Skeletal System. A little history first… This is a Baculum. – What is it? 2.

Skeletal System

A little history first…

• This is a Baculum.– What is it?

2

To explain, let us go back…

• Roman law: “No cutting up humans Yo!!!” – What animals have

skeletons?– Used nonhumans

instead.

3

Then comes this guy

Andries Van Wesel (1514)•Aka: Andreas Vesalius•“De humani corporis fabrica”

– (On the fabric of the human body)

Proved the world wrong.Osteology: study of bonesIntroduced Human Dissection.

4

Back to the Baculum

• It’s a penis bone found in most Placental mammals.

• But not humans… thanks to evolution

5

Lesson 8-1 Objectives

• List the functions of the skeletal system.• Describe the structure of a long bone.• Compare compact and spongy bone.• Describe how bones grow.• Describe the roles of osteoblasts and

osteoclasts.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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Skeletal System Overview

ENDOskeleton•The skeletal system is composed of

– Bones– Joints– Cartilage– Ligaments

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Functions of the Skeletal System

• Supports body weight• Supports and protects soft organs• With muscles, enables body movement• Stores important minerals, including calcium

and phosphorus• Contains bone marrow, which produces blood

cells


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Sizes and Shapes of Bones

• Long• Short• Flat• Irregular


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Two Types of Bone

• Compact or hard– Osteons– Shafts: Long bones

• Spongy or soft– Trabecular plates– Swiss cheese– Bone marrow

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Parts of Long Bone • Diaphysis• Epiphysis• Epiphyseal disc• Medullary cavity• Endosteum• Periosteum• Articular cartilage• Marrow

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Two Types of Ossification

• Intramembranous ossification– Replacement of thin connective tissue membrane

with bone– In flat bones

• Endochondral ossification– Replacement of fetal cartilage skeleton with bone– In long, irregular, and short bones

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Ossification in the Fetus

• Intramembranous ossification– In flat bones of skull

• Endochondral ossification– In all other bones


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Bones Growing Taller

• Occurs at the epiphyseal disc– Osteoblasts invade cartilage in disc.– They mature into osteocytes (bone).

• Affected by hormones– Growth hormone– Estrogen– Testosterone


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Bones Remodeling

• Osteoclastic activity is called resorption.

• Sculptor (osteoclasts) hollows bone.

• Builder (osteoblasts) deposits bone on outer surface.

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Bone FracturesBone FracturesA break in a bone

Types of bone fractures

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

Open (compound) fracture – broken bone penetrates through the skin

Greenstick- break in one side of bone

Bone fractures are treated by reduction and immobilization

Realignment of the bone

Types of Fractures

• Simple• Compound• Greenstick


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Common Types of FracturesCommon Types of Fractures

What type is this?Greenstick Compound

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What about this

Simple

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Bone Markings: Projections (Processes)• Condyle: Large knob (form joints)• Epicondyle: Enlargement near a condyle (muscle

attachment)• Head: Enlarged, rounded end (epiphysis)• Facet: Small flattened surface (flat bone)• Crest: Ridge (muscle attachment)• Spine: Sharp projection (vertebrae, muscle

attachment) • Tuberosity: Knoblike projection (muscle

attachment)• Trochanter: Large tuberosity only on femur

Bone Markings: Depressions and Openings

• Foramen: Opening, usually passage for nerves, blood vessels, ligaments

• Fossa: Groove (joints)• Meatus: Tunnel or tubelike passageway• Sinus: Cavity or hollow space within bone

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• List the bones of the axial skeleton.• List the bones of the appendicular skeleton.• Label important landmarks for selected bones

on the skeleton.


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Types of Bones

• Axial skeleton– 80 bones of the head and trunk

• Appendicular skeleton – 126 bones of the pelvis, shoulders,

arms, and legs

Bones of the Axial Skeleton

• Skull: Cranium, facial, middle ear bones

• Hyoid• Vertebral column• Thoracic cage: Ribs,

sternum, thoracic vertebrae

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Bones of the Skull• Cranial

– Held together by sutures

– Little movement

• Facial– Mandible contains

only movable joint

• Middle ear bones

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Special Markings • Temporal bone

– External auditory meatus

– Zygomatic process– Styloid process – Mastoid process

• Occipital bone– Foramen magnum– Occipital condyles


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The SkullThe Skull

Bones of the SkullBones of the Skull

Human Skull, Inferior ViewHuman Skull, Inferior View

Paranasal Sinuses

• Frontal• Ethmoidal• Sphenoidal• Maxillary

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Paranasal SinusesParanasal Sinuses

