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    Related Topics

    From Nervous System

    Spinal Cord
    Transmits neural signals between brain and body.
    Pineal Gland
    Secretes melatonin to regulate sleep-wake cycles.
    Thoracic Spinal Cord
    Middle portion of the spinal cord.
    Cerebellar Peduncles
    Connect the cerebellum to the brainstem.
    Arachnoid Mater
    Middle meningeal layer.
    Cerebrum
    Largest part of the brain responsible for voluntary actions, learning, and memory.
    Third Ventricle
    Midline cavity of the diencephalon.
    Fourth Ventricle
    Cavity between brainstem and cerebellum.
    Fornix
    Fiber tract involved in memory.
    Sacral Plexus
    Nerve network for pelvis and lower limb.
    Vagus Nerve
    Major parasympathetic nerve supplying thoracic and abdominal organs.
    Subthalamus
    Involved in motor control.
    Basal Ganglia
    Group of nuclei involved in movement regulation.
    Pons
    Connects upper and lower parts of the brain.
    Insular Cortex
    Involved in consciousness, emotion, and homeostasis.
    Epithalamus
    Contains the pineal gland, involved in circadian rhythms.
    Subarachnoid Space
    Contains cerebrospinal fluid.
    Cerebral Aqueduct
    Connects third and fourth ventricles.
    Cerebral Peduncles
    Connect the cerebrum to the brainstem.
    Filum Terminale
    Fibrous extension from conus to coccyx.
    Cauda Equina
    Bundle of spinal nerves below the conus medullaris.
    Internal Capsule
    White matter structure that carries information to and from the cerebral cortex.
    Parietal Lobe
    Processes sensory information such as touch, temperature, and pain.
    Cingulate Gyrus
    Processes emotions and behavior regulation.
    Cerebellar Hemispheres
    Lateral portions of the cerebellum.

    Brachial Plexus

    Reviewed by our medical team

    Nerve network for the upper limb.

    1. Overview

    The brachial plexus is a network of nerves that originates from the spinal cord and provides motor and sensory innervation to the upper limbs (arms and hands), as well as parts of the neck and shoulder. It is a crucial component of the peripheral nervous system, responsible for coordinating movements and sensations in the arms, shoulders, and parts of the chest. The brachial plexus is formed by the anterior rami of the lower four cervical nerves (C5-C8) and the first thoracic nerve (T1), and it branches into various nerves that innervate the muscles and skin of the upper body.

    2. Location

    The brachial plexus is located in the neck and upper chest. It arises from the anterior rami of the C5 to T1 spinal nerves, which emerge from the cervical and thoracic regions of the spinal cord. The plexus is positioned just above the clavicle (collarbone) and passes through the cervico-axillary canal, which is the passage between the neck and armpit. From there, the brachial plexus branches into various nerves that innervate the upper limbs, including the arm, forearm, and hand.

    3. Structure

    The brachial plexus consists of five major segments, which are organized in a specific order: roots, trunks, divisions, cords, and branches. Each of these segments gives rise to various nerves that provide motor and sensory innervation to the upper body.

    • Roots: The roots of the brachial plexus are the anterior rami of the C5, C6, C7, C8, and T1 spinal nerves. These roots merge to form the trunks of the plexus.

    • Trunks: The roots combine to form three trunks: the upper trunk (C5-C6), the middle trunk (C7), and the lower trunk (C8-T1). Each trunk then divides into anterior and posterior divisions.

    • Divisions: Each trunk splits into two divisions: an anterior division and a posterior division. These divisions will later rejoin to form the cords of the brachial plexus.

    • Cords: The divisions reorganize into three cords: the lateral cord (formed by the anterior divisions of the upper and middle trunks), the posterior cord (formed by the posterior divisions of all three trunks), and the medial cord (formed by the anterior division of the lower trunk).

    • Branches: The cords give rise to several major nerves that innervate the upper limb, including the musculocutaneous nerve, axillary nerve, radial nerve, median nerve, and ulnar nerve. These branches provide both motor and sensory functions to the muscles and skin of the arm and hand.

    4. Function

    The brachial plexus is responsible for transmitting motor and sensory signals between the spinal cord and the upper limbs. The main functions of the brachial plexus include:

    • Motor function: The brachial plexus controls the movement of muscles in the shoulder, arm, forearm, and hand. It innervates muscles that allow for movements such as lifting the arm, bending the elbow, and gripping objects.

    • Sensory function: The brachial plexus provides sensory innervation to the skin of the upper limbs, including the arm, forearm, and hand. This allows individuals to sense touch, pain, temperature, and proprioception (awareness of body position) in the upper extremities.

    • Reflexes: The brachial plexus also plays a role in the coordination of reflexes, such as the biceps reflex (a rapid contraction of the biceps muscle when the tendon is tapped) and the triceps reflex.

    5. Physiological Role(s)

    The physiological roles of the brachial plexus are critical for normal motor control and sensation in the upper body:

    • Upper limb movement: The brachial plexus coordinates voluntary muscle movements, allowing individuals to perform fine motor tasks such as writing, typing, or playing an instrument, as well as gross motor movements like lifting or pushing objects.

    • Grip strength and dexterity: The brachial plexus plays a key role in providing motor function to the muscles that control hand movements, allowing for grip strength and fine motor dexterity necessary for daily tasks.

    • Postural control: The brachial plexus contributes to maintaining upper body posture and stability through muscle coordination, particularly for movements involving the shoulder and arm.

    • Somatosensory perception: The brachial plexus provides sensory feedback to the brain from the skin and muscles of the upper limbs, which helps in body awareness and the adjustment of movements during tasks that require tactile feedback.

    6. Clinical Significance

    The brachial plexus is clinically significant because damage to any of its components can result in a range of disorders affecting motor and sensory functions in the upper limbs. Some common conditions include:

    • Brachial plexus injury: Injury to the brachial plexus, often resulting from trauma (such as during childbirth, car accidents, or sports injuries), can cause partial or complete loss of motor and sensory function in the arm and hand. Depending on the severity, brachial plexus injuries can lead to weakness, numbness, paralysis, and loss of function.

    • Erb's palsy: A type of brachial plexus injury that typically occurs during childbirth when excessive force is applied to the baby's head and neck, leading to damage of the upper roots (C5-C6). This condition results in weakness or paralysis of the shoulder and upper arm muscles.

    • Klumpke's palsy: A lower brachial plexus injury (affecting C8 and T1 roots) that often results from excessive pulling during childbirth or trauma. This condition causes weakness or paralysis of the hand and forearm muscles, leading to difficulty with hand movements.

    • Thoracic outlet syndrome (TOS): A condition in which the brachial plexus becomes compressed, typically between the collarbone and the first rib, leading to pain, numbness, tingling, and weakness in the arm and hand. TOS may be caused by anatomical abnormalities, repetitive movement, or injury.

    • Radiculopathy: Compression or irritation of the nerve roots that form the brachial plexus (often due to herniated discs or degenerative conditions) can result in pain, weakness, and numbness along the affected nerve pathways in the shoulder, arm, and hand.

    • Peripheral neuropathy: Damage to the peripheral nerves within the brachial plexus, often due to diabetes, infections, or toxins, can lead to sensory and motor deficits in the upper limbs.

    Damage to the brachial plexus can have a profound impact on upper limb function and quality of life. Early diagnosis and treatment are essential to prevent long-term disability, and rehabilitation strategies such as physical therapy, surgery, or nerve grafts may be used to improve recovery outcomes.

    Did you know? The human brain is the most energy-consuming organ, using around 20% of the body's total energy.