BIOLOGY 453 - COMPARATIVE VERT. ANATOMY WEEK 6, LAB 9 – Shark Muscles

Assignments

Readings Kardong & Zalisko: Chapter 6:88-98 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 won’t be chopped up. Coloring! Color these black-white drawings in Kardong & Zalisko: Fig. 6.6 pg. 93, Fig. 6. 9 pg. 96-97 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

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 tissues associated with muscles: fascia, raphe & myosepta. 3. Know the terms for muscle actions below: e.g. flexion, extension, abduction, etc. 4. Learn 1 origin & 1 insertion point for each muscle. 5. Learn at least 1 action for each muscle from the summary table. 6. Know the evolutionary origin of each muscle in the homologies table:

a. Epaxial & Hypaxial. b. Appendicular: dorsal or ventral & pectoral or pelvic. c. Hypobranchial. d. Branchiomeric arch 1, branchiomeric arch 2, or branchiomeric arches 3-7.

Additional Information MUSCLE ACTION & TERMINOLOGY Heithaus, P. 1999. Muscle Function. Cat Anatomy Tutorial. Dept. of Biology, Kenyon College.

http://biology.kenyon.edu/heithausp/cat-tutorial/function/function.htm Dauzvardis, MF. et. al. 1996-1998 (updated 2012). Master Muscle List. Loyola Univ. Med. Educ. Network (LUMEN)

http://www.meddean.luc.edu/lumen/MedEd/GrossAnatomy/dissector/mml/index.htm Univ. of Michigan. Learning Center. 1994. Hypermuscle: Muscles in Action. (Short film clips).

http://www.med.umich.edu/lrc/Hypermuscle/Hyper.html Univ. of Minnesota. 2011. Veterinary Anatomy Actions (with animations) Veterinary Anatomy, College Vet. Medicine.

http://vanat.cvm.umn.edu/anatDirections/Actions.html

SHARK MUSCLES Flashcard Exchange. 2009. Dogfish Muscles.

http://www.flashcardexchange.com/cards/dogfish-muscles-765345 Martin, RA. 2010. Feeding: White Shark Bite Kinematics. Biol. of Sharks & Rays. ReefQuest Centre for Shark Research.

http://www.elasmo-research.org/education/white_shark/bite.htm Martin, RA 2010. Anatomy: Swimming Muscles & Kinetic Jaws. Biol of Sharks & Rays. ReefQuest Centre for Shark Research.

http://www.elasmo-research.org/education/white_shark/muscles_jaw.htm Western Kentucky University. 1999. Shark Musculature. Digital Anatomy Online.

http://bioweb.wku.edu/faculty/ferrell/Digital/shark/muscles.html

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. Some muscles have several origins (called "heads"), which may be on more than 1 bone. Multiple insertions occur on the fingers or toes. 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, sheet-like 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

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.

Learn which cat & shark muscles fall into the same evolutionary “groups”.

Muscle Evol. Origin Chondrichthyes: Shark Muscles Mammalia: Cat Muscles Branchiomeric: 1st Arch Adductor mandibulae

Levator palatoquadrati Spiracularis Intermandibularis

Masseter Temporalis Anterior digastric Mylohyoid

Branchiomeric: 2nd Arch Levator hyomandibulae Interhyoideus

none examined in lab

Branchiomeric: 3rd - 7th Arches

Cucullaris [cucull = hood] Dorsal & ventral constrictors

Clavotrapezius Acromiotrapezius Spinotrapezius Sternomastoid

Hypobranchial Coracomandibularis Coracohyoid(eus) Coracoarcuals Coracobranchials

Geniohyoid Sternohyoid

Axial: Epaxial Dorsal longitudinal bundles; myomeres Multifidus spinae Longissimus dorsi

Axial: Hypaxial Lateral longitudinal bundles; myomeres Ventral longitudinal bundles; myomeres

Serratus ventralis & Rhomboideus External oblique & Rectus abdominus

Appendicular: Pectoral, dorsal

Pectoral extensors (abductors) Latissimus dorsi & Teres major Acromiodeltoid & Spinodeltoid

Appendicular: Pectoral, ventral

Pectoral flexors (adductors) Pectoralis major & Pectoralis minor Supraspinatus & Infraspinatus

Appendicular: Pelvic, dorsal

Pelvic extensors (abductors) Gluteus maximus & Gluteus medius Sartorius & Vastus lateralis

Appendicular: Pelvic, ventral

Pelvic flexors (adductors) Biceps femoris & Gracilis Adductor femoris & Semimembranosus

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.

