Human Anatomy Unit 1: Brain, Spinal Cord, and Neuroanatomy

General Organization of the Nervous System

ANATOMIA HUMANA Unit 1 1

Nervous System Terminology

1. The general organization of the nervous system and anatomical terminology Central Nervous System (CNS): - Brain: Located in the skull - Spinal cord: encircled by the vertebral column bones Peripheral Nervous System (PNS): All the nervous tissue outside the central nervous system (CNS). This nervous tissue connects the CNS with the peripheral structures of the body. It includes nerves (cranial and spinal), ganglia, plexuses and sensory receptors.

Brain Structures

Brain Divisions

BRAIN Brain Telencephalon Diencephalon Mesencephalon Pons Medulla oblongata Cerebellum

Spinal Cord Anatomy

Spinal Cord Segments

SPINAL CORD The spinal cord starts rostrally in the foramen magnum as an extension of the medulla oblongata. It is a segmented structure with: - 8 cervical segments - 12 thoracic segments - 5 lumbar segments - 5 sacral segments - 1 coccygeal segments The spinal cord ends caudally with the cauda equina (horse tail) and the filum terminale. Spinal nerves serving the upper or lower limbs coalesce to form the brachial or lumbar plexuses respectively. A plexus, therefore, refers to a network of peripheral nerves. The fibers of these plexuses are redistributed into the TELENCEPHALON the biggest part of the brain outer part DIENCEPHALON middle and below it is the brainstem - The Mesencephalon - Pons - Medulla oblongata CEREBELLUM is surrounded by pons.

Spinal Cord Connections

Base of skull Cervical enlargement CA F 12 " 13 T2 Thoracic nerves 17 18 19 Lumbar enlargement T10 -110 111 T12 T12 Comus medullaris L2 Cauda equina LA 15/ Termination of dural sac 51 "2 External filum terminale of dura mater 55 Coerygral nerve Sacral/ coccygeal nerves Lumbar nerves Ty Cervical nervesperipheral nerves. - The Foramen Magnum has a hole that permits the Medulla Oblongata to connect with the spinal cord. - Conus medullaris is the end (poi) form there it comes out the (horse stail) cauda equina and the filum terminale - Plexus: nerves that are concentrated in an area

Neuroanatomy Vocabulary

Gray and White Matter

NEUROANATOMY VOCABULARY Gray matter: CNS regions rich mainly in neuron cell bodies but also dendrites, unmyelinated axons and glial cells. For example, the central region of the spinal cord and the cerebral cortex. (Axon. Myelin sheath is the production of the axon) White matter: is the pale part of the CNS. Its color is due to the presence of axon myelinated fibers. (dendrites and soma)

Nervous System Overview

Nervous System Central Nervous System (CNS) brain SC Peripheral Nervous System (PNS) Somatic Nervous System monter info sensor info Autonomic Nervous System cannot control Sympathetic system fight or fly Parasympathetic system needs the other two to work Enteric system

Brain and Spinal Cord Matter

White matter Grey matter Coronal section of the brain Transversal section of the spinal cord Brain matter is GWG and spinal cord is WG (inside out)|

Neurons and Glial Cells

Neuron Types

NEURONS 2 - Unipolar: Has a small axon and doesn't have dendrites coming from the soma. Ej: Photoreceptive neurons (can detect light) - Bipolar: Has a unique dendrite and axon. Ej .: Photoreceptive neurons of the eye.- Pseudounipolar: A cell that has a peripheral and central projection. The soma sits beside the axon. They connect structures. Ej .: Sensitive afferences. - Multipolar: A big nucleus, loads of dendrites and a long axon. Ej .: In the nervous system A neuron is the individual anatomical, physiological, genetic, and trophic unit of the nervous system.

