Chapter 1 Basic Anatomy Chris Rorden Coordinates Introduction to the nervous system

What is an example of a common mnemonic? Multiple choice What is an example of a common mnemonic? Someone with blue eyes. Someone with odd eyes (one blue, one green). The left hand is controlled by the right side of the brain. Kings prefer chess over football, generally speaking.

Mnemonics: tools to aid memory Kings prefer chess over football generally speaking = Kingdom, phylum, class, order, family, genus, species. My very easy method, just set up nine planets = Mercury Venus Earth Mars Jupiter Saturn Neptune Pluto Other methods include loci (imagine a walk with different objects in different locations) or rhymes (one is a bun, two is a shoe…)

What is the symbol for Sagittarius? Multiple choice What is the symbol for Sagittarius? The Water Carrier. The Archer. The Sea-goat. The Lion.

Sagittarius

SLP and Neuroscience Speech-Language Pathology Neuroscience Study of developmental and acquired disorders of human cognition, language and speech Complete neurolinguistic assessments and management Neuroscience Neurology Neurosurgery Neuroanatomy Neuroradiology Neuroembryology Neurophysiology Neuropathology

Central Nervous System (CNS) Peripheral Nervous System (PNS) The Nervous System Central Nervous System (CNS) Brain + Spinal Cord Peripheral Nervous System (PNS) Cranial Nerves (never enter spinal column) Spinal Nerves All nerves to muscles and sensory reception sites

Fiber tracts like the internet – sending information across distances Terms for Fiber Tracts Fiber tracts like the internet – sending information across distances Bundle - a group of fibers Column - a pillar of fibers Fasciculus - a small bundle Funiculus - a cord; a cord of nerve fibers in a nerve trunk Lemniscus - a ribbon of fibers Tract - a large group of fibers, a pathway You should be familiar with primary pathways

Organization CNS Relays incoming and outgoing messages Integrates Information Higher mental functions (language, cognition) Regulates

The two hemispheres Left hemisphere is dominant for language and handedness Right hemisphere is dominant for music, emotion, and spatial processing Bilateral Anatomical Symmetry Connected by Corpus Callosum Unilateral Functional Differences Little lateralization of function at birth Gradual development of specialization

Laterality and Function Sensory information projects to opposite hemisphere Object felt in right hand, Information processed by left hemisphere Pain felt in left foot, Information processed by right hemisphere Motor functions are also contralateral Motor Functions Sensory Functions

Types of Brain Tissue Gray Matter: The neurons or cells which have specialized neurologic functions (motor or sensory) White Matter: Axons which form pathways for conducting different types of information.

Distinct Pathways Connections are not random – specific. organization of connections. Carry information from peripheral body parts to specific areas of the brain - project to particular cortex (outside bark) of the brain Each peripheral body part has a receptive area of the brain responsible for processing or receiving input Example: visual cortex

Plasticity of the Brain Brain injury is permanent, but individuals can show recovery. Plasticity refers to the brain’s ability to reorganize and modify functions and adapt to internal and external changes Important for learning Important for rehabilitation Younger brains tend to be more plastic

How do we learn about brain function? Classically, examine deficits following brain injury, infer that damaged brain area is required for task. Today, most studies of brain function utilize neuroimaging techniques such as fMRI (functional Magnetic Resonance Imaging) or PET(Positron Emission Tomography) – These studies usually focus on normal brains

MRI scan This image is in radiological orientation (left is shown on right). Images can also be in neurological orientation (left on left) These structural scans can show abnormalities and injury. L

CT Scans CT scans use X-Rays to see inside body. Excellent for bone Often first scan in acute care (e.g. unconscious patient can not tell us if they have pacemaker, cochlear implant, or other contraindications to MRI).

PET/SPECT Images Measures of blood flow can help determine brain metabolism. PET: Inject radioactively labeled glucose. Note: reduced uptake in posterior region.

Combining anatomy and metabolism Anatomical scans (T2 MRI) have excellent spatial resolution. Metabolic scans can identify abnormalities (e.g. tumor). Combining takes advantage of complementary strengths

Relative Coordinates On the globe we talk about North, South, East and West. Lets explore the coordinates for the brain.

Orientation Human anatomy described as if person is standing If person is lying down, we would still say the head is superior to feet.

