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56 terms

Exercise 47- External Features & Rat Skeletal System

STUDY
PLAY
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