Exercise 47- External Features & Rat Skeletal System

Created by Kenzie_Davis 

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What features of rats make them a good experimental model to learn about factors that affect humans?

small, familiar, and easily bred for experiments

Dorsal

toward the upper surface (back)

Ventral

toward the lower surface (belly)

Anterior

toward the head

Posterior

toward the tail

Medial

toward the midline of the body

Proximal

toward the end of the appendage nearest the body

Lateral

toward the midline of the body; toward the side

Distal

toward the end of the appendage farthest from the body

Frontal plane

divides body into dorsal & ventral halves; 2 dimensional plane parallel to the anterior-posterior axis & perpendicular to the dorsal-ventral axis

Transverse plane

a cross section; 2 dimensional plane perpendicular to the anterior-posterior axis of the body

Sagittal plane

divides body into left & right halves; 2 dimensional plane parallel to the anterior-posterior axis & parallel to the dorsal-ventral axis

cranial region

head

cervical region

neck

pectoral region

area where forelegs attach

thorax

chest region

abdomen

belly

pelvic region

area where hind legs attach

pelage

hairy coat that covers most of the rat's body

vibrissae

tactilely (related to touch) sensitive "whiskers" on the face

nares

nostrils; located at anterior end of head

incisors

subterminal mouth has a cleft that exposes large front teeth

large pupils

adaptation to nocturnal life; eyes bulge from head and enable the rat to see in almost all directions

nictitating membrane

located at inside corner of the eye; this translucent membrane may be drawn across the eyeball for protection

eyelids

similar to those found in humans

pinna

external ear

auditory meatus

ear canal

teats

6 pairs of these located on ventral surface

tail

located posteriorly (caudally) and is covered w/ hair & scales

anus

ventral to the base of the tail

clitoris

a small protuberance from which the urinary aperture opens lies just caudal to the last pair of teats in a female

vaginal orifice

just caudal to the clitoris; located in a small depression called the vulva

scrotal sacs

in males; lie on each side of the anus & contain testes, which produce sperm cells

prepuce

a bulge of skin surrounding the penis

preputial orifice

where penis can be extended from the prepuce

urogenital orifice

located at the end of the penis; where both urine & sperm cells exit the body

quadruped

rat has 4 legs w/ 4 digits and a vestigial thumb on each foot

plantigrade

a stance in which both the sole & heel of a rat's foot contact the ground as indicated by the lack of hair from the toes to the heel

digitigrade

animals that walk on their toes

mandible (part of skull)

lower jaw; contains a broad, flat surface for muscle attachment

maxilla (part of skull)

upper jaw

zygomatic arch (part of skull)

place where some jaw muscles pass under and attach to the lateral surface of the cranium

cranium (part of skull)

braincase

axial skeleton

formed by the skull & vertebral column

5 groups of vertebral column

cervical, thoracic, lumbar, sacral, caudal vertebrae

atlas & axis

2 cervical vertebrae; form a versatile joint and allow for a variety of head movements

ribs

extend from thoracic vertebrae; form an enclosure (rib cage)

caudal vertebrae

form a long tail

pectoral girdle

where bones of anterior appendages (forelegs) attach

pelvic girdle

where bones of the posterior appendages (hind legs) attach

appendicular skeleton

bones of forelegs & hind legs

integument

skin

genitals

external sex organs

fascia

connective tissue that is tough yet flexible

cutaneous trunci

thin sheets of muscle that attach to the skin

brown fat

a deposit of fat between the shoulder blades that is specialized for heat production if the animal is stressed by low temperatures

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