Anatomy Terms

Spatial Orientation

standing in the standard anatomical position, the space just before an animal into which it would move forward.

antero

relatively toward anterior or seen partly from in front

coronal

90 degree to the sagittal plane. latero-medial-lateral

inferior

standing in the standard anatomical position, the space just below an animal or in that direction

longitudinal axis

from nose to tail

median plane

the center sagittal plane that divides the body into two halves, left and right mirrored images.

posterior

standing in the standard anatomical position, the space just behind an animal from which it would move forward

sagittal plane

any dorsoventral plane parallel to the median plane

superior

transverse or horizontal plane

a plane through an animal parallel with level ground

Structural Orientation

abduction

motion away from the median

adduction

motion toward the median

appendicular

pectoral and pelvic subsystems

anatomical position

the standard anatomical position places the horse standing with weight equally shared from side to side. This position is the reference key for all language and orientation, organization, and plane.

axial subsystem

the somatic body composed of metameric segments from head to tail

bilateral

all structures lateral from median are symmetrically mirrored from side to side

caudal

tail end

cranial

head-end

distal

farther. relative distance from the medial plane, usually in reference to limbs

dorsal

epiaxial division of body served by "dorsal" roots of spinal nerves

epiaxial

in vertebrates, one of two divisions of the axial body. It is the zone from costal tubercles medially to the summits of vertebral spinous processes

extrinsic

muscles must have at least two attachment site in order to funciton. When one of those sites crosses from skeletal subsystem to subsystem, the muscle is "extrinsic" For example, the proximal attachment of latissimus dorsi in the horse is the axial skeleton, its distal attachment is the pectoral skeleton

hypoaxial

in vertebrats, one of two divisions of the axial body from costal tubercles to the sternal structure. In the equine Standard Anatomical Position, it refers to the lower rib elements and sternal anatomy

infra-

below

inter-

between

intrinsic

muscles must have at least two attachment sites in order to function. When all of those sites are with a single skeletal function, they are intrinsic. Biceps brachii attachments span from scapula to radius, both elements of the pectoral subsystem

lateral

relatively far from the median

magnus

biggest

major

the bigger of the two

medial

relatively close to the median or middle

medius

the middle of three in size or position

minimus

the lesser of three

oblique

angular direction

palmar

ventral surface of the hand

plantar

ventral surface of the foot

prone

dorsal surfaces facing ip

proximal

closer. relative closeness to the medial plane, usually in reference to limbs

supra

over or above

supine

ventral surfaces up

ventral

hypoaxial division of an animal, including branchial and appendicular

Functional Anatomy

agonist

a muscle which contracts in the primary intent of motion

antagonist

a muscle contracting in opposition to an agonist to modulate its motion in speed, power, etc

compression

force on a structure that would crush or bend the structure

eccentric contraction

eccentric contraction attempts to shorten a muscle fiber while it is being stretched by other forces

concentric contration

concentric contration shortens a muscle fiber, pulling its ends towards its center

contraction

electrochemical action within muscle fiber causes banded zones of the fiber to shorten, so that muscle only pulls. When activated, contraction is either on or off, and each activated fiber shortens, all or nothing

depressor

pulls down

erector

lifts or straightens

extensor

a muscle, the action of which decreases the angulation between two dorsal surfaces

exvaginate

to emerge from a sheath

flexor

a muscle, the action of which decreases the angulation between two ventral surfaces

levator

elevates

leverage

mechanical advantage results from increased work in bony levers about flcra joints. As ratio of length of force arm to work arm increases, the force arm gains strength of force advantage

motor unit

a group of muscle fibers spread throughout a region of a muscle that all contract when stimulated by a motor nerve.

proprioception

also called the kinesthetic sense, the bodymind gathers tension readings from millions of spindle cells. When learned patterns of relative tension are "read" moment to moment to determine a model in the mind of how the body is oriented in space

recruitment

since all muscle fibers are either ON, at the maximum contraction, or OFF, at resting length, the body provides a strategy for modulation of muscle function to slow down the lever arms in motion: by providing many muscle fibers in a set of given muscles, agonist and antagonist. For example, in a class 1 lever, to balance the lever on its fulcrum, the same number of motor units recruited on both sides of the level will cause it to stabilize. To speed up and empower a motion, more agonist motor units contract relative to the number of antagonist motor units. More and more motor units within a muscle can be "recruited" to increase force

rectus

a straightener or erector

rotation

joint articulation that translate compression forces into bending movement which can be employed in round joints

