BIOLOGY COMPARATIVE VERT. ANATOMY WEEK 6, Shark Muscles

Transcription

1 BIOLOGY COMPARATIVE VERT. ANATOMY WEEK 6, Shark Muscles Assignments Readings Kardong & Zalisko: Chapter 6:88-98 Tuesday Intro Read pg prior to coming to lab. In particular be aware of the advice on dissections. Read pages 2-3 of these Discussion notes too. The TAs will lead a discussion of muscle terminology as well as muscle actions. Work Work in teams to follow the dissection guidelines below. Compare your specimen with other teams; every animal can look a bit different. Change blades often. Be careful so that your shark s muscles are visible & not chopped up. Tuesday Each member of a team will present the evolutionary origin, the muscle s positional origin, insertion & action of some of Participation their dissected shark s muscles to a neighboring team. Complete the coloring of the 2 figures listed below. Coloring! Color these black-white drawings in Kardong & Zalisko: Fig. 6.6 pg. 93, Fig pg using these color codes: Epaxial lt brown; Hypaxial dark brown; Dorsal Appendicular lt red/pink; Ventral Appendicular dark red; Branchiomeric arch 1 green; Branchiomeric arch 2 purple, Branchiomeric arch 3-7 orange; Hypobranchial blue. Quiz Yourself Test your knowledge using the unlabeled images in the lab notes & the unlabeled diagrams in the Student Art Section that follows the Index: Fig. 6.6, & 6.9 Quiz 5 Will be at the end of the lab on Thursday. Quiz topics will be announced in lab on Tuesday. Learning Goals 1. Identify the red (aerobic) fibers in the shark by making a new cut through the tail region. 2. Identify these special connective tissue terms associated with muscles: fascia, raphe & myosepta. 3. Understand & be able to use the terms for muscle actions described below: e.g. flexion, extension, abduction, etc. 4. Learn 1 origin & 1 insertion point for each shark muscle in the evolutionary origins table. 5. Learn at least 1 action for each shark muscle in the evolutionary origins table. 6. Know the evolutionary origin of each shark muscle in the evolutionary origins table & name a cat muscle with the same origin: a. Epaxial & Hypaxial b. Appendicular: dorsal or ventral groups on both the pectoral & pelvic fins. c. Hypobranchial d. Branchiomeric arch 1, Branchiomeric arch 2 & Branchiomeric Arch 3-7 e. Hypomere Mesoderm Additional Information MUSCLE ACTION & TERMINOLOGY Heithaus P Muscle Function. Cat Anatomy Tutorial. Dept. of Biology, Kenyon College. Univ. of Michigan. Learning Center Hypermuscle: Muscles in Action. (Short film clips). Univ. of Minnesota Veterinary Anatomy Actions (with animations) Veterinary Anatomy, College Vet. Medicine. SHARK MUSCLES Flashcard Exchange Dogfish Muscles. Martin RA Feeding: White Shark Bite Kinematics. Biol. of Sharks & Rays. ReefQuest Centre for Shark Research. Martin RA Anatomy: Swimming Muscles & Kinetic Jaws. Biol of Sharks & Rays. ReefQuest Centre for Shark Research. Lorenzo A Shark Muscular System. Quizlet.com SUNY Orange The Muscular System, Comparative Anatomy, Online Biology Library, Orange County Com. Coll.