Myelin Sheath Components

- Oligodendrocyte (create the myelin sheath only in the central nervous system they surround the axon.)(oligodendrocytes are inside the glial cells) vs. Schwann cells (peripheral nervous system) - Nodes of Ranvier: the space between myelin sheath

Neuroimaging and Anatomical Planes

Neuroanatomical Terminology

PLANES, AXES ND NEUROIMAGING 3 The neuroanatomical terminology aims at defining, placing and orienting each part of an organism.

Anatomical Planes

Coronal Sagittal Horizontal The localization or position of any anatomical structure is referred to three orthogonal planes: horizontal (also called transverse), sagittal (also called medium) and coronal (also called frontal).

Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI) · Principle: Uses magnetic fields and radio waves to create detailed images of brain structure. · Advantages: High spatial resolution, non-invasive, no radiation. · Applications: Diagnosis of tumors, structural abnormalities. . Image: A detailed black-and-white image of the brain showing internal structures.

Functional Magnetic Resonance Imaging (fMRI)

Functional Magnetic Resonance Imaging (fMRI) · Principle: Measures changes in blood flow related to neuronal activity. · Advantages: Good balance between temporal and spatial resolution, non- invasive. · Applications: Studying brain activity during cognitive tasks · Image: Brain activity map with coloured areas indicating levels of activity

Computed Axial Tomography (CT scan)

Computed Axial Tomography (CT scan) · Principle: Uses X-rays to create cross-sectional images of the brain. · Advantages: Fast, effective for visualizing bones and acute injuries. · Disadvantages: Exposure to radiation. · Applications: Diagnosis of acute brain injuries, hemorrhages. · Image: Cross-sectional image of the brain with good contrast between dense (bones) and soft tissues.

Positron Emission Tomography (PET)

Positron Emission Tomography (PET) · Principle: Uses radioisotopes to measure metabolic activity of the brain. · Advantages: Provides precise functional information. · Disadvantages: Invasive, exposure to radiation. · Applications: Research on brain metabolism, neurodegenerative diseases. · Image: Colorful image showing metabolic activity in the brain, with high activity areas highlighted in warm colors.

Bone Protection of the CNS

CNS Protection Overview

UNIT 2 Bone protection The CNS is sustained and protected by bones and membranous meninges. The brain is localized inside the cranial cavity and the spinal cord in the vertebral canal of the vertebral column. Inside their bony coverings, the brain and the spinal cord are surrounded by three protective membranes, the meninges

Skull Structure

The skull supports the structures of the face like nerves, sensory organs, cavities of the digestive and respiratory systems and mimic muscles and muscles of mastication. The skull is composed of two parts: the neurocranium and the viscerocranium or facial skeleton.

Neurocranium Bones

Neurocranium The neurocranium is composed of eight bones: - four are single bones: frontal, occipital, sphenoid and ethmoid bone - Two are paired bones: parietal and temporal bones.

Spinal Nerve Origin and Vertebrae

Spinal Nerve Origin Cross Section through Thoracic Vertebra Meninges Vertebra of the Vertebral column Neurocranium Viscerocranium or facial skeleton

Neurocranium Bones Detailed

Frontal Bone

Frontal bone The frontal bone is located in the anterior part of the neurocranium. Two main parts are distinguished: the superior portion articulates with the two parietal bones by the coronal suture and the orbital portion that curves downward to make the upper margins of the orbits Frontal bone Orbital portion Frontal bone Coronal suture

Ethmoid Bone

Ethmoid bone The ethmoid bone is located in the anterior part of the base of the cranium, where the cribriform plate has small apertures through which olfactory nerve fascicle enter the cranium. The crista galli is a sharp upward projection for the attachment of the falx cerebri.

Sphenoid Bone

Sphenoid bone Bat shape having a centrally placed body with greater and lesser Wings on its sides. Its located in the middle of the cranial floor and has a deep depression= the sella turcica which lodges the hypophysis

Ethmoid Bone Views

Ethmoid Crista galli Cribiform plate Superior Posterior Inferior view view Lateral view Frontal view

Parietal Bones

Parietal bones Lambdoid suture Parietal bones

Temporal Bones

Temporal bones The temporal bones are at the lateral side of the cranium. Several parts can be distinguished: the squamous, the petrous and the tympanic parts and the mastoid, the styloid and the zygomatic processes.

