Neuroanatomy (Melissa) Flashcards
Structure and function of the brain stem?
Structure:
Midbrain
Pons
Medulla
Function:
Conduit for ascending & descending tracts connecting spinal cord to cerebrum and cerebellum
Contains important reflex centres associated with control of respiration, heart rate & blood pressure, and consciousness
Contains cranial nerve nuclei:
- Cranial nerves III - XII emerge from it.
Spinal nerves overview
Each spinal nerve has Roots that join together to form mixed* spinal nerves which then branch to reach their target structures in the body
Each segment of the spinal cord gives rise to a pair of spinal nerves that consist of:
1. Axons of motor neurons that innervate a group of muscles
2. Axons of sensory neurons that innervate a defined area of skin
3. Axons of sympathetic neurons to structures in the body wall that control body temp (blood vessels, sweat glands etc.)
What are cranial nerves?
Cranial nerves are the peripheral nerves in the head and neck, and they emerge from the brainstem (except I and II)
They follow a different pattern to spinal nerves
They can be purely sensory, purely motor, or mixed
They dont have the architecture of the spinal nerve
Cranial nerve locations
From front of brain to back of brain it goes
- Nerve I –> nerve XII
Cranial nerves arise:
- From the brain (I and II)
- From the brainstem (III through XII)
Midbrain = III and IV
Pons = V, VI, VII, VIII
Medulla = IX, X, XI, XII
They exit through the foramina (holes) in the skull
Cranial nerve names
I = Olfactory
II = Optic
III = Oculomotor
IV = Trochlear
V = Trigeminal
VI = Abducens
VII = Facial
VIII = Vestibulocochlear
IX = Glossopharyngeal
X = Vagus
XI = (Spinal) Accessory
XII = Hypoglossal
Which cranial nerves only contain sensory neurones and fibres?
I - Olfactory
- Sense of smell
- Neurones located in nasal epithelium
II - Optic
- Sense of sight
- Neurones located in retina
VIII - Vestibulocochlear
- Hearing and balance
- Neurones located in spiral ganglion and vestibular ganglion
Which cranial nerves only contain motor neurones and fibres?
III - Oculomotor
- Eye movements
- Neurones located in midbrain
IV - Trochlear
- Eye movements
- Neurones located in midbrain
VI - Abducens
- Eye movements
- Neurones located in the pons
XI - Accessory
- Motor to specific neck muscles
- Neurones located in spinal cord
XII - Hypoglossal
- Motor to tongue
- Neurones located in medulla
Which cranial nerves have a mix of motor and sensory neurones and fibres?
V - Trigeminal
- General (Head, Neck, Face, Motor, Muscles)
- Sensory neurones located throughout brainstem
- Motor neurones located in pons
VII - Facial
- Special Sensory - (Taste (gustation), Motor, Muscles (facial expression))
- Sensory neurones located throughout brainstem
- Motor neurones located in pons
IX - Glossopharyngeal
- Special sensory (gustation)
- General sensory (Tongue and Pharynx)
- Motor (Part of pharynx)
- Sensory neurones located throughout brainstem
- Motor neurones located in pons
X - Vagus
- Special Sensory (gustation)
- Motor (Part of larynx, pharynx)
- Sensory neurones located throughout brainstem
- Motor neurones located in medulla
Which cranial nerves also carry parasympathetic fibres?
III - Oculomotor
- Carries parasympathetic fibres to the eye
VII - Facial
- Carries parasympathetic fibres to nasal and salivary glands
IX - Glossopharyngeal
- Carries parasympathetic fibres to salivary glands
X - Vaus
- Carries parasympathetic fibres to heart, lungs and GI tract
What is the limbic system and what is its structure?
Relates to brain structures that deal with emotion, memory, and basic drives. Species preservation, self preservation.
Interconnected structures in telecephalon & diencephalon.
Sits on/around top of the brainstem.
Major component parts:
- Hypothalamus (output)
- Amygdala (input)
- Hippocampus (input)
What is the hypothalamus?
It is part of the diencephalon
Regulates homeostasis (autonomic control)
Helps control hunger, thirst, body temperature, hormones
Regulates sexual motivation & other emotional behaviours
Interacts with the endocrine system:
- Communicates with pituitary gland for hormone production/release
Hypothalamus role in the limbic system
It is the primary output node of the limbic system, with connections to the frontal lobes and brainstem
Receives input from hippocampus and amygdala
Suprachiasmatic nucleus - circadian rhythms
What is the amygdala?
Located within temporal lobe and is comprised of a group of nuclei
It is the emotional centre of the brain; Fear centre of the brain
Controls aggression (‘fight’) and (‘fear’)
Responsible for arousal, fear, excitement, anxiety, violence
Amygdala role in the limbic system
Has reciprocal connections with many brain regions (hippocampus, brain stem, diencephalon, olfactory cortex, etc).
Various (sensory) stimuli and autonomic input converge in amygdala
Generates ‘learned’ emotional responses
What is the hippocampus?
Located within temporal lobe
Involved in spatial memory
Memory processing (storage - short & long; consolidation, encoding, retrieving)
Hippocampus anatomy
Hippocampus (CA1 - CA4)
Dentate gyrus encompasses CA4 mainly
Parahippocampal gyrus
Subiculum (Main output)
Entorhinal cortex (Input)
