Neck

Question 1

Neck: Functional Units

Answer 1

Consits of several functional units:

1. The Vertebrae

• cervical vertebrae - 7 in number
• through their facet joints allow considerable flexibility to the neck region
• supports the head.

2. The Muscles

• sternocleidomastoid and trapezius muscles surround the posterior and lateral parts of the neck
• postural muscles lying in an intermediate layer
• deep layer which contains many proprioceptive and reflex fibres
• Anteriorly there are a series of strap muscles.

3. The Viscera

• form the passageways for air and food and consist of:
  
  • larynx and pharynx in the upper part of the neck
  • trachea and oesophagus in the lower part
• thyroid gland is found in the lower part of the neck on the lateral sides of the trachea.

4. The Carotid Sheath

• Lying bilaterally
• tubes of fascia containing the common carotid artery
  
  • lower part of the neck, the interval jugular vein and the vagus nerve.

Question 2

Support of the Skull

Answer 2

• no intervertebral discs between the base of the skull & C1 and C1 & C2
• the weight of the skull is supported by the synovial joints only
• reinforced by numerous ligaments to enhance their stability.

Question 3

Fascia of the Neck

Deep

Answer 3

• described as having a superficial investing layer and a deeper layer ensheathing the structures lying within the investing layer.
• The muscles invested:
  
  • sternocleidomastoid
  • trapezius
• Inferiorly attaches to the spine & acromion of the scapula, to the clavicle and the manubrium sterni of each side.
• Superiorly attached to the external occipital protuberance, superior nuchal line, and the mastoid process.
• Between the mastoid process and the ramus of the mandible it splits to enclose the parotid gland

Question 4

Prevertebral Fascia

Answer 4

• tough membrane covering the anterior aspect of the flexor muscles
• extends from the base of the skull to the body of the third thoracic vertebra.
• Laterally it passes in front of the scalene muscles and becomes continuous with the muscles enveloping the extensor vertebral muscles.

Question 5

Carotid Sheath

Answer 5

• attached to the base of the skull around the opening of the carotid canal superiorly
• inferiorly fuses to the with the connective tissue around the aorta.

Question 6

Pretracheal fascia

Answer 6

• delicate
• surrounds the thyroid gland

Between the layers of the deep fascia there is a potential space which can form a pathway for infection.

Question 7

Posterior Triangle

Answer 7

important structures related to the triangle are the :

• accessory nerve which crosses the triangle almost vertically from the posterior border of the sternocleidomastoid to the anterior border of the trapezius, and the
• 4 superficial branches of the cervical plexus which emerge around the posterior border of the sternocleidomastoid.
• external jugular vein passes obliquely down over the sternocleidomastoid muscle to enter the posterior triangle. It ends at the clavicle where it enters the subclavian vein.

Question 8

Anterior Triangle

Answer 8

muscles

• grouped according to their position
• suprahyoid muscles which have their origins above the hyoid bone
• infrahyoid muscles which originate below the hyoid bone

nerves

parts of the cervical plexus

vagus

hypoglossal nerves.

Question 9

Arteries of the Ant Triangle

Answer 9

• derive from the common carotid artery.
  
  • common carotid artery arises from the brachiocephalic artery on the right side of the body and directly from the arch of the aorta on the left side.
  • artery enters the neck within the carotid sheath and gives no branches.
  • divides at the level of the hyoid bone into internal and external carotid arteries.
    
    • internal carotid artery continues in the carotid sheath to the cranial base where it enters the carotid canal.
    • external artery gives off a series of branches which supply the head and neck regions.

Question 10

Veins of the Ant Triangle

Answer 10

• internal jugular vein is the main vein of the neck.
  
  • emerges from the base of the skull and travels in the carotid sheath
  • receives tributaries from most of the head and neck regions
• anterior jugular veins drain the anterior region of the neck eventually draining into the internal jugular vein.

Question 11

Cervical Spinal Nerves

Answer 11

8 cervical spinal nerves which, typical of spinal nerves, divide into anterior and posterior branches

posterior branches supply the extensor muscles of the vertebral column and, except for C1, supply the skin of the posterior parts of the scalp and neck

The anterior rami form the cervical and brachial plexuses.

Question 12

Cervical Plexus (C1-C4)

Answer 12

• nerves supply the muscles and cutaneous region of the neck and also form the phrenic nerve.
• cervical plexus may be divided into superficial and deep groups
• superficial supply the skin of the anterior and lateral parts of the neck and the side of the head while the deep group supplies muscle.

Question 13

Lymphatic Drainage

Answer 13

• All of the lymph vessels in the head & neck drain into the deep cervical lymph nodes
  
  • ​either directly from the tissues
  • or indirectly after passing through other groups of nodes.
• The efferent vessels of the deep cervical nodes form the jugular trunk which enters the thoracic duct on the left and on the right, usually end by entering the venous system at the junction of the internal jugular and subclavian veins.