2024-2025 IMU Introduction to Musculoskeletal System PDF

INTRODUCTION TO MUSCULOSKELETAL SYSTEM Prof. Dr. Burak BİLECENOĞLU, DDS, PhD Ankara Medipol University, Faculty of Medicine Department of Anatomy [email protected] MOVEMENT PASSIVE STRUCTURES BONES (Osteology) JOINTS (Arthrology) ACTIVE STR...

INTRODUCTION TO MUSCULOSKELETAL SYSTEM Prof. Dr. Burak BİLECENOĞLU, DDS, PhD Ankara Medipol University, Faculty of Medicine Department of Anatomy [email protected] MOVEMENT PASSIVE STRUCTURES BONES (Osteology) JOINTS (Arthrology) ACTIVE STRUCTURES MUSCLES (Myology) BONES Rigid form of connective tissue forming the skeleton 2nd hardest structure in the body (1st is the enamel of the teeth) Approx. 15% of the total body weight (10-14 kg) Forms framework of the body Forms Stores insertion Ca and P location for muscles Protects Produces some of blood cells the organs BONES Bones are living structures having a blood and nerve supply All bones are covered with a layer called periosteum except their joint surfaces Bones in the living body have some elasticity (provided by the organic substances) and great rigidity (provided by the unique internal anatomy constituted by inorganic substances, mainly CaPO4) INTERNAL STRUCTURE of a BONE Compact bone Spongy (cancellous) bone Bone marrow (medullary cavity) Red bone marrow Yellow bone marrow Nutrient foramina & nutrient arteries  SKELETON 206 bones Provide structure and support for soft tissue 2 parts Axial skeleton which is the central core of the body (skull, vertebrae, ribs, and sternum) Appendicular skeleton which forms the bones of the upper and lower limbs SKELETON Axial skeleton Vertebral column……....................................26 Cranium.......................................................22 Hyoid bone.....................................................1 Thoracic cage...............................................25 Appendicular skeleton Upper limb…………………................................64 Lower limb………………...................................62 Auditory bones (in the middle ear)....................................................................6 TOTAL…..........................................................................................................206 (>270 in the newborn) DIFFERENT TYPES of BONES Long bones Have a shaft and two ends Short bones More or less cuboidal in shape Flat bones Irregular bones Pneumatic bones Contains air cells / sinuses Sesamoid bones Bones in certain tendons Accessory bones Develops as a result of additional ossification center or lack of fuse SURFACE FEATURES on the BONES Surfaces of the bones are not smooth, bones display elevations, depressions and holes The surface features on the bones are given names to distinguish and define them Linear elevations > line, crest Round elevations > tubercule (small eminence), protuberance (swelling) Sharp elevations > spine, process Rounded articular areas > head, condyle Openings > foramen, fissure, aperture Canal > a foramen having length Meatus > a canal entering a structure Facets > joints surfaces Depressions > fossae (small depression), groove (sulcus, long narrow depressions) JOINTS Arthrology is the study of joints Joints are formed by the articulation between the articular surfaces of two or more bones Articular system consists of joints and their associated bones and ligaments CLASSIFICATION of JOINTS Cartilaginous joints Synovial joints Fibrous joints (fixed) (slightly moveable) (freely moveable) Sutures Symphysis Hinge joints only in the skull A fibrous cartilage (disc) Bicondylar joints Gomphosis btw. articular surfaces (e.g. pubic symphysis) Pivot joints btw. teeth & jaws Synchondrosis Saddle joints Syndesmosis A hyaline cartilage btw. Condyloid joints Articulating surfaces are articular surfaces is lost connected firmly by a Ball and socket joints within time and the joint connective tissue lose the ability of Plane type joints movement. Temporary type of joint (e.g. sphenoid-occipital) SYNOVIAL JOINTS COMMON FEATURES Articular (joint) cavity Space btw. the articular surfaces Articular cartilage Cartilage covering the articular surfaces Articular capsule Capsule surrounding the joint formed of two layers Fibrous membrane Protects and gives firmness to the joint stability Synovial membrane Lines the inner surface of the fibrous membrane. Secretes the synovial fluid that reduces the friction btw. articular surfaces SYNOVIAL JOINTS ACCESSORY FEATURES Ligaments Dense connective tissue Connect the articulating bones Limit the undesired and/or excessive movements of the joints Intrinsic/extrinsic ligaments Articular disc Eliminate the irregularity btw. articular surfaces Labrum A fibrocartilaginous ring in some synovial