Comparitive Anatomy Test 3

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Transcript of Comparitive Anatomy Test 3

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Test 3 Study Objectives

1. Describe the distinguishing characteristics of the structure of smooth muscle, striated muscle and cardiac muscle, and name the embryonic tissue layer from which muscle is derived. Muscle Type Defining CharacteristicsEmbryonic Layer from which muscle is derived

Smooth Muscle Looks different and occurs in different places Spindle shaped cells Single nucleus No banding patterns/striations Occur in thin sheets of muscle in walls of organ, blood vessels and tissues Makes up muscle that is under involuntary control Entirely conserved with visceral muscles- might be considered as a type of visceral muscle Can be influenced by hormones Electrically coupled- one muscle to anotherOf the GI tract: Splanchnic mesodermsurrounding the endoderm of theprimitive gut and its outgrowthsWalls of blood vessels+lymphatic channel:Somatic mesodermIris and Mammary glands:Ectoderm

Local mesenchyme

Striated Muscle Cylindrical cells Multiple nuclei in each striated cell Banding patterns/ striations present : product of arrangement of contractile elements in muscle tissue Makes up muscle that is under voluntary control Ex: Cardiac muscle

Splanchnic mesoderm

Cardiac Muscle Multinucleated, Nuclei are located centrally Cells are branched/ woven together Multinucleated, but the nucleus is centrally located No striation Makes up muscle that is under involuntary control Innate tendency to contract Specialized conduction system Intercalated disks: place where two cells meet, allows rapid transmission of signals from one cell to the next Only found in the heartSplanchnic mesoderm surrounding the early endocardial heart tube

2. Name and describe the types of muscles that are categorized as skeletal muscles and that are categorized as non-skeletal musclesMuscle TypeDefining CharacteristicsEmbryonic layer from which muscle is derived

Skeletal Muscle Skeletal Muscles Trunk and tail Associated with the vertebral column They are the Myotome of somite that grows ventrally during the development of the vertebrae They make a connection with the vertebrate and they are supplied by spinal nerves Metameric and form blocks (it gets less visible as we move up in time) Divides into hypaxial and epaxial muscles In tetrapods the muscles are much more developed From 3 layers External oblique Internal oblique Transverse septum Hypaxial muscles become more important for locomotion and the epaxial muscles are not that important and become less developed. Fish Trunk Muscles They are metameric and form visible blocks The myosepta becomes attached to the axial skeleton There is visible horizontal septum that divides into the epaxial and hypaxial muscles. Epaxial muscles are more developed because they are responsible for locomotion Tail musculature is important because it is the one that helps propel the fish. And it is derived to be strong Amphibians Epaxial muscles are still one muscle Hypaxial muscles become more derived and segmented You can see traces of the horiztontal septum Reptiles Horizaontal septum is lost Epaxial musculature is lost more Hypaxial muscle becomes more assoiciated with the body segment The epaxial muscle is divided into the dorsomedial, medial, and lateral Tetrapods You see development of obliques Highly developed hypaxial muscles No horizontal septum

