Lecture 2 Muscular System F24 (1) PDF

Skeletal Muscles Basics and Specifics SUNYmusc Canine muscle - origins, insertions, actions and nerve innervation  What are we going to learn? Lecture Lab...

Skeletal Muscles Basics and Specifics SUNYmusc Canine muscle - origins, insertions, actions and nerve innervation  What are we going to learn? Lecture Lab List the 3 types of muscles and describe the characteristics of Microscopic appearance of different types of muscle cells each. Location on body and actions of important muscles (muscles Describe the microscopic anatomy of skeletal, smooth, and of the head and neck, abdomen, thoracic limb, pelvic limb, cardiac muscle cells. and the muscles of respiration) List the components of a neuromuscular junction and IM (intramuscular) injection sites describe the function of each. Describe the events that occur in muscle cells during muscle contraction and relaxation. Lecture 1 Describe the events that occur in muscle cells during muscle contraction and relaxation. Describe the structure and function of tendons and aponeuroses Describe the structure and function of bursae and tendon sheaths Define muscle origin and insertion using the gastrocnemius muscle and common calcanean tendon as examples. Differentiate between prime mover, antagonist, syngergist, and fixator muscles. Describe cutaneous/twitch muscles – specifically the cutaneous trunci muscle. Locate and know the function of the muscles of mastication. Lecture 2 Locate and know the function of the muscles of the abdominal wall and different ways surgeons enter the abdomen. Locate and know the function of the muscles of respiration. What are we going to learn? Bursas and tendon sheaths Cutaneous muscles Muscles of mastication Muscles of the abdominal wall Muscles of breathing/respiration Need to know muscle lists Review from last lecture (was a long time ago!) 1 2 3 8 4 7 5 6 Skeletal muscle – gross anatomy Tendon Aponeurosis (pl. is aponeuroses) Connects ___ to ___ Connects muscle to muscle Made out of ____________ Muscle to bone connective tissue Sheet not band Continuation of epimysium a tendon for flat muscles Both made of _______ _______ connective tissue Most famous aponeurosis: linea alba (the white line) Rectus abdominus m. Make incision here External abdominal oblique m. Internal abdominal oblique m. Transverse abdominal m. Muscles on left and right of midline joined by sheet of fibrous tissue – the linea alba! Muscles on the ventral abdomen of a dog Another view of the aponeuroses of the abdominal wall Outside the body Inside the abdomen Dog Spay Surgery | Canine Ovariohysterectomy Detailed Walkthrough 3:15 – 3:53 and 8:00 – 9:00 to see linea alba Linea Alba Make your incision here to enter the abdomen – why? Pros – 3 Cons – 2 Cows? Protecting tendons – the bursa (plural= bursae) Bursa (latin for purse/bag) Which bone is marked A? A https://youtu.be/Y-JTzpaIgys So much tension on the tendons – bursae help protect them from the underlying bone  Bicipital bursa and tendon on larger dogs – inflammation here is a common cause of lameness in performance dogs. (Bicipitial bursa under the blue circle) Protecting tendons - Tendon Sheaths Take home message – sheath with underlying synovial fluid surrounds tendon.  Skeletal muscle attachment sites Origin Doesn’t move much Usually proximal Insertion This site moves when the muscle contracts NOTE – 5 muscles actually insert on the calcaneus as the common calcanean tendon (aka Achilles tendon) 1) gastrocnemius m. 2) SDF 3) gracilis (part of the quadriceps m.) 4) biceps femoris m. 5) semitendinosius m. Action Common calcanean tendon (aka Achilles tendon) rupture – what would happen to the hock? Skeletal muscle groups – muscles can take on any of these 4 roles depending on the movement desired Agonist Antagonist Synergist fixator Skeletal muscle groups Agonist Antagonist Main mover Does the opposite movement from the agonist Stabilizes joint Creates smoother movement Skeletal muscle groups Synergist Contracts at same time as agonist to help with the action SDF, DDF  SDF and DDF are