Human Skeleton and Joints PDF

Human skeleton and Joints Assistant Prof. Dr. Ghada Omar 1 Objectives (ILO) After studying this lecture, the students will be able to: 1. Identify the bones of the human skeleton and distinguish between the axial and appendicular divisions. 2. Des...

Human skeleton and Joints Assistant Prof. Dr. Ghada Omar 1 Objectives (ILO) After studying this lecture, the students will be able to: 1. Identify the bones of the human skeleton and distinguish between the axial and appendicular divisions. 2. Describe the different types and shapes of bones and relate them to function. 3. Describe how joints in the human body are named and identify all joints of the skeleton. 4. Classify the different types of joints in the human body by structure and function and give an example of each. 5. Recognize the basic structures of a synovial joint. 6. Identify the six types of synovial joints and provide an example of each. The Human Skeleton The 206 bones of the human skeleton can be divided into two parts: The axial skeleton forms the body’s "axis": that is, it makes up the center of the body. It is composed of bones of the head and trunk, including the skull and associated bones, hyoid, sternum, ribs, vertebrae, sacrum, and coccyx. A typical adult skeleton contains 80 bones in the axial division. The appendicular skeleton is "appended" to the axial skeleton. In a typical adult, it contains 126 bones arranged in the following structures: The shoulder girdle includes the clavicle and scapula. The upper limb includes the humerus, radius, ulna, carpals, metacarpals, and phalanges. The pelvic girdle includes the coxal bone (coxa means hip), which is actually three fused bones (the ilium, ischium, and pubis). The lower limb includes the femur, tibia, fibula, tarsals, metatarsals, and phalanges. The upper and lower limbs, or appendages, are essential to independent movement and full interaction with the environment, but wheelchairs, artificial limbs, and other devices have made it possible to live a rewarding life without them. Types of human skeleton bone Video  1. Flat Bones Protect Internal Organs There are flat bones in the skull (e.g. occipital, parietal, frontal, nasal), the thoracic cage (sternum and ribs), and the pelvis (ilium, ischium, and pubis). The function of flat bones is to protect internal organs such as the brain, heart, and pelvic organs. Flat bones are somewhat flattened, and can provide protection, like a shield; flat bones can also provide large areas of attachment for muscles. https://www.healthline.com/health/flat-bones 2. Long Bones Support Weight and Facilitate Movement The long bones, longer than they are wide, include the femur (the longest bone in the body) as well as relatively small bones in the fingers. Long bones function to support the weight of the body and facilitate movement. Long bones are mostly located in the appendicular skeleton and include bones in the lower limbs (the tibia, fibula, femur, metatarsals, and phalanges) and bones in the upper limbs (the humerus, radius, ulna, metacarpals, and phalanges). 3. Short Bones Are Cube-shaped Short bones are about as long as they are wide. Located in the wrist and ankle joints, short bones provide stability and some movement. The carpals in the wrist (scaphoid, lunate, triquetral, hamate, pisiform, capitate, trapezoid, and trapezium) and the tarsals in the ankles (calcaneus, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, and medial cuneiform) are examples of short bones. 4. Irregular Bones Have Complex Shapes Irregular bones vary in shape and structure and therefore do not fit into any other category (flat, short, long, or sesamoid). They often have a fairly complex shape, which helps protect internal organs. For example, the vertebrae, irregular bones of the vertebral column, protect the spinal cord. The irregular bones of the pelvis (pubis, ilium, and ischium) protect organs in the pelvic cavity. 5. Sesamoid Bones Reinforce Tendons Sesamoid bones are bones embedded in tendons. These small, round bones are commonly found in the tendons of the hands, knees, and feet. Sesamoid bones function to protect tendons from stress and wear. The patella, commonly referred to as the kneecap, is an example of a sesamoid bone. Joints Definition: Joint is the meeting of two bones or more in the skeletal system. It is the connection or articulation between any rigid components of the skeleton whether bones or cartilages. Arthrology: is the study of joints, how and why joints move the way they do. Arthr =means joint or articulation. Ology= means the science which deal with. 10 Function of the joint The joints of the human body serve functions similar those of joints used in the construction of buildings, furniture, and machines. Bones come together in the body to form joints which connect different segments together to: ❖ Give the skeleton mobility. ❖ Hold the skeleton together (Stability). 