USMLE Step 1 Review 01 22 The Brachial Plexus

USMLE Step 1 Review 01 22 The Brachial Plexus

On these “Gold Standard Step 1 Facts” pages you will find Free:

  • USMLE Audio Review files from our “Gold Standard USMLE Reviews”
  • Transcriptions of those files
  • And videos (as they become available)

 

The idea is that you can review for the USMLE online by:

  • Listening to the Audio
  • Following along with the transcription
  • Or by watching the video (if available)

If you like what you here, you can purchase the entire Gold Standard Step 1 MP3 audio USMLE review for your iPhone, iPod, or computer here.

Let’s continue our USMLE Review with Anatomy from the Gold Standard USMLE Step 1 Audio Review program.

 

Play USMLE Audio MP3 01 13 Anatomy Dermatomes Below

USMLE Step 1 01 13 Anatomy Dermatomes Audio

 

Begin 01 13 Anatomy Dermatomes Transcription

Skin zone innervation. The key concepts here for learning these- there’s two of them. Know the zones first, then learn the key dermatomes.

What is the zone that is the front half of the head?

  • The cranial zone.

What’s the nerve for that?

  • Cranial nerve 5, the trigeminal and its three divisions.

What’s the zone that is the back of the head, all of the neck and shoulders, and all the upper limb, except the axial and the medial arm?

  • Cervical zone.

What’s the zone of the torso?

  • The thoracic zone.

What’s the zone of the pelvis and the front of the lower limbs?

  • The lumbar zone.

What’s the zone of the anus, the penis and the posterior lower limbs?

  • The sacral zone.

Let’s turn it around.

What’s the cranial zone innervated by cranial nerve 5?

  • The front half of the head.

What’s the cervical zone?

  • The back half of the head, all the neck, the shoulders, and all of the upper limbs except for the axilla and the medial arm.

What’s the thoracic zone?

  • All the torso, the axilla and the medial arm.

What’s the lumbar zone?

  • The pelvis and the front of the lower limbs.

What’s the sacral zone include?

  • The anus, the penis, the posterior lower limbs and the bottom of the feet.

This time, I’ll name the structure and you respond with the zone.

Penis?

  • Sacral zone.

Anus?

  • Sacral zone.

Nipples?

  • Thoracic zone.

Nose?

  • Cranial zone.

Back of the head?

  • Cervical zone.

Bottom of the heels?

  • Sacral zone.

Knee caps?

  • Lumbar zone.

Shoulders?

  • Cervical zone.

Alright, key dermatomes.

What is C2?

  • The back of the skull.

What’s C6?

  • The thumb.

What is L4?

  • The big toe, and knee reflex.

What is T4?

  • The nipple.

What is T10?

  • The umbilicus.

What is S3?

  • Penis.

S5?

  • Anus.

S1?

  • Ankle reflex.

Let’s go the other way.
What is the dermatome for the back of the skull?

  • C2.

Dermatome for the thumb?

  • C6.

For the big toe?

  • L4.

For the nipple?

  • T4.

For the umbilicus?

  • T10.

For the penis?

  • S3.

For the anus?

  • S5.

For the knee reflex?

  • L4.

For the ankle reflex?

  • S1.

Let’s work on the circular dermatomes around the anus.

The anus dermatome again is what?

  • S5

Then, the ring of skin around the anus is?

  • S4.

Then there’s another ring of skin, including more of the buttocks around S4.

What’s that?

  • S3.

And then finally, around S3 and then down the back of the legs is?

  • S2.

What are the soles of the feet?

  • S1.

Alright, the cranial zone again includes what?

  • The front half of the head.

And how many divisions of that are there?

  • Three.

The first is the ophthalmic division of the trigeminal nerve, that’s cranial nerve V1. What are the two areas covered by that?

  • The forehead and bridge of the nose.

What is the second division of the cranial zone innervated by?

  • The maxillary division of the trigeminal nerve, cranial nerve V2.

There are two areas of skin in this dermatome. What are they?

  • The sides of the nose and the upper lip.

There’s a third division of the cranial zone. What’s the nerve?

  • The mandibular division of the trigeminal nerve, cranial V3.

There are five skin areas for this third division of the cranial zone. What are they?

  • The temples, ears, sides of the cheeks, the lower lip and the chin.

****END OF TRANSCRIPTION****

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