Neurocranium Lateral View

Neurocranium - lateral view 1. Zygomatic process 2. Mastoid process 3. Styloid process Parietal bone Frontal bone Lambdoid suture Squamous suture Temporal bone Occipital bone 2 3 Auditory channel Occipitomastoid suture Coronal suture as Zygomatic process Tympanic part Styloid process 11 ue Eur

Parietal Bones Articulation

Partial bones The two parietal bones from the sides and roofs of the cranium and articulate with each other in the midline at the sagittal structure They articulate with the occipital bone at the lambdoid structure Anterior Posterior Anterior Superior Inferior Sagittal suture Squamous part

Cranial Fossae

Middle Cranial Fossa

Middle cranial fossa Neurocranium - cranial fossa The brain sits over the base of the skull, which is divided into three cranial fossae. The anterior cranial fossa is formed by the frontal, the ethmoid and the sphenoid bones and contains the two frontal lobes of the cerebrum. The middle cranial fossa is formed by the tempora l and the sphenoid bones and hosts the temporal lobes. The posterior cranial fossa is formed by the occipital and the petrous parts of the temporal bones. It hosts the cerebellum and contains the foramen magnum where the brainstem lodges.

Cranial Fossa Diagram

Anterior cranial fossa Posterior cranial fossa

Vertebral Column

Vertebral Column Functions

Vertebral column The vertebral column is the central bony pillar of the body and has several functions. - Support for the skull - Support for the upper limbs - Support for the thoracic cage - Transmission of body weight to the lower limbs - Protection of the spinal cord

Vertebral Column Curves and Composition

The vertebral column laterally has four curves (kyphosis or lordosis): the cervical, thoracic, lumbar and sacral curves. When viewed from the back, the vertebral column runs straight. / 7 x cervical vertebrae 12 x thoracic vertebrae K Intervertebral disc 5 x lumbar vertebrae K € 5 x sacral vertebrae 4 x coccygeal vertebrae Vertebral column composed of 33 vertebrae, 5 sacral fused to form the sacrum and the lower 3 coccygeal fused too. The vertebrae are joint by fibrocartilage intervertebral discs, making it a flexible structure

Vertebral Column Views

Dorsal view Ventral view Lateral view

Cervical Vertebrae

C1 Cervical vertebrae (Cervical curve) Intervertebral discs Thoracic vertebrae (Thoracic curve) Intervertebral foramina T12 T12 T12 41 Lumbar vertebrae (Lumbar curve) Sacrum (Sacral curve) Coccix

Atlas and Axis Vertebrae

Vertebral column The two first cervical vertebrae are slightly different, because they have to sustain the skull but, at the same time, they have to permit its rotation.C1 vertebra is also known as atlas and lacks the body.C2 vertebra is also known as axis, is very robust and has the odontoid process or dens, that is articulated with the vertebral arch of atlas allowing the skull rotation.

Meninges of the Brain

Brain Meninges Layers

Meninges Meninges of the brain The brain, inside the cranium, is surrounded by three protective membranes that are called meninges. - The external one is the dura mater and is a hard fibrous membrane. - The arachnoid mater is the middle layer and is a spider-like membrane composed of processes called arachnoid trabeculae. - The dura mater and the arachnoid mater are separated by the subdural space. - The internal meninge is the pia mater, a fine and delicate membrane intimately attached to the brain. - The arachnoid and the pia mater are separated by the subarachnoid space, which is filled with cerebrospinal fluid (CSF)

Meninges Diagram

bone dura mater arachnoid arachnoid trabeculae - pia mater glial limiting membrane vessel - perivascular space brain Bicep/Ep