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The Skeletal System

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Dr. Naim Kittana

Faculty of Medicine & Health Sciences

An-Najah National University

Declaration

• The content and the figures of this seminar were directly adopted from the text book “Human Anatomy and Physiology / Ninth edition/ Eliane N. Marieb 2013”

2 Dr. Naim Kittana, Dr. Suhaib Hattab

The Skeletal System

• Parts of the skeletal system:

1. Bones (skeleton)

2. Joints

3. Cartilages

4. Ligaments

• Divided into two divisions

1. Axial skeleton

2. Appendicular skeleton

3 Dr. Naim Kittana, PhD

Functions of Bones

• Support of the body

• Protection of soft organs

• Movement due to attached skeletal muscles

• Storage of minerals and fats

• Blood cell formation


Bones of the Human Body

• The skeleton has 206 bones

• Two basic types of bone tissue

• Compact bone

• Spongy bone


Classification of Bones


Structure of Flat Bones


Structure of Long Bones


Microscopic Anatomy of Compact Bone

Five major cell types populate bone tissue: osteogenic cells, osteoblasts, osteocytes, bone lining cells, and osteoclasts

• Osteogenic cells (osteoprogenitor cells), are mitotically active stem cells found in the membranous periosteum and endosteum. When stimulated, these cells differentiate into osteoblasts or bone lining cells

• Osteoblasts are bone-forming cells that secrete the bone matrix.

• Osteocytes: The spidery osteocytes are mature bone cells that occupy spaces (lacunae) that conform to their shape. Osteocytes monitor and maintain the bone matrix.



• Bone lining cells: are flat cells found on bone surfaces where bone remodeling is not going on. Like osteocytes, they are thought to help maintain the matrix.

• Osteoclasts: are giant multinucleate cells located at sites of bone resorption



• Osteon (Haversian System) The structural unit of compact bone.

• Each osteon is an elongated cylinder oriented parallel to the long axis of the bone.

• Functionally, osteons are tiny weight-bearing pillars.


Microscopic Anatomy of Spongy Bone

• The trabeculae in spongy bone align precisely along lines of stress and help the bone resist stress.

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Bone Markings


Capsule of hip-joint, Posterior aspect.

Upper surface of right tibia


Long Bone Formation and Growth

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The Axial Skeleton

• Forms the longitudinal part of the body

• Divided into three parts

1. Skull

2. Vertebral column

3. Bony thorax


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The Skull

• Two sets of bones

1. Cranium

2. Facial bones

• Bones are joined by sutures

• Only the mandible is attached by a freely movable joint


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The Skull: Lateral View

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The Skull: Superior View

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The Skull: Inferior View

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Paranasal Sinuses

Hollow portions of bones surrounding the nasal cavity


The Hyoid Bone

• The only bone that does not articulate with another bone

• Serves as a moveable base for the tongue


The Vertebral Column

• Vertebrae separated by intervertebral discs

• The spine has a normal curvature

• Each vertebrae is given a name according to its location


Structure of a Typical Vertebrae


Dr. Naim Kittana, PhD 31

rib vertebrae joint

Regional Characteristics of Vertebrae

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The Bony Thorax

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The Appendicular Skeleton

• Limbs (appendages)

• Pectoral girdle

• Pelvic girdle


The Pectoral (Shoulder) Girdle

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The humerus of the right arm

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Bones of the Upper Limb

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Bones of the Upper Limb

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Bones of the Pelvic Girdle


Bones of the Pelvic Girdle

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Gender Differences of the Pelvis

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Gender Differences of the Pelvis

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Bones of the Lower Limbs

• The thigh has one bone: femur – thigh bone

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Bones of the Lower Limbs

The leg has two bones:

• Tibia

• Fibula

The tibia and fibula of the right leg

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Bones of the right foot

The foot:

1. Tarsus – ankle

2. Metatarsals – sole

3. Phalanges – toes


Bones of the right foot

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Arches of the Foot

Together, the arches of the foot form a half dome that distributes about half of a person’s standing and walking weight to the heel bones and half to the heads of the metatarsals. 49

Joints

• Articulations of bones

• Functions of joints:

