Lab3

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University Of Connecticut *

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2100

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Anatomy

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Apr 3, 2024

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P ATH 2100 202 3 PVS 2100 Lab 3 . Muscular System. You must be wearing a lab coat, gloves and eye protection when examining the wet specimens. INTRODUCTION The Latin root for muscle is “myo”. Muscles contract. Skeletal muscle contracts to move bones in relation to each other during locomotion and other coordinated movements, and contracts to support viscera and hold bones stable in place to counteract gravity. The diaphragm and intercostal muscles contract to expand the thoracic cavity, serving as a bellows to move air in and out of the lungs. Rapid repeated contractions— experienced as shivering—can produce heat to counteract hypothermia. Contraction of muscles across joints (i.e. bone articulations) affords motion to that joint if it is movable. Muscles have an origin and an insertion: generally, the proximal/medial end is the origin, and the distal/lateral end is the insertion. Muscles can be classified in different ways, but one common way is in describing the motion afforded a particular joint, set of joints, or limb. Many muscles affecting he appendicular skeleton are described by the effect they have on limb joint motion occurring in a sagittal plane – with flexion describing motion that decreases the angle of a joint, and extension increasing the angle. Thus, it is important to realize which angle of a joint decreases from full extension see joint schematic figure at end of this worksheet. For instance, the shoulder and hip of a quadruped flex in different directions: the shoulder flexes with the limb moving caudally and the hip flexes with the limb moving cranially. Useful is knowing major muscles what affect flexion and extension of joints in the limbs – you should have an idea of representative appendicular flexors and extensors after completing the pre-lab assignment. Important muscles affecting motion of the neck and trunk of animals including epaxials, hypaxials, and abdominals. Epaxial and hypaxial mm. are located respectively above and below the transverse processes of the vertebrae, and act to extend (epaxials) and flex (hypaxials) the vertebral column. Abdominal muscles are located in several layers around the abdominal cavity, with their fibers running in direction different between layers. From deepest to most superficial (and with fiber directions in parentheses) are the transversus abdominus m . (ventral), internal abdominal oblique m. (cranioventral), and external abdominal oblique m. (caudoventral). These sheets of muscles lead to fibrous sheets of aponeurosis that meet ventrally at the midsagittal line referred to as the linea

P ATH 2100 202 3 alba (white line). The rectus abdominus runs caudad from sternum to pubis within the fibrous medial aponeuroses of other abdominal muscles. OBJECTIVES: 1. Understand the motion concepts associated with joint flexors/extensors, abductors/adductors and antagonistic muscle pairs 2. Be able to name several sets of muscles affecting joints of the appendicular skeleton, and how they affect the motion of a given joint. 3. Identify the muscles of the pectoral girdle. 4. Know the musculature of the abdominal body wall 5. Identify tendons and synovial structures that protect muscles and tendons. 6. Recognize aponeurosis and its association with sheets of muscles. Prior to class – do or answer the following questions: Do and turn in the pre-lab assignment posted under / &RXUVH &RQWHQW / 3UH DQG 3RVW /DE 4XL]]HV Lab :Muscles/Flex-extend_labeling. On the worksheet entitled “Lab :Flex-extend_exercise.ppt”, use your class notes and textbook to fill in the appropriate labels in boxes and flexion angles at joints. Other than the rectus abdominus, what are the other 3 layers of abdominal muscle from superficial to deep, and what direction do the muscles orient? Superficial:__________________, direction= __________________ Middle:__________________, direction= __________________ Deep:__________________, direction= __________________ What do synovial bursa and sheaths provide to moving structures? ________________________________________________________ What is an annular ligament? ________________________________ Consider the semitendinosus muscle (slides 69 and 71 in class notes): D How does it act on the stifle joint?_______________________ E On what bone is its origin? _______________________ F On what bone is its insertion?_______________________ G What is a muscle that antagonizes its action on the stifle? __________________________

