Definition: The ulnar nerve is a peripheral nerve which originates at the brachial plexus from the medial cord of nerve roots C8 and T1. This nerve is the largest unprotected nerve of the human body, thus making it prone to injury. The ulnar nerve runs along the medial aspect of the arm passing posteriorly to […]

Definition: The median nerve is a peripheral nerve originating at the brachial plexus from the lateral and medial cords of the ventral roots of C6, C7, C8 and T1. The median nerve enters the arm through the axilla at the inferior border of the teres major muscle. Its descent continues running alongside the brachial artery, […]

Definition: Blood supply to the spinal cord is supplied by three main arteries which travel along the length of the spinal cord, originating at the brain, and receiving numerous tributaries along their course. These three main arteries are named: the anterior, left and right spinal arteries. These arteries travel alongside the spinal cord within the […]

Definition: The radial nerve is a peripheral nerve, originating from the posterior cord of the brachial plexus, at nerve roots C7, C8, and T1. It provides the medial and lateral heads of triceps brachii with motor innervation, as well as the extensors of the wrist, brachioradialis, and the overlying skin and articulation with sensory information. […]

Definition: The posterior column, also known as the dorsal column, consists of the white matter within the dorsomedial portion of the spinal cord. It is composed of the fasciculus gracilis and cuneatus, which itself is part of the dorsal funiculus. Its primary role is to convey afferent information regarding fine touch, vibration, barognosis, graphesthesia, stereognosis, […]

Definition: The spinothalamic tracts, sub-divided into anterior and lateral spinothalamic tracts are responsible for conveying sensory information to the thalamus. The lateral spinothalamic tract transmits information regarding pain and temperature, whereas the anterior spinothalamic tract conveys information about crude, poorly localised touch, and pressure. A lesion within this system describes a pathological process with the […]

Definition: The femoral nerve is a peripheral nerve which originates from the lumbar plexus at levels two to four, and lies in the antero-medial portion of the thigh, running distally towards the medial aspect of the knee giving rise to numerous branches along its course. It can be anatomically separated into an anterior and posterior […]

Definition The corticospinal tract is primarily responsible for relaying impulses between the motor cortex of the brain and the skeletal muscles. It is subdivided into an anterior and a lateral corticospinal tract. Corticospinal tract lesions defines any pathological process capable of negatively affecting the function of this tract. Causes There are numerous different types of […]

Definition The axillary nerve also known as the circumflex nerve, emerges from the brachial plexus, derived from the fifth and sixth cervical nerve roots of the upper trunk, and posterior division of the posterior cord. The axillary nerve wraps around the anatomical neck of the humerus, giving of an anterior and posterior branch. Axillary nerve […]

Definition The anal reflex, also known as the anal wink, anocutaneous reflex, and perineal reflex is a reflexive contraction of the external anal sphincter upon stroking of the skin surrounding the anus. Causes The contraction is elicited by the anal sphincter muscles supplied by the second, third, and fourth sacral spinal cord segments, upon detection […]

Definition Lesions in the peripheral nervous system affecting neurons after their synapses in the anterior gray horn of the spinal cord or after their synapses in the ganglia of the cranial nerves. These neurons send impulses to the skeletal muscles by way of the ventral roots and spinal peripheral nerves. Or in the case of […]

Definition: This implies lesions of the corticospinal tracts. These are made up of the neurones which control voluntary movement. A lesion affecting these neurones anywhere from their origin (where their cell bodies reside) in the motor cortex or the pre-central gyrus ( the region between the frontal and parietal lobes) and throughout the course of […]