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Term Paper on the Human Neck
Term Paper Contents:
- Term Paper on the Introduction to the Human Neck
- Term Paper on the Anatomical Features of the Human Neck
- Term Paper on the Visceral Compartment of the Human Neck
- Term Paper on the Side of the Human Neck (Quadrilateral Space)
- Term Paper on the Omohyoid
- Term Paper on the Subdivisions of Anterior Triangle of the Human Neck
- Term Paper on the Relations of Sterno Mastoid
Term Paper # 1. Introduction to the Human Neck:
ADVERTISEMENTS:
Neck is that part of body which connects the head to the upper part of trunk. It is cylindrical in shape and is like a tube.
Boundaries:
Superior:
Lower border of the body of mandible, i.e., the line joining angle of mandible to mastoid process.
ADVERTISEMENTS:
Superior nuchal line.
External occipital protuberance.
Inferior:
From anterior to posterior, neck is bounded by:
ADVERTISEMENTS:
i. Supra sternal notch of manubrium sterni.
ii. Upper surface of clavicle.
iii. Acromion process of scapula and spine of C7.
iv. Line extending from the acromion process to spine of C7 vertebra.
ADVERTISEMENTS:
Term Paper # 2.
Anatomical Features of the Human Neck:
ADVERTISEMENTS:
Consists of following layers:
1. Skin:
Skin is thin.
ADVERTISEMENTS:
2. Superficial Fascia:
Containing loose connective tissue.
A thin sheet of muscle – Platysma.
Cutaneous nerves, blood vessels and lymphatics.
ADVERTISEMENTS:
Cutaneous Nerves:
These are branches of cervical plexus formed by upper four cervical nerves:
(a) Lesser occipital nerve (C2).
(b) Great auricular nerve (C2 and C3).
(c) Transverse cervical nerve (C2 and C3).
(d) Supra clavicular nerves (C3 and C4). It divides into three branches – medial, intermediate and lateral supra clavicular nerves. They supply skin of upper part of thorax and shoulder down to 2nd intercostal space.
3. Deep Cervical Fascia (Fascia colli):
Deep fascia of the neck is a fibrous sheet that encircles the neck from all sides just like a collar.
It is divided into following layers:
(a) Investing layer of fascia
(b) Pre-tracheal fascia
(c) Pre-vertebral fascia
(d) Carotid sheath
(e) Bucco-phyaryngeal fascia.
(a) Investing Layer of Deep Fascia of Neck:
It invests the neck from all sides.
It covers all cervical structures except— platysma, superficial vessels and nerves.
Forms roof of the posterior triangle of the neck.
It splits and encloses.
a. Two muscles- Trapezius and sternocleidomastoid.
b. Two glands- Parotid and submandibular gland.
c. Two spaces- Supra sternal and supra clavicular space.
It forms two pulleys to bind the respective tendons of the digastric and omohyoid muscles.
Attachments:
Superiorly:
External occipital protuberance
Superior nuchal line
Mastoid process
Lower border of zygomatic arch.
Posteriorly:
Ligamentum nuchae
Spine of C7 vertebra.
Postero Inferiorly:
Spine of scapula
Acromion process of scapula.
Antero-Inferiorly:
Clavicle
Manubrium sterni.
Antero-Superiorly:
Symphysis menti.
Lower border of mandible.
An imaginary line joining the angle of mandible and mastoid process.
Fascia forming the roof of posterior triangle pierced by external jugular vein and supra clavicular nerves (medial, intermediate and lateral branches)
Between the angle of mandible and styloid process of temporal bone this fascia is thickened to form stylomandibular ligament, which separates parotid gland from sub-mandibular gland, this ligament is pierced by facial artery.
Supra Sternal Space of Burn’s:
Near the lower part of midline of neck fascia splits and encloses this space.
Structures present in this space are:
i. Jugular venous arch – connecting two anterior jugular veins.
ii. Lymph glands – 1 or 2.
iii. Sternal head of sternocleidomastoid muscle.
iv. Inter clavicular ligament.
Supra Clavicular Space – Contains:
i. Lower portion of external jugular vein and
ii. Supra clavicular nerves.
(b) Pre-Tracheal Fascia:
Enclosing visceral compartment of neck.
It is attached:
a. Superiorly- Hyoid bone.
b. Inferiorly- Extends into thorax and joins fibrous pericardium.
c. Laterally- It fuses with carotid sheath. Through this sheath it is continuous with the investing layer of deep fascia.
d. Medially- It splits and encloses the thyroid gland.
