VT 105

Lab Objectives – Lab Chapter 8

part 1 – muscle microscopic anatomy

Be able to identify slides, models, or diagrams of skeletal, cardiac, and smooth muscle.

For each type of muscle, be able to define and identify (where possible) the following features.

skeletal muscle

long cell

striations

multinucleate

myofibrils

sarcomeres

thick filaments / myosin

thin filaments / actin

tendon

aponeurosis

deep fascia / muscle compartments

neuromuscular junction

somatic motor neuron

synapse / acetylcholine

cardiac muscle

branched cell

one nucleus

strations

intercalated discs

smooth muscle

spindle-shaped cell

central nucleus

no striations

For each type of muscle, know where in the body it is found.

VT 105

Lab Objectives – Lab Chapter 8

part 2 – skeletal muscles

Be able to locate and identify the following muscles on diagrams, dissection specimens, or live animals.Know the origin, insertion, and action of each muscle listed.

Muscle Name / Origin / Insertion / Action
Head Muscles
Digastric / caudal skull / mandible / opens mouth
Masseter / zygomatic arch / mandible / closes mouth
Temporalis / lateral skull / mandible / closes mouth
neck and trunk Muscles
Epaxial muscles / numerous muscles on dorsal spine and ribs, from caudal skull to sacrum and pelvis / extend head and spine
laterally flex spine
Sternocephalicus / sternum / caudal skull / flex neck & head
Brachiocephalicus
(cleidocervicalis portion) / clavicle / caudal skull / flexes neck
draws limb cranially
RESPIRATORY Muscles
External intercostals / cranial rib / caudal rib / draw ribs cranially
(breathing in)
Internal intercostals / caudal rib / cranial rib / draw ribs caudally
(breathing out)
Diaphragm / inner surface of
rib cage / central tendon / enlarges thoracic
cavity (breathing in)
ABDOMINAL MUSCLES
Rectus abdominis / pubis / sternum and
costal cartilages / flexes spine
External oblique &
Internal oblique / caudal ribs and
lumbar fascia / linea alba / flex and rotate
spine
Transversus
abdominis / lumbar fascia / linea alba / supports abdomen
Pectoral limb muscles
Muscle Name / Origin / Insertion / Action
Serratus ventralis / ventral ribs / dorsomedial scapula / pulls scapula ventrally
(supports body)
Trapezius / cervical & thoracic vertebrae / spine of scapula / adducts scapula
Rhomboid group / cervical and thoracic vertebrae / scapula / adduct and stabilize scapula
Pectoralis group / ribs and sternum / humerus / adduct pectoral limb
Supraspinatus / scapula
(above the spine) / humerus / extends shoulder
Deltoid / scapula / humerus / abducts or draws pectoral limb caudally
Latissimus dorsi / thoracic and lumbar vertebrae & fascia / humerus / draws pectoral limb caudally
Brachiocephalicus
(cleidobrachialis portion) / clavicle / ulna
(humerus in other species) / draws limb cranially
Biceps brachii / scapula / radius / flexes elbow
Triceps brachii / caudal humerus and scapula / olecranon process of ulna / extends elbow
Extensor compartment of carpals & digits / cranial antebrachium / carpals and phalanges / extend carpus and digits
Flexor compartment
of carpals & digits / caudal antebrachium / carpals and phalanges / flex carpus and digits
Pelvic limb muscles
Muscle Name / Origin / Insertion / Action
Adductor group
(+ Gracilis) / pubis / femur & tibia / adduct hip
Gluteus group / pelvis and sacrum / femur / abduct and extend hip
HAMSTRING GROUP
Semitendinosus / ischium / medial tibia / flexes knee and extends hip
Semimembranosus / ischium / medial tibia / flexes knee and extends hip
Biceps femoris / ischium & femur / lateral tibia / flexes knee and extends hip
Quadriceps femoris / femur(ilium) / via patellar ligament to tibial tuberosity / extends stifle
(rectus femoris also flexes hip)
Gastrocnemius / caudal femur / calcaneus / extends hock
Flexor compartment of digits / caudal tibia and fibula / tarsals and phalanges / flex digits and extend hock
Extensor compartment of digits / cranial tibia and fibula / tarsals and phalanges / extend digits and flex hock

Know which muscles are appropriate sites for intramuscular injections.

Be able to identify the following structures associated with the skeletal muscles.

linea alba

patella

patellar ligament

calcaneal (Achilles) tendon

fabellae

Be able to identify the following structures of the pony or horse leg.

superficial digital flexor

deep digital flexor

suspensory ligament

proximal sesamoids

navicular bone