Neuroanatomy 1 PDF

**Neuroanatomy 1** **Sagittal:** Divide body into right and left planes. **Coronal**: Divides body into anterior and posterior. **Transverse (Axial)**: Divides body into superior and inferior. **Anterior**- Towards the front, in upright position can be used interchangeably with **ventral** as ve...

**Neuroanatomy 1** **Sagittal:** Divide body into right and left planes. **Coronal**: Divides body into anterior and posterior. **Transverse (Axial)**: Divides body into superior and inferior. **Anterior**- Towards the front, in upright position can be used interchangeably with **ventral** as ventral means towards the stomach. **Posterior**- Or **dorsal**. Towards the back. **Superior**- Towards the top. Interchangeable with **rostral**. **Inferior**- Towards the feet. Interchangeable with **caudal**. Caudal means towards the tail.  **Nucleus (Gray Matter):** A nucleus in neuroanatomy is a cluster of cell body and their dendrites in the CNS where synapses are made, and information is processed. **Tracts (White Matter)**: Bundles of myelinated axons form tracts connecting nuclei. **Spinal Cord Transverse Section:** - Gray matter lies deeper. **Terminology:** **Afferent:** Going towards the central nervous system= Sensory Neurons. **Efferent**: Leaving the CNS= Motor neurons. **Somatic**: Relating to the body (Soma= Body). **General Somatic Afferent (GSA)** = Carrying [sensory] information to the CNS from [muscles] and skin. **General Somatic Efferent (GSE)** = Carrying [motor] information from the CNS to [skeletal muscles]. **General Visceral Afferent (GVA)** = Carrying [sensory] information from [organs] and [blood vessels] to CNS. **General Visceral Efferent (GVE)** = Carrying [motor] information from CNS to [smooth muscle] and [glands] (parasympathetic innervation). Cranial nerves have [special senses.] **Special somatic afferent (SSA)** = Vision, hearing and balance. **Special visceral afferent (SVA)** = Smell, taste. **Special visceral efferent (SVE)** = Branchial arch striated muscles (head and neck muscle). **Ganglion** - a collection of cell bodies of neurones found in the **peripheral nervous system** e.g. dorsal root ganglion. ***Remember***: Nucleus (CNS) vs Ganglion (PNS). **Neural Tube and what they give rise to:** **Telencephalon**- Cerebral cortex and basal ganglia. **Diencephalon**- Thalamus, hypothalamus, pituitary gland, optic stalk, pineal gland. **Mesencephalon**- Midbrain. **Metencephalon**- pons and cerebellum. **Myelencephalon**- Medulla Oblongata.   **Corpus Collosum**- Nerve fibre that communicates the two hemispheres. - The **cortex** is a **6 layered** sheet of **grey matter on the outside**. - Folding this sheet **increases surface** area for the grey matter sheet. - Grey matter in **spinal cord** lies deeper than white matter in spinal cord but opposite in the brain. - **Sulcus**= Groove **Gyrus**= Ridge - **Sulcus and Fissure** are both depressions in the brain, but fissure is a deeper groove. **Central Sulcus=** Separates frontal lobe from parietal lobe. **Lateral Sulcus=** Separates temporal lobe from frontal and parietal lobes above it. *Lateral sulcus= Sylvian fissure* **Parietal occipital sulcus=** Separates occipital lobe from parietal lobe.  - **Another** sulcus in occipital lobe called the Calcarine sulcus. Important landmark to identify the primary visual cortex. **Precentral Gyrus-** Primary motor area. **Postcentral gyrus-** somaesthetic (somatosensory) area.  **Primary auditory area=** Hearing **Primary visual area=** Seeing **Phineas Gage: Importance of prefrontal cortex.** Iron rod pierced his skull, damaging his **prefrontal cortex**. Before: responsible, hardworking, and well-mannered. After: Impulsive, aggressive, and unreliable. critical role of the **prefrontal cortex** in regulating personality, emotions, and decision-making. In the 19th century, Korbinian Brodmann (German anatomist) divided the cortex into a number of regions based on fine structures and neuronal components of its six layers. These later turned out to correspond quite well to functional regions of the cortex, so his numerical system is still used today. **Ventricular System:** **Ventricles:** Spaces within the brain that are filled with cerebrospinal fluid (CSF). **Functions:** The brain floats in CSF which supports its weight, preventing compression of its blood supply. It buffers the brain against the effects of blows to the head. Also, It may wash out metabolic waste products.  **Septum Pellucidum =** Separates the right and left lateral ventricle. **Blood Supply: Arteries and Veins** **Arteries**- Carry blood **AWAY** from the **HEART** to pats of the body. (mostly move oxygenated blood to organs). **Veins**- Carry blood **TOWARDS** the **HEART** from parts of the body. (mostly drain the deoxygenated blood from the organ (via dural venous sinuses in the brain). **Brain Arterial Circulation**- Two large arteries supply the brain on each side. - **Internal carotid arteries-** Goes into the cranial cavity to supply the brain. - **Vertebral arteries-** Associated with the cervical vertebrae. The internal carotid artery gives off two major branches, one branch is known as the anterior cerebral artery, another is middle cerebral artery. The vertebral arteries, which travel up through the cervical vertebrae, converge to form the basilar artery at the base of the brain-supplies blood to brain stem etc. Gives off two terminal branches, Posterior cerebral artery and Superior Cerebellar Artery. All of this can be grouped as the VERTEBRAL BASILAR SYSTEM. **Circle of Willis**- Right and the left anterior cerebral arteries are united by the anterior communicating artery. Form a circle. Beneficial if there's a blood clot.  **Meninges:** - 3 layers of membranes surround the brain. **Dura Mater:** - Outer and inner layer of dura mater lay close together but also separate. When they separate, they form two groups of structures: - **Dural venous sinuses**, spaces that contain venous blood from the brain (blue). - **Dural partitions**. Inner meningeal layer falls inwards, dividing cranial cavity into compartments. **Dural Partitions:** Two main partitions: 1. The **falx cerebri** lies on the midline, between the two cerebral hemispheres of the forebrain. 2. The **tentorium cerebelli** lies between the occipital lobe of the cortex and the cerebellum. **Dual Venous Sinuses:** Dural venous sinuses are spaces within the two layers of the dura that drain blood from veins within the brain. **Great cerebral vein** drains venous blood from our brain and unites with the inferior sagittal synapse to form the straight sinus. The place where the **straight sinus** and **transverse sinus** meet is called the **confluence of sinuses**. The arrows in the diagram illustrate the preferred direction of venous blood flow through the dural sinuses, guided by gravity. Blood from the superior sagittal, inferior sagittal, and straight sinuses ultimately converges and flows into the transverse sinuses. From there, it drains into the sigmoid sinuses, which exit the cranial cavity through the jugular foramen, eventually reaching the internal jugular vein to return deoxygenated blood to the heart.  The sigmoid sinus is the final collecting venous structure within the cranial cavity before blood exits the skull. It curves downward in an S-shaped pathway and passes through the jugular foramen, where it becomes continuous with the internal jugular vein. This connection allows deoxygenated blood from the brain to flow out of the cranial cavity and into the internal jugular vein, which transports it back to the heart for reoxygenation. This pathway is crucial for maintaining proper cerebral venous drainage and systemic circulation. In some areas the arachnoid mater is modified to become the **arachnoid granulations**. The cerebrospinal fluid (CSF) that fills the **subarachnoid space** around the brain is drained through the **arachnoid granulations** into the **superior sagittal sinus**, which is a large venous channel. This process allows the CSF to return to the venous blood circulation, maintaining a balance in CSF volume and pressure.