PP 03c-Gross anatomy, in more detail

Brainstem Structures: Structures: –Midbrain –Pons –Medulla

Brainstem Functions: Functions: –Genetically wired auto-control mechanism called __________ system, for vital visceral functions such as ________ and ________ vital visceral functions such as ________ and ________ With reticular projections form reticular activating system, that regulates arousal & consciousness, as they affect higher cortical functions such as thought and attention With reticular projections form reticular activating system, that regulates arousal & consciousness, as they affect higher cortical functions such as thought and attention –Connection of cortex to sensory and motor areas of face and body Ascending somato-sensory tracts Ascending somato-sensory tracts Descending motor tracts Descending motor tracts Synapses in the brainstem occur in the cranial nerve nuclei (groups of cell bodies), which are part of the pathways important for speech and swallowing Synapses in the brainstem occur in the cranial nerve nuclei (groups of cell bodies), which are part of the pathways important for speech and swallowing Reticular projections connect through thalamus = “gateway” to cortex

Midbrain Anatomy and functions: Anatomy and functions: –Tectum Superior colliculus - visual reflexes and eye/head/balance coordination Superior colliculus - visual reflexes and eye/head/balance coordination Inferior colliculus - audition Inferior colliculus - audition –Tegmentum –Basis pedunculi includes substantia nigra- Parkinson’s disease –Red nucleus (rubro-spinal pathway)

Pons Function: Function: –Regulation of sensorimotor and cranial nerve functions –Especially important for its connections to the cerebellum Anatomy: Anatomy: –Middle cerebellar peduncle –Pontine tegmentum –4 th ventricle

Medulla Oblongata Functions Functions –Modulation of sensorimotor and cranial nerve activities and –regulation of vital (cardiac, swallowing, & respiratory) centers part of ______________ system part of ______________ system Anatomy Anatomy –Descending motor (pyramidal) tract –Ascending sensory tract –Inferior olivary nucleus (hearing) –Inferior cerebellar peduncle –Sensory decussation (contralaterality) –Pyramidal decussation (contralaterality)

Cont’d Spinal Divisions (31 Pairs of Nerves) Spinal Divisions (31 Pairs of Nerves) –Cervical (n=8) –Thoracic (n=12) –Lumbar (n=5) –Sacral (n=5) –Coccygeal (n=1)

Cerebellum Function: Function: –Modification of cortical motor functions (coordination) Coordination of skilled motor activity with inputs from basal ganglia and cerebral cortex Coordination of skilled motor activity with inputs from basal ganglia and cerebral cortex –Maintenance of equilibrium, with inputs from the vestibular system Anatomy Anatomy –Surface of gray matter & medullary core of white matter –Hemispheres –Lobes (anterior posterior & floccular nodular) –Cerebellar peduncles (superior, middle, and inferior)

Cont’d Cerebellar Peduncles Cerebellar Peduncles –Connecting cerebellum with brainstem Input to Cerebellum Input to Cerebellum –Middle cerebellar peduncle- afferents from the motor cortex –Inferior cerebellar peduncle- afferents from trunk/limbs & vestibular information to cerebellum Output from Cerebellum Output from Cerebellum –Superior cerebellar peduncle- corrective feedback to opposite motor cortex, reticular formation & spinal cord

Spinal Cord: Structure Link between brain & body Link between brain & body –Regulation of sensorimotor reflexes and autonomic activities –Foramen magnum- exit point –Afferent sensory fibers, connect to afferent white matter of interneurons –Efferent motor fibers, receive connections from efferent white matter of interneurons

Spinal Anatomy Spinal Anatomy Internal Anatomy Internal Anatomy –Gray & white matters –Dorsal & ventral horns –Sensory & motor nerve fibers Spinal Nerves Spinal Nerves –Dorsal & ventral rami

Spinal Distribution Dermatomal RepresentationDermatomal Representation –Cutaneous body region receiving its sensory innervation from one spinal nerve Myotomal Representation Myotomal Representation –Muscles innervated by the motor neurons of a single spinal segment (indicated in orange, in figure on right)

Spinal nerves (PNS) carry both sensory and motor impulses

Think: Which nerves below are important for communication, and which spinal nerves do they emerge from?