Video summary

Muscles of the Neck (Groups, Origin, Insertion, Function)

Main summary

Key takeaways

Educational

Main ideas / lessons

  • The neck muscles can be classified into 5 anatomical groups (the specific groupings may vary by source, but the muscles themselves are the same).
  • The video’s goal is to describe, for each group’s main muscles:
    • Origin
    • Insertion
    • Function
  • Key anatomical themes:
    • Deep muscles mainly move/fix the head and neck.
    • Lateral muscles are mostly scalenes, supporting the neck/spine and relating to nearby vessels.
    • Suprahyoid vs. infrahyoid muscles are organized by whether they attach above or below the hyoid bone, and many help stabilize the hyoid.
    • Craniothoracic muscles connect the head/neck to the thorax/shoulder region and drive major head/scapular movements.
    • Platysma is a superficial muscle involved in facial/neck skin tension.

Muscle groups covered (with origins, insertions, functions)

1) Deep muscles of the neck

Main muscles: Longus capitis, Longus colli, Rectus capitis anterior, Rectus capitis lateralis.

A) Longus capitis

  • Origin: Transverse processes of C3–C6
  • Insertion: Inferior surface of the basilar part of the occipital bone
  • Function:
    • Bilateral contraction: ventrally flexes the head (flexion)
    • Unilateral contraction: turns the head to the side

B) Longus colli (3 parts)

  • Superior oblique part
    • Origin: Transverse processes of C3–C5
    • Insertion: Anterior tubercle of the atlas (C1)
  • Vertical part
    • Origin: Body of C5–T3
    • Insertion: Body of C2–C4
  • Inferior oblique part
    • Origin: Body of T1–T3
    • Insertion: Transverse processes of C5–C6
  • Function (overall):
    • Same concept as longus capitis:
      • Bilateral contraction: flexes the neck
      • Unilateral contraction: turns the cervical vertebral column to the side

C) Rectus capitis anterior

  • Origin: Lateral mass of atlas (C1)
  • Insertion: Basilar part of the occipital bone
  • Function:
    • Unilateral contraction: lateroflexes (tilts) the head
    • Bilateral contraction: ventral flexion (flexion) of the head

D) Rectus capitis lateralis

  • Origin: Transverse process of atlas (C1)
  • Insertion: Lateral part of the occipital bone
  • Function: primarily lateral flexion of the head

2) Lateral muscles of the neck (scalenes)

Main muscles: Scalenus anterior, scalenus medius, scalenus posterior.

A) Scalenus anterior

  • Origin: Transverse processes of C3–C6
  • Insertion: Scalenus tubercle on the 1st rib
  • Function: grouped with scalenes (not separately emphasized in detail in the subtitle)

B) Scalenus medius

  • Origin: C1–C7 or C2–C7 (varies by source)
  • Insertion: Surface of the 1st rib, behind scalenus anterior
  • Function: grouped with scalenes (not separately emphasized in detail in the subtitle)

C) Scalenus posterior

  • Origin: Transverse processes of C5–C6
  • Insertion: Surface of the 2nd rib
  • Function: grouped with scalenes (not separately emphasized in detail in the subtitle)

Additional concept mentioned:

  • The subclavian artery passes between scalenus anterior and scalenus posterior, and becomes the axillary artery after passing the region.

3) Suprahyoid muscles (above the hyoid bone)

Main muscles: Digastricus (digastric), Stylohyoid, Mylohyoid, Geniohyoid.

Shared idea / common function:

  • These muscles primarily attach to the mandible/temporal bone and then connect to the hyoid bone.
  • Their common function is to fixate/stabilize the hyoid bone by pulling on it from different directions.

A) Digastricus (two bellies)

  • Posterior belly
    • Origin: Mastoid notch of the temporal bone
    • Insertion: Tendon associated with insertion at the hyoid bone
  • Anterior belly
    • Origin: Tendon associated with insertion at the hyoid bone
    • Insertion: Digastric fossa of the mandible
  • Function: pulls on the hyoid bone to keep it in place

B) Stylohyoid

  • Origin: Styloid process of the temporal bone
  • Insertion: Hyoid bone
  • Function: pulls/fixates the hyoid bone

C) Mylohyoid

  • Origin: Mylohyoid line of the mandible
  • Insertion: Hyoid bone
  • Function: contributes to hyoid stabilization

D) Geniohyoid

  • Origin: Mental spine of the mandible
  • Insertion: Hyoid bone
  • Function: contributes to hyoid stabilization

4) Infrahyoid muscles (below the hyoid bone)

Main muscles: Sternohyoid, Sternothyroid, Thyrohyoid, Omohyoid.

Shared organizing concept:

  • Located under the hyoid bone.
  • Some contain “thyro” and therefore also attach to the thyroid cartilage.

A) Sternohyoid

  • Origin: Sternum and clavicle
  • Insertion: Hyoid bone
  • Function: pulls on the hyoid to fixate it

B) Sternothyroid

  • Origin: Sternum and clavicle
  • Insertion: Thyroid cartilage
  • Function: pulls the thyroid cartilage downward

C) Thyrohyoid

  • Origin: Thyroid cartilage
  • Insertion: Hyoid bone
  • Function: fixates the hyoid bone

D) Omohyoid

  • Origin: Scapula
  • Key structure: has a tendinous intersection dividing it into:
    • Superior belly
    • Inferior belly
  • Insertion: Hyoid bone
  • Function:
    • Depresses the hyoid bone
    • May assist with elevation of the scapula in some occasions
    • The tendinous intersection is attached to the carotid sheath, so it can pull to help dilate the internal jugular vein

5) Craniothoracic muscles (cranium to thorax)

Main muscles: Sternocleidomastoideus (SCM), Trapezius, Platysma.

A) Sternocleidomastoideus (SCM)

  • Origin: Sternum and clavicle
  • Insertion: Mastoid process and superior nuchal line
  • Functions:
    • Unilateral contraction: lateral flexes head and rotates it to the opposite side
    • Bilateral contraction (anterior fibers): ventrally flexes the head
    • Bilateral contraction (posterior fibers): dorsiflexes the head

B) Trapezius (3 parts)

  • Superior part
    • Origin: Superior nuchal line, external occipital protuberance, nuchal ligament
    • Insertion: Acromial end of clavicle, and acromion of scapula
  • Middle part
    • Origin: Spinous processes of C7–T3 (or T4)
    • Insertion: Spine of scapula and acromion
  • Inferior part
    • Origin: Spinous processes of T4–T12
    • Insertion: Spine of scapula
  • Function:
    • Inferior fibers: pull shoulder downward
    • Middle + superior fibers: pull scapula toward midline and elevate scapula
    • Strong contraction may extend the head to the side
    • Primarily associated with scapular movements

Note: The subtitle mentions trapezius can be considered a back muscle depending on the source.

C) Platysma

  • Location: very superficial on the anterior neck
  • Origin: pectoral and deltoid fascia
  • Insertion: base of mandible, lower lip, and skin around the mouth
  • Function:
    • Controls tension of the neck skin
    • When tensed, fibers may protrude on the neck
    • Can depress the angle of the mouth and the mandible

Speakers / sources featured

  • Speaker: “Meditay” (listed as Meditay here)

Original video