Lec 2 Anatomy (Dr. Khairy) PDF

# General Arthrology (علم المفاصل) (Syndesmology) By Dr. Mahmoud Khairy ## Vet Nerd Team - Arthrology: science deals with different types of joints. - Joint or (an articulation): formed by union of 2 or more bones or cartilages by uniting medium. - Uniting medium: May be fibrous tissue or cartila...

# General Arthrology (علم المفاصل) (Syndesmology) By Dr. Mahmoud Khairy ## Vet Nerd Team - Arthrology: science deals with different types of joints. - Joint or (an articulation): formed by union of 2 or more bones or cartilages by uniting medium. - Uniting medium: May be fibrous tissue or cartilage or others. ### Function of joint: 1. Facilitate the movement 2. Flexibility and stability between bones. ## Classification of joints ### I- Functional Classification of joints According to: 1. the presence or absence of movement 2. degree of mobility | Joint Type | Description | |---|---| | Synarthrosis (fixed joint) (Immovable joint) | | | Amphiarthrosis (tight joint) (partly movable joint) | | | Diarthrosis (true joint) (movable joint)| | ### II- Structural Classification of joints According to : 1. the uniting medium 2. the presence or absence of joint cavity | Joint Type | Description | |---|---| | Fibrous Joint | United by fibrous tissue with no joint cavity (Immovable joint) | | Cartilaginous Joint | United by cartilage (hyaline or fibrocartilage) with no joint cavity (partly movable joint) | | Synovial Joint | United by synovia filled joint cavity (freely movable joint) | ## Synarthrosis **Def:** A group of joints in which the bones are united by uniting medium in a manner that movement is prevented. They are characterized by: 1. No movement (fixed or immovable joints). 2. No joint capsule (cavity). 3. Are temporary as the uniting medium being ossified with age. ### Classification of Synarthrosis (Acc. To the uniting medium): - Syndesmosis (desmos = ligament = C.T) - Synchondrosis (chondros= cartilage= hyaline cart.) - Synostosis (os= bone) - Synsarkosis (sarx- meat- muscle) - Sutures (fibrous tissue) ## Types of joints: 1. **According to uniting medium:** ### I- Fibrous Joints (Synarthrosis) * **Characterized by:** - Uniting medium is fibrous tissue - No joint cavity - In young - Temporary → uniting medium being ossified and called **synostosis** - No movement - False joint - Location in axial skeleton ### II- Cartilaginous Joints (Amphiarthrosis) * **Characterized by:** - Uniting medium is cartilage - No joint cavity - In young - Temporary - No or very limited movement - False joint - Location in In axial skeleton ### III- Synovial Joints (Diarthrosis) * **Characterized by:** - Uniting medium is joint capsule - Joint cavity present - Movable - True joint - In limbs - **Parts of:** - Articular surfaces - Articular cartilage - Joint capsule - Joint cavity - Synovia * **The chief types or examples:** - Suture - Syndesmoses - Gomphoses * **Types or examples:** - Synchondrosis (Hyaline cartilage joint). - Symphysis (Fibrocartilagenous joint). ## I- Fibrous Joints (Synarthrosis) ### a) Sutures * **Types:** - Joints in skull → adjacent bony edges united by fibrous tissue (Sutural ligament) - **Ex:** - **Sutura Serrata**: has serrated (interlocking) borders are saw like edges. Ex. Interfrontal suture - **Sutura Squamosa** (flat and overlapped edges). Ex. Suture between temporal and parietal bones. - **Sutura Harmonia** (plana) (parallel smooth edges). Ex. Internasal suture - **Sutura Foliata**: edge of bone fits into the adjacent bone. EX Zygomatico maxillary suture in skull of dog (skull of young horse) ### b) Syndesmosis * **Description:** - Uniting medium is fibrous or elastic tissue or mixture. - **Ex:** - Joints between shafts of metacarpal bones of horse. - Joints between radius &ulna of young horses. ### c) Gomphosis * **Description:** - Implantation of teeth in alveoli by periodontal ligament - (gomphosis is considered not a joint → teeth are not parts of skeleton) ## II- Cartilaginous Joints (Amphiarthrosis) ### 1-Synchondrosis (Hyaline cartilage joint) - **Primary** (temporary cartilaginous joint) → cartilage is converted into bone before adult life. * **Examples:** - Epiphysis and diaphysis junction of long bones in young united by a cartilaginous Epiphyseal (Growth) plates. ### 2-Symphysis (Fibrocartilaginous joint) - **Secondary** cartilaginous joint. * **Example:** - Pelvic symphysis. - Intervertebral discs * **Examples:** - Costochondral junctions - Intermandibular synchondrosis. ## Sutures (skull of young horse) - **A-Serrated sutures:** - **B-Squamous sutures:** - **C-Plane suture:** - **D- Foliate suture:** ## General Neurology (علم الأعصاب) ### Vet Nerd Team - Nervous System (NS) → system which controls all functions of other systems. - **Divided into:** - Central nervous system (CNS) - CNS → receive different sensations, associates, integrate and elaborate them. - CNS selects the motor neurons → send motor orders → proper muscles or glands → proper response. - Protected by bones (brain in the skull and spinal cord in vertebral canal). - Peripheral nervous system (PNS) - Part of nervous system present outside skull and vertebral canal. - Receives sensations from sense organs (receptors) and transmits it to CNS (sensory nerve fibers) - Carries motor orders from CNS to muscles and glands (effectors) by motor nerve fibers. - Cranial Nerves → 12 Pairs & Spinal nerves → 42 Pairs ### Divisions of PNS → 1- **Sensory or afferent division** - Carry sensory information to CNS - **Grouped into:** - **Somatic afferent division** → Carry sensory information of voluntary activities to CNS - like of skin, skeletal muscles, joints - **Visceral afferent division** → Carry sensory information of involuntary activities to CNS like glands and smooth muscles of internal organs 2- **Motor or efferent division** - Carry information from CNS to effectors - **Grouped into:** - **Somatic Nervous System**→ Voluntary nervous system → Carry from CNS to skeletal muscles - **Autonomic Nervous System (ANS)** → Involuntary nervous system → Carry from CNS to smooth & cardiac muscle, glands - Could be: - **Sympathetic Division:** "fight or flight" - **Parasympathetic Division:** "rest and digest" → antagonize each other ### CNS contains 2 major parts → - **Brain** - control center of NS - **Spinal cord** - vital link between brain and body * **Features:** - Has about 10^13 cells (glial cells and neurons) - Exhibits some functional independence from brain. - 10^15 synapses. ## Nervous tissue: Two cell types → make up nerve system are neurons and neuroglial cells ### 1- Neurons - Functional units of nerve system - Specialized for generation and transmission of nerve impulse. - Sensory function - Generation of thought - Storage of memory - Integration of idea - Coordination of muscular activities ### 2- Neuroglial cells - Non excitable cells found in association with neurons. - Provide supporting functions to neurons - Meaning "nerve glue" - Another type of brain cells → Glial cells make up 90% of brain's cells. - Nerve cells that don't carry nerve impulses. * **Functions:** - Digestion of parts of dead neurons - Manufacturing myelin for neurons - Providing physical and nutritional support for neurons * **Types:** - Astrocyte - Microglia - Ependymal - Oligodendrocytes - Schwann's Cells. ## A- Neuroglial cells - Neuroglial cells outnumber neurons by about 20x - 5 types of supporting cells, 4 are found in the CNS: ### 1. Astrocytes: * **Description:** - Star-shaped cells - Guide the migration of developing neurons - Involved in formation of blood brain barrier ### 2. Microglial cells: * **Description:** - Specialized immune cells that act as the macrophages of CNS ### 3. Ependymal Cells: * **Description:** - Line ventricles of brain and central canal of spinal cord - Ciliated → facilitates movement of cerebrospinal fluid (CSF) ### 4. Oligo-dendrocytes:** * **Description:** - Produce myelin sheath which provides electrical insulation for neurons in CNS ### 5. Schwann cells:** * **Description:** - Form myelin sheaths around the larger nerve fibers in PNS. - Vital for neuronal regeneration ## B- Neurons→ Functional structures - Neurons are functional units of the nervous system. - Specialized to conduct information from one part to another - Neurons are cells that send and receive electro-chemical signals. - There are about 100 billion neurons in the brain. ### Typical neuron has 3 parts → 1- **Dendrites** → Collect information and send it to cell body. 2- **Cell body** → Connect dendrites and axon, main bio-synthetic and metabolic center 3- **Axon** → Take information away from cell body to another cell ### Structures of Neuron: - **1- (Cell-body) or Soma-center:** - Contains cell's Nucleus: - Round, centrally located structure - Contains DNA - Controls protein manufacturing - Has No role in neural signaling - Directs metabolism - Contains all organelles of cell except centrosome. - Contains Nessel's granules→ protein manufacture - **2- Dendrites:** - Information Collectors. - Receive inputs from neighboring neurons. - **Dendrites Growth:** - Mature neurons generally can't divide. - But new dendrites can grow more connections to other neurons. - New connections are the basis for learning. - **3- Axon:** - **Axon-cable** extends and carries nerve signals away from the soma. - The cell's output structure - One axon per cell - Has two distinct parts → - Tube like structure - Branches at end → connect to dendrites of other cells (Axon terminals). - A white fatty casing on axon - Made from glial cells → Oligo-dendrocytes & Schwann cells - Prevents current from leaving the axon - Acts as an electrical insulator - Not present on all cells - When increases → ↑ speed of neural signals down the axon. ## Classification of Neurons ### Morphological or Structural classification 3 classes → - **Multipolar neurons** - Neurons having more than 2 processes (axon) - Motor in function - **Bipolar neurons** - Neurons with 2 processes - Found in retina and inner ear - Sensory in function - **Unipolar neurons** - Neurons having only one process - Sensory in function - **Pseudo-unipolar** - Have one axon → 2 branches - Interneuron in function??? - Communicate with spinal cord & other with skin or muscle. - Examples are dorsal root ganglia cells ### Functional Classification 3 classes → - **Sensory (afferent):** - Conduct impulses from periphery to CNS - **INPUT** From sensory organs to the brain and spinal cord. - Vision, hearing, taste and smell nerves are cranial, not spinal - **Inter-neurons (association or integrative or spelling cell) :** - Carry information between other neurons: - 1- Receive and interpret sensory information - 2- Conduct formulated response to effectors via motor area. - Only found in brain and spinal cord. - **Motor (efferent):** - Conduct impulses from CNS to periphery - **OUTPUT** From the brain and spinal cord To the muscles and glands. ## Synaptic cleft → - Space between axon terminal and dendritic spine - Allows neurons to communicate with each other. ## Synapse → Junction between dendrites and axon terminals ### How neurons communicate? (Synapse) - Neurons communicate by electrical signal called Action Potential - Action Potentials are based on movements of ions between outside and inside of the cell - When an Action Potential occurs → a molecular message is sent to neighboring neurons ## Life span of neurons: - Neurons cannot re-grow after damage (except neurons from the hippocampus) - Fortunately, there are about 100 billion neurons in the brain. ## Spinal cord - With brain → from (CNS) → nerves that are not in brain or spinal cord are part of (PNS). - Spinal cord itself is in spinal canal of vertebral column (back bone) ### Internal Anatomy of spinal cord: - Dorsal median sulcus & ventral median fissure → penetrate white matter of spinal cord and divide it into right and left sides. - Gray matter of spinal cord is shaped like letter H or a butterfly and is surround by white matter. - Gray matter consists primarily of cell bodies of neurons and neuroglia and unmyelinated axons and dendrites of association and motor neurons. - Gray matter is divided into horns → which contain cell bodies of neurons. - White matter consists of bundles of myelinated axons motor and sensory neurons. - White matter is divided into columns contains tracts either ascending or descending. ## Branching of the typical spinal nerve: - Spinal nerves formed from dorsal and ventral roots → Dorsal root> ventral root - Spinal nerves branched into dorsal and ventral rami → Ventral ramus>dorsal ramus - Dorsal rami supply skin and muscles of the back. - Ventral rami form a plexus → supplies anterior part of trunk and thoracic limbs. ### Nerve Plexus: - Axons from ventral rami of spinal nerves **except for thoracic nerves** do not go directly to the body structures they supply → they form networks on both left and right sides of body by joining with various numbers of axons from ventral rami of adjacent nerves. - Such a network of axons is **called a plexus (network).** - Ex. → Brachial plexus ### Reflex Arc: → Rapid Adjustment - Specific nerve impulse pathway - **Five components of reflex arc:** - 1. receptor - 2. sensory neuron - 3. integrating center - 4. motor neuron - 5. effector