joints that deepens the articular surface SYNOVIAL JOINTS Synovial joints are classified according to the shape of joint surfaces There are seven major types of synovial joints Hinge joints Bicondylar joints Pivot joints Saddle joints Condyloid joints Ball and socket joints Plane joints HINGE JOINTS (GINGLYMUS, TROCHLEAR) These types of joints are uniaxial and permit flexion & extension around the transverse axis Bones are joined with strong collateral ligaments e.g., elbow joint PIVOT JOINTS These types of joints are uniaxial and permit rotation (internal rotation & external rotation) around the vertical axis Rounded part of a bone rotates in a sleeve or ring like fibro-osseous structure e.g. radioulnar joints SADDLE JOINTS These types of joints are biaxial and permit flexion & extension around the transverse axis and abduction & adduction around the sagittal axis The articular surfaces resemble a saddle shape and are concave and convex respectively e.g. carpometacarpal joint of the thumb CONDYLOID JOINTS These type of joints are biaxial and permits flexion & extension around the transverse axis and abduction & adduction around the sagittal axis The articular surfaces resemble an ellipsoid shape and are concave and convex respectively e.g. radiocarpal joint, metacarpophalangeal joints BALL & SOCKET JOINTS These types of joints are multiaxial and permit flexion & extension around the transverse axis, abduction & adduction around the sagittal axis, and rotation (internal rotation & external rotation) around the vertical axis The spheroidal surface of a bone articulates with the socket-shaped articular surface of another bone e.g. shoulder joint PLANE JOINTS These types of joints lack any axis and they permit gliding or sliding movements and articular surfaces are almost flat Plane joints are the most common type of joint in the human body e.g. intercarpal joints NERVES & VESSELS of the JOINTS NERVE SUPPLY OF THE JOINTS Hilton’s law The nerves innervating a joint are the branches of the nerves that innervate the muscles acting on that joint and the nerves innervating the sensory areas around that region The nerves convey impulses regarding conscious proprioception (from the joint capsule) and pain (from the fibrous membrane) VESSEL SUPPLY OF THE JOINTS Numerous vessels contribute to the blood supply of a joint, branching off from the surrounding vessels FEATURES SUPPORTING THE JOINT STABILITY (These features prevent the dislocation of a joint) The negative pressure within the joint cavity Joint capsule and the ligaments Muscles and their tendons around the joint Shapes of the articular surfaces  MUSCLES Skeletal (voluntary) muscles Mostly allows voluntary movement (with some exceptions) Smooth (involuntary) muscles Muscle movement controlled by internal mechanism Cardiac (involuntary) muscle Heart muscle PARTS of a SKELETAL MUSCLE and RELATED TERMS Belly (fleshy part) Tendon (in certain muscles termed as aponeurosis) Tendons attach to the bones / cartilages / skin / superficial fascia Origin and insertion FASCIAL SYSTEM of the HUMAN BODY Superficial fascia Superficial layer of the superficial fascia Deep layer of the superficial fascia Deep fascia MUSCLE TERMINOLOGY Name of a muscle can include one or more of the below Shape (deltoid, quadratus…) Size (major, minor…) Number of heads/bellies (biceps, triceps…) Depth (superficial, internal…) Attachment (coracobrachialis, brachioradialis…) Position (brachii, dorsi, pectoralis…) Action (extensor, levator…) MUSCLE CONTRACTION When a muscle contracts its length decreases by 1/3 or 1/2 Isotonic contraction - the length ↓ Isometric contraction - the length does not decrease INNERVATION of the MUSCLES The smallest structure related to muscle innervation is a motor unit A motor neuron and all the muscle cells (fibers) innervated by this neuron INNERVATION of the MUSCLES A single motor neuron may innervate thousands of muscle fibers but in certain muscles, a motor neuron may innervate a smaller number of muscles (e.g. eye muscles, 3-4 fibers are innervated by a motor neuron). This is closely related to the precision of the muscle There are many motor units in a single muscle. The number of these units is again related to the precision of the muscles (Muscles related to precise movements [e.g., muscles in your fingers] have much more motor units) Whole of the motor units does not necessarily contract during a muscle contraction Number of contracting units determines the force of contraction DURING A SINGLE JOINT MOVEMENT, A NUMBER OF MUSCLES CONTRACT Prime mover Synergist muscles (support the movement) Antagonist muscles (oppose the movement) Fixator muscles (the muscles that prevent the undesired movements)