2 General Concepts Muscle Attachments: Typically, a muscle is attached to two different bones. For a given body movement, one bone (origin) is fixed in some way, the other (insertion) moves as a result of muscle contraction. The origin is often the proximal bone and the insertion the distal bone. There are many exceptions. Connective Tissues: Typically muscles attach to bones via a slender, cord-like unit of dense, regularly arranged connective tissue called a tendon [tend = stretch]. Some muscles attach to other muscles directly on broad insertion points. Sheets of connective tissues that surround a muscle are called fascia [= bundle]. An aponeurosis [apo = from, neuro = sinew, cord] is a broad thin, sheetlike tendon that attaches a muscle onto a bone. Two mirror-image muscles, on either side of the mid-dorsal or midventral line may attach to each other along a long, thin line of connective tissue, called a raphe. Thus, a raphe is a long, seam-like tendon such as the linea alba. In fishes, axial muscles are divided by myosepta. A horizontal septum divides the epaxial & hypaxial muscles of the shark. In addition, most of these terms are defined in your lab manual pg. 87. Muscle Actions: Depending on the orientation and attachment of their fibers, muscles may act in one or several directions. Long muscles are usually kinetic (able to produce highly visible external motion). Short, deep muscles tend to be responsible for precise, small-scale adjustments rather than gross movements. When we speak of a particular movement, the muscle that produces it is called an agonist. A muscle that produces the opposite movement is called an antagonist. Mutually opposing muscles often function together to fix or stabilize a bone. Different muscles that cooperate to produce the same action are called synergetic. Muscle Physiology: Red muscle fibers are aerobic which means they have long endurance. Red fibers have a higher myoglobin content that gives them a red color (myoglobin stores oxygen). Red fibers have a richer blood supply & more mitochondria in their cells. Vertebrates use red muscle for locomotion at low to moderate speeds or for endurance activities. This tissue forms thin sheets on the outermost edges of the trunk & tail in most fishes. White muscle fibers are anaerobic and are used for short bursts of speed or power. White muscle fibers are usually larger in diameter than red fibers & thus are stronger. However, they produce most of their force anaerobically causing a build-up of lactic acid. High levels of lactic acid can induce muscle fatigue, thus the short-term effectiveness of white fibers. In typical fishes, white fibers make up most of the body mass in the trunk & tail. Greek & Latin Roots Indicating Direction, Relative to Axes of Body dorsi - dorsal intrinsic - inside superficialis - superficial externus- superficial lateralis - lateral superioris - superior (dorsal) extrinsic - outside medialis - medial, middle transversus - transverse internus - deep, internal obliquus - oblique ventralis - ventral Greek & Latin Roots Indicating Specific Regions of the Body acromio - tip coraco - coracoid hyomandibulae - hyomandibular scapularis - scapula abdominis - abdomen femoris - femur ilio - ilium spino - spine capitus - head genio - chin mandibular - mandible sterno - sternum cervicis - neck gluteo - rump mastoid - breast shaped temporalis - temples cleido/clavo - clavicle hyoid/hyoideus - hyoid palatoquadrati - palatoquadrate cart. thoracis - thoracic region Greek & Latin Roots Indicating Shape, Size, or Color of Muscle deltoid - triangle longissimus - longest platys - flat serratus - serrated digastric - two "bellies" magnus/major - larger rectus - straight, parallel teres - long & round gracilis - short, slender maximus - largest rhomboideus - rhomboid trapezius - trapezoid latissimus - widest minimus - smallest semi - half, partly vastus - great Roots Describing Muscle Actions masseter - chewing mylo - mill, molar sartorius - " sits" like a tailor

3 Muscle Action Terminology Levator: elevate; lifts bone in vertical plane; move body part to a superior position. Depressor: lowers bone in vertical plane; move body part to an inferior position. Extension: to open, or unfold; increase angle of a joint to its normal anatomical position; or movement in a sagittal plane that takes part of the body backward from anatomical position. Hyperextension: increase the angle of a joint beyond its normal anatomical position. Flexion: to fold or decrease the angle between articulating bones or body regions; movement in a sagittal plane takes a limb forward from anatomical position. Lateral Flexion: for the trunk or neck, movement in the frontal plane away from the median also called side bending. Adduction: to pull toward the midline, a movement in a frontal plane that takes a part of the body towards the midline. Abduction: to pull away from midline, movement in a frontal plane that takes a part of the body away from midline. Lateral Rotation: a movement in a transverse plane that takes a part of the body outward; or lateral (outward) movement on a limb's long axis. Medial Rotation: movement in a transverse plane that takes a part of the body inward; or medial (inward) movement on a limb's long axis Pronate: turn the ventral side down, e.g. forearm - palm of the hand faces backward. Supinate: turn the ventral side up, e.g. forearm - palm faces forward. Constrict: close or contract a circular muscle. Dilate: open or relax a circular muscle. Protract: drag forward in the horizontal plane. Retract: drag back in the horizontal plane.

