The Skeletal System

By: Alaa Alshaibani and Alexis Samuelson

System Structures

and locationlink to video:

http://www.youtube.com/watch?

v=gp4SBFiP4-Y

The Skull

• Made up of the cranium and the facial bones

• It is located at the top of the body, the head of the body

• Made up of roughly 22 bones:

Cranial Bones:

• Frontal bones

• Parietal bones

• Occipital bone

• Temporal bone

• Sphenoid bone

• Ethmoid bone

Facial bones:

• Mandible

• Maxillae

• Palatine bones

• Zygomatic bones

• Lacrimal bones

• Nasal bones

• Vomer bone

• Inferior nasal conchae

Vertebral Column

• Begins at the base of the skull and ends at the pelvis.

• Composed of vertebrae that are separated by intervebral discs

• The column is divided into three parts

• The final five is what creates the lumbar vertebrae

• The sacrum forms the bottom of the lumbar vertebrae, the tip being the coccyx

Vertebral Column

Cervical Vertebrae

• The first seven vertebrae

• The first two are the atlas and axis and they help to rotate the head

• The vertebrae are special in that they have transverse foramina and their spinous processes are bifid.

Thoracic Vertebrae

• The next 12 bones of the vertebral column

• Long pointed spinous process, the bodies increase in size as you go down

• Connects to the ribs

Lumbar Vertebrae

• The final five vertebrae

• The sacrum forms the bottom of the lumbar vertebrae, the tip being the coccyx

Thoracic Cage

• Made up of: • The ribs • Thoracic

vertebrae • Sternum • Costal

cartilages

• 24 ribs total which attach to each of the thoracic vertebrae

• The sternum is made up of the manubrium, body, and xiphone together are the breast bone

Pectoral Girdle

• Located at the shoulder

• Made up of the clavicles (collarbones) and scapulae (shoulder blades)

Upper Limb

Upper Limb

• Bones form framework for arm, forearm, and hand

• Provide attachments for muscles, function in levers

• Bones include: humerus, radius, ulna, carpals, metacarpals, and phalanges

Upper Limb - Humerus

• Extends from the scapula to the elbow

• Greater and lesser tubercles provide attachments for muscles

• Deltoid tuberosity provides attachment for deltoid muscle that raises the upper limb horizontally to the side

• Coronoid fossa receives a process of the ulna when the elbow bends

• Olecranon fossa receives ulnar process when upper limb straightens at elbow

• The capitulum helps the humerus articulate with the radius

Upper Limb - Humerus

Upper Limb - Radius

• Located on thumb side of forearm; extends from elbow to wrist and crosses over ulna when palm faces backward

• Head at upper end of radius articulates with humerus and a notch of the ulna

• Allows radius to rotate freely

Upper Limb - Ulna

• Longer than radius; overlaps the end of the humerus posteriorly

• Trochlear notch articulates with the humerus

• Olecranon process and coronoid process provide attachments for muscles

• Head articulates laterally with a notch of the radius

Upper Limb – Radius and Ulna

Upper Limb - Hand

• Made up of the wrist, palm, and fingers

• Eight small carpal bones that are bound in two rows of four bones

• Five metacarpal bones form framework of the palm

• Each finger has three phalanges (proximal, middle, and distal phalanx), except for thumb

Upper Limb - Hand

Pelvic Girdle

• Consists of two coxae which articulate with each other anteriorly and with the sacrum posteriorly

• Sacrum, coccyx, and pelvic girdle form pelvis

• Girdle supports trunk of the body, provides attachments for lower limbs, protects the urinary bladder and reproductive organs

• Each coxa develops from an ilium, an ischium, and a pubis

Pelvic Girdle

Pelvic Girdle

Lower Limb

Lower Limb

• Bones form frameworks of the thigh, leg, and foot

• Includes femur, tibia, fibula, tarsals, metatarsals, and phalanges

Lower Limb - Femur

• Extends from hip to knee

• Large, rounded head projects medially into acetabulum of the coxa

• Patella (kneecap) articulates with femur

• Lateral and medial condyles articulate with tibia

Lower Limb - Femur

Lower Limb - Tibia

• Larger of the two leg bones, located on medial side

• Medial and lateral condyles articulate with condyles of the femur

• Tibial tuberosity provides an attachment for patellar ligament

• Inferior surface of tibia’s distal end articulates with the talus of the ankle

Lower Limb - Fibula

• Long, slender bone on lateral side of the tibia

• Head articulates with tibia just below the lateral condyle, but does not enter into the knee joint