The pre-tracheal fascia invests the infrahyoid muscles.
It is attached to thyroid and cricoid cartilages as suspensory ligament of Berry. It binds the thyroid gland to the larynx.
(c) Pre-Vertebral Fascia:
Attachments:
i. Superiorly- It extends to the base of skull.
ii. Inferiorly- Extends into posterior mediastinum and attached to T4 vertebral body and even extends into abdomen.
iii. Laterally- It extends to the carotid sheath and via this sheath, it is connected to investing layer of deep fascia on the medial surface of sternocleido mastoid muscle.
(d) Carotid Sheath:
Carotid sheath is formed by:
Anteriorly- Pre-tracheal fascia.
Posteriorly- Pre-vertebral fascia.
Extends from base of skull to the root of neck.
Above to arch of aorta below.
Ansa cervicalis is situated on the surface of carotid sheath.
Carotid sheath encloses:
i. Internal carotid artery
ii. Common carotid artery
iii. Internal jugular vein
iv. Vagus nerve.
4. Bucco-Pharyngeal Fascia:
Extends from base of skull downwards.
It covers posterior and lateral surfaces of pharynx.
Retropharyngeal space is found between this fascia and pre-vertebral fascia – containing lymph nodes.
A fascial septum connects this fascia to pre vertebral fascia and divides into right and left retro pharyngeal space.
Term Paper # 3.
Visceral Compartment of the Human Neck:
Space between pretracheal and prevertebral fascia is occupied by viscera of neck, e.g., pharynx, larynx, oesophagus, trachea and thyroid gland.
Prevertebral fascia covers the scalene muscles and forms fascial floor of posterior triangle and continued downwards as axillary sheath, which contains axillary vessels and brachial plexus. It extends upto elbow.
Applied Anatomy:
1. Cold abscess from cervical vertebra may pass behind prevertebral fascia – it may push forward to the middle of posterior wall of pharynx. It may track down along the floor of posterior triangle of neck to the axilla via axillary sheath.
2. Abscess – formed from retro pharyngeal lymph nodes may be unilateral and pressing one side of pharynx forwards.
3. Fasciaitis- This is inflammation of fascial sheath due to infection.
4. Pre-verterbral and pre-tracheal fascia are slippery in nature allows free movement of trachea, oesophagus and pharynx during swallowing and neck movements.
5. Thyroid gland moves on swallowing because of attachment of pre-tracheal fascia to hyoid bone and thyroid cartilage.
Term Paper # 4.
Side of the Human Neck (Quadrilateral Space):
It is rectangular space.
Divided into following two triangles by sternocleido-mastoid muscle:
1. Anterior triangle neck.
2. Posterior triangle neck.
1. Anterior Triangle Neck:
Boundaries:
Anterior- Anterior midline of neck extending from symphysis menti above to middle of sternal notch below.
Posterior- Anterior border of sternocleido mastoid muscle.
Base- Lower border of mandible and line joining the angle of mandible with mastoid process.
Apex- Suprasternal notch.
2. Posterior Triangle Neck:
Situation:
Postero lateral aspect of neck.
Boundaries:
Anteriorly- Posterior border of sternomastoid muscle.
Posteriorly- Anterior border of trapezius muscle.
Base- Middle 1/3 of clavicle.
Apex- At superior nuchal line on overlapping of sternomastoid on trapezius muscle.
Floor:
Musculo fascial- Prevertebral fascia carpets the muscles forming the floor.
Semispinalis capitis
Splenius capitis
Levator scapulae
Scalenus medius
Scalenus anterior.
Roof:
Skin
Superficial fascia containing platysma and cutaneous nerves and vessels.
Investing layer of deep cervical fascia.
It is pierced by:
a. Supra clavicular nerves.
b. External jugular vein – injury may lead to air embolism.
Parts:
Inferior belly of omohyoid divides the triangle into two parts:
(a) Occipital triangle above
(b) Subclavian triangle below.
Contents of Posterior Triangle:
1. Arteries:
(a) IIIrd part of sub-clavian artery
(b) Supra scapular artery
(c) Transverse cervical artery
(d) Occipital artery
(e) Dorsal scapular artery (Occasionally present).
2. Veins:
(a) Subclavian vein
(b) External jugular vein
(c) Transverse cervical vein
(d) Supra scapular vein
(e) Occipital vein.
3. Nerves:
(a) Cervical plexus with its branches
(b) Accessory spinal nerve root
(c) Brachial plexus and its branches.
