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Muscles which possess more motor units (and thus have greater individual motor neuron innervation) are able to control force output more finely. Motor units are organized slightly differently in invertebrates : each muscle has few motor units (typically less than 10), and each muscle fiber is innervated by multiple neurons, including excitatory ...
The brachialis muscle is innervated by the musculocutaneous nerve, which runs on its superficial surface, between it and the biceps brachii. [2] However, in 70-80% of people, the muscle has double innervation with the radial nerve (C5-T1). The divide between the two innervations is at the insertion of the deltoid. [3]
The triceps, or triceps brachii (Latin for "three-headed muscle of the arm"), is a large muscle on the back of the upper limb of many vertebrates. It consists of three parts: the medial, lateral, and long head. [1] It is the muscle principally responsible for extension of the elbow joint (straightening of the arm).
The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm. The intrinsic group are the smaller muscles located within the hand itself. The muscles of the hand are innervated by the radial, median, and ulnar nerves from the brachial plexus. [1]
It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. [2] Muscles require innervation to function—and even just to maintain muscle tone, avoiding atrophy. In the neuromuscular system, nerves from the central nervous system and the peripheral nervous system are linked and work together with muscles. [3]
A common example of reciprocal innervation, is the effect of the nociceptive (or nocifensive) reflex, or defensive response to pain, otherwise commonly known as the withdrawal reflex; a type of involuntary action of the body to remove the body part from the vicinity of an offending object by contracting the appropriate muscles (usually flexor ...
Anatomy figure: 04:03-06 at Human Anatomy Online, SUNY Downstate Medical Center – "Superficial muscles of the anterior chest wall." Anatomy figure: 05:02-07 at Human Anatomy Online, SUNY Downstate Medical Center – "Schematic illustration of a transverse section through the axilla." "Anatomy diagram: 25466.098-1".
Motor neural degeneration is the progressive weakening of neural tissues and connections in the nervous system. Muscles begin to weaken as there are no longer any motor nerves or pathways that allows for muscle innervation. Motor neuron diseases can be viral, genetic or be a result of environmental factors.