Muscle Fiber Anatomy: Basic Sarcomere Subdivisions The basic function of skeletal muscle is to move various parts of the body via muscle contraction. Muscle structure is specifically related to its function. Muscles are composed of numerous multinucleated muscle cells called…
Neuromuscular Junction The outflow of nearly all behavior depends upon the neuromuscular system, where nerves emanating from the spinal cord and brainstem make connections with skeletal muscles that allow us to move, stand, and express ourselves. The numbers of skeletal…
Peripheral Nervous System: Overview The major function of the nervous system is the transmission and processing of information. This relies on propagation of electrical signals between the peripheral nervous system and the central nervous system. The somatic peripheral nervous system…
Neonatal Hypotonia Neonatal hypotonia, often referred to as the “floppy infant,” is the main presenting clinical feature of most neuromuscular diseases of early life. However, disorders of the central nervous system may also manifest with hypotonia. Two types of muscle…
Pain Pathways Anatomy Ascending Pathways Endorphin System Pain propagation is initiated with activation of nociceptors, distributed within skin, muscle, joints, and viscera. These receptors include small-diameter Aδ and C-fiber free nerve endings representing distal primary afferent neurons. Cutaneous Aδ fibers…
General Topography of Autonomic Nervous System The nervous system is divided into somatic and autonomic divisions: the somatic division controls predominantly voluntary activities, while the autonomic system regulates involuntary functions. The two divisions develop from the same primordial cells; they…
Peripheral Nerve The main function of the peripheral nerve is to rapidly conduct electrical signals between the central nervous system and end organs. The neuronal cell body is the main functional component that maintains the neuron and produces important structural…
Compression Neuropathies Compression neuropathies occur acutely (e.g., proximal radial nerve palsy, peroneal neuropathy at the fibular hear) or more gradually (e.g., median neuropathy at the wrist, ulnar neuropathy at the elbow). Acute compressive neuropathies typically develop at sites where external…
Cervical Disk Herniation Cervical disk disease is a common disorder, accounting for 1% to 2% of all hospital admissions in the United States. Unlike lumbar disk disease, which is approximately six times more common, cervical disk disease is rarely caused…
Spinal Column The spinal column is built up from alternating bony vertebrae and fibrocartilaginous disks, which are intimately connected by strong ligaments and supported by powerful musculotendinous masses. The individual bony elements and ligaments are described in Plates 3-2 to…