Orientation - animals Dorsal back Caudal tail Ventral belly Rostral Caudal Ventral Cranial head Rostral beak Caudal tail Ventral belly

Coordinates – Dorsal Ventral Human dorsal/ventral and rostral/caudal differ for brain and spine. Head/Foot, Superior/Inferior, Anterior/Posterior not ambiguous. Dorsal Ventral Superior Inferior Dorsal Ventral

Coordinates – Human Human dorsal/ventral and rostral/caudal differ for brain and spine. Head/Foot, Superior/Inferior, Anterior/Posterior not ambiguous. C R R R C Anterior Posterior C

Anatomy – Relative Directions lateral < medial > lateral Posterior <> Anterior Ventral/Dorsal aka Inferior/Superior aka Foot/Head Ventral <> Dorsal Anterior/Posterior aka Rostral/Caudal Posterior <> Anterior

Coordinates - Anatomy 3 Common Views of Brain: Coronal (head on) sagittal coronal axial 3 Common Views of Brain: Coronal (head on) Sagittal (profile) Axial (bird’s eye), aka Transverse. The book calls this ‘Horizontal’ but it is not horizontal when we are lying in a scanner.

Coronal Corona: ‘crown’ a coronal plane is parallel to crown that passes from ear to ear Coronal cut creates anterior, posterior portions

Transverse: perpendicular to the long axis These cuts are also referred to as Axial. Example: cucumber slices are transverse to long axis.

Sagittal – ‘arrow like’ Sagittal cut divides object into left and right sagittal suture looks like an arrow. top view

Sagittal and Midsagittal A Sagittal slice down the midline is called the ‘midsagittal’ view. midsagittal sagittal

Oblique Slices Slices that are not cut parallel to an orthogonal plane are called ‘oblique’. The oblique blue slice is neither Coronal nor Axial. Cor Oblique Ax

Distance from midline Medial – near sagittal midline Optic chiasm C medial of eyes Lateral – far from sag. Midline Eyes are lateral of optic chiasm Ipsilateral – same side Damage to A will cause blindness in ipsilateral eye Contralateral –different side Damage to D will lead to a contralateral field cut. Note: after brain injury (lesions) we talk about contralesional and ipsilesional Damage to visual cortex G leads to problems with contralesional vision.

Relative positions Distance From Body Distance from Surface Proximal, Central: near center of body Think ‘proximity’ Shoulders are proximal parts of arms Distal,peripheral: away from body Think distant Fingers are distal parts of the arms Distance from Surface Superficial, external: near surface The bump bruised superficial tissue. Profound, deep: far from surface The car crash injured deep organs.

Movements Flexion Extension - Increasing angle between two body parts (-Flexion). Adduction - Pulls body part toward midline (-Abduction) Pronation - A rotation of the forearm that moves the palm from an anterior-facing position to a posterior-facing position (-Supination) Supination Pronation Extension Abduction Adduction

Types of cells in the brain Neuron: Cell which is responsible for receiving, transmitting and synthesizing information cell body: contains organelles for metabolism and a nucleus Glial Cells: Support cells for Neurons (CNS: oligodendrocytes, astrocytes, ependymal cells, radial glial; PNS : Satellite and Schwann cells)

Neuron Types Neurons come in different types – some only communicate locally, while others have very long axons that communicate with distant regions.

Glial Cells Glial cells have crucial functions www.mult-sclerosis.org/glialcells.html Repair, maintenance and cleaning. They produce new myelin when it become damaged, lay down scar tissue, and remove dead cells and other debris. Physical support. They have hairlike filaments which hold the neurons in place and allow the central nervous system to retain its structural integrity. CNS development. Help migration of neurons. Chemical regulation. Supply chemicals such as potassium and calcium and regulate neurotransmitter levels. Ten times as many glial cells as neurons

Why is the difference between a tumor and a cancer? Multiple choice Why is the difference between a tumor and a cancer? Cancer involves neurons, tumors involve other cells (e.g. glial cells). Tumor involves neurons, cancer involves other cells (e.g. glial cells). Tumor is due to virus, cancer is due to bacteria A tumor can be benign, pre-malignant or malignant, whereas cancer is by definition malignant.

Tumor from the Latin "swelling“ Tumors Tumor from the Latin "swelling“ In medicine, swelling due to abnormal, uncontrolled cell division Brain tumors are usually due to glial cells (gliomas). Glial cells more common, so higher probability of cell becoming cancerous. Neuron’s usually stop dividing earlier.

