Comparative Anatomy and Physiology of Animals
Lecture 29 The CNS and its structure 01/03/21
The Central Nervous System
- Parts of the nervous system encased in bone: the brain and the spinal cord.
- The brain has three parts common to all mammals: the cerebrum, the cerebellum, and the
brain stem.
The Cerebrum
- The largest part of the brain.
- It is split down the middle into two cerebral hemispheres separated by the
longitudinal cerebral fissure connected by the Corpus callosum.
- It is crossed-wired: RHS to left body, LHS to right body.
The Cerebellum
- Contains as many neurones as both cerebral hemispheres combined.
- Primarily a movement control centre.
- Extensive connections with the cerebrum and the spinal cord.
- Ipsilateral projections: RHS to right body, LHS to left body.
The Brain Stem
- Consists of a midbrain, pons, and medulla.
- A complex nexus of fibres.
- Relays information from the cerebrum to the spinal cord and
cerebellum, and vice versa.
- The site where vital functions (breathing, consciousness, and
the control of the body temperature) are regulated.
- It is the most primitive part of the mammalian brain, the
most important to life.
The Spinal Cord
- Encased in the bony vertebral column and attached to the brain
stem.
- The major conduit of information from the skin, joints, and muscles
of the body to the brain and vice versa.
- Communicates to the body via the spinal nerves of the peripheral
nervous system.
The Somatic PNS
- All the spinal nerves that innervate the skin, the joints, and the
muscles that are under voluntary control.
The Visceral PNS
- The involuntary, vegetative, or autonomic nervous system.
- All of the neurones innervating internal organs, blood vessels, and
glands.
- Visceral sensory axons: information about visceral functions (blood
pressure and oxygen content in the arteries) to the central nervous system.
- Visceral motor fibres: contraction and relaxation of smooth muscles. Emotional reactions
beyond voluntary control, such as blushing.
, Afferent and Efferent Axons
- Afferent: carry to, towards the somatic or visceral sensory axons bringing information into
the CNS.
- Efferent: carry from, away from the axons from the CNS; innervating muscles and glands.
The 12 Pairs of Cranial Nerves
Lecture 29 The CNS and its structure 01/03/21
The Central Nervous System
- Parts of the nervous system encased in bone: the brain and the spinal cord.
- The brain has three parts common to all mammals: the cerebrum, the cerebellum, and the
brain stem.
The Cerebrum
- The largest part of the brain.
- It is split down the middle into two cerebral hemispheres separated by the
longitudinal cerebral fissure connected by the Corpus callosum.
- It is crossed-wired: RHS to left body, LHS to right body.
The Cerebellum
- Contains as many neurones as both cerebral hemispheres combined.
- Primarily a movement control centre.
- Extensive connections with the cerebrum and the spinal cord.
- Ipsilateral projections: RHS to right body, LHS to left body.
The Brain Stem
- Consists of a midbrain, pons, and medulla.
- A complex nexus of fibres.
- Relays information from the cerebrum to the spinal cord and
cerebellum, and vice versa.
- The site where vital functions (breathing, consciousness, and
the control of the body temperature) are regulated.
- It is the most primitive part of the mammalian brain, the
most important to life.
The Spinal Cord
- Encased in the bony vertebral column and attached to the brain
stem.
- The major conduit of information from the skin, joints, and muscles
of the body to the brain and vice versa.
- Communicates to the body via the spinal nerves of the peripheral
nervous system.
The Somatic PNS
- All the spinal nerves that innervate the skin, the joints, and the
muscles that are under voluntary control.
The Visceral PNS
- The involuntary, vegetative, or autonomic nervous system.
- All of the neurones innervating internal organs, blood vessels, and
glands.
- Visceral sensory axons: information about visceral functions (blood
pressure and oxygen content in the arteries) to the central nervous system.
- Visceral motor fibres: contraction and relaxation of smooth muscles. Emotional reactions
beyond voluntary control, such as blushing.
, Afferent and Efferent Axons
- Afferent: carry to, towards the somatic or visceral sensory axons bringing information into
the CNS.
- Efferent: carry from, away from the axons from the CNS; innervating muscles and glands.
The 12 Pairs of Cranial Nerves
