Neck Lecture 1

the neck extends from the base of the skull and the lower border of the mandible to the superior thoracic aperture. The boundaries of the superior thoracic vertebra. The superior thoracic aperture dips inferior to the clavicles

External occipital protuberance: on the occipital bone, this is superior attachment of nuchal ligament

Vertebra prominens: this is the spine of the 7th cervical vertebra

1. Atlas (C1) the transverse process can be palpated between the angle of the mandible and point just anterior and inferior to the mastoid process.
2. Hyoid bone: lies at level of 3rd cervical vertebra, superior to thyroid cartilage. Point of attachment for supra- and infra- hyoid muscles
3. thyroid cartilage: forms the larngeal prominence of the anterior neck. Largest cartilage of the larynx
4. Cricoid cartilage: inferior to thyroid cartilage . lies at level of 6th cervical vertebra
5. Jugular notch

rounded depression in the superior border of the manibrium of the sternum. It is bounded laterally by the medial ends of the clavicles

inferior to the thyroid cartilage and articulates with it. The cricoid cartliage lies at level of 6th cervical vertebra. It is shaped like a singet ring, with its wide part to the posterior and the narrow arch at the anterior

the superficial fascia of the head and neck is continuous with that of the pectoral, shoulder, and back regions. In the neck it includes the platysma muscle and cutaneous nerves

has 3 layers
1. superficial investing layer
2. pretracheal layer
3. prevertebral layer

continuous with the ligamentum nuchae posteriorly and splits to enclose trapezius and SCM on each side. continuous with anterior midline.
Forms the roof of the posterior triangle
On the deep side it invests the omohyoid muscle and contributes to the carotid sheath
continuous with fascia of the head
attaches to the clavicle, hyoid bone, and lower border of the mandible.
Envelops the muscles connected to the mandible. It also splits the enclosed parotid gland.

prolongation of the visceral fascia of the mediastinum, where it is continuous with the fibrous pericardium. It encloses the esophagus, trachea, thyroid gland, pharynx, larynx, and contributes laterally to the carotid sheath. Posteriorly this layer forms the buccopharyngeal fascia and attaches to the pharyngeal tubercle at teh base of the skull. Anteriorly it attaches to the thyroid cartilage and runs inferiorly and posterior to infrahyoid muscles to attach to the posterior side of the sternum and fibrous pericardium. The pretracheal layer of cervical fascia is generally thin, and with the carotid sheath encloses the visceral compartment of the neck.

this begins in the posterior midline and encloses the intrinsic deep muscles of the spine. It continues forward across the floor of the lateral triangle and covers the scalene muscles, where it is called scalene fascia. It then attaches to the transverse process of the cervical vertebra and splits into two layers that continue across the front of the vertebral column and fuse again as they attach to the transverse processes of the opposite side. The anterior lamina ends inferiorly by blending with the fascia on the posterior wall of the upper esophagus. The posterior lamina continues downward along the front of the thoracic vertebral column. The prevertebral layer also contributes to the carotid sheath

an extension of the prevertebral fascia that envelops the brachial plexus and axillary vessels

at the cervicothoracic aperture, the prevertebral fascia expands over the apex of the lung to form the cervical diaphragm

Pretracheal space
Retropharyngeal space

the pretracheal space is, as the name implies, directly anterior to the trachea, extending from the thyroid cartilage to the superior mediastinum. It is enclosed by the pretracheal layer of deep cervical fascia

the retropharyngeal space is a potential space between the prevertebral layer of deep cervical fascia and the buccopharyngeal fascia around the pharynx
It runs from the cranial base to the superior mediastinum at about the T2 level

spread of infection through the spaces of the neck.
With the advent of antibiotics deep infections in the neck became more treatable, and with CT they became easier to diagnose.
These spaces are routes to spread infection in the neck and into the upper mediastinum
Infections may begin in the tonsils, gums, salivary glands, sinuses, or nasopharyngeal space.

superior head: attached to mastoid process of temporal bone
two inferior heads: attached to manibrium of the sternum and superior surface of the medial third of the clavicle.

clinical landmark for the jugular vein
this fossa is created by the two inferior heads of the SCM

