Anatomical Position and Terms

Overview

This lesson covers anatomical directional terms used to describe body positions and locations. Understanding these terms requires knowing the standard anatomical position and reference planes.

Standard Anatomical Position

• Standing upright with head and eyes directed straight ahead
• Arms hanging at sides, slightly away from trunk, not touching
• Palms facing forward with thumbs pointing away from body
• Legs parallel with feet flat on ground, facing forward
• Right and left refer to patient's perspective (opposite of observer's view)
• Provides consistent universal reference for discussing anatomy

Medial and Lateral

• Medial: Toward the midline or middle of the body
• Lateral: Toward the side or away from the midline
• Sagittal plane divides body into right and left sections
• Midline is imaginary vertical line dividing body into equal halves
• Memory trick: Medial/Midline/Middle all start with M
• Memory trick: Lateral relates to "lats" (side back muscles)
• Examples: Nose is medial to eyes; eyes are lateral to nose
• Lungs are lateral to heart; heart is medial to lungs

Superior and Inferior

• Superior: Above or toward the head (also called cranial)
• Inferior: Below or away from the head (also called caudal)
• Transverse plane divides body into upper and lower sections
• Memory trick: Superior/Skull both start with S
• Memory trick: Inferior has F like "floor"
• Cranial references the cranium (head); caudal means toward tail
• Examples: Eyes are superior to nose; mouth is inferior to nose
• Heart is superior to liver; liver is inferior to heart

Anterior and Posterior

• Anterior: Front or toward the front of body (also called ventral)
• Posterior: Back or toward the back of body (also called dorsal)
• Coronal (frontal) plane divides body into front and back sections
• Memory trick: A comes before P in alphabet (anterior before posterior)
• Ventral relates to stomach/abdomen/front (ventriloquist = stomach talker)
• Dorsal relates to back (think dorsal fin on fish)
• Examples: Frontal lobe is anterior to occipital lobe
• Patella (kneecap) on anterior side; olecranon (elbow) on posterior side

Proximal and Distal

• Proximal: Toward the trunk or near point of attachment/origin
• Distal: Away from the trunk or far from point of attachment/origin
• Most commonly used for extremities and tubular structures
• Memory trick: Proximal relates to "proximity" (near or close)
• Memory trick: Distal relates to "distant" (far away)
• Examples: Wrist is proximal to hand; hand is distal to wrist
• Elbow is proximal to wrist; wrist is distal to elbow
• In colon: Ascending colon is proximal end; descending colon is distal end

Superficial and Deep

• Superficial: Closer to the surface of the body
• Deep: Away from the surface of the body
• Memory trick: Superficial/Surface both start with S
• Deep is self-explanatory term
• Examples: Skin is superficial to ribs; ribs are superficial to lungs
• Lungs are deep to ribs; ribs are deep to skin

Unilateral and Bilateral

• Unilateral: Involving one side of the body
• Bilateral: Involving both sides of the body
• Uni means one or single
• Bi means two or double
• Example unilateral: Rash on only right arm
• Example bilateral: Rash on both arms

Ipsilateral and Contralateral

• Ipsilateral: On the same side of the body
• Contralateral: On opposite sides of the body
• Ipsi means "same"
• Contra means "opposite"
• Example ipsilateral: Laceration and abrasion both on right arm
• Example contralateral: Laceration on right arm, abrasion on left arm

Key Terms & Definitions