Pinpoint
Muscles/Neck

Neck

sternocleidomastoid

ster-noh-kly-doh-MAS-toyd

Prominent neck muscle turns/tilts head, flexes neck, aids breathing. Visible in fitness for posture/aesthetics.

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Common Pain & Injury

Unilateral neck pain, headaches from tension. Doctor if swallowing issues.

Anatomy & Function

Origin

Sternum and clavicle (breastbone/collarbone).

Insertion

Mastoid process occiput (skull bump behind ear).

Actions

  • Ipsilateral neck flexion/rotation (turns head to same side)
  • Contralateral tilt
  • Assists forced inhalation

Innervation

Accessory nerve (CN XI) and C2-C3.

Muscle Relationships

Antagonists

Splenius capitis

Synergists

Scalenes

Trigger Points

Sternomastoid belly refers to cheek/ear; clavicular to frontal headache.

Stretches

1SCM stretch contralateral tilt
2Doorway neck stretch
3Seated neck rotation

Common Conditions

Sternocleidomastoid strainTorticollisMyofascial pain syndrome

Anatomical Parts

Right sternocleidomastoidLeft sternocleidomastoid

FAQ

What does sternocleidomastoid do?

Turns and tilts head; tenses in stress.

Sternocleidomastoid pain causes?

Poor posture, whiplash; refers to head.

How to stretch sternocleidomastoid?

Tilt/rotate head opposite to tight side.

SCM muscle twitch?

Benign fasciculations or strain.

Exercises for sternocleidomastoid

8

Also Works sternocleidomastoid

1

Related Neck Muscles

arytenoid cartilage
Paired laryngeal cartilages in throat enabling voice production via vocal cord movement. Not muscle but closest for neck; singers train supporting muscles. Vital for breathing/speaking.
Ascending part of right trapezius
The ascending part of the right trapezius is the uppermost portion of the trapezius muscle on the right side, running from the base of the skull and upper cervical spine up toward the clavicle and shoulder. It elevates the scapula (shoulder blade) and assists in neck extension and rotation, crucial for shrugging movements and maintaining upright posture during lifts. Strong ascending traps prevent neck strain in overhead presses and rows.
cervical rotator
Cervical rotators are deep neck muscles like obliquus capitis inferior and splenius cervicis that turn the head side-to-side. Located deep in the upper cervical spine, they enable rotation for looking over shoulder. Vital for neck mobility in sports and daily turns.
cricothyroid
The cricothyroid is a small intrinsic laryngeal muscle in the anterior neck, tensing vocal cords for higher pitch. Located between cricoid and thyroid cartilages, it's key for singing and speaking. Matters for vocal athletes like singers.
digastric
The digastric has anterior and posterior bellies under the jaw, opening the mouth by depressing mandible. Runs from mandible to mastoid via sling, key for chewing and yawning.
geniohyoid
Thin neck muscle under chin pulling hyoid forward/up, geniohyoid aids swallowing and tongue movement. Supports neck stability in planks.
hyoglossus
The hyoglossus is a thin tongue muscle running from the hyoid bone (under chin) up into the tongue's side. It depresses and retracts the tongue, aiding swallowing and speech. Rarely targeted in fitness, but dysfunction affects eating and breathing mechanics.
iliocostalis cervicis
Iliocostalis cervicis is the neck portion of the erector spinae, running vertically along upper back to cervical ribs. It extends and laterally bends the neck, vital for posture in overhead lifts and sports. Supports head stability in fitness.

Neck Pain Guide

Common causes and relief

Activities & Sports

See which activities use sternocleidomastoid

Pinpoint·Interactive 3D Anatomy & Exercise Guide