1 Myology Muscles of the Anterior Neck. 2 Muscles of the Neck Overview Muscle of neck are divided...

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Myology

Muscles of the Anterior Neck

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Muscles of the Neck Overview• Muscle of neck are divided into two groups:

– Anterior• Superficial (2)• Hyoids

– Infrahyoids (4)– Suprahyoids (4)

• Scalenes (3)• Deep (4)

– Posterior• Superficial (4)• Deep (4)

• Note: Some sources divide neck into anterior, posterior, & lateral.

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Muscles of Neck Overview

• Functionality– Since these muscles cross the joints of the cervical

spine, they can move the neck at the cervical spinal joints

– If a muscle also crosses the atlanto-occipital joint (C0/C1) then it can move the head upon the neck.

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Muscles of Neck Overview

• General Rules:– If a muscle crosses the neck posteriorly, it can extend the

neck at the cervical spinal joints.

– If a muscle crosses the neck anteriorly, it can flex the neck at the cervical spinal joints.

– If a muscle crosses the neck laterally, it can laterally flex the neck at the cervical spinal joints.

– If a muscle wraps around the neck, it can cause rotation of the neck at the cervical spinal joints.

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Muscles of the Anterior Neck – Superficial (2)

• Platysma :– By function it is primarily a muscle of facial expression i.e.

innervated by CN VII.– Platysma of one side blends with contralateral side and

other facial muscles in lower face.– Considered to by remnant of a broader muscle called

panniculus carnosus found in four-legged animals. Enables horses to shake off flies and cats to raise hair on its back.

– When contracted it is reminiscent of “Creature from the Black Lagoon” creature.

• Sternocleidomastoid (SCM):– Since it attaches to sternum, SCM is considered an

accessory muscle of respiration.

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PlatysmaO: Subcutaneous Fascia of

Superior Chest

I: Mandible and subcutaneous fascia of lower face

A: Draws up the skin of superior chest and neck, creating ridges in neck skin.

Assists in drawing the lip laterally and depresses the mandible

N: CN VII (Facial nerve)

Palpation: Page 138

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O: Sternal Head: manubrium Clavicular Head: Medial clavicle

I: Mastoid process

Actions: Bilateral contraction: flexion of the neck. Unilateral contraction results in Lateral flexion of neck/head and Contralateral rotation of neck/head

N: Spinal accessory nerve (CN XI)

Sternocleidomastoid (SCM)

Palpation: Page 141

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Muscles of the Anterior Neck – Infrahyoids (4)

• All 4 infrahyoid muscles are located below the hyoid bone i.e. the pull hyoid bone inferiorly when contracted.

• All hyoid muscle are important in moving and/or fixating the hyoid bone. These functions are necessary for chewing, swallowing, & speech.

• Sternohyoid:– “Sterno” refers to sternum– “hyoid” refers to hyoid bone

• Sternothyroid:– “thyroid” refers to thyroid cartilage

• Thyrohyoid• Omohyoid:

– “Omo” refers to the shoulder

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O: Posterior aspect of the manubrium and medial clavicle

I: Inferior Hyoid

A: Depression of hyoid

N: Ansa cervicalis of the cervical plexus

Sternohyoid

Palpation: page 147

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O: Posterior Sternum and 1st costal cartilage

I: Thyroid Cartilage

A: Depression of thyroid cartilage


Sternothyroid

Palpation: page 150

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O: Thyroid Cartilage

I: Hyoid (inferior aspect)

A: Depression of hyoid and

Elevation of thyroid cartilage

N: CN XII (Hypoglossal nerve)

Thyrohyoid

Palpation: page 152

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O: Inferior Belly: Superior angle

of the scapula

Superior Belly: Clavicle via

the central bound to the clavicle

I: Inferior belly: Clavicle (via the central bound to the clavicle)

Superior belly: hyoid

A: Depression of hyoid


Omohyoid

Palpation: page 155

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Muscles of the Anterior Neck – Suprahyoids (4)

• Digastric:– “Di” means two; “gastric” means belly– External carotid lies inferior and deep to anterior belly

• Stylohyoid:– External carotid lies inferior and deep to stylohyoid

• Mylohyoid:– “mill” refers to molar teeth

• Geniohyoid:– “genio” refers to chin

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O: Posterior belly: mastoid notch of temporal bone

Anterior belly: Inner surface of the mandible

I: Hyoid (via the central tendon)

A: Elevation of hyoid, depression of the mandible, and retraction of the mandible.

