Joints (2) PDF - Najran University 1445 - 2024

KINGDOM OF SAUDI ARABIA Ministry of Education Najran University College of Medicin...

KINGDOM OF SAUDI ARABIA Ministry of Education Najran University College of Medicine Anatomy Department Joints 1445 - 2024 ‫العام‬ Dr. Itedal Ahmed Dr. Aymen Nasreldin Associate professor Assistant professor  Objectives(ILOS) By the end of the lecture, the student should be able to: Define the joint. Identify types of joints and their characters. Recognize the factors affecting the stability of the joints. Classify the joints giving an example of each type. Determine the movements of different types of joints. List the factors affecting the range of movement. Define Hilton’s law. Know applied anatomy  WHAT IS A JOINT ? It is a meeting of two or more bones. Femur Every bone in the body forms a joint with at least one or more bone. Patella Joints have two functions: They hold the bones together securely. Also it give the rigid skeleton mobility. Tibia Fibula X-ray of the knee joint  CLASSIFICATION Joints could be classified according to the intervening tissue into: - Fibrous Joints - Cartilaginous - synovial joints  I- Fibrous joints They are fixed immovable joints in which the bone surfaces connected together by a fibrous tissue. Fibrous joints include 3 varieties A. Skull sutures : The serrated margins of skull bones are strongly united by thin fibrous tissue “sutural ligament” which is continuous externally with the periosteum “pericranium’’ and internally with endosteum “endocranium”.  B- syndesmoses B- Inferior tibiofibular joint : where no movement is allowed. The lower end of tibia and fibula are connected by a fibrous tissue called interosseous ligament.  C- Gomphosis “Teeth in their alveoli”. The tooth is fastened in its socket in the mandible and maxilla by a dense fibrous tissue called periodontal ligament (like peg and socket). II.CARTILAGINOUS JOINTS In cartilaginous joints: the 2 bone ends are connected by cartilage. Cartilaginous joints present 2 subtypes Primary and secondary  A- Primary Cartilaginous Joints ❖In these joints there is a temporary plate of hyaline cartilage in between 2 bony ends permitting no movement (immobile). ❖This plate ossifies at certain age. ❖These joints include: 1) Union between epiphysis and diaphysis of growing long bones. 2) Union between the first rib and the manubrium sterni (First sternocostal joint). 3) Union between the basiocciput and basisphenoid (clivus). 4) Union between petrous part of temporal and jugular processes of the occipital bone. 5) Costochondral junction. The hyaline-cartilage Epiphysial plates of growing long bones are immovable primary cartilaginous joints.  B- Secondary Cartilaginous Joints Articular bony ends are covered by thin hyaline cartilage with a disc of fibro- cartilage intervening in between, permitting limited degree of mobility. They are found in joints of median plane including: 1- Intervertebral discs: (Cartilaginous plates in-between vertebrae permitting clear movements motion). 2- Symphysis pubis: Hormones of pregnancy softens its ligaments and cartilage widening birth canal for the baby. 3- Manubriosternal joint (between the manubrium sterni and the body of the sternum. 4- Xiphisternal joint (between the xiphoid process and the body of the sternum. SECONDARY CARTILAGINOUS JOINTS 2.The intervertebral discs of the vertebral column (secondary cartilaginous) where the articulating bone surfaces are connected by pads (discs) of fibrocartilage, are also slightly movable The intervertebral discs is composed of nucleus pulposus surrounded with annulus fibrosus  Intervertebral discs ❖They are fibro-cartilaginous plates of varying thickness that bind two adjacent vertebral bodies together. ❖They show a slight movement between each two vertebrae. ❖They act as shock absorbers. ❖Each disc is composed of two parts: 1- Annulus fibrosus: It is the firmer outer portion which is composed of circularly arranged fibro- cartilaginous fibers. 2- Nucleus pulposus: It is the softer, compressible central part which is formed of mucoid material. Annulus intervertebral fibrosus disc Concentric Nucleus lamellae of fibrous tissue pulposus Symphysis pubis (Secondary cartilaginous) slightly movable joints.  