Terminology/Definitions

Dorsal: relating to the back (spine)

Ventral:  relating to the underside (sternum)

Posterior/Caudal:  relating to the end (tail)

Anterior/Cranial:  relating to the front/top (head)

Rostral:  towards the nose

Medial/Median:  relating to the midline of the body

Lateral:  relating to the side; any area away from the midline of the body

Transverse:  across the body (90 degrees to the midline)

Proximal:  close to the midline of the body (relative to another structure)

Distal:  away from the midline of the body (relative to another structure)

Origin:  site of muscle attachment on a bone that is fixed in position when the muscle shortens; usually closest to the midline (same as Proximal Attachment)

Insertion: site of muscle attachment on a bone that moves; usually farthest from the midline (same as Distal Attachment)

(Most of these terms are not specifically asked on quizzes or exams; however questions will include these terms, so if you are not familar with their meanings, you will be unable to correctly answer a question containing one of these terms.)

Tendon: a white cord of fibrous connective tissue which connects a muscle to a bone or other attachment surface.

Aponeurosis: a tendon which is flat and sheet-like rather than cord-like in shape (due to Beta folding, if you'd like to relate this back to your organic chemistry). Do know the definition of this term.

Types of Muscle Actions

Flex: movement that brings a distal limb segement toward the next proximal one. Curling up of the limb. Flexor = a muscle that by its contraction bends a limb or any portion of it. (flexus=bending)

Extend: a movement that carries a distal limb segement away from the next proximal segment. Straightening out of the limb. (ex = out + tendere = to stretch)

Abduct: movement away from a point of reference, such as the midventral line of the body. (ab = away + ductus = led, from ducere = to lead)

Adduct: a movement toward a point of reference, such as the midventral line of the body. (ad = toward + ductus = led)

For Your Added Information

The difference between visceral and branchial arches:  there are seven visceral arches.   In protochordates (no jaws, i.e. hagfish), all seven are retained.  In chordates, the first and second visceral arch has been modified:  arch one becomes the mandibular arch, while the second visceral arch is modified into the hyoid arch.  3-7 are retained as the branchial arches, usually for gas exchange (i.e. breathing) but sometimes for feeding (as in the urochordata).  Is this test material?  Were you supposed to read this somewhere?  Is this covered in a prerequisite and you just missed it?  Nope on all three.  We just thought you'd like to know.