Biology 11 (LAB) - Muscle System and Internal Anatomy of the Toad

Rectus Abdominis

Rectus Abdominis

2 thin longitudinal muscles which run antero-posteriorly in the belly; located at the midventral portion of the toad and separated by a connective tissue, the linea alba; divided into 5 segments by the inscription tendinae; it plays a crucial role in flexing the trunk and compressing the abdomen.

External Oblique

the broad muscles found on either side of rectus abdominis which cover the belly of the toad; these muscles slant from either sides of the toad towards the rectus abdomis

Longissimus dorsi

paired thin muscle runs anteroposteriorly along the medial dorsal plane of the toad

Latissimus dorsi

paired muscles is adjacent to the longissimus dorsi; runs antero-posteriorly but at a slightly oblique angle

Scapularis

the muscles that are found covering the scapula

Gastrocnemius

large muscle seen both dorsally and ventrally; involved in leg movement and flexing the foot.

Tibialis posticus

a long slender muscle located between the gastrocnemius & the shank bone, tibio-fibula;

Tibialis anticus

a muscle located in the anterior part of the leg, responsible for dorsiflexion of the foot and aiding in foot inversion.

Peroneus

located at the dorsal side of the shank beside the gastrocnemius and involved in foot eversion and stabilization during movement.

Semimembranosus

a large broad muscle located at the dorsal portion of the thigh

Triceps femoris

another large broad muscles that covers the outer ventral surface of the thigh & extends dorsally; composed of smaller muscles: vastus internus (ventral muscle), rectus femoris anticus (middle muscle), vastus muscle (dorsal muscle)

Biceps femoris

a muscle located on the lateral side of the thigh, part of the hamstring group, and involved in knee flexion and hip extension.

Gracilis minor (rectus internus minor)

a thin strip of flat muscle that covers the innermost side of the thigh; visible on both dorsal & ventral sides of the thigh

Gracilis major (rectus internus major)

a large muscle located on the ventral side of the thigh, immediately next to gracilis minor

Semitendinosus

a slender muscle more easily seen from the ventral side; located beneath the gracilis major; adducts the femur and flexes the leg

Sartorius

a narrow strip of muscle which traverses the thigh obliquely & covers the lower portion of the adductor magnus; flexes the shank & adducts the thigh

Adductor magnus

muscle is next to the gracilis major & partially covered by the sartorious; bends the thigh ventrally

Adductor longus

thin flat muscle found beneath the sartorious muscle

Abdominal cavity

occupied by organs of reproduction & digestion

Heart

occupies the center of the chest region

Lungs

found on either side of the heart

Gallbladder

greenish in color in preserved specimens/transparent to pinkish in new ones

Mesentries

sheets of membrane connect the internal organs to each other & suspend the organs from the dorsal body wall

Serous coat

the outermost covering of the organs

Spleen

a small round organ suspended in the mesenteries of the small intestine

Stomach

a J-shaped muscular organ partially covered by the liver; located at the right side of the abdominal cavity; controls the food that enters the small intestine

Esophagus

a tube leading to the the stomach

Cardiac end

anterior portion of the stomach

Pyloric end

posterior end of the stomach; leads to the duodenum has a sphincter muscle;

Pancreas

organ associated with the digestive system; a discrete organ located within the mesentery at the loop of the duodenum & underneath the stomach

Small intestine

a long tubular structure located posterior to the stomach

Duodenum

portion nearest the stomach; secretions of the liver & the pancreas are deposited

Ileum

the remainder of the small intestine

Large intestine

the continuation of the small intestine; it is larger & shorted than the small intestine & located almost at the junction of the thighs

Cloaca

attached to the large intestine; received ducts from the kidneys & the reproductive system; opens to the outside through the anus