4. Lymph Nodes:
(a) Lateral group of inferior deep cervical lymph nodes.
(b) Supra clavicular group of lymph nodes.
5. Fat and connective tissue.
6. Muscle – inferior belly of omohyoid.
Nerves in Posterior Triangle:
1. Trunks of brachial plexus between scalenus anterior and scalenus medius.
2. Supra scapular nerve – C5, C6 – from Erb’s Point
3. Nerve to subclavius – C5, C6 – from Erb’s Point
4. Supraclavicular nerves – C3, C4
5. Nerve to Levator Scapulae – C3, C4
6. Nerve to Rhomboideus – C5
7. Accessory nerve (Spinal root)
8. Phrenic nerve – C3, C4, C5
9. Long thoracic nerve – C5, C6, C7
10. Lesser occipital nerve – C2, C3
11. Greater auricular nerve – C2, C3
12. Transverse cutaneous nerve of neck – C2, C3.
Term Paper # 5.
Omohyoid:
Superior belly ascends vertically in anterior triangle of neck and inserted into lower border of body of hyoid bone.
Intermediate Tendon is held in position by loop of deep fascia that slings the tendon to clavicle and Ist rib.
Inferior belly arises from supra scapular ligament and the bone of superior border of scapula near the ligament and crosses the posterior triangle in its lower part and it divides into two triangles – occipital and subclavian triangle.
Action:
Depresses the hyoid bone.
Nerve Supply:
C1, C2 and C3 via – Ansa cervicalis loop.
(A) Contents of Occipital Triangle:
(a) Occipital artery and vein.
(b) Spinal root of accessory nerve.
(c) Lymph nodes – along accessory nerve and occipital lymph nodes.
(d) Branches of cervical plexus of nerves – cutaneous and muscular branches.
(B) Contents in Subclavian Triangle:
I. Nerve:
(a) Three trunks of brachial plexus.
(b) Nerve to serratus anterior (Long thoracic C5, C6, and C7).
(c) Nerve to subclavius (C5, C6).
(d) Supra scapular nerve C5, C6.
II. Vessels:
(a) Third part of subclavian artery and vein.
(b) Supra scapular artery and vein.
(c) Transverse cervical artery and vein.
(d) Lower part of external jugular vein.
III. Lymph Nodes:
Supra clavicular chain.
Sternocleidomastoid:
Strap like muscle.
Origin:
a. By a rounded tendon from the front of the upper part of manubrium sterni.
b. By a muscular head from the medial 1/3 of upper surface of clavicle.
Insertion:
Two heads join one another and inserted on:
i. Mastoid process of temporal bone by thick tendon.
ii. Lateral (1/2) part of superior nuchal line of occipital bone by thin aponeurosis.
Nerve Supply:
Spinal part of accessory nerve and anterior rami of C2 and C3 proprioceptive in nature.
Actions:
Both muscle acting together – Extend the head at the atlanto occipital joint and flex the head during eating and lifting from pillow – flex cervical part of the vertebral coloumn.
Contraction of the muscle – Pulls the ear down to the tip of the shoulder on the same side and rotates the head, so that the face looks upward to the opposite side.
Also acts as accessory muscles of inspiration – when origin is moving and insertion end is fixed.
When head is fixed by pre and post-vertebral muscles.
Enclosed in two layers of investing layer of deep fascia.
Pierced by:
i. Accessory nerve.
ii. 4 stemomastoid arteries and 2 branches from occipital artery.
1 branch from superior thyroid artery.
1 branch from supra scapular artery.
Arterial supply by sternomastoid arteries – 4 branches.
Term Paper # 6.
Subdivisions of Anterior Triangle of the Human Neck:
It is divided by digastric muscle and superior belly of omohyoid into four parts:
1. Submental triangle
2. Digastric triangle
3. Carotid triangle
4. Muscular triangle.
1. Submental Triangle:
Boundaries:
On each side – Anteior belly of digastric.
Base – Body of hyoid bone.
Apex – Chin or symphysis menti.
Floor – Mylohyoid muscles both side.
Roof – Skin, superficial fascia, platysma and fascia colli (investing layer).
Contents:
a. Submental lymph nodes (2-3).
b. Submental veins and commencement of anterior jugular vein.
2. Digastric Triangle:
Boundaries:
Anteroinferior – Anterior belly of digastric
Postero-inferior – Posterior belly of digastric
Base – Lower border of mandible and an imaginary line-joining angle of mandible to mastoid process.
