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Lecture 6

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University of Toronto Scarborough
Biological Sciences
Connie Soros

1 Lecture 6 The Muscular System Axial & Appendicular Musculature The Skeletal System: Articulations The body cannot move without joints • Movements are linked to the range of joint action • Joints (arthroses) are connections between bones that may or may not permit movement • Two bones may be in direct contact with each other or separated by: o Cartilage o Fluid o Fibrous tissue Joints are classified based on: o Function o Range of motion o Structure o Makeup of the joint Classification of Joints • Joints can be classified based on their range of motion (function) o Synarthrosis (immovable joint)  Sutures (joints found only in the skull)  Bones are interlocked together – sutural ligament, type of unossified connective tissue  Gomphosis (joint between teeth and jaw bones)  Periodontal ligaments of the teeth - fibrous  Synchondrosis (joint within epiphysis of bone)  Binds the diaphysis to the epiphysis (syn – together, chondro – cartilage)  Synostosis (joint between two fused bones)  Fusion of the three coxal bones – no boundary between fusion, totally rigid o Amphiarthroses (slightly movable joints)  Syndesmosis (ligaments that connect two bones but limit their motion)  Between the radius and ulna, between the tibia and fibula (desmos – band, ie. band of ligament)  Symphysis (bones are separated by a wedge or pad of cartilage)  Between the pubic bones of the two coxal bones and intervertebral discs – fibrous o Diarthroses (freely movable joints)  Also called synovial joints  Typically found at the ends of long bones  Examples of diarthroses joints: shoulder joint, elbow joint, hip joint, knee joint  Synovial joints : Three main functions: 1. provide lubrication 2. nourish the chondrocytes 3.shock absorption  All synovial joints have six basic characteristics: o A joint capsule © 2012 Pearson Education, Inc. 2 o The presence of articular cartilages o A joint cavity with synovial fluid – lubricates the surfaces of the articular cartilages and reduces friction, nourishes the chondrocytes by entering and exiting the articular cartilage due to forces acting on the joint and acts as a shock absorber o A synovial membrane o Accessory structures (cartilage, ligaments, tendons, bursae sacs – small fluid filled pockets found where ligaments and tendons rub against other tissues to reduce friction) o Sensory nerves and blood vessels Structural Classification of Synovial Joints  Plane joints (gliding joints) monaxial – movement in only one plane o Eg. Carpal/carpal – Tarsal/tarsal – Vertebrae/vertebrae – Clavicle/sternum  Hinge joints o Flexion and extension - monaxial o Eg. Elbow and knee  Pivot joints o Rotational movements including supination and pronation - monaxial o Eg. Atlas/axis  Condylar joints (ellipsoidal joints) o Oval articular surface on one bone articulates with a depression on another bone, biaxial joint, movement in two planes o Eg. Radius/capitulum – Radius/carpals – Phalanges/metacarpals – Phalanges/metatarsals  Saddle joints o Biaxial joints that allow some circumduction, angular movement without rotation o Eg. Pollex/metacarpal  Ball and socket joints o Triaxial joints, angular movement and rotation o Eg. Shoulder joint – Hip joint Introduction • The skeletal muscle of the body can be subdivided into: • Axial musculature o Muscles that position the head and vertebral column o Muscles that move the rib cage • Appendicular musculature o Muscles that stabilize or move the appendicular skeleton The Axial Musculature • The axial muscles can be placed into four groups based on location or function o Muscles of the head and neck o Muscles of the vertebral column o Oblique and rectus muscles o Muscles of the pelvic floor © 2012 Pearson Education, Inc. 3 • Muscles of the Head and Neck o Can be subdivided into several different groups  Muscles of facial expression (mouth, eye, nose, scalp, neck)  Extraocular muscles (muscles that control eye movement)  Muscles of mastication (chewing)  Masseter – elevates mandible and closes jaws, assists in protracting and retracting mandible and moving mandible from side to side (origin – zygomatic arch of zygomatic bone; insertion – mandible)  Temporalis – elevates mandible and closes jaws, assists in retracting and moving mandible from side to side (origin – along temporal ljnes of skull; insertion – mandible)  Medial Pterygoid – elevates the mandible and closes the jawa, or moves the mandible side to side (origin – palatine bone, maxilla; insertion – mandible)  Lateral Pterygoid – opens jaws, protrudes mandible, or moves mandible side to side (origin – palatine bone, maxilla; insertion – mandible)  Muscles of the tongue  Muscles of the pharynx (pharyngeal constrictors, laryngeal elevators, palatal muscles)  Muscles of the anterior neck • Digastric – depresses mandible, opening mouth, and/or elevates larynx (origin – mandible and temporal bone; insertion – hyoid bone)  Sternocleidomastoid –together they flex the neck, alone one side bends neck toward shoulder and turns face to the opposite side, sterno = sternum, cleido = clavical, mastoid = mastoid process of temporal bone (origin – sternum and clavical; insertion – mastoid process of temporal bone)  Sternohyoid – depresses hyoid bone and larynx (origin – sternum; insertion – hyoid bone)  Sternothyroid – depresses hyoid bone and larynx (origin – sternum; insertion – thyroid cartilage of larynx)  Thyrohyoid – elevates larynx depresses hyoid bone (origin – thyroid cartilage; insertion – hyoid bone)  Stylohyoid – elevates larynx stylos = pillar or any slender pointed process also found on radius and ulna (origin – styloid process of temporal bone; insertion – hyoid bone) • Muscles of the Vertebral Column o Back muscles form three distinct layers  Superficial layer (extrinsic back muscles): move the neck  Trapezius – extends neck (will come back to more actions for
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