Non-skeletal muscle Extrinsic eye muscles There are 6 extrinsic eye muscels Superior/inferior oblique Superior/inferior rectus Medial/lateral rectus Supplied by cranial nerves-not spinal nerves Derived from Myotome and part of somites Preotic somites give rise to the 6 muscles They are skeletal muscles that allow the eyeball to move Hypobranchial muscles and tongue muscles in tetrapods They are located ventral to the pharynx The from somite buds They form the floor of the pharynx (also gill arches) and they also surround the pericardial cavity They are associated with movement of jaw and gill slit Muscles in the tongue are derived from Hypobranchial muscles Innervated by spinal nerves Appendicular 2 types- extrinsic and intrinsic Involves the appendages and the paired fins and any muscles associated with any unpaired fins in fishes Extrinsic muscles are muscle that attach to the limb or girdle in the axial skeleton When they contract they move the limb entirely Intrinsic muscles occur completely within the limb or girdle and when they contact they only move part of the appendage relative to the other part of the appendage Example finger muscles Develop from blastemas from the hypaxial Appendicular muscles are not well developed in fish because there is no heavy movement of the fins In tetrapods appendicular muscles become much more important and they change drastically Limbs arise from blastemas that developed that appear within the limb bud that give rise to the intrinsic muscles Extrinsic muscle comes from blastemas migration in hypaxial myotems maintain connect with the skeleton Innervated by spinal nerves Fishess Not well developed because the fish used its axial musculature for locomotion, and they only supported the paired fin Tetrapods Two opposing muscles, dorsal and ventral Much more distinct muscles due to locomotion Birds Axial decreases and appendicular muscles increase They are bunched proximally due to flight and landing Wing muscles are more powered for flight Integumentary Muscles associated with the integument Some are extrinsic muscles because they are attached to the skeleton Striated Allows movement of skin Facial expression Pull lip back Temporal portion of skull Intrinsic muscles Entirely within the integument Occur in birds and mammals Moves the hair or feathers Branchiomeric muscles They are muscles associated with the pharyngeal arch Visceral muscles because they are derived from splanich mesoderm They are voluntary and striated Occur in pharyngeal arches Skeletal elements are associated with these Innervated by cranial nerves Function in jaw movement, gill movement, hyoid apparatus movement, facial muscles, neck and throat muscles, and larynx. Important feeding apparatus in fishes Helps with pumping of water Electric Organs They are capable of producing electric discharges in vertebrate Some are myotomic and some are Branchiomeric This suggest that this arose more than one time in evolution Produce low voltage Used for radar Navigation Signaling Able to do this by mormyomasts: receptor cells in the lateral system and ear that detect electric field changes around them Made of many stacks of thin muscle fibers The charge is on one face of the muscle

3. Name and describe the origin of muscles that are categorized as somatic muscles and those that are categorized as visceral muscles; describe the differences between somatic and visceral muscle

Somatic Muscle vs. Visceral Muscle

Somatic MuscleVisceral Muscle

- Origin made of bone- Insertion is the dermis- Derived from myotome somite in developing vertebrae- Muscles that control the activity of organs, vessels or ducts- Derived from splanchnic mesoderm

4. Describe the ontogeny of trunk muscle and the distinguishing features of the trunk musculature in fishes and tetrapods; identify the important trend inthe evolution of trunk musculature in vertebrates.


Myotome of the somite, it grows ventrally and we get this ventral growth and as development process we get development of the vertebrae in the midline and they go all the way down to the ventral part of the body and the meet each other and they make the linea alba and you get further development as this proceeds This Myotome make a connection with the vertebrate and they are supplied from nerves from the spinal nerve and its associated with the region with two associated vertebrate. They are metameric because they form blocks By the time we look at a fish, you can see the nature of the trunk muscles divided into the dorsal (epaxial) and ventral (hypaxial) muscles. Each segment represents a Myotome from a somite and they are skeletal muscles In anamiote you see the horizontal septa In tetrapods, muscles are much more developed and you dont see a horizontal septa, instead you see 3 layers of muscles called the external oblique, internal oblique, and transverse septum Evolution of trunk musculature in vertebrates

How the trunk and tail musculature has changed phylogenetically

In fish this muscles are particular critical for producing locomotion and these muscles are extremely well developed (divided to hypaxial, epaxial, and a sheet in between) because of the role they play in locomotion In tetrapods locomotion is associated with the muscles associated with the appendages and the hypaxial muscles tend not to be quite developed, the exception is the semi aquatic forms In amphibians and amniotes, hypaxial muscles tend to be divided into 3 distinct layers that we see in the cat External oblique Internal oblique Transverse muscles are in between. Support the abdomen against gravity Because they are secondarily adapted and highly derived for life in water, some of those characteristics are not well developed

One of the other aspects that we look at is the presence of a specialized structure called the diaphragm

The muscles in the diaphragm there is a basic connective tissue structure in rep and birds that dont have all of this muscle than in the mammal, the muscle comes from myomeres up in the neck region anterior to where we see the formation of diaphragm The muscles that provide the musculature of the diaphragm comes from myomeres from somite and the nerves that innervate the diagraph are spinal nerves So structures that are derived from myomeres are innervated with spinal nerves As we go from fish to tetrapods, the myomeres instead of retaining that clear segme