PP 02- Gross anatomy, terms of direction, and sections/planes

Two Major Divisions of Nervous System (NS) CNS: Brain & Spinal Cord CNS: Brain & Spinal Cord –Protection by bony shell, meninges, & CSF PNS: Sensorimotor (Spinal/Cranial) Nerves: Innervation of organs, muscles, joints, & skin PNS: Sensorimotor (Spinal/Cranial) Nerves: Innervation of organs, muscles, joints, & skin –Somatic nervous system –Autonomic nervous system (ANS) Sympathetic and parasympathetic systems Sympathetic and parasympathetic systems

CNS levels Cerebrum Cerebrum – incl. basal ganglia, limbic system Diencephalon (thalamus and hypothalamus) Diencephalon (thalamus and hypothalamus) Brainstem Brainstem –Midbrain, pons, medulla Cerebellum Cerebellum Spinal cord Spinal cord

Terms of Direction: Overview Terms of direction denote relative position of one neurological structure to another Two systems of “higher, lower, more forward, more backward”: Two systems of “higher, lower, more forward, more backward”: –System referenced to person standing in 3-D space Superior / inferior ; anterior / posterior Superior / inferior ; anterior / posterior –System referenced to anatomical neuraxis, which is straight in many animals, and curved in humans. Rostral / caudal; ventral / dorsal Rostral / caudal; ventral / dorsal A system of “closer to the midline, farther from the midline” A system of “closer to the midline, farther from the midline” Medial / lateral Medial / lateral A system of “how close to the point of connection with the body” A system of “how close to the point of connection with the body” Proximal / distal Proximal / distal

First system of “higher, lower, more forward, more backward” –System referenced to human in anatomical position in 3D space Superior / inferior ; anterior / posterior Superior / inferior ; anterior / posterior 6- Superior 2- Inferior 1- Anterior 5- Posterior Superior Inferior Anterior Posterior Human anatomical position = Body erect, hands at side, palms facing outward When referring to structures of the head as superior to other structures, the terms cranial or cephalic are sometimes used as terms of direction

First system of “higher, lower, more forward, more backward” Examples: The brain is superior to the spinal cord The brain is superior to the spinal cord The brain is cephalic to the spinal cord The brain is cephalic to the spinal cord The brain is cranial to the spinal cord The brain is cranial to the spinal cord The spinal cord is inferior to the brain The spinal cord is inferior to the brain The brain stem is anterior to the cerebellum The brain stem is anterior to the cerebellum The cerebellum is posterior to the brain stem The cerebellum is posterior to the brain stem

Second system of “higher, lower, more forward, more backward” System referenced to anatomical neuraxis, which is straight in many animals, and curved in humans. rostral/ caudal; ventral / dorsal 1- early human embryo neurological system, straight like the salamander’s Human anatomical neuraxis = brain and spinal cord The human anatomical neuraxis starts as a straight tube (called the neural tube). During development it bends/curves almost 90 degrees at the juncture of the brainstem and diencephalon 2- human embryo neurological system- 3 weeks; curved neuraxis! 3-mature human; major curve remains near juncture of brainstem and diencephalon; neuraxis “mushrooms out” around curve

Second system of “higher, lower, more forward, more backward” Examples: The front part of the cerebrum is rostral to the spinal cord The front part of the cerebrum is rostral to the spinal cord The spinal cord is caudal to the front part of the cerebrum The spinal cord is caudal to the front part of the cerebrum The brain stem is ventral to the cerebellum; the lower part of the cerebrum is ventral to the upper part of the cerebrum The brain stem is ventral to the cerebellum; the lower part of the cerebrum is ventral to the upper part of the cerebrum The cerebellum is dorsal to the brainstem; the upper part of the cerebral is dorsal to the lower part of the cerebrum The cerebellum is dorsal to the brainstem; the upper part of the cerebral is dorsal to the lower part of the cerebrum

Compare the two systems of “higher, lower, more forward, more backward” Compare the two systems of “higher, lower, more forward, more backward” The neuraxis bends around the junction between the midbrain and diencephalon, so…. –At the level of the spinal cord and brainstem Anterior=ventral Anterior=ventral Posterior=dorsal Posterior=dorsal Superior=rostral Superior=rostral Inferior=caudal Inferior=caudal –At the level of the diencephalon and the telencephalon Inferior=ventral Inferior=ventral Superior=dorsal Superior=dorsal Superior Inferior Anterior Posterior Rostral

System of “closer to the midline, farther from the midline” Medial/ lateral Lateral view of brain medial lateral Anterior view of brain Medial view of brain

System of “how close to the point of connection with the body” Proximal= nearer to the point where the structure connects to the body vs. Distal = farther from the point where the structure connects to the body Example: The shoulder is more proximal to the body than the fingers. The fingers are more distal from the body than the shoulder. Shoulders more proximal, fingers more distal…… Superior Inferior Anterior Posterior

Limb Movement Terms Flexion Flexion Extension Extension Abduction Abduction Adduction Adduction Pronation Pronation Supination Supination

Sections/Planes: A cut through the body, or a part of it, is called a section; the resulting cut surface is called a plane

Sections/Planes First system based on slices through 3-D space First system based on slices through 3-D space –Horizontal section/plane (A) –Coronal section/plane (B) –Sagittal section/plane (C) Superior Inferior Anterior Posterior A B C

C. Midsagittal (also called medial) C. Parasagittal B. Coronal (when anterior, also called frontal) A. Horizontal Sections/Planes: First System (Continued)

Sections/Planes: Second system Second system based on slices at right angles to longitudinal axis of the structure Second system based on slices at right angles to longitudinal axis of the structure –Transverse or cross section/plane Remember that the longitudinal neuraxis is curved

Compare the two systems of sections/planes The neuraxis bends around the junction between the midbrain and diencephalon, so…. –At the level of the spinal cord and lower brainstem Horizontal=transverse Horizontal=transverse –Near the bend (upper brainstem and diencephalon) Transverse has no analog in the 3-D system of sections/planes Transverse has no analog in the 3-D system of sections/planes –Rostral to the diencephalon Coronal = transverse and is also called a frontal section/plane Coronal = transverse and is also called a frontal section/plane

Anatomic vs. clinical orientation (from readings) Compare the two. See especially pp. 24 and 25 (Figure 1-9) Compare the two. See especially pp. 24 and 25 (Figure 1-9)