Gross Anatomy of The Brain Pt. II Flashcards
What is the corpus callosum?
White matter that links the two cerebral hemispheres allowing communication
What are corona radiata?
Myelinated axons (white matter) that pass through the corpus callosum
Describe the internal capsule
Has an anterior limb and posterior limb which join to form a V shape around the lentiform nucleus
What makes up the lentiform nucleus?
The plutamen
The globule pallidus
What are basal nuclei?
Grey matter areas of cell bodies primarily involved in motor control but can have other roles
They project neurones into the thalamus which is involved in relaying this information to the cerebral cortex
Name the basal nuclei
(Basal ganglia)
Corpus striatum (caudate nucleus and lentiform nucleus)
Substantial Nigra
Subthalamic nucleus
Where is the hypothalamus found?
Inferior and anterior to the thalamus
What does the hypothalamus do?
Involved in maintaining homeostasis by monitoring internal environment and controlling autonomic systems
Controls release of hormones from pituitary which is connected via the pituitary stalk
What does the pituitary gland do?
Regulates hormone release through releasing or inhibiting hormones
Where is the pituitary gland found?
Continuous with the hypothalamus inferiorly in the middle cranial fossa and sella turcica
Give examples of hormones released from the pituitary gland
Growth hormone
Thyroid stimulating hormone
Follicle stimulating hormone
What causes acromegaly?
Over production of growth hormone by the pituitary gland
Most commonly pituitary tumour and due to slow growth of these can take years for symptoms to arise and a diagnosis to be made
What are the symptoms of acromegaly?
Growth of hands and feet
Lips, nose and tongue become larger
Voice becomes deeper
Increase in size of jaw leading to gaps between teeth
What can untreated acromegaly lead to?
High blood pressure
Diabetes
Sleep apnoea
What are ventricles and what do they do?
Cavities within the brain filled with CSF to protect the brain
They produce and circulate CSF
How is CSF produced?
By choroidal epithelial cells (modified endymal cells) of choroid plexus which are located in each ventricle
What ventricles are found in the brain?
2 lateral ventricles, one in each hemisphere
Midline 3rd ventricle
Midline 4th ventricle
What separates the lateral ventricles?
The septum pellucidum
What connects the lateral ventricles to the 3rd ventricle?
The interventricular foramen
What connects the 3rd and 4th ventricles?
The cerebral aqueduct
What happens to CSF in the 4th ventricle?
Leaves via lateral apertures and median aperture into subarachnoid space
What is the brainstem?
The connection between the cerebrum, cerebellum and spinal cord
What is found in the brainstem?
Can be split into midbrain, pons and medulla
Contains many nuclei and neuronal tracts and is the region where cranial nerves exit the brain
Where does the spinal cord begin and end?
Begins at foramen magnum of skull as continuation of medulla
Ends at L1/L2 vertebrae in adults
Describe the inferior end of the spinal cord
Known as the conus medullaris and continues as the film terminale (pia mater)
How long is the average spinal cord?
42 - 45 cm long
Where are enlargements in the spinal cord found?
Cervical enlargement between C4-T1 - contributes to the brachial plexus
Lumbosacral enlargement between T11-S1 - contributes to the lumbosacral plexus
Describe the internal structure of the spinal cord
Grey matter surrounded by white matter
Grey matter forms H shape comprising of ventral horns, lateral horns and dorsal horns
White matter forms the anterior column, lateral column and dorsal column
Central canal found in the middle of the grey matter
How are spinal nerves formed?
Rootlets emerge from the horns of the spinal cord which converge to become roots which form the spinal nerves
Which type of roots emerge from the ventral horns?
Efferent motor fibres which carry information from the CNS to the PNS
Which type of roots emerge from dorsal horns?
Sensory afferent roots which carry information from the periphery to the CNS
What happens when afferent and efferent fibres converge to form a spinal nerve?
They pass through the intervertebral foramina as a mixed structure then divide to form ventral and dorsal rami
These rami contain both sensory and motor fibres however will have a primary function - either sensory or motor
Where do spinal nerves emerge?
All emerge between adjacent vertebrae except C1 which emerges between the occipital bone of the skull and C1 (atlas)
How are cervical spinal nerves numbered
According to the vertebra below
C8 is an exception - there are 7 cervical vertebrae and 8 spinal nerves
How many thoracic, lumbar, sacral and coccygeal nerves are there and how are they numbered?
12 Thoracic
5 Lumber
5 Sacral
1 Coccygeal
Numbered according to the vertebra above
How is the spinal cord protected?
3 meningeal layers
Dura mater - outer
Arachnoid matter - middle
Pia mater - inner
Deep to the pia mater is subarachnoid space with CSF
What are myotomes?
Anatomically and functionally related groups of skeletal muscles (links with embryology) that are supplied by a specific single spinal nerve
What are dermatomes?
Localised areas of skin which are supplied by a specific single spinal nerve
