Anatomy of the Nervous System 2023-24 PDF

Anatomy Of The Nervous System Dr.Sayed Jahin Lecturer of anatomy and embryology  2 Divisions Of The Nervous System Central 1-The nervous system (CNS) is composed of the brain and spinal cord. 2-The Peripheral nervous system (PNS) is made up of peripheral nerves that connec...

Anatomy Of The Nervous System Dr.Sayed Jahin Lecturer of anatomy and embryology  2 Divisions Of The Nervous System Central 1-The nervous system (CNS) is composed of the brain and spinal cord. 2-The Peripheral nervous system (PNS) is made up of peripheral nerves that connect the CNS to the rest of the body and consist of:- 31 pairs of spinal nerves 12 pairs of cranial nerves  1- Central nervous system (CNS) It consist of Brain & Spinal cord 1- Brain Subdivision: 1- Cerebrum: RT&LT cerebral hemispheres 2- Cerebellum: below posterior part of cerebrum 3- Brain stem: formed of the following:- 1- Medulla 2- Pons 3- Midbrain Brain covering or Meninges: The brain and spinal cord are covered by a tissue known as the Dura meninges, which made up of 3 layers: 1-The dura mater is outer layer, and attached to the inside of the skull. 2-The arachnoid mater: the layer between the dura mater and the pia mater 3-The pia mater, which attached to the inner surface of the brain. The space between the arachnoid layer and the pia mater is called the Subarachnoid space and it contains theCerebrospinal fluid.  1- Cerebrum 1)The cerebrum forms the major portion of the brain 2)It is divided into the right and left cerebral hemispheres. 3)The two hemispheres are separated by a groove called the median longitudinal fissure and are joined at the bottom of this fissure by a structure called the corpus callosum which allows communication between the two sides of the brain. 4)The surface of the cerebral cortex appears wrinkled with small grooves that are called sulci and bulges between the grooves that are called gyri.  Lobes of the cerebrum: Each cerebral hemisphere has 4 lobes which are separated by large fissures:- 1-The frontal lobe are responsible for voluntary movement, speech, behavioral functions, memory, intelligence, concentration and personality. 2- The parietal lobe processes signals received from other areas of the brain (such as vision, hearing, motor, sensory and memory) 3- The occipital lobe is responsible for processing visual information. 4- The temporal lobe is involved in visual memory and allows for recognition of objects and peoples' faces, as well as verbal memory which allows for remembering and understanding language Each hemisphere generally control function on the opposite side of the body.  2- Cerebellum: The cerebellum is located at the lower back Occipital lobes of cerebrum. of the brain under theoccipital lobes of cerebrum. It is separated from the cerebrum by part of the dura called tentorium Cerebellum cerebelli. It consists of two cerebellar hemispheres connected together by structure called vermis resembling the butterfly. Function of cerebellum:- 1- Maintaining balance and coordinating movements. 2- Balance and control of eye movement 3- Enhances muscle tone and coordinates skilled voluntary movement  BRAIN STEM 1-The midbrain: Is the most upper part of the Midbrain brainstem that connects the pons and cerebellum with the cerebrum. Pons Is the shortest part of the brainstem. It contain nuclei of cranial nerves Medulla numbers 3rd & 4th cranial nerves which are responsible for eye movements.  2-Pons It contains the sensory and motor nuclei for middle four cranial nerves:5,6,7&8. Also, contains the tracts Cerebellar peduncles Cerebellum fibers linking the cerebellum with the brain stem, cerebrum and spinal cord 3- Medulla oblongata It Contains relay stations and reflex centers:- 1- Cardiovascular center: which regulates heart rate and contraction of blood vessels. 2-Respiratory center: regulates normal breathing rhythm. Contain nuclei of lower 4 cranial nerves: 9,10,11&12  Ventricles of the brain & CSF The human brain contains four cavities called ventricles. In the cerebrum→ two largest ventricles named lateral ventricles In the diencephalon (part inside the cerebrum) named:→ The third ventricle. At the back of the pons andmedulla oblongata& in front of cerebellum →The fourth ventricle These ventricles are concerned with the production and circulation ofcerebrospinal fluid Cerebrospinal Fluid(CSF): CSF is a clear fluid that surrounds the brain and spinal cord, and protect these structures from injury. This fluid circulates through channels around the spinal cord and brain where is it finally reabsorbed through systemic circulation.  Cranial Nerves: There are 12 pairs of nerves that originate from the brain itself. These nerves are responsible for specific activities in head and neck and are named and numbered as follows: Cranial nerve 1 (Olfactory nerve): Smell Cranial nerve 2(Optic nerve): Vision Cranial nerve 3(Oculomotor nerve): Eye movements Cranial nerve 4(Trochlear nerve): Eye movements Cranial nerve 5 (Trigeminal nerve): Facial sensation and movement (Abducens nerve): Eye movements Cranial nerve 6 (Facial nerve): facial expression and taste Cranial nerve 7 (Vestibulocochlear nerve): Hearing and sense of sensation (Glossopharyngeal nerve): Taste sensation and Cranial nerve 8 (Vagus nerve): Heart rate, swallowing, and balance (accessory nerve): Control of neck muscles Cranial nerve 9 (Hypoglossal nerve): Tongue movement swallowing  Spinal cord It is the part of CNS enclosed inside the vertebral canal of vertebral column Length: 45 cm in adult Begging: as a continuation of medulla oblongata Termination: at lower border of lumber vertebra number L-1. It is surrounded by spinal meninges or membranes) as the brain. Functions: 1.Transmission of neural signals between thebrainand the rest of the body. The spinal cord act as a center for 2 coordinating certain reflexes. It contains 31 pairs of. spinal nerves; 8 cervical, 12 thoracic, 5 lumbar, 5 3 sacral and 1 coccygeal spinal nerves.. 4.These spinal nerves are mixed nerves (motor and sensory).  Peripheral Nervous System PNS can be subdivided into 2 divisions: (1) Autonomic nervous system – Cranial & spinal nerves connecting CNS to heart, stomach, intestines, glands = internal organs – Controls unconscious activities (2)Somatic nervous system – Cranial & spinal nerves connecting CNS to skin & skeletal muscles –Oversees conscious activities.  Autonomic division of the nervous system can be subdivided into 2 divisions: (1) Parasympathetic Sometimes called the rest and digestsystem, as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract. It consist of cranial nerves (3, 7, 9&10) and sacral nerves of spinal nerves. (2) Sympathetic Decreases digestion, pupil size, urinary output Increases heart rate, bronchiole dilation, blood glucose, “fight or flight” - It consists of lower cervical and all thoracic spinal nerves.  The spinal cord ends at the lower border of The outer layer of the brain meninges is ……. A. T12 A.Pia mater B. L1 B.Dura mater C. L2 C.Arachnoid mater D. L3 D. Choroid plexus The number of cervical spinal nerves is: The part of the brain that maintains the balance and A. 12 coordination is: B. 5 C. 4 A. Cerebrum D. 8 B.Medulla The part of the peripheral nervous system that control C. Pons involuntary activities is: D.Cerebellum A. Somatic NS The cardiovascular center is present in which part of B. Spinal NS C. Autonomic NS the brain? D. Central NS The type of autonomic nervous system that act during the A. Cerebrum rest is: C. Pons B.Medulla A. B. Parasympathetic D. Cerebellum C. D. Somatic Sympathetic The ventricles found in the cerebrum named as: - Central A. Fourth ventricle The nerves that arise from the brain named as: B. The lateral ventricles A. Spinal C. Third ventricle B. Cerebral D. Subarachnoid space C. Cranial D. Peripheral