N: anterior belly: CN V (Trigeminal nerve)

posterior belly CN VII (Facial nerve)

Digastric

Palpation: page 158

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O: Styloid process of temporal bone

I: Hyoid

Actions: Elevation of hyoid

N: CN VII (Facial nerve)

Stylohyoid

Palpation: page 161

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O: Entire inner surface of mandible (this muscle forms the muscular floor of the mouth)

I: Hyoid

A: Elevation of hyoid and depresses the mandible

N: CN V (Trigeminal nerve)

Mylohyoid

Palpation: page 164

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O: Inner surface of mandible, deep to the mylohyoid

I: Hyoid

A: Elevation of hyoid

N: CN XII (Hypoglossal nerve)

Geniohyoid

Palpation: page 167

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Muscles of the Anterior Neck – Scalenes (3)

• As a group, they attach superiorly from cervical TP's to inferiorly on the 1st and 2nd ribs

• As a group, scalenes flex and laterally flex the neck

• By reverse muscles action, the scalenes can elevated the 1st & 2nd rib i.e. they are also considered accessory muscle of respiration.

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O: Anterior tubercles of the TP’s of C3 – C6

I: 1st Rib

A: Bilateral contraction: flexion of the neck. Unilateral contraction causes lateral flexion and contralateral rotation of the neck. Reversed muscle action causes Elevation of 1st rib

N: Ventral rami of the cervical spinal nerves

Anterior Scalene

Palpation: page 173

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O: Posterior tubercles of the TP’s of C2 to C7

I: 1st Rib

A: Bilateral contraction: flexion of the neck. Unilateral contraction causes lateral flexion of the neck. Reversed muscle action causes Elevation of 1st rib


Middle Scalene

Palpation: page 176

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O: Posterior tubercles of the TP’s of cervical spine

I: 2nd Rib

A: Unilateral contraction causes lateral flexion of the neck.

Reversed muscle action causes Elevation of 2nd rib


Posterior Scalene

Palpation: page 179

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The Scalene Group

• Scalenes, as well as SCM, are often injured during MVA called whiplash.

• Also known as cervical acceleration deceleration (CAD) injury

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Muscles of the Anterior Neck – Deep Prevertebral Group (4)

• Called prevertebral muscles since they lie directly on the cervical spine vertebral bodies

• Important at fixating (stabilizing) and neck/head while talking, swallowing, coughing, & sneezing

• May also be injured during CAD• Longus Colli:

– Has 3 parts: superior oblique, inferior oblique, & vertical– Considered to be a strong neck flexor

• Longus Capitis• Rectus Capitis Anterior• Rectus Capitis Lateralis

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O: Bodies of the C3-T3 vertebrae

I: TP’s and Bodies of the C1-C6 vertebrae

A: Bilateral contraction causes weak flexion of neck. Unilateral contraction causes lateral flexion and contralateral rotation of the neck.


Longus Colli

For the purpose of HS 113, this muscle is not palpable

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O: TP’s of C3 – C5

I: Basilar portion of the occiput

A: Bilateral contraction causes

Flexion of head/neck.

Unilateral contraction causes

Lateral flexion of head/neck


Longus Capitis


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O: TP of the Atlas (C1)

I: Inferior surface of the basilar portion of the occiput

A: Flexion of head

N: Ventral rami of the cervical

spinal nerves

Rectus Capitis Anterior


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O: TP of the Atlas (C1)

I: Inferior surface of the Occiput

A: Lateral flexion of head


Rectus Capitis Lateralis


1 Myology Muscles of the Anterior Neck. 2 Muscles of the Neck Overview Muscle of neck are divided...

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