Veterinary Anatomy 1 Lecture Notes PDF

Faculty of Veterinary Medicine Anatomy and Embryology 1 (ANH121) Lecture 2: General myology General arthrology Dr : Mohamed Mahdy General Myology  Muscles Muscle tissue is classified both morphologically and functionally as Skeletal Muscle...

Faculty of Veterinary Medicine Anatomy and Embryology 1 (ANH121) Lecture 2: General myology General arthrology Dr : Mohamed Mahdy General Myology  Muscles Muscle tissue is classified both morphologically and functionally as Skeletal Muscle It moves bones of the skeleton. Striated fibers (by microscope they show transverse striation). Voluntary (under the will of the animal) Muscle fibers are not formed after birth. Cardiac Muscle Striated fibers Involuntary Stimulated by autonomic nervous system. Forms the heart muscle  Smooth Muscle  Non-striated fibers  Involuntary  Stimulated by autonomic nervous system.  Found in the walls of small blood vessels and many visceral organs. The red flesh (meat) of our domestic animals is called the skeletal muscles  Muscles The fleshy part of the muscle is called belly. It has two ends which are called attachments. - The attachment may be: a) Directly through the muscular tissue itself. b) Through fibrous structures called tendons or aponeurosis. Tendon is a ribbon-like rounded, short stout white fibrous tissue. Aponeurosis is a flattened, expanded, sheet-like white fibrous tissue.  Muscles Each muscle has two attachments at both ends. The least movable attachment is called the origin The more movable one is called the insertion. In the limbs the proximal attachment is the origin, the distal one is the insertion.  Action of muscles Flexor muscle: decrease the angle between the two bones. Extensor muscle: increase the angle between the two bones. Adductor muscle: pull the limb toward the median plane. Abductor muscle: move the limb away from the median plane.  Sphincter muscle: present around the natural openings  Name of muscles The name of the muscle can be according to: Shape: serratus Action: retractor, extensor, flexor Position: superficial, deep gluteal Direction of fibers: rectus abdominus Number of divisions: biceps brachii Attachment: sternocephalic Size: long digital extensor Forms of skeletal muscles According to the arrangement of their fibers, the skeletal muscles are classified into: 1. Parallel arrangement: fibers are parallel to each other. e.g. abdominal muscles. 2. Fusiform arrangement: fibers are arranged in spindle form. e.g. Flexor Muscles. 3. Pennate arrangement: fibers have feather-like arrangement. Veterinar y Anatomy 1 General Arthrology  Joint: Where 2 or more bones join. Classification of Joints: - According to uniting medium: Fibrous joints: the uniting medium is fibrous tissue Cartilaginous joints: the uniting medium is cartilage Synovial joints: the uniting medium is synovia  1- Fibrous Joints (Synarthroses) United by dense white fibrous connective tissue. Types: Sutures: narrow strips of Connective tissue. - Present between the adjacent flat bones of the skull - Allows the growth of bone plates. Syndesmosis: The fibrous tissue forms an interosseous ligament - Present between radius and ulna Gomphosis: Between the tooth and the bon socket Not movable  2- Cartilaginous Joints Uniting medium is cartilage. Types: Synchondrosis:  Uniting medium is hyaline cartilage  E.g: costochondral junction Symphysis:  Uniting medium is fibrocartilage  E.g: pelvic symphysis Slight movement  3- Synovial Joints Uniting medium is synovia (synovial fluid) >> clear viscous fluid. Has synovial cavity. Synovial fluid is secreted by synovial membrane. Movable.  The Structure of a Synovial Joint: 1. Articular surface: Smooth 2. Articular cartilage: Hyaline cartilage. Cover the articular surfaces of the bones. Protects ends of bones from crushing. 3. Joint Capsule: Consists of 2 layers Outer fibrous layer. “Protection & support” Inner synovial layer. “Secrete synovial fluid” 4. Synovial fluid: fills the joint capsule Functions: 1- Reduce friction by: - lubricating the joint - absorb concussions 2- Supply oxygen and nutrients to the cartilage 5. Ligaments: strong, fibrous connective tissue bind bones together. Function: Keep the joint stable by helping to prevent dislocation. 6. Articular disc and Menisci Plates of fibrocartilage between the articular surfaces of the bones. Allow bones of different shapes to fit together more tightly. Synovial Joint Structure 1. Synovial fluid / space 2. Synovial membrane 3. Articular cartilage 4. Fibrous joint capsule 5. Periosteum 6. Cortex 2 + 4 = joint capsule Classification of synovial joints: A. According to number of bones: Simple joint: formed between two bones Compound (composite) joint: formed between more than two bones Shoulder Joint Elbow Joint B. According to Geometry (3D Shape): 1. Plane joint: Flat articular surfaces, bones slide over each other. Movement is gliding carpal joints 2. Hinge (ginglymus joint): Permit only flexion and extension. Elbow joint.  3. Pivot (trochoid joint): Permit rotation movement. Atlantoaxial joint. 4. Condylar joint: Condyle articular surface fit into elliptical cavity. Permit all movements except rotation. Temporomandibular joint. 5. Ellipsoid joint: Ellipsoidal articular surface fit into in an oval depression. Permit all movements except rotation. Atlantooccipital joint. 6. Saddle joint: Articular surface of one bone is saddle-shaped. Permit all movements except rotation. Interphalangeal joints in the dog. 7. Ball and socket joint: Ball-like surface of one bone fitting into a cup-like depression of another bone Permit all types of movements Shoulder and hip joints.  Movements of synovial joints There are 3 main types of movements: A. Gliding: sliding without changing orientation B. Rotation: rotation of one segment around the longitudinal axis of the other segment. E.g. Atlantoaxial joint  C. Angular: Increase or decrease in the angle between articulating bones. 1. Extension: increase joint angle 2. Flexion: decrease joint angle Hyper extension (flexion) beyond normal ranges. 3. Adduction: Movement of a bone toward the median plane 4. Abduction: Movement of a bone away from the median plane. 5. Circumduction: Combination of all angular movements  Synovial structures 1. Synovial bursa: Sac-like structure contains synovial fluid. Located between two structures which tend to rub against each other. Help reduce friction 2. Synovial (tendon) sheath: Cylinders of connective tissue lined with synovial membrane and wrapped around a tendon. Between the tendon and underlying hard structure. Reduce friction. e.g. digital tendon sheath  Reading Sources Dyce, Sack, Wensing; Textbook of Veterinary Anatomy 5th Edition. See pages 47 - 54