Neuroanatomy 2 Flashcards
Diencephalon Components (3)
Epithalamus
Thalamus
Hypothalamus
*superior to midbrain
Thalamus
80% of diencephalon
-Paired oval masses of grey matter organized into nuclei
-Major relay centre for sensory impulses (exception= smell/olfaction)
-Also contributes to motor functions by transmitting information from cerebellum to primary motor cortex of cerebrum
-Plays a role in regulation of autonomic activities and maintenance of consciousness
-Internal capsule sits lateral to thalamus, is a thick band of white matter (axons pass through for info from thalamus to cerebral cortex)
Hypothalamus
Major regulator of homeostasis, produces hormones that act on pituitary gland, regulates emotional and behavioural patterns with limbic system, circadian rhythm, internal temp.
*autonomic system
Infundibulum connects hypothalamus to pituitary gland
Epithalamus
Contains Habenular nuclei for smell/olfaction, and Pineal gland that is also part of endocrine system, secretes hormone melatonin to help regulate circadian rhythm
Brainstem 3 Components
Midbrain
Pons
Medulla Oblongata
Medulla Oblongata
Continuation of the superior part of the spinal cord, forms the inferior part of the brainstem
*begins at foramen magnum, extends up to inferior border of pons
Contains all sensory (ascending) and motor (descending) tracts that connect the spinal cord to the brain
*Anterior aspect of the medulla has 2 prominent bulges called pyramids
Decussation of Pyramids
-90% of axons cross to opposite side, crossing is called the decussation of pyramids
-Allows for contralateral control
Pons
-Superior to medulla, anterior to cerebellum
-Contains a control centre for respiration
-Transmit signals between your forebrain and cerebellum. The pons is essential in sending information to your body, giving you sensory cues and motor information
Midbrain
-Extends upward from pons to diencephalon
-Involved in auditory and visual pathway
*cerebral aqueduct passes through midbrain to connect 3rd and 4th ventricles
Contains superior colliculi (vision) and inferior colliculi (hearing)
Cranial Nerves
-Cranial nerves numbered cranial to caudal by Roman numerals
-Names indicate the distribution, structure and function
*12 pairs of nerves, part of the PNS
12 Cranial Nerves
- Olfactory (S)
- Optic (S)
- Oculomotor (M)
- Trochlear (M)
- Trigeminal (B)
- Abducens (M)
- Facial (B)
- Vestibulocochlear (S)
- Glossopharyngeal (B)
- Vagus (B)
- Accessory (M)
- Hypoglossal (M)
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Cranial Nerve Classification/Function
Sensory nerves: contain axons of sensory neurons- 1, 2, 8
Motor nerves: contain axons of motor neurons- 3, 4, 6, 11, 12
Mixed nerves: contains axons of sensory and motor neurons- 5, 7, 9, 10
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CN I
Olfactory Nerve (S)
Function: olfaction (smell)
Exits: cribriform plate
CN II
Optic Nerve (S)
Function: vision (sight)
Exits: optic canal
CN III
Oculomotor Nerve (M)
Function: movement of eyeballs (4 out of 6 muscles)
Exits: superior orbital fissure
CN IV
Trochlear Nerve (M)
Function: movement of eyeballs (superior oblique muscle)
Exits: superior orbital fissure
CN V
Trigeminal nerve (B)
Function: sensory innervation to the face, motor innervation to muscles of mastication
3 Branches:
Ophthalmic branch (V1)- exits superior orbital fissure
Maxillary branch (V2)- exits foramen rotundum
Mandibular branch (V3)- exits foramen ovale
CN VI
Abducens Nerve (M)
Function: movement of eyeballs (lateral rectus muscle)- abducts
Exits: superior orbital fissure (3, 4, 5, 6 s.o.f)
CN VII
Facial Nerve (B)
Function: control muscles of facial expression, taste for anterior 2/3 tongue
Exits: stylomastoid foramen
CN VIII
Vestibulocochlear Nerve (S)
Function: hearing and equilibrium
Exits: Internal acoustic meatus
CN IX
Glossopharyngeal Nerve (B)
Function: taste for posterior 1/3 tongue, motor for throat and mouth (swallowing)
Exits: jugular foramen
CN X
Vagus Nerve (B)
Function: autonomic regulation
Exits: jugular foramen
CN XI
Accessory Nerve (M)
Function: innervation of trapezius and sternocleidomastoid muscles
Exits: jugular foramen and foramen magnum
CN XII
Hypoglossal Nerve (M)
Function: speech, manipulation of food, swallowing (motor of tongue)
Exits: Hypoglossal foramen
Protective Structures of Spinal Cord (3)
- Vertebral column
- Spinal meninges (pia, arachnoid and dura mater; innermost to outermost)
- CSF
Spinal Cord Enlargements (2)
- Cervical enlargement (C4-T1)
-Supplies upper extremities - Lumbosacral enlargement (T9-T12)
-Supplies lower extremities
Spinal Cord External Anatomy (3)
- Conus medullaris
-Termination of spinal cord (between L1-L2) - Filum terminale
-Extension of pia mater, attaches spinal cord to coccyx - Cauda equina
-Lumbar, sacral and coccygeal spinal nerves (“Horses tail”)
-Nerves that don’t exit at the same level of the cord, descend to form cauda equina
Clinical Application: Lumbar Puncture
Needle carefully inserted into lumbar cistern passes harmlessly among nerve roots, allowing safe sampling of CSF
Lumbar cistern= enlarged aspect of CSF created from separation of arachnoid and pia mater in area (subarachnoid space)
Internal Structure of Spinal Cord (5)
- White matter
- Grey matter
- Central canal
- Anterior median fissure
- Posterior median sulcus
White Matter Structure (3)
Posterior funiculus
Lateral funiculus
Anterior funiculus
*more superficial
Grey Matter (3)
Posterior horn
Lateral horn
Anterior horn
*more deep
