41 Questions
What is the primary function of cutaneous innervation?
To provide sensation to the skin
What is the name of the nerve that supplies the muscle compartment of the arm?
Axillary Nerve
What is the term for the areas of skin supplied by specific segments of the spinal cord?
Dermatomes
What is the name of the classification system used to describe injuries to the brachial plexus?
Power Modification of Leffert Classification
What is the main function of the brachial plexus?
To control movement of the upper limb
Which nerve is responsible for supplying the muscle compartment of the forearm?
Musculocutaneous Nerve
What is the term for the types of nerve fibers that control muscle movement?
Motor Innervation
What is the result of an injury to the long thoracic nerve?
Weakness of the shoulders
What does the serratus anterior muscle do?
Pulls the scapula forward and around the ribcage
What is the sign of a winging of the right scapula?
Right scapula is prominent
What is the diagnosis of Erb's Palsy?
When the baby's hand is in a waiter's tip position
What is the cause of Shoulder Dystocia?
Obstructive labor
What is the position of the baby's hand in Erb's Palsy?
Waiter's tip position
What is the nerve affected in winging of the scapula?
Long thoracic nerve
What is the condition that occurs when the anterior shoulder of the infant does not come out after the delivery of the head?
Shoulder dystocia
What is the result of excessive angulation between the neck and the shoulders?
Shoulder dystocia
What is the name of the condition caused by injury to the lower brachial plexus, resulting in wrist drop or claw hand?
Klumpke's Palsy
Which nerve is affected in Honeymoon Palsy?
Radial nerve
What is the primary cause of Klumpke's Palsy in obstetric cases?
Difficulty during vaginal delivery
What is the term for the inability to extend the wrist and fingers at the metacarpophalangeal joints?
Wrist drop
Which of the following is NOT a type of palsy caused by compression of the radial nerve?
Klumpke's Palsy
What is the resulting position of the wrist in wrist drop due to gravity?
Partly flexed
Which nerve roots are affected in Klumpke's Palsy?
C8 and T1
What is the primary cause of Horner's Syndrome in Klumpke's Palsy?
Interruption of fibers to the cervical sympathetic trunk
Which of the following is a characteristic of Klumpke's Palsy?
Weak grasp
What is the nerve that supplies the flexor carpi ulnaris muscle?
Ulnar nerve
What is the purpose of the interosseous membrane in the forearm?
To separate the anterior and posterior compartments
Which nerve supplies the posterior compartment of the forearm?
Radial nerve
What is the function of the Musculocutaneous nerve?
To provide sensory innervation to the lateral forearm
Which nerve supplies the ulnar half of the flexor digitorum profundus?
Ulnar nerve
What is the purpose of the Guyon's Canal?
To allow the ulnar nerve to pass through to the hand
What is the nerve that supplies the extensor carpi ulnaris muscle?
Radial nerve
What is the cutaneous innervation of the lateral forearm?
Lateral cutaneous nerve of the forearm
What is the nerve that supplies the brachialis muscle?
Musculocutaneous nerve
What is a common symptom of median nerve injury?
Numbness in the thumb, index, and middle fingers
What is a sign of injury to the long thoracic nerve?
Winging of the scapula
What is thenar atrophy caused by?
Carpal tunnel syndrome
What is claw hand deformity caused by?
Injury to the ulnar nerve
What is the name of the nerve that supplies the thenar muscle?
Median nerve
What is a common manifestation of median nerve injury?
Difficulty raising the arm to brush hair
What is atrophy of the deltoid muscle a sign of?
Injury to the axillary nerve
Study Notes
Musculocutaneous Nerve
- The musculocutaneous nerve pierces the coracobrachialis muscle and then goes between the brachialis and biceps brachii muscles.
- It gives cutaneous innervation to the lateral cutaneous nerve of the forearm.
- Helpful mnemonic: MMR (Musculocutaneous, Median, Radial)
Forearm Anatomy
- The forearm is divided into anterior and posterior compartments by an interosseous membrane.
- Anterior compartment: flexors, pronator, and nerve supply from the median nerve (except for Flexor Carpi Ulnaris and ulnar half of Flexor Digitorum Profundus).
- Posterior compartment: extensors, supinator, and nerve supply from the radial nerve.
Nerve Supply of the Upper Limb
- Radial nerve supplies all muscles of the posterior compartment of the forearm and serves motor and sensory functions in the arm and forearm.
- Ulnar nerve innervates only one and a half muscles (Flexor Carpi Ulnaris and ulnar half of Flexor Digitorum Profundus).
- Cutaneous innervation of the arm:
- Lateral cutaneous nerve: a continuation of the musculocutaneous nerve.
- Middle cutaneous nerve: an independent branch of the medial cord.
- Posterior cutaneous nerve: from the radial nerve.
Injuries to the Upper Trunk
- Erb's Palsy (Erb-Duchenne's Palsy): a specific case of obstetric injury that occurs during delivery, where the shoulder fails to deliver shortly after the delivery of the head.
- Injury to the long thoracic nerve (C5, C6, and C7) results in weakness of the shoulders and winging of the scapula.
Median Nerve Injury
- Characterized by:
- Awakening with tingling and/or pain in the thumb, index, and middle fingers.
- Gradual numbness of fingers while driving.
- Difficulty raising the arm to brush hair.
- Atrophy of thenar muscles.
- Caused by:
- Carpal Tunnel Syndrome.
- High-velocity gunshot wounds.
Ulnar Nerve Injury
- Characterized by:
- Claw hand deformity.
- Atrophy of the hypothegar compartment.
Brachial Plexus
- Injuries to the brachial plexus can result in various types of palsy, such as:
- Erb's Palsy.
- Klumpke's Palsy.
- Saturday Night Palsy (Honeymoon Palsy).
- Crutches Palsy.
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