Muscles and Nerves 1 Flashcards
"Basic introduction"
Name the 3 basic functions of muscles.
Movement: skeleton, intestines, heart and blood vessels.
Static support: (keeping us upright)
Heat production: the stronger/bigger the muscle then the more heat is able to be generated.
Describe the connection of skeletal muscle to the skeleton.
Skeletal muscle is attached to the bones by tendons. However there is sometimes when there is direct attachment of the fleshy part of the muscle to bone.
Describe the structure of skeletal muscle.
The membrane cover the whole muscle is called the epimysium.
Inside the epimysium, there are multiple fascicles, which are bundles of muscle fibres.
The membrane of fascicles is called perimysium.
The individual muscle fibres have their own individual membranes, endomysium.
Describe parallel v pennate skeletal muscle.
Parallel
-Fascicles run along the long axis of the muscle.
Pennate
-Fascicles connect with the main tendon at an angle.
E.g. unipennate, bipennate, multipennate.
Describe the importance of connective tissue in muscles.
Individual muscle fibres are surrounded by an endomysium, and this is a thin layer of connective tissue.
Tendons are composed of dense fibrous connective tissues, with the main component being collagen fibres (arranged in parallel). This is important for the strength of the muscle as tendons do not shorten and can absorb and transmit muscle forces.
Describe the united function of muscles in the elbow joint.
These muscles are flexors and extensors that work in opposition with each other to allow movement of the elbow.
Describe the united function of the muscles of the shoulder joint.
The shoulder joint is stabilised by the joint action of rotator cuff muscles which embrace the shoulder joint closely.
Describe the united function of the muscles within the forearm and hand.
The forearm muscles allow for a powerful grip - these muscles are significantly larger than the muscles of the hand.
The intrinsic hand muscles for precision are much smaller.
Give an example of muscle compartments in the arm, and describe their nerve supply.
The arm has two compartments, anterior (flexor) and posterior (extensor).
The forearm has these compartments but they have slightly different names;
flexor-pronator and extensor-supinator.
All compartments in the upper limbs are supplied by the radial nerve.
Describe the basic anatomy of a motor unit.
Motor units are composed of one motor neuron and a varying number of muscle fibres, the number of fibres will increase with size (of the muscle).
Describe the basic anatomy of spinal nerves.
There are 31 pairs of spinal nerves, these are split into 5 regions.
The C1 spinal nerve exits between atlas and skull.
All nerves exit the vertebrae from the intervertebral foramen, however the cervical nerves exit above the associated vertebrae and the thoracic nerves exit below.
Describe the spinal nerve plexus.
A plexus is a network.
All nerves supplying upper and lower limbs originate in plexuses. The fibres coming from the spinal nerves, arrive at the plexus where they are rewired. They then exit the plexus as a mixture of fibres.
Name the subdivisions of the nervous system.
The structural division: Central nervous system, consisting of the brain and the spinal cord. The peripheral nervous system, consisting of the 12 cranial and 31 spinal nerves.
The functional division: Somatic (voluntary). Autonomic (involuntary): sympathetic - fight or flight, or parasympathetic (rest and digest).
+ enteric (gut).
Describe the differences between somatic pathways and autonomic pathways.
In the somatic pathway, once the nerve impulse is stimulated, there is no synapse in motor fibre so the signal is sent along one long neuron from the CNS to skeletal muscle.
In the autonomic pathway, there are presynaptic and postsynaptic portions of the pathway. A parasympathetic motor sends a signal to the heart, and then a postsynaptic sympathetic motor sends a signal to the ganglia, which sends the response to smooth and cardiac muscle, and glands.
Define the term “dermatome”
Dermatomes are areas supplied by a single spinal nerve, this is upon the skin.