synergistic muscles (Note: flexors are on the caudal aspect, extensors are on the cranial aspect of the forelimb)  Skeletal muscle groups Fixator Keeps joint from moving while joints nearby are bending or flexing Radial carpal extensor m. works to stop carpus from flexing when DDF flexing digits Kneading cat – note straight carpi, flexed digits Cutaneous muscles Twitch muscles Move as a reflex to touch In CT below skin Unique to non-humans Not attached to bone Panniculus Warning – dissection video below Cutaneous trunci and platysma m. on the dog - start 1:00 carnosus Cutaneous Platysma Panniculus reflex horse trunci m. m.  Chewing muscles in action - Muscles of mastication relaxation video Temporalis m. (A) Masseter m. (B) Digastricus m. (C) Both A and B bring up the mandible for chewing C opens the mouth Masseter can move the mandible side to side Watch for digesta coming up from the rumen into mouth to be re-chewed (at 1:18)! Muscles of the abdominal wall OUT External abdominal oblique m. Internal abdominal oblique m. Transversus abdominis m. Rectus abdominis m. IN Job of these muscles: flex vertebral column, respiration, support/protect and create Flank spay feline 0 – 2:53 abdominal pressure – i.e. ?? dissecting through the Cody Creelman, Cow Vet blogger - C-section muscle layers – not cutting Start at 8:00 Canine flank feline – note minimal bleeding https://www.youtube.com/watch?v=oaIlDQQuaAY 9 minute video of a dissection of a dog showing the abdominal muscles External abd. obl. m. Internal abd. obl. m. Transverse abd. m. Rectus abdominis m. Muscles of breathing/respiration Inspiration: Expiration: Diaphragm contracts to flatten Internal intercostal muscles External intercostal muscles (pull Abdominal muscles (if needed) ribs out and back) Intercostal muscles How ribs move during breathing red lines = external intercostal m blue lines = internal intercostal m Extrinsic muscles of thoracic limb Attach limb to body Origins – neck or thorax Insert – shoulder or forelimb 8 in domestic mammals  Extrinsic muscles of thoracic limb Trapezius Brachiocephalic m. Omotransversarius m. Latissimus dorsi Superficial pectoral m. (2 parts) Deep pectoral m. Serratis ventralis Rhomboideus (deep to trapezius) Need to know in red Pectoral muscles – origin: ??, insertion – greater/lesser tubercle of humerus action: ?? Minor = deep (3) Major = superficial (2)  Ventral aspect of a cat → Muscles to know: head and neck Masseter m. Temporalis m. Digastricus m. Splenius m. – extend neck, raise head Serratus ventralis (ventral serratus) Trapezius m. - extend neck, raise head Brachiocephalic(us) m. - flexes neck if forelimb fixed, pulls front limb forward Sternocephalic(us) m. – flex neck, lower head Muscles to know: thoracic limb Latissimus dorsi m. – spine to humerus – flexes shoulder pectoral m. (don’t worry about superficial and deep) – sternum to humerus – a?ductor Triceps brachii m. Carpal and digital extensors – as a group where found (cranial aspect of lower forelimb) Carpal and digital flexors – as a group where found (caudal aspect of lower forelimb) Muscles to know: abdominal muscles External abdominal oblique m. Internal abdominal oblique m. Transversus abdominis m. Rectus abdominis m. Muscles to know: pelvic limb Gluteal mm. – hip extensors Hamstring group – biceps femoris, semimembranosus, semitendinosus - hip extensors Quadriceps femoris (its tendon becomes the patellar tendon) – stifle extensor Gastrocnemius m. – distal femur to calcaneus (Slide 6) – its tendon is part of the common calcanean tendon Extensors of tarsus and flexors of digits (caudal aspect of lower limb) Flexors of tarsus and extensors of digits (cranial aspect of lower limb) Muscles to know: muscles of respiration Diaphragm External intercostal m. Internal intercostal m. Muscles to know: cutaneous muscles Cutaneous trunci m. Muscles to know: injection sites Back muscles for IM injections in dogs/cats – epaxial muscles, aka paralumbar muscles Triceps m Pectoral m Hamstrings (know each one) Triangle on horse’s neck (3) Gluteal m To be Discussed in this week’s lab