The Central Nervous System Telencephalon (Cerebrum) Cortex Basal Ganglia Diencephalon Thalamus Hypothalamus) Mesencephalon (Midbrain) Colliculi Substancia Nigra Rhombencephalon Cerebellum Pons Medulla

Deep Structures Basal Ganglia – Initiates movements Caudate nucleus, Putamen,Globus pallidus Diencephalon Thalamus: Relay from body to cortex Hypothalamus and pituitary gland: Regulation (e.g. hormone secretion)

Deep Structures Basal Ganglia – Initiates movements Caudate nucleus(red) Putamen (green) Globus pallidus (blue) Diencephalon Thalamus: (yellow) Hypothalamus: (not shown)

Brain Stem Pons Midbrain Medulla Oblongata CN III and IV emerge Early auditory/visual processing Dopamine for movement control CN III and IV emerge Pons CN V, VI, VII VIII Medulla Oblongata Pyramidal decussation: nerves from left cross to right side and vise versa CN IX, X, XI, XII

Cortex – ‘Bark’ shell of brain – mostly gray matter The cortex Cortex – ‘Bark’ shell of brain – mostly gray matter ~80% of human brain ~20% of squirrel brain

What does ‘temporal’ usually refer to? Multiple choice What does ‘temporal’ usually refer to? Space. Color. Time. Loudness.

Why is it called the temporal lobe? Multiple choice Why is it called the temporal lobe? This area handles memory – remembering previous times. This lobe processes hearing – hearing requires good temporal precision. This lobe is under the temples, where the hair turns gray early in life. This area helps with counting –which we use for timing events.

Cortical folding increases surface area. Ridges are called Gyri (singular = Gyrus) Greek gyros = circle, hence a coil of brain cortex Valleys are called Sulci (singular = Sulcus). Latin = a groove. Gyri Sulci

Gray and White Matter The outer surface of the cortex is gray matter: lots of interconnected neurons (like cities) Underneath is the white matter – the highways connecting regions.

Functional Classifications Some neurons transmit general information Pain and Temperature Originate in surface structures Other neurons transmit specialized information Specialized receptors Hearing and vision Somatic: Skeletal muscles Visceral: Refer to internal vital body organs Can be either Afferent: Sensory Efferent: Motor

Cortical layers Neurons are in six layers Functions I. Molecular layer II. External granular layer III. External pyramidal layer IV. Internal granular layer V.Internal pyramidal layer VI. Fusiform layer Functions Superficial layers (I-III): inter-cortical connections IV: input from thalamus V,VI: outputs to leave cortex

The big folds The folds of your brain are like a fingerprint – there are a few general patterns, with individual variability. Two main folds Central Sulcus Fissure of Rolando Rolandic sulcus Lateral sulcus Sylvian fissure

Describing cortex location Brodmann Areas (BAs, 1909) Appearance of cortex under microscope Not necessarily function Arbitrary numbers are hard to remember Some are crucial for a speech pathologist: 44 Broca’s Area 22 Wernicke’s Area

Brodmann Areas (medial slice) Note that gray matter is located in the longitudinal fissure (between the two hemispheres)

Cortical Names Much of cortex referred to by combination of coordinate+lobe+gyrus E.G. Superior Temporal Gyrus (STG) Middle Temporal Gyrus(MTG) Lateral Occipital Gyrus (LOG)

Cortical names Tip of an object called a ‘pole’ Frontal Pole Temporal Pole

Many of sulci referred to by combination of coordinate+lobe+sulcus Sulci names Many of sulci referred to by combination of coordinate+lobe+sulcus Superior temporal sulcus (STS) Inferior frontal sulcus (IFS) Precentral and postcentral sulci are just anterior and posterior to the central sulcus.

Brain function Anatomy is interested with the structure of an organism. Physiology is interested in the function of the structure. We are still learning about brain function Modern maps of brain function are primitive…

Brain function Much of the primate cortex devoted to vision. In some monkeys, up to 50% of neocortex is devoted to vision.

Two striking features of human brain Brain function Two striking features of human brain Lots of cortex ‘left over’ (yellow): not devoted to specific task – we are flexible Not much of the cortex is solely devoted to language.