. Lateral
4. Connected to the ulna by interosseous membrane to keep bones a fixed distance and allow rotation
5. Radial head articulates with radial notch on ulna (proximal)
6. Has a styloid process (distal)

Pronation (Upper Limb)

1. Radius crosses over ulna
2. When palm faces posteriorly
- Bones cross and form an X

Supination (Upper Limb)

1. Radius parallel to ulna
2. In standard anatomical position
- Radius is lateral and ulna is medial

Where do the ligaments that anchor to the wrist attach?

Ligaments that anchor the the wrist attach to the radial and
ulnar styloid processes

Wrist Fractures

1. Typically fracture distal radius while catching yourself during a fall
2. Common in older females
3. “Dinner-fork ” presentation
4. Can lead to nerve damage and dysfunction

Carpals

1. Appendicular skeleton
2. Found in wrist
3. 8 carpal bones make up wrist
4. Proximal end of hand
5. Arranged (roughly) in 2 rows
- Straight Line To Pinky, Here Comes The Thumb
6. Very flexible because of the gliding motions at articulations
7. Scaphoid is fractured most frequently

Metacarpals

1. Appendicular skeleton
2. Found in hand
3. Each digit has one metacarpal

Phalanges (Upper Limb)

1. Appendicular skeleton
2. Found in hand
3. Digits II-V have three phalanges
- Proximal, middle and distal
4. Digit I (Pollex or Thumb) has two phalanges
- Proximal and distal

How are the digits in the hand labeled?

1. There are 5 digits in each hand
2. They are labeled I-V starting at the thumb and ending at the pinky

Pelvis

1. Part of both the appendicular and axial skeleton
2. Consists of
- Hip bones
- Sacrum
- Coccyx
3. Attaches the lower limbs to the trunk
- Body weight passes through pelvis to the lower limbs
4. Supports viscera
5. Strong attachment to axial skeleton at the sacroiliac joint (very stable)
6. Less freedom of movement compared to pectoral girdle

Ossa Coxae

1. AKA Hip bones
2. Appendicular skeleton
3. Found in pelvis
4. Consists of three bones that fuse by adulthood
- Ilium
- Ischium
- Pubis

Acetabulum

1. Appendicular skeleton
2. Where the ilium, ischium, and pubis fuse
3. Found in hipbone in pelvis
4. Cup-shaped lateral socket where head of the femur articulates
5. Composed of all three pelvic bones

Pubic Symphysis

1. Appendicular skeleton
2. Where the two hip bones articulate (join) anteriorly

Ilium

1. Appendicular skeleton
2. Hip bone found in pelvis
3. Iliac crest is superior ridge of the bone
4. Greater sciatic notch allows passage of sciatic nerve to lower limb

Ischium

1. Appendicular skeleton
2. Hip bone found in pelvis
3. Ischial tuberosities are the “sit bones"

Pubis

1. Appendicular skeleton
2. Hip bone found in pelvis
3. Along with the ischium contributes to obturator foramen