Hollow portions of bones surrounding the nasal cavity

Figure 5.10

Paranasal SinusesParanasal Sinuses Functions of paranasal sinuses

Lighten the skull

Give resonance and amplification to voice

The Hyoid BoneThe Hyoid Bone The only bone that

does not articulate with another bone

Serves as a moveable base for the tongue

Figure 5.12

Fetal Skull and Fontanels• Fontanels are

soft spots– Not yet

converted to bone

– Covered with fibrous tissue

– Allow for cranial growth

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Vertebral Column• Sections

– Cervical (C1-C7)– Thoracic (T1-T12)– Lumbar (L1-L5)– Sacrum and coccyx

• Curves– Cervical– Thoracic– Lumbar– Sacral

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Vertebrae • Atlas (C1): Nods “yes”• Axis (C2): Rotates

“no”• Other vertebral parts

– Vertebral foramen– Body– Lamina– Spinous process– Padded by

intervertebral discs

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Cervical Vertebrae

Disorders of the Vertebral Column

• Scoliosis: Lateral curve

• Kyphosis: Hunchback

• Lordosis: Swayback

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Thoracic Cage• Sternum

– Manubrium (Upper part)– Body– Xiphoid process (lower part)

• Ribs (12 pairs)– Seven pairs of true ribs– 3 pairs of false ribs– 2 pairs of floating ribs

• Thoracic vertebrae

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Sternum

True Ribs (7)

False Ribs (3)

Floating Ribs (2)

Sternum

True Ribs (7)

False Ribs (3)

Floating Ribs (2)

The Thoracic CageThe Thoracic Cage

Sacrum & CoccyxSacrum & Coccyx

Bones of the Appendicular Skeleton

• Pectoral girdle

• Upper limbs• Pelvic girdle

–Coxal bones• Lower limbs

Pectoral Girdle and Upper Limb• Pectoral girdle

– Clavicle (collarbone)– Scapula (shoulder

blade/wing bone)

• Upper limb– Humerus – Radius and ulna – Carpals – Metacarpals – Phalanges

Important Landmarks of Upper Limbs

• Acromion: tip of shoulder(scapula), articulates with clavicle

• Olecranon process: elbow• Glenoid Cavity: Arm socket/shoulder socket

– Where humerus fits into shoulder joint

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Pelvic Girdle: Coxal Bones• Functions

– Weight bearing– Attachment for lower

limbs– Protection of organs

• Coxal bone – Ilium– Ischium– Pubis

• Acetabulum (hip socket)

• Symphysis pubis

Lower Limb• Thigh

– Femur ( with trochanters)

• Leg bones– Patella– Tibia (with medial

malleolus)– Fibula (with lateral

malleolus)

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Lower Limb: Ankle and Foot

• Foot bones– Tarsals – Metatarsals – Phalanges

• Arches– Form instep


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• List the main types and functions of joints.• Describe the types of joint movement.


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Types of Joints

Articulation: point of contact between bones

–Synarthroses: Immovable–Amphiarthroses: Slightly movable–Diarthroses: Freely movable

Types of Synarthroses

• Sutures: found in skull

• Gomphoses: between root of tooth and process in mandible/maxilla (GUMphoses)

• Syndesmoses: ligaments connecting 2 bones

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Amphiarthroses

Cartilaginous joints: joined by hyaline cartilage or fibrocartilage

–Synchondroses: between articulating bones (sternum to ribs)

–Symphyses- pad or disk of cartilage between 2 bones (between vertebrae)

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Diarthroses• Synovial joints: Freely moving joints

–Lots of moving parts• Joint Capsule: casing around ends of

bones that binds them together• Synovial Membrane: lines joint capsule

and secretes synovial fluid• Articular cartilage: cartilage covering

articular surfaces of bone

Parts continued…• Joint cavity: space between two bones

• Menisci (Articular disks): pads of fibrocartilage between articulating bones

• Ligaments: strong cords that hold bones of synovial joint

• Bursae: synovial membrane filled with synovial fluid, cushions joints

Structure of Freely Movable Joints

• Articular cartilage• Joint capsule• Synovial membrane• Synovial fluid• Cartilage• Some joints also have

– Bursae– Ligaments

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Types of Freely Movable Joints• Hinge: Elbows, knees• Ball-and-socket:

Shoulders, hips• Pivot: Atlas-axis joint• Saddle: Carpometacarpal• Gliding: Wrist• Condyloid: Knuckles

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Joint Names: Articulating Bones• Tibiofemoral

– Tibia and femur• Humeroulnar

– Humerus and ulna• Metacarpophalangeal

– Metacarpal bone and phalange

• Glenohumeral– Glenoid cavity and

humerus

Types of Joint Movement• Flexion-extension• Inversion-eversion• Supination-pronation• Abduction-adduction• Dorsiflexion-plantar

flexion• Hyperextension• Circumduction

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Skeletal System. A little history first… This is a Baculum. – What is it? 2.

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