PP 03c-Gross anatomy, in PP 03c-Gross anatomy, in more detailmore detail

BrainstemBrainstem• Structures:Structures:

– MidbrainMidbrain– PonsPons– MedullaMedulla

BrainstemBrainstem• Functions:Functions:

– Genetically wired auto-control Genetically wired auto-control mechanism called __________ mechanism called __________ system, forsystem, for• vital visceral functions such as vital visceral functions such as

________ and ________________ and ________• With reticular projections form With reticular projections form

reticular activating systemreticular activating system, that , that regulates arousal & consciousness, as regulates arousal & consciousness, as they affect higher cortical functions they affect higher cortical functions such as thought and attentionsuch as thought and attention

– Connection of cortex to sensory Connection of cortex to sensory and motor areas of face and bodyand motor areas of face and body• Ascending somato-sensory tractsAscending somato-sensory tracts

• Descending motor tractsDescending motor tracts

• Synapses in the brainstem occur in the Synapses in the brainstem occur in the cranial nerve nuclei cranial nerve nuclei (groups of cell bodies), (groups of cell bodies), which are part of the pathways important which are part of the pathways important for speech and swallowingfor speech and swallowing

Reticular projections

connect through thalamus =

“gateway” to cortex

MidbrainMidbrain

• Anatomy and functions:Anatomy and functions:– Tectum Tectum

• Superior colliculus - visual reflexes and Superior colliculus - visual reflexes and eye/head/balance coordinationeye/head/balance coordination

• Inferior colliculus - auditionInferior colliculus - audition

– TegmentumTegmentum– Basis pedunculi includes substantia nigra- Basis pedunculi includes substantia nigra-

Parkinson’s diseaseParkinson’s disease– Red nucleus (rubro-spinal pathway)Red nucleus (rubro-spinal pathway)

PonsPons• Function:Function:

– Regulation of sensorimotor Regulation of sensorimotor and cranial nerve functionsand cranial nerve functions

– Especially important for its Especially important for its connections to the connections to the cerebellumcerebellum

• Anatomy:Anatomy:– Middle cerebellar peduncleMiddle cerebellar peduncle– Pontine tegmentum Pontine tegmentum – 44thth ventricle ventricle

Medulla OblongataMedulla Oblongata

• FunctionsFunctions– Modulation of sensorimotor and Modulation of sensorimotor and

cranial nerve activities and cranial nerve activities and – regulation of vital (cardiac, regulation of vital (cardiac,

swallowing, & respiratory) centersswallowing, & respiratory) centers

part of ______________ systempart of ______________ system• AnatomyAnatomy

– Descending motor (pyramidal) tract Descending motor (pyramidal) tract – Ascending sensory tractAscending sensory tract– Inferior olivary nucleus (hearing)Inferior olivary nucleus (hearing)– Inferior cerebellar peduncleInferior cerebellar peduncle– Sensory decussation Sensory decussation

(contralaterality)(contralaterality)– Pyramidal decussation Pyramidal decussation

(contralaterality)(contralaterality)

Cont’dCont’d• Spinal Divisions (31 Pairs of Nerves)Spinal Divisions (31 Pairs of Nerves)

– Cervical (n=8)Cervical (n=8)– Thoracic (n=12)Thoracic (n=12)– Lumbar (n=5)Lumbar (n=5)– Sacral (n=5)Sacral (n=5)– Coccygeal (n=1)Coccygeal (n=1)

CerebellumCerebellum• Function:Function:

– Modification of cortical motor Modification of cortical motor functions (coordination)functions (coordination)

• Coordination of skilled motor activity with inputs from Coordination of skilled motor activity with inputs from basal ganglia and cerebral cortexbasal ganglia and cerebral cortex

– Maintenance of equilibrium, with Maintenance of equilibrium, with inputs from the vestibular systeminputs from the vestibular system

• AnatomyAnatomy– Surface of gray matter & Surface of gray matter &

medullary core of white mattermedullary core of white matter– HemispheresHemispheres– Lobes (anterior posterior & Lobes (anterior posterior &

floccular nodular)floccular nodular)– Cerebellar peduncles (superior, Cerebellar peduncles (superior,

middle, and inferior)middle, and inferior)

Cont’dCont’d• Cerebellar PedunclesCerebellar Peduncles

– Connecting cerebellum with brainstemConnecting cerebellum with brainstem• Input to CerebellumInput to Cerebellum

– Middle cerebellar peduncle- afferents from the Middle cerebellar peduncle- afferents from the motor cortexmotor cortex

– Inferior cerebellar peduncle- afferents from Inferior cerebellar peduncle- afferents from trunk/limbs & vestibular information to cerebellumtrunk/limbs & vestibular information to cerebellum

• Output from CerebellumOutput from Cerebellum– Superior cerebellar peduncle- corrective feedback Superior cerebellar peduncle- corrective feedback

to opposite motor cortex, reticular formation & to opposite motor cortex, reticular formation & spinal cordspinal cord

Spinal Cord: StructureSpinal Cord: Structure• Link between brain & bodyLink between brain & body

– Regulation of sensorimotor Regulation of sensorimotor reflexes and autonomic reflexes and autonomic activitiesactivities

– Foramen magnum- exit pointForamen magnum- exit point– Afferent sensory fibers, Afferent sensory fibers,

connect to afferent white connect to afferent white matter of interneuronsmatter of interneurons

– Efferent motor fibers, receive Efferent motor fibers, receive connections from efferent connections from efferent white matter of interneuronswhite matter of interneurons

Spinal AnatomySpinal Anatomy• Internal AnatomyInternal Anatomy

– Gray & white mattersGray & white matters– Dorsal & ventral hornsDorsal & ventral horns– Sensory & motor nerve Sensory & motor nerve

fibersfibers

• Spinal NervesSpinal Nerves– Dorsal & ventral ramiDorsal & ventral rami

Spinal DistributionSpinal Distribution

• Dermatomal RepresentationDermatomal Representation– Cutaneous body region Cutaneous body region

receiving its sensory receiving its sensory innervation from one spinal innervation from one spinal nervenerve

• Myotomal RepresentationMyotomal Representation– Muscles innervated by the Muscles innervated by the

motor neurons of a single motor neurons of a single spinal segment (indicated spinal segment (indicated in orange, in figure on right)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?