---
title: "Anterior Scalene | Anatomy and Physiology I"
description: "Anterior scalene is a neck muscle that bends the neck and lifts the first rib during inhalation, linking axial muscles to breathing in Anatomy and Physiology I."
canonical: "https://fiveable.me/anatomy-physiology/key-terms/anterior-scalene"
type: "key-term"
subject: "Anatomy and Physiology I"
unit: "Unit 11"
---

# Anterior Scalene | Anatomy and Physiology I

## Definition

The anterior scalene is a deep neck muscle on the side of the cervical spine. In Anatomy and Physiology I, you learn it as a neck flexor and an accessory muscle of inhalation that elevates the first rib.

## What It Is

The anterior scalene is a deep muscle in the side of the neck, part of the scalene group. In Anatomy and Physiology I, it is usually identified as one of the muscles that runs from the cervical vertebrae to the first rib, which is why it matters for both neck movement and breathing.

Its main actions are lateral flexion of the neck and elevation of the first rib. Lateral flexion means tilting the head toward the same side, so if the right anterior scalene contracts, the head can tip slightly to the right. When the neck is fixed, the muscle can help pull the first rib upward during inhalation. That makes it an accessory muscle of respiration, especially when breathing becomes more forceful than quiet resting breathing.

The phrase accessory muscle matters here. The diaphragm does most of the work during normal inhalation, but the anterior scalene can assist when you need extra air, such as during exercise or respiratory distress. By lifting the first rib, it increases the upper size of the thoracic cage a little, which helps air move into the lungs. It does not replace the diaphragm, and it is not the main breathing muscle, but it becomes more noticeable when breathing demands increase.

Anatomy students often place the anterior scalene in the neck region because it sits deep to more obvious surface muscles, including the sternocleidomastoid muscle. That makes it easy to miss on a superficial diagram. When you are labeling a muscle image, look for a small deep muscle attaching from the cervical vertebrae to the first rib rather than a broad sheet or a jaw muscle.

Another useful way to think about it is by action and location together. If a muscle runs from the cervical spine to a rib, it is likely to influence both posture and the rib cage. The anterior scalene is a good example of how one muscle can connect the musculoskeletal system to respiration. In lab practicals, that often shows up as a need to identify where it is, what it attaches to, and which movement it creates.

## Why It Matters

The anterior scalene matters because it connects two big Anatomy and Physiology I ideas: skeletal muscle action and respiratory mechanics. You are not just memorizing a neck muscle name. You are seeing how a muscle can produce movement at the cervical spine while also changing the shape of the thoracic cage during inhalation.

It also helps you separate primary from accessory breathing muscles. Students often remember the diaphragm first, but the anterior scalene is a good example of what the body recruits when breathing becomes harder. That shows up in a lot of course language around forced inhalation, exercise physiology, and clinical signs of respiratory effort.

This muscle also gives you a strong anatomy pattern to recognize. If you know where it starts and ends, you can predict its function instead of memorizing it as a random fact. That skill shows up again and again with muscles in the head, neck, and back: origin, insertion, action, and location all work together.

The anterior scalene is also useful for comparison with the other scalene muscles and with the sternocleidomastoid muscle. Those comparisons help you sort out deep versus superficial neck structures and avoid mixing up muscles that may be close together on a diagram but do different jobs.

## Connections

### Diaphragm

The diaphragm does most of the work in quiet inhalation, while the anterior scalene assists when breathing becomes deeper or more forceful. Comparing the two shows the difference between a primary respiratory muscle and an accessory one. If the diaphragm lowers the floor of the thoracic cavity, the anterior scalene helps lift the top ribs to expand the chest further.

### [Sternocleidomastoid Muscle](/anatomy-physiology/key-terms/sternocleidomastoid-muscle)

Both muscles are in the neck, but they do different jobs and have different attachment patterns. The sternocleidomastoid is a larger, more obvious surface muscle, while the anterior scalene is deeper and attaches to the first rib. They can both contribute to neck movement, but the anterior scalene is the one you connect more directly to first-rib elevation.

### [Cervical Vertebrae](/anatomy-physiology/key-terms/cervical-vertebrae)

The anterior scalene begins on the cervical vertebrae, so you need to know the neck vertebrae to understand where the muscle comes from and why it moves the neck the way it does. This connection is a good reminder that muscle action depends on what bones it crosses. The cervical spine is the fixed point in many neck movements.

### [erector spinae group](/anatomy-physiology/key-terms/erector-spinae-group)

The erector spinae group is another major muscle group that helps support posture and movement along the back and neck. Comparing it with the anterior scalene helps you see the difference between deep postural muscles and muscles that also affect respiration. Both matter in axial muscles, but they act on different regions and movements.

## On the AP Exam

A practical or image-based quiz often asks you to identify the anterior scalene on a neck diagram and describe its action. You may need to tell whether it is a neck flexor, an accessory muscle of inspiration, or both. If the question gives a scenario, think about what happens when someone needs stronger inhalation, because the muscle’s first-rib elevation is the clue.

On muscle charts, you should connect the origin and insertion to the action. If you can trace the muscle from the cervical vertebrae to the first rib, you can explain why it affects both neck position and rib movement. That same reasoning is useful on short-answer questions that ask you to compare deep neck muscles or describe breathing muscles beyond the diaphragm.

## Key Takeaways

- The anterior scalene is a deep muscle on the side of the neck that belongs to the scalene group.
- It flexes the neck laterally and helps elevate the first rib during inhalation.
- Its breathing role is accessory, which means it assists the diaphragm when breathing demand increases.
- Knowing its attachments helps you predict its actions instead of memorizing the term as a list item.
- It is easy to miss on diagrams because it sits deeper than large surface muscles like the sternocleidomastoid muscle.

## FAQs

### What is the anterior scalene in Anatomy and Physiology I?

The anterior scalene is a deep neck muscle that runs from the cervical vertebrae to the first rib. In Anatomy and Physiology I, you learn it as a muscle that laterally flexes the neck and helps lift the first rib during inhalation. That makes it part of both the muscular system and respiratory mechanics.

### Does the anterior scalene help with breathing?

Yes. It is an accessory muscle of inspiration, so it helps during stronger inhalation rather than doing most of the work all the time. By elevating the first rib, it gives the thoracic cavity a little more room for air. That is why it becomes more noticeable during exercise or lab discussion about forced breathing.

### How is the anterior scalene different from the sternocleidomastoid muscle?

Both are neck muscles, but they sit at different depths and have different roles. The sternocleidomastoid is a large, superficial muscle that is easy to spot, while the anterior scalene is deeper and connects to the first rib. The anterior scalene is the one you connect more directly to accessory inhalation.

### How do I identify the anterior scalene on a diagram?

Look for a deep muscle in the lateral neck that attaches to the first rib rather than to the jaw or skull. If a diagram shows several small muscles beside the cervical vertebrae, the anterior scalene is the one with a rib attachment. On practicals, pairing the attachment with its action is usually the fastest way to confirm it.

## Related Study Guides

- [11.3 Axial Muscles of the Head, Neck, and Back ](/anatomy-physiology/unit-11/3-axial-muscles-head-neck/study-guide/T18iHjO6luAZ0pd7)

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