P ATH 2100 202 3 In-person (or using online images) –answer the following questions: STATION 1. Vertebral columns a. At what label would you expect to find epaxial muscles? A ____ b. When epaxial muscles contract, would the spine curve up at the cranial/caudal ends, or curve down a the cranial/caudal ends _____ UP _ (extensors of the vertebral column) _________ c. What set of muscles provide an antagonistic set of muscles to epaxials__ Hypaxials (flexors of the vertebral column) ____. STATION 2. Cow model, deep half. Match the following with labels on the model. If the structure is not labeled on the model, type in ‘no label’ Epaxial muscles ____ No _____ Hypaxial muscles ___ 3 _______ Transversus abdominus muscle ____ 1 _____ Rectus abdominus muscle ___ 2 _______ Internal intercostal muscle____ 4 _______ STATION 3. Abdominal body wall model Using the stripes to indicate the direction of fibers in the four layers of abdominal muscle, assemble the 4 panels to recreate the layers of the right side of the abdominal body wall, being able to identify the cranial, caudal, dorsal, and ventral borders (ventral border is the central midline, marked with an ‘M’). From the intro above, what is the connective tissue structure located at the central midline where abdominal muscles attach? _______ Linea alba _________________________ Excluding the rectus abdominis, list the abdominal muscles layered here from superficial to deep 1. ___ B EXTERNAL OLBIQUE _ __ 2. ___ D INTERNAL OBLIQUE ____3. C _ TRANSVERSE __________

P ATH 2100 202 3 STATION 4. Cow model, superficial half. From background above and figures at the end of the worksheet (extrinsic muscle and abdominal muscles), match pins from specimens with structures below: external oblique abdominal muscle_____ 54 ___ aponeurosis__ A _ _________ Extrinsic muscles of forelimb (see figure at end of worksheet for reference): Brachiocephalicus (skull+cervical vertebrae to humerus, found as ‘a’+‘b’)_ 46 Latissimus dorsi (dorsal midline to humerus)__ 51 _ _____ Trapezius (midline to lateral scapula)__ 45 _______ Serratus ventralis (saw-like muscle, body wall to medial scapula)_ 52 ______ Pectoral muscles (sternum to medial humerus)__ 50 _____ FOR STATIONS 5 – 7, Using the supplied ribbons to represent muscles, place a ‘muscle’ between bones and across joints so that the ‘muscle’ would perform the appropriate actions. (Remember that prominences on bones are great places for muscles to attach!) STATION 5. Standing cow forelimb. A) Place a ribbon ‘muscle’ from the infraspinatus fossa of the scapua (caudal and ventral to the scapular spine) to the caudal face (GREATER TUBERCLE) of the humerus. This represents the infraspinatus muscle . a. If this muscle contracted (pulled) what action would it provide to the shoulder? Extend______ Flex___ X(also serves as collateral ligment, abduct and outwardly rotate) ____ (mark one) B) An antagonistic muscle to the infraspinatus is the supraspinatus m . Place a ribbon from the suprapinatus fossa to the cranial face (GREATER TUBERCLE) of humerus to visualize it.

P ATH 2100 202 3 STATION 6. Standing horse forelimb. A) Place 1 ribbon ‘muscle’ from the caudal border of scapula to the olecranon process on the ulna. Place a second from the medial humer al diaphysis also to the olecranon. Place another from the lateral humer al diaphysis to the olecranon. These would represent 3 ‘heads’ of the triceps brachii muscle. a. If the triceps contracts, what action would it provide to the elbow? Extend___ X ___ Flex_______ (mark one) B) Place a ribbon for the biceps brachii m. (from scapula near glenohumeral joint to the proximal radius to see how it antagonizes the triceps brachii). STATION 7. Standing hindlimb. A) Place ribbon ‘muscle’ from to flex the stifle. If you represent the semitendinosus m. from pre-lab questions, to which bones does the muscle attach? Sacrum to cranial tibia a. In flexing the stifle, is the muscle on the cranial or caudal part of the limb? _____ Caudal _________________ B) Place a ribbon ‘muscle’ that is antagonistic to the semitendinosis m. above. (hint: it would likely insert at the patella/patellar tendon). What muscle could this be? __ Quads ______________________ STATION 8. Wet forelimb. Match pinned region close to the structure listed below and answer questions: Biceps__ 5, Flex Elbow ____ Triceps__ 1, Extend elbow _ ___ Digital flexors__ 3 ___ Digital extensors__ 4 ___ Supraspinatus__ 2 __ Do these also flex or extend the carpus?__ 3 flexes, 4 extends __ Does this flex or extend the shoulder? _ 2 extends ___

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