Lower Limb – Tibia and Fibula

Lower Limb - Foot

• Made up of the ankle, the instep, and the toes

• Ankle is composed of seven tarsal bones (largest is calcaneus)

• Instep is made up of five elongated metatarsal bones that articulate with the tarsus

• Phalanges align and articulate with the metatarsals; each toe has three phalanges except for the great toe (no middle phalanx)

Lower Limb - Foot

Skeletal System

Information

Function of Skeleton

• The skeleton serves to: • Protect vital organs • Support the body• Create blood cells• Help to stabilize and shape the body

Bones, Tendons, Ligaments

• Bones: the organs of the skeletal system made up of cartilage, bone tissue, dense connective tissue, and nervous tissue

• Tendons: white fibrous connective tissue that attaches muscle to bone

• Ligaments: connective tissue that ties together two or more bones at a joint

Structures of a long bone

• Epiphysial plates, articular cartilage, compact bone, medullary cavity, yellow marrow, periosteum, proximal epiphyses, diaphysis, distal epiphysis, endosteum

Bone growth• Endochondral bones begin as a cartilaginous model.

As it grows the diaphysis in the middle, with the help of osteoblasts replace the cartilage with spongy bone—the primary ossification center, and form a thin layer of compact bone around it.

• Secondary ossification centers form in the epiphyses, an epiphyseal plate separates the two ossification centers, which expands, causing the bone to lengthen.

• The extracellular matrix calcifies, osteoclasts break it down, osteoblasts release new bone tissue to replace it.

• The bone continues to lengthen, only stopping once the diaphysis and epiphysis ossification centers meet.

Joints

Joints

• Bind parts of skeletal system, allow bones to grow, permit the skeleton to change shape during childbirth, and let the body respond to skeletal muscle contractions

• Can be immovable, slightly movable, or freely movable

• Vary in structure and function

Classification of Joints by Tissue

Classification - Fibrous

• Lie between bones that closely contact one another

• Formed by thin layer of dense connective tissue

• Doesn’t allow much movement

• Examples: • Sutures between pairs of flat bones of the

skull• Articulations of teeth in jaw bones

(gomphosis)

Classification - Cartilaginous

• Hyaline cartilage (fibrocartilage), makes for slight flexibility

• Helps to absorb shock and equalize pressure

• Examples:• Intervertebral discs are composed of a

band of fibrocartilage surrounding gelatinous core

• Symphysis pubis

Classification - Synovial

• Allow free movement, make up a majority of joints within skeletal system

• Articular ends of bones in synovial joints are covered with hyaline cartilage and a surrounding capsule of dense connective tissue

• This + an outer layer of ligaments + inner lining of synovial membrane = joint capsule

Classification - Synovial

• Menisci – flattened, shock-absorbing pads of fibrocartilage between articulating surfaces of bones

• Bursae – fluid-filled sacs lined with synovial membrane• Commonly located between tendons

and bony prominences (patella, elbow, etc.)

6 Types of Synovial

Joints

Ball-and-Socket Joint

• Consists of a bone with a ball-shaped head that articulates with the cup-shaped cavity of another bone

• Allows widest range of motion and movements in all planes, in addition to rotational movement

• Example:• Shoulder and hip joints

Condyloid Joint

• Oval-shaped condyle of one bone fits into elliptical cavity of another

• Permits a variety of movement in different planes, but not rotational movement

• Example:• Joints between metacarpals and

phalanges

Gliding Joints

• Articulating surfaces are nearly flat or slightly curved

• Allow sliding and twisting movements

• Examples:• Most joints within the wrist and ankles• Sacroiliac joints and joints formed

between ribs 2-7 that connect with the sternum

Hinge Joint

• Convex surface of one bone fits into concave surface of another

• Resembles the hinge of a door• Permits movement in one plane only

• Examples:• Elbow• Joints of phalanges

Pivot Joint

• Cylindrical surface of one bone rotates within a ring formed of bone and ligament