4 Muscle Homologies & Evolutionary Origins Cranial Muscles: Branchiomeric muscles formed as a series of repeated elements that controlled movement of the gills of jawless fishes. Some of the gill muscles moved with the jaws and the hyoid arch when these skeletal changes were made. With the loss of the gills in most tetrapods, many muscles were lost, but some took on new functions in the throat and laryngeal region, and even as an appendicular muscle. Hypobranchial muscles evolved as a series of long muscles that ran anterior-posterior from the jaws to the pectoral girdle. Their primary functions are opening the mouth or expansion of the gill chamber. In mammals, these muscles are reduced in size, but still run anterior-posterior from the pectoral girdle forward to the larynx, hyoid or chin. Trunk Muscles: Epaxial muscles in a shark are large and show their original metameric design. The muscles are held together with tough sheets of connective tissues (myosepta). The myosepta divide the muscle segments (myomeres) that are major locomotory structures (for lateral undulation.) In mammals, these muscles are greatly reduced and highly modified. Most epaxial muscles extend across many vertebrae and aid support & extension of the back. These muscles attach to neural spines and transverse processes on the vertebrae. They are most readily seen in the lumbar region. They are present in the neck and thoracic area as well, but are often covered by pectoral muscles. The hypaxial muscles run below the horizontal septum. They are also important for lateral undulation, but show a less complex arrangement & form thinner sheets in the trunk to support the viscera. Mammals have reduced these muscles to several very thin sheets in the abdominal region. These muscles aid flexion of the trunk, and support the viscera. They are still relatively strong because the sheets run in different directions (i.e. plywood effect). In the thoracic region these muscles are deep to the pectoral musculature, and are often divided into small units by the ribs. Appendicular Muscles: In a shark, extrinsic muscles form two thin, flat sheets that extend out onto the pterygiophores. The dorsal sheet allows abduction or extension of the fin and the ventral sheet allows adduction or flexion of the fin. Mammals have a large amount of intrinsic and extrinsic musculature associated with the limbs. The mammalian pectoral muscles are primarily associated with the scapula. Muscles literally hold the pectoral girdle in suspension in a cat because the clavicle is reduced to a fragment. A few muscles that now located on the pectoral girdle may have originated from branchiomeric or hypaxial muscle sources that from a ventral to a more dorsal position. Drawings by Rachel Simon. She is a former biology undergraduate & then peer TA for this class, as well as an outstanding artist. Her color codes may not match what I asked you to use, but enjoy her diagrams.

5 Learn which cat & shark muscles have the same evolutionary origins. These muscles are not always listed with a one to one match in the two columns. You are only required to know the broader relationships. Know which muscles have the same evolutionary origin, not the homologies between individual muscles. Muscle Evol. Origin Chondrichthyes: Shark Muscles Mammalia: Cat Muscles Branchiomeric: 1 st Arch Adductor mandibulae Levator palatoquadrati Spiracularis Intermandibularis Masseter Temporalis Anterior digastric Mylohyoid Branchiomeric: 2 nd Arch Branchiomeric: 3 rd - 7 th Arches Levator hyomandibulae Interhyoideus Dorsal & ventral constrictors none examined in lab Hypomere (Lateral Plate Mesoderm) Hypobranchial Cucullaris [cucull = hood] Coracomandibularis Coracohyoid(eus) Coracoarcuals Clavotrapezius Acromiotrapezius Spinotrapezius Sternomastoid Geniohyoid Sternohyoid Axial: Epaxial Dorsal longitudinal bundles; myomeres Multifidus spinae Longissimus dorsi Axial: Hypaxial Appendicular: Pectoral, dorsal Appendicular: Pectoral, ventral Appendicular: Pelvic, dorsal Appendicular: Pelvic, ventral Lateral longitudinal bundles; myomeres Ventral longitudinal bundles; myomeres Pectoral extensors (abductors) Pectoral flexors (adductors) Pelvic extensors (abductors) Pelvic flexors (adductors) Serratus ventralis & Rhomboideus External oblique & Rectus abdominus Latissimus dorsi & Teres major Acromiodeltoid & Spinodeltoid Pectoralis major & Pectoralis minor Supraspinatus & Infraspinatus Gluteus maximus & Gluteus medius Sartorius & Vastus lateralis Biceps femoris & Gracilis Adductor femoris & Semimembranosus