Joints mobility fibrous joints are synovial joints are immovable freely movable Primary cartilaginous joints are immovable Secondary cartilaginous joints are slightly movable 16  III.SYNOVIAL JOINTS Synovial joints are those in which the articulating bone ends are separated by a joint cavity which contains a synovial fluid. They account for all joints of the limbs. 17  FEATURES OF SYNOVIAL JOINTS 1- Articular bony ends covered by thin hyaline cartilage. 2- Joint cavity contains thin film of a lubricant fluid. 3- Fibrous capsule. 4- Synovial membrane. 5- Capsular, extracapsular and intra-capsular ligaments. 6-Freely movable 18  ❖The fibrous articular Capsule surrounds and protects the synovial membrane ❖the synovial membrane lines the capsule and covers all intracapsular structures except articular surfaces. ❖Synovial membrane may protrude through a capsular hole forming a pouch or bursa. 19  TYPES OF SYNOVIAL JOINTS BASED ON SHAPE Based on the shape, the synovial joints can be classified as: a) Plane b) Hinge c) Pivot d) Condyloid e) Ellipsoid f) Saddle g) Ball and socket 20  PLANE JOINTS In a plane joint, the articular surfaces are flat, and only short slipping or gliding movements are allowed. Examples: The intercarpal joints acromioclavicular joint 21  HINGE JOINTS In a hinge joint, the cylindrical end of one bone fits into a trough- shaped surface on another bone. Movement is allowed in just one plane, like a hinge. Hinge joints are Uniaxial ; they allow movement around one axis only. Examples: elbow & ankle and the interphalangeal joints of the fingers. 22  Elbow joint 23  PIVOT JOINT In a pivot joint, the rounded end of one bone fits into a ring of bone (or ligaments). Pivot joints are Uniaxial joints, because bone can turn only around its long axis, Axis of movement Examples: superior and inferior radioulnar joints & Median atlantoaxial joint. 24  CONDYLOID JOINTS In a condyloid joint, the egg- shaped articular surface of one bone fits into an oval concavity in another. Both of these articular surfaces are oval. Movement occurs around two axes, hence these joints are biaxial, as in knuckle (metacarpophalangeal joints). Axes of movement Condyloid joints allow the moving bone to move: a) from side to side b) back and front but the bone cannot rotate around its long axis. 25  Ellipsoid joint This joint looks like condyloid joint except for the shape of articulating surfaces, which is elliptical (oval) having 2 axes long and short which are perpendicular to each other. Movement occurs around two axes, hence this joint is biaxial, as in wrist joint. Wrist (radiocarpal) joint between the inferior surface of the distal end of radius and the proximal row of carpal bones  SADDLE JOINTS In saddle joints, each articular surface has both convex and concave areas, like a saddle. These biaxial joints allow essentially the same movements as condyloid Axes of joints, but there is slight movement rotation. Example: 1stcarpometacarpal joint of the thumb. 27  BALL AND SOCKET JOINTS In a ball & socket joint, the spherical head of one bone fits into a round socket in another. I t is a multiaxial joints allow movement in all axes, including rotation, and are the most freely movable joints. Examples: shoulder and hip. 28  Joints with intraarticular disc Some synovial joints have distinguishing features such as a fibrocartilaginous articular disc or meniscus in the cavity , which are present when the articulating surfaces of the bones are incongruous. Examples: 1-knee joints. 2-sterno-clavicular joints. 3-Tempromandibular joints. Intra-articular Sternoclavicular joint disc Clavicle Hyaline cartilage  Joint Stability 1) Adaptation between articulating ends depending on their shape, size and orientation. 2) Presence of strong fibrous (ordinary) ligaments. They may be subjected to stretch or tear in prolonged or sudden stresses. N. B.: Elastic (special) ligaments e. g. ligaments of ear ossicles, containing elastic fibers which help ligaments to resist stresses. 3) The tone of surrounding muscles (it is important for shoulder and foot). 4) Atmospheric pressure resists dislocation of head of femur from out of the acetabulum in the hip joint. 5) Supporting tendons (long head of biceps supports head of the humerus in shoulder Joint). Joint movements 1) Gliding Movement: - Slight frictional (non-axial i.e. in random direction) movement, which is neither angular nor rotatory. - It occurs in acromio-clavicular and in most carpal and tarsal joints. 