CN XI
variable contribution from branches of ventral rami of cervical spinal nerves C2-C4

bilaterally: bring the chin to the chest and protrude the chin
unilaterally: muscle rotates the ear toward the shoulder on the same side

torticollis
caused by shortening of the SCM and is the result of CN XI lesion

the posterior border of the SCM
the anterior border of trapezius m. & clavicle
Inferior belly of omohyoid m. crosses the posterior triangle, dividing it further into an occipital triangle above and omoclavicular/supraclavicular below

superficial side of the posterior triangle is referred to as the roof. This is formed by the superficial investing fascia. Superficial to this fascial roof is the platysma muscle located in subcutaneous connective tissue

the deep side of the posterior triangle is referred to as the floor.
The floor is formed by the muscles which are invested by the prevertebral fascia.
1. semispinalis capitis m.
2. splenius capitis m.
3. levator scapulae m.

found at the apex of the posterior triangle

inferiorly and medially, attached to the ligamentum nuchae and the spinous processes of the upper three thoracic vertebra and that of C7
At its superior and lateral extent, it attached to the mastoid process and lateral aspect of the superior nuchal line.

lateral branches of the dorsal rami of the middle cervical spinal nerves

with spleniu cervicis, splenius capitis pulls the head back (extension of the neck)
unilaterally pulls the head to the side and rotates it

attached to transverse processes of C1-C4 superiorly and inferiorly to the angle of the scapula

spinal accessory nerve is found on the superficial surface of levator scapula, but does NOT innervate levator scapula

Direct branches of C3, C4, C5 via dorsal scapular nerve

elevates the scapula
acts in complex synergy with other muscles to stabilize the shoulder.
if shoulder is fixed levator scapula pulls the head to one side

scalenus posterior and medius mm.

attached superiorly to the posterior tubercle of the 4,5,6th cervical vertebra and inferiorly to the outer edge of the 2nd rib

Innervated by branches of ventral rami of cervical spinal nerves 5-8

attached superiorly to the posterior tubercles of all cervical vertebra and inferiorly to posterior part of the 1st rib

Innervated by branches of ventral rami of cervical spinal nerves 3-8

this is usually attached to tubercles of vertebra 3-6 and at its inferior end to scalene tubercle of the first rib

innervated by branches from ventral rami of cervical spinal nerves 4-6

all the scalene muscles can act to flex the neck, bringing the head forward or forward and to one side or if the neck is help upright contraction of the scalenes raises the second rib

YES

omohyoid muscle
external jugular vein
subclavian vein
accessory nerve (CN XI)

this muscle joins the scapula and the hyoid
it has two bellies
the inferior belly crosses the posterior triangle dividing the posterior triangle into an occipital triangle above and supraclavicular triangle below

this is formed by confluence of the posterior auricular and retromandibular veins.
It crosses the SCM and runs through the roof of the posterior traingle, emptying into the subclavian vein about 2 cm above the clavicle

this is the major vein draining the upper limb
Curves through the inferior part of the posterior triangle
the subclavian vein and internal jugular vein join to form the brachiocephalic vein. It runs posterior to the clavicle and subclavius muscle, and anterior to the subclavian artery

this is a cranial nerve and has cranial and spinal roots

C1-C5

spinal root of C1-C5 and passes upward through the foramen magnum to join the cranial root from the medulla. Briefly combined roots leave the posterior cranial fossa through the jugular foramen of the skull and then the cranial roots splits off and is incorporated into CN X

the spinal roots of CN XI innervate SCM, along with branches from the second cervical spinal nerve

the accessory nerve then leaves the posterior border of the SCM, crosses the posterior triangle, and enters the deep surface of the trapezius muscle

C3 and C4

the spinal accessory nerve is the nerve most commonly damaged in the course of treatment because of its long course and relatively superficial location
Lymph node biopsies in the posterior triangle present particular risk because of their close anatomical relationship

Variable
Presumably because of branches of the cervical plexus contribute variably by individual innervation of the trapezius muscle.
May present with:
shoulder pain
limitation of arm abduction
drooping shoulder due to paralysis of trapezius
Atrophy of trapezius
Winging of scapula

TRUE
due to innervation being variable

some compensation by levator scapula muscle may occur, in which case the individual may be able to shrug (elevate shoulder) but NOT ABDUCT the arm above horizontal

secondary traction on the brachial plexus

accessory nerve innervates SCM and damage would result in weakness in turning head toward side of uninjured side against resistance