• Movement limited to rotation around central axis

• Example:• Joint between proximal ends of the

radius and the ulna

Saddle Joint

• Forms between bones whose articulating surfaces have both concave and convex regions

• Surface of one bone fits the complementary surface of the other

• Permits variety of movements

• Example:• Joint between carpal (trapezium) and

metacarpal bones of thumb

Types of Joint

Movement

Joint Movements

• One end of muscle is attached to a relatively immovable part on one side of joint, other end fastened to movable part

• When muscle contracts, the fibers pull the insertion (movable end) towards the origin (fixed end)

Joint Movements

• Flexion: Bending parts at a joint so the parts come closer together (angle between decreases)

• Extension: Straightening parts so that they move further apart (angle between widens)

• Dorsiflexion: Bending the foot at the ankle upwards

• Plantar flexion: Bending the foot downwards

Joint Movements

• Hyperextension: Excess extension of the parts at a joint beyond anatomical position

• Abduction: Moving a part away from the midline

• Adduction: Moving a part towards the midline

• Rotation: Moving a part around an axis

• Circumduction: Moving a part in a circular motion

Joint Movements

• Pronation: Turning the hand so that the palm is facing downwards

• Supination: Turning the hand so the palm is facing upward

• Eversion: Turning the foot so that the sole faces laterally

• Inversion: Turning the foot so that the sole faces medially

Joint Movements

• Retraction: Moving a part backward

• Protraction: Moving a part forward

• Elevation: Raising a part

• Depression: Lowering a part

Distinguish Between the Appendicular and Axial Skeletons

Axial Skeleton

• Consists of the bony and cartilaginous parts that support and protect the organs of the head, neck, and trunk

1.Skull – Composed of the cranium and facial bones

2.Hyoid bone – Located between lower jaw and larynx; supports the tongue and is an attachment for muscles that move the tongue

Axial Skeleton

3. Vertebral column – Consists of many vertebrae separated by cartilaginous intervertebral discs, the sacrum, and the coccyx

4. Thoracic cage – Protects the organs of the thoracic cavity and upper abdominal cavity; composed of 12 pairs of ribs, and the sternum

Appendicular Skeleton

• Consists of the bones of the upper and lower limbs and the bones that anchor the limbs to the axial skeleton

1.Pectoral girdle – Scapula and clavicle form the pectoral girdle on both sides of body; connects bones of upper limbs and aids in movement

2.Upper limbs – Each consists of a humerus, radius, and ulna, which articulate with each other at the elbow joint. At the distal end are carpals, metacarpals, and phalanges.

Appendicular Skeleton

3. Pelvic girdle – Two coxae connect the bones of the lower limbs to the axial skeleton; form the pelvis with the sacrum and coccyx

4. Lower limbs – Each consists of femur, tibia, fibula, and a foot. The patella covers the anterior surface of the knee joint. The foot consists of tarsals, metatarsals, and phalanges.

Diseases/Disorders

Osteogenisis Imperfecta

• Literally translated to mean: “bone that is imperfectly made from the beginning of life.”

• A genetic bone disorder, caused by a mutation that prevents the creation of collagen, resulting in extremely brittle bones, bones break easily

Hemarthrosis

• When there is bleeding in a joint, due to joint pain/ swelling

Rickets

• Caused by a lack of either Vitamin D, Phosphate, or calcium

• Bones become weakened and curve

Osteochondritis Dissecans

• Occurs when a fragment of bone in a joint separates from the rest of the bone because its blood supply was not sufficient

• The joint will become inflamed and painful, and can catch or lock during movements

• Most common in the knee, but can also occur in other joints, such as the hip or ankle

• Can be caused by repeated stress on the joint, inherited faulty genes, or ischemia, which restricts a bone’s blood supply

Osteochondritis Dissecans

Osteoid Osteoma

• A benign bone tumor that has a center of growing cells surrounded by a shell of thickened bone

• Most common in long bones, but can occur in any bone of the body

• Occurs primarily in males of 4-25 years of age

• Can sometimes disappear on its own, or be treated surgically

Osteoid Osteoma

Epiphysiolysis

• The loosening or separation of the epiphysis from the shaft of the bone

• Some treatments include physical therapy or prosthetic implants

• Occurs often in hip and leg bones

Epiphysiolysis