Anatomy
Summary
The brachial plexus is a complex network of nerves originating from the cervical and upper thoracic spinal cord that controls sensory and motor functions in the shoulder, arm, and hand. Injuries that occur in the upper brachial plexus present as Erb's palsy, also known as waiter's tip deformity, which results from injury to the C5-C6 nerve roots or the superior trunk of the brachial plexus. This injury is commonly caused by forced lateral neck extension and manifests as arm adduction, internal rotation, elbow extension, and wrist flexion, along with the absence of the biceps tendon reflex. Prominent causes include shoulder dystocia during childbirth and forceps delivery, as well as from motorcycle accidents.
On the other hand, Klumpke palsy stems from an injury to the C8-T1 nerve roots or inferior trunk, typically due to forced arm abduction, and results in a "claw hand" deformity. During injury to the lower trunk, this injury may co-occur with Horner syndrome (ptosis, anhidrosis, and miosis). The lower trunk can also be compromised by thoracic outlet syndrome, pancoast tumors, or anomalous cervical ribs. Injury to the long thoracic nerve (C5-C7) can result in a winged scapula, affecting the stability and mobility of the shoulder.
Lesson Outline
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FAQs
A brachial plexus injury involves damage to the network of nerves that sends signals from the spinal cord to the shoulder, arm, and hand. It occurs when these nerves are stretched or compressed, or in severe cases, severed. This could be due to physical trauma, such as during a motor vehicle accident or a sports injury, or it could result from conditions such as inflammation or tumors.
Erb's Palsy and Klumpke Palsy are both types of brachial plexus injuries, but they affect different parts of the arm. Erb's Palsy is caused by damage to the upper brachial plexus nerves (C5-C6) and typically results nternal rotation, elbow extension, wrist flexion posture and absence of the biceps tendon reflex. Klumpke Palsy affects the lower brachial plexus (C8-T1) and presents with a complete claw hand posture.
Pancoast tumors, which are lung cancers located at the extreme apex of the lung, can affect the brachial plexus due to their proximal location to the nerve network. As the tumor grows, it can compress or invade the lower part of the brachial plexus, leading to pain and neurological symptoms in the arm and hand.
Damage to the long thoracic nerve presents with a winged scapula, where the shoulder blade protrudes outwards in an abnormal position. This nerve supplies the serratus anterior muscle, which helps hold the scapula against the chest wall. When the long thoracic nerve is damaged, it can lead to a weakening or paralysis of the serratus anterior and present as the classic 'winged' scapula.