6 HANDLING OF SHARPS/SCALPEL BLADES & TOOLS Use a hemostat to hold a scalpel blade when you put on or remove a blade from a handle. Watch one of the TAs demonstrate this before you attempt it. Keep the end of the blade facing down, not towards someone across from you when attaching or removing a blade. Used blades should be disposed of immediately into a red sharps container. Again, pick it up with a hemostat, not hands! If your gloves get slippery, wipe them off with paper towels while working to avoid slipping & cutting yourself or someone else. Be particularly careful when someone else is working on the same specimen! DISSECTION ADVICE As you make the first incision, pull up on the free edge of the skin with a pair of forceps. A shark s skin is very thin; it is easy to cut through the entire ventral body wall, so be careful. Go just deeply enough to see the yellowish muscle tissue clearly. If you are too shallow, you will only see the connective tissue of the dermis & the fascia that covers the muscles. Once you are at the right "depth" use the forceps to pull or peel the skin back from the muscle. Use a blunt probe to separate the skin from the muscle tissue if you can. If necessary, cut the white fascia while pulling tightly on the skin to lift the fascia off the muscle before you cut. In general, remove skin in the same direction as the pattern of the muscle fibers. You will be less likely to tear muscles. REVIEW: When you have completed your dissections, you should be able to label these images on your own. Anterior is to the left in both photos of dissected sharks. Lateral View Ventral View superficial muscles only on the left, diagram shows both deep & superficial muscles.

7 Step 1: Midventral, near posterior border of pectoral fins Begin on the ventral body wall, between the pectoral fins, this is usually easy to skin. As your skill improves, you will reach the more difficult parts of the body. Make a short, very thin, transverse incision in line with the posterior border of the pectoral girdles. Thin means a few mm only. Lift up the skin & then start a mid-sagittal incision so you have a corner of skin to pull on. Thus you can "peel" back the skin on the right & left sides of the ventral body wall in this region easily. You will be exposing the hypaxial myotomes that form the ventral longitudinal bundle, are in series down the abdomen. Muscle Hypaxial myomeres: ventral longitudinal bundles Body Region Relative location in that Region Origin & Insertion trunk, caudal mid-ventral o: myosepta i: post. myosepta Actions lateral undulation, support viscera Superficial, Anterior Superficial, Posterior mid-ventral raphe myosepta Step 2: Pectoral fin Cleaning the dorsal & ventral sides of 1 pectoral fin is relatively easy. We ll wait & do pelvic fins with the reproductive system. Just follow the orientation of the muscle fibers as you pull. Don t pull so hard that the pectoral muscles pull off of the body wall. Muscle Body Relative location Origin & Insertion Actions Region in that Region Pectoral pectoral fin dorsal, superficial o: scapular portion of scapulocoracoid extend or abduct pectoral fin extensors i: dorsal side of pterygiophores Pectoral Extensor Pectoral Flexor scapular process Pectoral flexors Pelvic extensors pectoral fin ventral, superficial o: coracoid portion of scapulocoracoid i: ventral side of pterygiophores pelvic fin dorsal, superficial o: trunk myomere, ischiopubic bar i: dorsal side of pterygiophores Pelvic Extensor Pelvic Flexor (deep to siphon on male shark) flex or adduct pectoral fin extend or abduct pelvic fin siphon clasper Pelvic flexors pelvic fin ventral superficial o: ischiopubic bar i: ventral side of pterygiophores flex or adduct pelvic fin

8 Step 3: Chest, gills & throat When you near the throat, you will find a pair of large, triangular shaped muscles called the coracoarcuals. Anterior to the coracoarcuals, the muscle fibers run transversely across the jaws from right to left, forming the intermandibularis. You will need to change directions & perhaps make a new incision to clean this muscle. You don't need to remove all of the skin that covers the gill slits. Just remove enough so you can ID the ventral superficial constrictors. We may have half of the class stop their dissection of the throat after these superficial muscles are exposed, because the intermandibularis must be cut to see the other muscles in this region. Get help from a TA before you start exposing the interhyoideus & other branchial muscles. The interhyoideus is another thin sheet just beneath the intermandibularis, but the two muscles are difficult to separate. The fibers of the interhyoideus run at slightly different angles to the intermandibularis. The mid-ventral raphe is continuous with a sheath of connective tissue that encloses the very thin, whitish coracomandibularis. The fibers of the coracomandibularis run anteriorly-posteriorly & it attaches to the middle of the coracoarcuals. This is the easiest muscle to miss or destroy because of this sheathing. Deep to the coracomandibularis lie the large, paired, coracohyoideus muscles. Muscle Ventral constrictors (vc) Coracoarcuals (ca) Intermandibularis (im) Body Region Relative location in that Region branchial lateral, superficial, below gill slits superficial; paired; posterior to intermandibularis chest throat superficial; transverse across lower jaws Superficial, Anterior Origin & Insertion Actions o: ventral gill raphe compress gills i: next ventral raphe o - coracoid of depress Meckel s cart., scapulocoracoid expand oral cavity i - coracohyoid ms. o: Meckel s cart. elevate floor of mouth, i: mid-ventral raphe compress oral cavity Superficial, Anterior im im ca Interhyoideus (ih) Coracomandibularis (cm) Coracohyoideus (ch) throat vc deep to intermandibularis throat deep to interhyoideus, anterior to coracoarcuals hyoid Paired, deep to coracomandibularis Deep vc ca o: hyoid arch i: midventral raphe o: coracoarcuals i: Meckel's cart. o: coracoarcual ms. i: hyoid arch compress gills depress Meckel's cart. (open mouth) depress Meckel's cart.; depress hyoid Deep im ih ch ch im cm ih cm ch