DISSECTION ADVICE TECHNIQUE! As you make the first incision, pull up on the free edge of the skin with a pair of forceps. Go 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. Shark skin is thin, it is easy to cut through the ventral body wall, so be careful. 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.

Lateral View

Ventral View

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 Body Region Relative location in that Region Origin & Insertion Actions Hypaxial myomeres: ventral longitudinal bundles

trunk, caudal mid-ventral o: myosepta i: post. myosepta

lateral undulation, support viscera

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 Region

Relative location in that Region

Origin & Insertion Actions

Pectoral extensors

pectoral fin dorsal, superficial o: scapular portion of scapulocoracoid i: dorsal side of pterygiophores

extend or abduct pectoral fin

Pectoral Extensor

Pectoral Flexor

Pectoral flexors

pectoral fin ventral, superficial o: coracoid portion of scapulocoracoid i: ventral side of pterygiophores

flex or adduct pectoral fin

Pelvic extensors

pelvic fin dorsal, superficial o: trunk myomere, ischiopubic bar i: dorsal side of pterygiophores

extend or abduct pelvic fin

Pelvic Extensor

Pelvic Flexor (deep to siphon on male shark)

Pelvic flexors

pelvic fin ventral superficial o: ischiopubic bar i: ventral side of pterygiophores

flex or adduct pelvic fin

Superficial, Anterior Superficial, Posterior

mid-ventral raphe myosepta

scapular process

siphon

clasper

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 Body Region

Relative location in that Region Origin & Insertion Actions

Ventral constrictors (vc)

branchial lateral, superficial, below gill slits o: ventral gill raphe i: next ventral raphe

compress gills

Coracoarcuals (ca)

chest superficial; paired; posterior to intermandibularis

o - coracoid of scapulocoracoid i - coracohyoid ms.

depress Meckel’s cart., expand oral cavity

Intermandibularis (im)

throat superficial; transverse across lower jaws

o: Meckel’s cart. i: mid-ventral raphe

elevate floor of mouth, compress oral cavity

Superficial, Anterior

Superficial, Anterior

Interhyoideus (ih)

throat deep to intermandibularis o: hyoid arch i: midventral raphe

compress gills

Coracomandibularis (cm)

throat deep to interhyoideus, anterior to coracoarcuals,

o: coracoarcuals i: Meckel's cart.

depress Meckel's cart. (open mouth)

Coracohyoideus (ch)

hyoid paired; deep to coracomandibularis

o: coracoarcual ms. i: hyoid arch

depress Meckel's cart.; depress hyoid

Deep

Deep

vc ca ca vc

im

im

cm

cm ch ch

im ih

ih

im

ch

ch

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

Origin & Insertion Actions

Adductor mandibulae (am)

head lateral, superficial o: palatoquadrate i: Meckel's cart.

elevate Meckel's cartilage (close jaws)

Levator hyomandibulae (lh)

head lateral, superficial o: otic capsule i: hyomandibular

compress gills, rotate hyomandibular cartilage forward as jaws open

Levator palatoquadrati (lp)

head lateral, deep to fascia, anterior to spiracularis

o: otic capsule i: palatoquadrate

elevate palatoquadrate

Spiracularis (sp)

head lateral, deep to fascia, just in front of spiracle

o: otic capsule i: palatoquadrate

elevate palatoquadrate

Cucullaris (cc)

branchial lateral, superficial o: epaxial fascia i: scapular process on scapulocoracoid

elevate scapulocoracoid

Dorsal constrictors (dc)

branchial lateral, superficial, above gills o: dorsal gill slit raphe i: post., dorsal gill raphe

compress gills

Lateral view

Lateral view

Step 5: Dorsal to the gills

lh lh

am am

lp lp sp sp

cc

dc dc dc

epaxial epaxial

cc

dc dc dc

dc

dc

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

Origin & Insertion Actions

Epaxial myomeres: dorsal longitudinal bundle

trunk, tail lateral & then to dorsal midline, above lateral line

o: myosepta i: post. myosepta

lateral undulation; white fibers

Hypaxial myomeres: lateral longitudinal bundle

trunk, tail below epaxial myomeres & below lateral line

o: myosepta i: post. myosepta

lateral undulation; red fibers

Lateral view, past pectoral fin

Dark regions show red muscle distribution

Transverse section through tail

epaxial

hypaxial

red fibers

hypaxial lateral longitudinal bundle

epaxial