• Hold bones together

• Allow for mobility

• Ways joints are classified:

• Functionally

• Structurally


Functional Classification of Joints:

1. Immovable joints

2. Slightly moveable joints

3. Freely moveable joints

Structural Classification of Joints:

1. Fibrous joints: Generally immovable

2. Cartilaginous joints: Immovable or slightly moveable

3. Synovial joints: Freely moveable

Classifications of Joints


Fibrous Joints

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Cartilaginous Joints

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Synovial Joints

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The General Structure of Synovial Joint

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Summary of joint classes


Types of movements allowed by Synovial Joints

• Gliding occurs when one flat, or nearly flat, bone surface glides or slips over another (back-and-forth and side-to-side)

• Angular movements increase or decrease the angle between two bones. These movements may occur in any plane of the body and include

flexion

extension

hyperextension

abduction

adduction

circumduction



• Flexion: bending movement, usually along the sagittal plane, that decreases the angle of the joint and brings the articulating bones closer together

• Extension: is the reverse of flexion and occurs at the same joints

• Hyperextension: Continuing such movements beyond the anatomical position is called



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• Abduction (“moving away”): is movement of a limb away from the midline or median plane of the body, along the frontal plane

• Adduction (“moving toward”): is the opposite of abduction, so it is the movement of a limb toward the body midline or, in the case of the digits, toward the midline of the hand or foot

• Circumduction: is moving a limb so that it describes a cone in space. The distal end of the limb moves in a circle, while the point of the cone (the shoulder or hip joint) is more or less stationary.

• Rotation: is the turning of a bone around its own long axis



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Types of Synovial Joints Based on Shape

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Synovial joints

1- Plane joints

Permit gliding or sliding movements in the plane of the articular surfaces.

The opposed surfaces of the bones are flat or almost flat, with movement limited by their tight joint capsules.

Plane joints are numerous and are nearly always small.

An example is the acromioclavicular joint between the acromion of the scapula and the clavicle.


Synovial joints

2- Hinge joints

Permit flexion and extension only

Movements occur in one plane (sagittal) around a single axis that runs transverse uniaxial joints

The joint capsule of these joints is thin and lax anteriorly and posteriorly where movement occurs

The bones are joined by strong, laterally placed collateral ligaments. The elbow joint is a hinge joint


Synovial joints

3- Pivot joints

• Permit rotation around a central axis; thus they are uniaxial. In these joints, a rounded process of bone rotates within a sleeve or ring.

• The median atlantoaxial joint is a pivot joint in which the atlas (C1 vertebra) rotates around a finger-like process, the dens of the axis (C2 vertebra), during rotation of the head.


Pivot joints



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Synovial joints

4- Condyloid joints

• Permit flexion and extension as well as abduction and adduction; thus condyloid joints are also biaxial

• Movement in one plane (sagittal) is usually greater (freer) than in the other. Circumduction, more restricted than that of saddle joints, is also possible

• The metacarpophalangeal joints (knuckle joints) are condyloid joints



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Synovial joints

5- Saddle joints

• Permit abduction and adduction as well as flexion and extension.

• Movements occurring around two axes at right angles to each other; thus saddle joints are biaxial joints that allow movement in two planes, sagittal and frontal.

• The performance of these movements in a circular sequence (circumduction) is also possible.

• The opposing articular surfaces are shaped like a saddle (i.e., they are reciprocally concave and convex).

• The carpometacarpal joint at the base of the 1st digit (thumb) is a saddle joint. 71 Dr. Naim Kittana, PhD

Synovial joints

6- Ball and socket joints

• Allow movement in multiple axes and planes:

• Flexion and extension, abduction and adduction, medial and lateral rotation, and circumduction; thus ball and socket joints are multi-axial joints.

• In these highly mobile joints, the spheroidal surface of one bone moves within the socket of another.

• The hip joint is a ball and socket joint in which the spherical head of the femur rotates within the socket formed by the acetabulum of the hip bone.


Download - The Skeletal System - An-Najah National University System... · • Parts of the skeletal system: 1. Bones (skeleton) 2. ... • Movement due to attached skeletal muscles ... movement

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