Neuro anatomy gross

• Divisions of the nervous system

  • Central nervous system (Brain & spinal cord)
  • Peripheral nervous system
  • Cranial Nerves
  • Spinal nerves
  • Autonomic nervous system
  • Sympathetic nervous system
  • Parasympathetic nervous system
• Telencephalon (or cerebrum)


  Consists of two cerebral hemispheres plus a small mid-line component called lamina terminalis
• Lamina terminalis

  • Forms the rostral wall of the third ventricle and contains the rostral commissure
• Lobes of the cerebral hemisphere

  • Frontal lobe
  • Occipital lobe
  • Temporal lobe
  • Parietal lobe
• Cerebral hemisphere

  • Composed of surface gray matter called cerebral cortex, underlying white matter and deep masses of gray matter called basal nuclei
  • Contains a cavity called the lateral ventricle
  • Each lateral ventricle communicates with the third ventricle through an interventricular foramen
• Cerebral cortex

  Superficial gray matter of the cerebral hemisphere (most of the cortex is neocortex, in contrast to old paleocortex of the piriform lobe)
• Cerebral white matter


  Contains fibers that connect neighboring or distant gyri, fibers that communicate between hemispheres, and fibers that connect the hemisphere with the brainstem
• Corpus callosum


  A mass of fibers that connect right and left cerebral hemispheres
• Internal capsule


  Fibers running to and from the brain stem
• Rhinencephalon


  The phylogenetically old portion of the cerebral hemisphere located ventrally, deals with olfaction
• Hippocampus


  A deep component of the rhinencephalon, a bilateral gray matter structure that begins deep to the piriform lobe and curves dorsally and rostrally
• Diencephalon

  Gives rise to the optic nerve, can be divided into four regions: thalamus, hypothalamus, subthalamus and epithalamus
• Thalamus

  • Composed of a large number of individual nuclei, each communicating with a region of cerebral cortex
  • All input to the neocortex relays first in the thalamus
  • The thalamus of right and left sides make contact at the midline, forming an interthalamic adhesion which obliterates the center space of the third ventricle
• Third ventricle

  • Communicates with each lateral ventricle via an interventricular foramen
  • Communicates with the fourth ventricle via the mesencephalic aqueduct
• Hypothalamus

  • Visible on the ventral surface of the diencephalon, includes the optic chiasm and mamillary bodies
  • Between these, the hypophysis (pituitary gland) is attached via a hollow stalk (infundibulum)
  • Plays an important role in controlling endocrine and autonomic functions
• Mesencephalon


  • Gives rise to oculomotor (III) and trochlear (IV) cranial nerves
  • Contains the mesencephalic aqueduct
• Tectum

  • The midbrain region dorsal to the mesencephalic aqueduct, consists of bilateral rostral and caudal colliculi
  • The rostral colliculus is a visual reflex center
  • The caudal colliculus is an auditory reflex center
• Substantia nigra

  Gray matter located immediately dorsal to the crus cerebri
• Tegmentum


  The region between the substantia nigra and the tectum, contains a mixture of gray and white matter
• Metencephalon

  Has two major components: pons and cerebellum
• Pons


  • Part of the brainstem, contains the rostral end of the fourth ventricle and gives rise to the trigeminal nerve
  • The ventral surface features bulging transverse pontine fibers which become the middle cerebellar peduncle
  • The ventral pons also includes pontine nuclei
  • The dorsal part, known as pontine tegmentum, extends from the ventral pons to the fourth ventricle
• Cerebellum

  • Divided into a median region, the vermis, and bilateral cerebellar hemispheres
  • The cerebellar surface is partitioned into folia separated by sulci
  • Histologically, consists of superficial gray matter (cerebellar cortex) and deep cerebellar white matter containing embedded cerebellar nuclei
  • Communicates with the rest of the brain via three cerebellar peduncles
• Myelencephalon (medulla oblongata)


  • Gives rise to seven cranial nerves (VI through XII) and contains most of the fourth ventricle
  • Features bilateral pyramids along the ventral surface, containing fibers which arise in the motor cortex and travel to the spinal cord as corticospinal fibers
• Choroid plexus

  • A highly vascular, villus structure that produces cerebrospinal fluid
  • A portion of each plexus passes through the lateral foramen of the fourth ventricle and spills into the subarachnoid space
• Cisterna magna


  An enlargement of the subarachnoid space, a common site for obtaining cerebrospinal fluid
• Arteries supplying the brain

  • Vertebral arteries
  • Internal carotid arteries
• Circle of Willis

  An anastomotic circle formed by the terminal branches of the vertebral and internal carotid arteries within the cranial vault
• Spinal cord

  • A cylindrical, greyish-white structure
  • Arises cranially as a continuation of the medulla oblongata
  • Travels inferiorly within the vertebral canal, surrounded by the spinal meninges containing cerebrospinal fluid
  • Tapers off at the L2 vertebral level, forming the conus medullaris
  • The spinal nerves that arise from the end of the spinal cord are bundled together, forming the cauda equina
• Cervical enlargement

  • Located at the C4-T1 level, represents the origin of the brachial plexus
• Lumbar enlargement

  • Located between T11 and L1, represents the origin of the lumbar and sacral plexi
• Spinal meninges

  • Three membranes that surround the spinal cord - the dura mater, arachnoid mater, and pia mater
  • Contain cerebrospinal fluid, acting to support and protect the spinal cord
  • Distally, the meninges form the filum terminale which attaches to the vertebral bodies of the coccyx
• Epidural space


  The space between the spinal dura mater and the walls of the vertebral canal, contains loose connective tissue and the internal vertebral venous plexus
• Dura mater

  The most external of the spinal meninges, extends from the foramen magnum to the filum terminale
• Cauda equina


  A bundle of spinal nerves that arise from the distal end of the spinal cord
• Spinal cord

  • It occupies around two thirds of the vertebral canal
  • There are two points of enlargement: the cervical enlargement at C4-T1 and the lumbar enlargement between T11 and L1
• Cauda equina


  They run in the subarachnoid space, before exiting at their appropriate vertebral level
• Spinal meninges

  Three membranes that surround the spinal cord: dura mater, arachnoid mater, and pia mater
• Filum terminale


  A strand of fibrous tissue that attaches to the vertebral bodies of the coccyx and acts as an anchor for the spinal cord and meninges
• Dura mater

  • The most external of the meninges, extending from the foramen magnum to the filum terminale
  • Separated from the walls of the vertebral canal by the epidural space
  • As the spinal nerves exit the vertebral canal, they pierce the dura mater and the dura mater surrounds the nerve root, fusing with the epineurium
• Arachnoid mater


  • A delicate membrane located between the dura mater and the pia mater
  • Separated from the pia mater by the subarachnoid space which contains cerebrospinal fluid
  • Distal to the conus medullaris, the subarachnoid space expands, forming the lumbar cistern