spindle cell

a nerve combining both sensory and motor ending embedded in muscle. The sensory end coils around the length of a "spindle" shaped fascia bundle. It senses the tension with a muscle by monitoring the stretching of its spindle. When the speed or amount of tension does not fit the predicted model of movement at the spinal cord level, its motor component triggers contraction to counteract the tension

stretch reflex

when the sensory nerve senses the the bundle is being over-stretched, its motor ending reflexively triggers contraction in its associated muscle cell. The response is faster than normal cerebellum to cord to peripheral nerve to muscle neuromuscular function

synergist

a muscle acting directly neither in agonism or antagonism, but modifying the action of one or both

tensile

forces which tend to pull things apart

tension

stretch. a tensor applies tension

torque

twisting force

translation

relocation of an anatomical component due to movement

envaginate

to enter a sheath

Anatomy & Development

-ceps

from Greek "cephalic;" Latin capitus head(s) of a muscle, referring to separate, usually proximal, main parts"

acromion process

terminal end of the scapular spine

ala

wing (Latin)

analogy

in morphology, analogue (also analogy) refers to a similar function produced by dissimilar anatomy. For example, wings of birds are arms put to the use of flight, while insects develop wings separate from limbs

aponeurosis

a sheet of tendon from a sheet of muscle, an aponeurosis. Greeks thought nerves looked like connective tissue, so the "neurotic" component

articulation

a joint between bones, usually mobile

attachment

each muscle cell inhabits a fibrous cocoon of fascia. The fibers reach beyond the cell to blend wit the fibers of the periosteum, or fibrous casing of bones. When the casings attach the "belly" of muscle cells closely to the bone, the attachment is called "fleshy." When the casing extend some distance beyond the belly, the fibrous continuations are called "tendons" and such muscles and their attachments are called "tendinous." Tendinous attachments are relatively small and focused. Fleshy attachments are broad, dispersing muscle fibers across relatively large surfaces of periosteum

belly

fleshy part of any muscle containing the bulk of contractile muscle fibers

bursa

a capsule filled with synovial fluid that occurs in places where bones are padded against tendinous friction

calcaneus

the heel bone

carpus, carpal

two tiers of bones at the wrist between radius and metacarpals

cartilage

(Latin for wickerwork) Non-osseu skeletal material made up of collagen in various compositions, sometimes including elastic fibers. Tey perform several functions in the body, such as juvenile patterns for bone to replace adult, articular surfaces in joints, fibrocartilage connections, and flexible skeletal elements

collagen

structural matrix of protein that cells use in building connective tissue

concha

seashell

condyle

From Greek for Knuckle; rotary articular surfaces around which another bone glides

chordate

refers to the spinal cord. One of several phyla of basic animal classifications or taxons. The phylum chordata compromises animals who share these basic elements: metameric segmentation; bilateral symmetry; a notochord; a dorsal nerve cord which interconnects the segments; and gill-arch structures

cornu

horn

costal

reference to ribs or costae

crest

a marked ridge of bone

crus

leg or legs (crura of a cross)

diaphysis

the main bone growth center of the often hollo shaft of a long bone

digastric

two-bellied

digitation

division of muscle or tendon into fingers for attachment to segments

eminence

a gentle elevation of bone

epicondyle

bony eminence proximal to (above) a condylar joint

epiphysis

in the growth of long bones, working joints prohibit length from being added at the ends. Instead, zones between the join-ends (epiphyses) and the shaft (diaphyses) develop cartilage for replacement bone that lengthens the bone as long as the caritlage is produced. When growth is complete, the cartilage disappers and the epiphyses and diaphysis unite

eukaryotic

a cell that contains a nucleus within its membranes

facet

"small face." A small articular surface

fascia

the connective fibrous sheets that provide flexible structure for the living cells of the body. For each muscle fiber, collagen fibers weave together into a housing (endomysium); for each group of fibers bundled into a fascicle (perimysium); and for packaging the fascicles into a muscle (epimysium)

fenestration

a window through a structure

foramen

a sizable hole

fossa

a depression in the surface of a bone or an organ

glenoid fossa

a shallow depression

head

one or two or more distinct, proximal components within a muscle

heterochrony

changing morphology within a basic genetic formula by altering development timing of any part of the animal, either lengthening the time for development or by shortening it

hiatus

a yawn, an opening is soft tissue

homology

development of the same morphological element into varying functions. Fin=arm=wing are all homologus