2) Angular Movements: - It occurs around transverse axes (perpendicular to the moving bones). - It increases or decreases the angle between articulating bones in either planes (sagittal or coronal) - Angular movements include: a- Flexion (bending or angling). b- Extension (straightening). c- Abduction (bringing away). d- Adduction (bringing nearer or closer). e- Circumduction: Summation of the 4 previous types of angular movements (as in shoulder & hip joints). 3) Rotatory movement The movement occurs around a longitudinal axis which may be: 1] Inside the rotating bone [its own longitudinal axis (e.g. humerus in shoulder joint]. 2] Inside the next succeeding bone (rotation of atlas around the dens of axis. 3] An axis, which is parallel or nearly parallel to rotating bone (e.g. rotation of radius around ulna in pronation & supination of forearm. The axis nearly passes from the head of radius to the head of ulna). * Limitation of movements: Movements are limited (stopped) by certain factors: i- Articular surfaces are used up (finished) and contraction of antagonistic muscles. ii- Moving parts come in contact with each other or with other body parts. iii- Connecting ligaments become tense. Immovable & slightly movable joints are restricted mainly to the axial skeleton, where firm attachments and protection of internal organs are priorities. Freely movable joints predominate in the 36 limbs where mobility is important. MOVEMENTS FLEXION, EXTENSION & HYPEREXTENSION 37  ABDUCTION, ADDUCTION, ROTATION CIRCUMDUCTION 38 DORSIFLEXION AND INVERSION AND PLANTAR FLEXION EVERSION 39 SUPINATION AND PRONATION 40  Hilton’s law This law states that "the nerves supplying the muscles, which move a joint, supply also the joint and a patch of skin overlying the joint (This seems to be logic and essential to perform local reflexes necessary to active movements and maintenance of posture). * Capsule and ligaments are the richest in sensory (articular) nerve supply while articular cartilages are the least. * Overstretching of capsule and ligaments causes pain together with reflex contraction of surrounding muscles. * Afferent impulses from capsule and ligaments of a joint inform C.N.S about the joint state maintaining postural tone and coordination of movements. * Articular blood vessels are sympathetically innervated. Applied anatomy 1] Arthritis: is inflammation of the joint. 2] Arthralgia: is pain in the joint. 3] Traumatic effusion: is distension of the synovial cavity with serous fluid after joint trauma or an inflammation. 4] Joint stiffness: is painful limitation of movement of a joint after disease, trauma or prolonged immobilization. 5] Dislocation: is painful separation between articulating ends of bones with loss of normal articular relations. It could be congenital or acquired. It needs reduction (returning to the normal position) under sedation.  Rheumatoid arthritis ❖ an autoantibody called rheumatoid factor attacks the synovial membranes. ❖ Inflammatory cells accumulate in the synovial fluid and produce enzymes that degrade the articular cartilage. ❖The synovial membrane thickens and adheres to the articular cartilage, fluid accumulates in the joint capsule, and the capsule is invaded by fibrous connective tissue. ❖As articular cartilage degenerates, the joint begins to ossify, and sometimes the bones become solidly fused and immobilized, a condition called ankylosis. References 1-Gray's Anatomy. The Anatomical Basis of Clinical Practice. 42nd edition. Susan Stand ring, Ph.D. Churchill Livingstone Elsevier. (2021). 2- Netter Atlas of human anatomy. A system approach John T. Hansen, Netter's with Elsevier, Standard 8th Edition (2023). 3-Last’s anatomy Regional and applied,12th edition. Chummy S. Sinnatamby FRCS, Churchill Livingstone (2011). 4-Clinically oriented anatomy / Keith L. Moore, Arthur F. Dalley, Anne M.R. Agur. —9th ed. North American Edition, Revised Reprint Lippincott Williams & Wilkins (2023). 5-Essentials of Human Anatomy & Physiology, 13th Global Edition by Marieb and Keller(2021). Published by pearson education limited. E book available from British library. 6-Human Anatomy, Ken Saladin, 5th edition (2016).