11 Naming Joints Joints are named according to the bones or bony landmark that form them. Ex, Humeroulnar joint: forms by articulating the humerus bone of the upper arm with the ulna of the forearm. GIVE MORE EXAMPLES???? There are a few exceptions to these rules. For example, the hip joint would be the ilioischiopubofemoral joint. Another example, the clinical name for the ankle joint is the talocrural joint (i.e. talus plus (lower leg = crural). 12 Classification of joints Classification according to number of axes of motion provided by each joint These joints are divided into three categories: Uniaxial: are joints in which the bony components are free to move in one plane around a single axis. These joints have one degree of freedom such as rotation occurs in Atlantoaxial joint and Radioulnar joints. Biaxial: are joints in which the bony components are free to move in two planes around two axes. These joints have two degrees of freedom such as Metacarpophalangeal joints and Radiocarpal joints Triaxial or multiaxial: are joints in which the bony components are free to move in three planes around three axes. These joints have three degrees of freedom such as the hip and shoulder joints. 14 Video Structural Classification Structural classification focuses on: The material binding bones together and Whether or not a joint cavity is present Three major structural categories are used when describing joints: Fibrous, Cartilaginous, and Synovial.  Characteristics of Fibrous Joints They have firm connections between bones. There is minimal joint cavity (or no space between the articulating surfaces), A collagen-dense connective tissue holds the bones tightly together. Little or no movement is possible at these joints; thus, they are the most A. Sutures of the skull. B. Syndesmosis formed by the ligaments and interosseous membrane of the stable type. lower leg. C. Gomphoses between the teeth and their sockets in the mandible. 17  Types of fibrous joints There are three types of fibrous joints: 1) Sutures: are continuous periosteal connections between bones, such as between the cranial bones. 2) Syndesmoses: are fibrous joints held together with a cord (ligament) or sheet (interosseous membrane) of connective tissue. Example is the inferior tibiofibular joint. 3) Gomphoses: are the specific fibrous joints at which teeth fit into sockets in the jaw (gomphos- means bolt or nail). 18 Cartilaginous joints Joints that unite bones with cartilage are called cartilaginous joints. 19 Cartilaginous Joints Characteristics Functions They lack a joint cavity & have slightly more Allowing the vertebral column to absorb movement than fibrous joints. loads from walking, running, jumping, The cartilage separates the articulating and lifting. surfaces of adjacent bones. Cartilaginous joints allow the ribcage to The cartilage increases the pliability of the expand and contract for breathing. joint, allowing slight movement. When we are walking and running, This type of joint is present between the particularly on uneven surfaces, this slight bodies of the vertebrae, at the costochondral capacity for movement allows the pelvic junctions (where the ribs meet the sternum), girdle to serve as a suspension system. at the pubic symphysis (where the two pubic bones meet at the front of the pelvic girdle). 20 Types of Cartilaginous Joints There are two types of cartilaginous joints: A synchrondosis is an immovable cartilaginous joint. One example is the joint between the first pair of ribs and the sternum (sternocostal joints) A symphysis consists of a compressible fibrocartilaginous pad that connects two bones. This type of joint allows for some movement. The hip bones, connected by the pubic symphysis, and the vertebrae, connected by intervertebral discs, are two examples of symphyses.  Synovial Joint Synovial joints are the most mobile of all the joints. They are named for their distinctive structure, which resembles an egg (syn- means together and ovi- means egg). Several unique features are present in this type of joint, including: A thick joint capsule, divided into an outer fibrous capsule and inner synovial membrane. The synovial membrane produces synovial fluid, reducing friction in the joint cavity. Smooth articular cartilage covers the articulating bone ends and acts like a shock absorber to further reduce friction during movement. Ligaments support the fibrous capsule, providing stability to the joint. 