9 Step 4: Lateral side of jaw & head The adductor mandibulae is the largest of the muscles here. It cleans relatively easily, but it does have lots of connective tissue & nerves running over it. Try to get this region clean enough to see the muscle fibers. The levator hyomandibulae is dorsal to the adductor mandibular & forms a thin sheet along the side of the head. The other muscles can only be seen by shaving away part of the top of the neurocranium between the spiracle & the orbit. Do this gradually so that you don t cut the muscles. Both the spiracularis and the levator palatoquadrati are on the anterior to the spiracle. The spiracularis is smaller & posterior to the levator palatoquadrati. Look at the TA shark first to see where these muscles are located. Muscle Body Region Relative location in that Region Adductor mandibulae (am) Levator hyomandibulae (lh) head lateral, superficial head lateral, superficial sp lp Origin & Insertion o: palatoquadrate i: Meckel's cart. o: otic capsule i: hyomandibular lh Actions elevate Meckel's cartilage (close jaws) compress gills, rotate hyomandibular cartilage forward as jaws open lp sp am Levator palatoquadrati (lp) Spiracularis (sp) Cucullaris (cc) Dorsal constrictors (dc) head head Above gills branchial am lateral, deep to fascia, anterior to spiracularis lateral, deep to fascia, just in front of spiracle lateral, superficial lateral, superficial, above gills Lateral view o: otic capsule elevate palatoquadrate i: palatoquadrate o: otic capsule elevate palatoquadrate i: palatoquadrate o: epaxial fascia elevate scapulocoracoid i: scapular process on scapulocoracoid o: dorsal gill slit raphe compress gills i: post., dorsal gill raphe Lateral view epaxial cc epaxial cc dc dc dc dc dc lh dc dc dc

10 Step 5: Dorsal to the gills Put a new blade on your scalpel if you have not done so yet. The skin acts like sandpaper because of the small placoid scales & it quickly dulls your blades. The epaxial myomeres that form the dorsal longitudinal bundle are the most challenging to skin. The muscles have large tendons that attach to the skin & the muscle fibers change direction frequently. Work slowly & carefully. Pull the skin to lift the fascia & then cut the line between the muscle & the raised skin, cut into the white fascia. If you cut the muscle, you aren't pulling up enough on the skin or you are cutting too deep. If you don t remove enough of the fascia, you won t see the muscle fibers. If you run into trouble (cutting deep into muscle, you may need to change directions or start at a new point to get back on track. Be particularly careful of the cucullaris, a triangular muscle below the myomeres & just above the gills. The dorsal constrictors muscle fibers run between gill raphes. These are very thin sheets & tear easily, so don t try to expose these muscles down to the top of the gill slits. When you are posterior to the cucullaris, you will see the hypaxial myomeres that form the lateral longitudinal bundle. The lateral bundle is a narrow strip with fibers that run laterally along the body, simpler than the dorsal longitudinal bundle. The lateral longitudinal bundle is dark because it is composed of red muscle fibers. Muscle Body Region Relative location in that Region Epaxial myomeres: dorsal trunk, tail lateral & then to dorsal longitudinal bundle midline, above lateral line Hypaxial myomeres: trunk, tail below epaxial myomeres & lateral longitudinal bundle below lateral line Lateral view, past pectoral fin Origin & Insertion o: myosepta i: post. myosepta o: myosepta i: post. myosepta Actions lateral undulation; white fibers lateral undulation; red fibers epaxial Hypaxial lateral longitudinal bundle Dark regions show red muscle distribution Transverse section through tail epaxial red fibers hypaxial