The Skeletal System Dr. Naim Kittana Dr. Suhaib Hattab Faculty of Medicine & Health Sciences An-Najah National University 1
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 Dr. Naim Kittana, Dr. Suhaib Hattab 2
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 Dr. Naim Kittana, PhD 3
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 Dr. Naim Kittana, PhD 4
Bones of the Human Body The skeleton has 206 bones Two basic types of bone tissue Compact bone Spongy bone Dr. Naim Kittana, PhD 5
Classification of Bones Dr. Naim Kittana, PhD 6
Structure of Flat Bones Dr. Naim Kittana, PhD 7
Structure of Long Bones Dr. Naim Kittana, PhD 8
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. Dr. Naim Kittana, PhD 9
Microscopic Anatomy of Compact Bone 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 Dr. Naim Kittana, PhD 10
Microscopic Anatomy of Compact Bone 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. Dr. Naim Kittana, PhD 11
Microscopic Anatomy of Spongy Bone The trabeculae in spongy bone align precisely along lines of stress and help the bone resist stress. 12
Microscopic Anatomy of Compact Bone 13
Microscopic Anatomy of Compact Bone Dr. Naim Kittana, PhD 14
Bone Markings Dr. Naim Kittana, PhD 15
Bone Markings Dr. Naim Kittana, PhD 16
Upper surface of right tibia Capsule of hip-joint, Posterior aspect. Dr. Naim Kittana, PhD 17
Long Bone Formation and Growth 18
The Axial Skeleton Forms the longitudinal part of the body Divided into three parts 1. Skull 2. Vertebral column 3. Bony thorax Dr. Naim Kittana, PhD 19
The human skeleton 20
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 Dr. Naim Kittana, PhD 21
The Skull: Anterior view 22
The Skull: Lateral View 23
The Skull: Superior View 24
The Skull: Inferior View 25
Paranasal Sinuses Hollow portions of bones surrounding the nasal cavity Dr. Naim Kittana, PhD 26
The Hyoid Bone The only bone that does not articulate with another bone Serves as a moveable base for the tongue Dr. Naim Kittana, PhD 27
The Vertebral Column Vertebrae separated by intervertebral discs The spine has a normal curvature Each vertebrae is given a name according to its location Dr. Naim Kittana, PhD 28
Structure of a Typical Vertebrae Dr. Naim Kittana, PhD 29
Regional Characteristics of Vertebrae 30
Regional Characteristics of Vertebrae Dr. Naim Kittana, PhD 31
Regional Characteristics of Vertebrae 32
The Bony Thorax 33
The Appendicular Skeleton Limbs (appendages) Pectoral girdle Pelvic girdle Dr. Naim Kittana, PhD 34
The Pectoral (Shoulder) Girdle 35
The humerus of the right arm 36
Bones of the Upper Limb 37
Bones of the Upper Limb 38
Bones of the Pelvic Girdle Dr. Naim Kittana, PhD 39
Bones of the Pelvic Girdle 40
Gender Differences of the Pelvis 41
Gender Differences of the Pelvis 42
Bones of the Lower Limbs The thigh has one bone: femur thigh bone 43
Bones of the Lower Limbs The leg has two bones: Tibia Fibula The tibia and fibula of the right leg 44
Bones of the right foot The foot: 1. Tarsus ankle 2. Metatarsals sole 3. Phalanges toes Dr. Naim Kittana, PhD 45
Bones of the right foot 46
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. 47
Joints Articulations of bones Functions of joints: Hold bones together Allow for mobility Ways joints are classified: Functionally Structurally Dr. Naim Kittana, PhD 48
Classifications of Joints 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 Dr. Naim Kittana, PhD 49
Fibrous Joints 50
Cartilaginous Joints 51
Synovial Joints 52
The General Structure of Synovial Joint 53
Summary of joint classes Dr. Naim Kittana, PhD 54
Types of movements allowed by Synovial Joints 55
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 Dr. Naim Kittana, PhD 56
Types of movements allowed by Synovial Joints 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 Dr. Naim Kittana, PhD 57
Types of movements allowed by Synovial Joints 58
Types of movements allowed by Synovial Joints 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 Dr. Naim Kittana, PhD 59
Types of movements allowed by Synovial Joints 60
Types of Synovial Joints Based on Shape 61
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. Dr. Naim Kittana, PhD 62
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 Dr. Naim Kittana, PhD 63
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. Dr. Naim Kittana, PhD 64
Pivot joints Dr. Naim Kittana, PhD 65
Types of Synovial Joints Based on Shape 66
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 Dr. Naim Kittana, PhD 67
Types of Synovial Joints Based on Shape 68
5- Saddle joints Synovial 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. Dr. Naim Kittana, PhD 69
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 multiaxial 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. Dr. Naim Kittana, PhD 70