24 Synovial Membrane and Synovial Fluid Synovial membrane surrounds the joint cavity interior to fibrous capsule and forming synovial cavity, which contains synovial fluid. Knee joint is the largest joint of body contains 0.5 ml of fluid 25 3-11-1432  Ligaments surround the joint and strength the Ligaments joint. The ligaments may be extra-capsular or intra-capsular 3-11-1432 27 Types of Synovial Joint All synovial joints consist of the basic structures just identified, but their shape varies, allowing different movement possibilities: Ball and socket joints, Hinge joints, Pivot joints, Ellipsoid (or condyloid) joints, Saddle joints, and Gliding joints. 28 ✓ Ball and socket joints They have a spherical head on one bone that fits into a rounded cavity on another. These joints have the greatest movement possibility and are considered triaxial because they can move in all three planes: sagittal, frontal, and transverse. Examples of ball and socket joints in the body include: Hip joint The glenohumeral joint of the shoulder and The hip joint. 29 ✓ Hinge joints They have a cylindrical prominence on one bone that fits into a corresponding depression on another. These joints are uniaxial in that they move in a single plane. An example of a hinge joint in the body is: The humeroulnar joint of the elbow. Humeroulnar joint The temporomandibular joint of the jaw and the tibiofemoral joint of the knee are Modified hinge joints: both of them allow additional movements besides their primary hinging motion. 30 Pivot joints Atlantoaxial joint They have a cylindrical segment of one bone that fits into a corresponding cavity of another. Pivot joints are also uniaxial in that they only allow rotational (longitudinal) movements at that joint. There are pivot joints at: The atlantoaxial joint of the cervical spine and The radioulnar joints of the forearm. 31 ✓ Ellipsoid (or condyloid) joints They are similar to ball and socket joints, but have oval-shaped joint surfaces that resemble a flattened circle or ellipse (ellip- means shortened). Some resemble a condyle, which can be defined as a prominence that forms joints. Ellipsoid joints are biaxial because they can move on two planes. Examples are: o The radiocarpal joints of the wrist & Metacarpophalangeal joints o The metacarpophalangeal joints of the hand. 32 ✓ Saddle joints They are made up of two bony surfaces that are concave in one direction and convex in the other. They fit together like a rider sitting in a saddle, hence their name. These joints are also biaxial and found only in the carpometacarpal joint of the thumbs (between 1st metacarpal bone and trapezium bone) 1 st Carpometacarpal This allows unique movements in the joint (thumb) thumbs that are found in none of the other digits. 33 Gliding joints They have flat surfaces that allow small, planar movements. These joints are considered nonaxial because they are the least mobile of all synovial joints. Limited movement is allowed between the articular processes of the vertebrae, the bones of the shoulder girdle, and the carpal bones of the hand. Acromioclavicular joint Functional Classification 35  Functional Classification There are three categories that describe a joint's function: Synarthrotic joints have little or no movement (syn =together+ arthrothsis = articulation ),is an articulation in which the bones are rigidly joined together. Amphiarthrotic joints are slightly movable, (amphi = means surrounding or on both sides), allows limited motion. Diarthrotic joints are the most mobile of all joints, ((di- means separate or apart). 36 Synarthrotic Joints Synarthrotic joints have articulating surfaces that are very close together. This limits their mobility. Some fibrous joints are synarthrotic, as is another type of joint called a synostosis (osseous connection between bones). An example of a synostosis is the connection between the ilium, ischium, and pubis of the pelvic girdle. 37 Amphiarthrotic Joints Amphiarthrotic joints have articulating surfaces that are farther apart, with a pliable structure between or around them. This allows greater mobility at amphiarthrotic joints. The pliable structure can be in the form of: Ligaments (syndesmosis) or Fibrocartilage (symphysis). Amphiarthrotic joints are found between the tibia and fibula of the lower leg and the anterior pelvic girdle. 38 Diarthrotic Joints Diarthrotic joints are freely movable because their joint surfaces are furthest apart. This separation allows the greatest mobility of all joint types. Synovial joints tend to be diarthrotic. Their joint cavity, in conjunction with other anatomical features, creates a highly mobile joint. A typical diarthrodial joint 39  Cael C, (2010) “Functional Anatomy: Musculoskeletal Anatomy, Kinesiology, and Palpation for Manual Therapists. “ Chapter 2, Lippincott Williams & Wilkins. Levangie PK, Norkin CC, (2005) “Joint Structure and Function: A Comprehensive Analysis.”, Chapter 2, 4th ed. Philadelphia, FA Davis Co. References Gray’s Anatomy: http://www.bartleby.com/107/ Types of Joints. http://www.mananatomy.com/basic- anatomy/types-joints. Types of Joints. http://www.teachpe.com/anatomy/joints.php. 40 Any Questions ? ? 41