Apex – Intermediate tendon of digastric muscle bound down to hyoid bone by a facial sling.
Floor – Mylohyoid muscle anteriorly. Hyoglossus muscle and a small portion of middle constrictor posteriorly.
Roof – Skin, superficial fascia, platysma, investing layer of deep cervical fascia.
Main Contents of Digastric Triangle:
1. Submandibular gland.
2. Submandibular lymph nodes.
3. Hypoglossal nerve (XIIth C.N.).
4. Submental artery and vein, branches of facial artery.
5. Mylohyoid nerve and vessels.
6. Carotid sheath with its contents posteriorly and external carotid artery with its branches anteriorly.
7. External carotid artery with its branches – lingual artery, facial artery and posterior auricular artery.
8. Structures passing between external and internal carotid artery are:
i. Styloid process
ii. Styloglossus muscle
iii. Stylopharyngeus muscle
iv. Glassopharyngeal nerve
v. Lower end of parotid gland
vi. Pharyngeal branch of vagus nerve (X).
Digastric muscle has the following parts:
i. Posterior Belly:
Arises from medial surface of mastoid process of temporal bone (mastoid notch).
This passes – downwards and forwards across carotid sheath and ends in intermediate tendon. It pierces the stylohyoid insertion and held in position by a loop of deep fascia – bounds the tendon to the junction of body and greater cornu of hyoid bone.
ii. Anterior Belly:
Attached to the lower border of the body of mandible near median plane (Digastric notch of mandible).
Nerve Supply:
Facial nerve supplies posterior belly. Anterior belly by nerve to mylohyoid (V3).
Action:
Depresses the mandible or elevates the hyoid bone.
Relations of Posterior Belly of Digastric:
I. Superficial Relations:
1. Mastoid process.
2. Muscles attached to mastoid process – sternocleido mastoid, splenius capitis and longissimus capitis.
3. Lower part of parotid gland.
4. Retro mandibular vein.
5. Stylohyoid muscle.
6. Submandibular gland.
7. Submandibular lymph nodes.
8. Angle of mandible with insertion of medial pterygoid.
Upper border is related to – posterior auricular artery and stylohyoid muscle.
Lower border is related to – occipital artery.
II. Deep Relations:
1. Transverse process of atlas.
2. Rectus capitis lateralis.
3. Obliqus capitis superior.
4. External carotid artery.
5. Lingual artery.
6. Facial artery.
7. Occipital artery.
8. Internal carotid artery.
9. Vagus, accessory and hypoglossal nerve.
10. Internal jugular vein.
11. Upper deep cervical group of lymph nodes.
Mylohyoid Muscle:
Arises from mylohyoid line on medial aspect of body of mandible.
Insertion:
On median fibrous raphe extending from mid-point of symphysis menti above middle of body of hyoid bone below.
It forms a diaphragm for floor of mouth and is continuous with the mylohyoid muscle of opposite side through mid-line raphe that extends from the mandible to the hyoid. Superficial to mylohyoid is anterior belly of digastric muscle both derived from mandibular arch in embryo and are innervated by V3 (mylohyoid nerve).
Hyoglossus:
Arises from greater cornu and body of hyoid bone and inserts into tongue.
Important relation with XIIth nerve (hypoglossal) on its external surface and lingual artery on its internal surface in digastric triangle.
Middle Constrictor of Phyarnx:
Arises from V shaped union of greater and lesser omohyoid bone and from stylohyoid ligament that attaches to lesser cornu. Its fibres pass posteriorly to lateral wall of pharynx.
Stylohyoid Muscle:
Origin:
From styloid process of temporal bone.
Insertion:
Into junction of the body with greater cornu of hyoid bone. Tendon is pierced by intermediate tendon of digastric near its insertion.
Action:
i. Pulls the hyoid bone upward and backward
ii. Keep the hyoid in its position.
Nerve Supply:
Branch from facial nerve.
3. Carotid Triangle:
Boundaries:
Antero-superiorly – Posterior belly of digastric and stylohyoid muscle
Antero-inferiorly – Superior belly of omohyoid muscle
Posteriorly – Anterior border of sterno cleidomastoid muscle
Roof – Skin, superficial fascia, platysma, cervical branch of facial nerve, transverse cutaneous nerve of neck. Investing layer of deep cervical fascia.
Floor – Thyrohyoid and hyoglossus muscle – anteriorly, middle and inferior constrictor of pharynx posteriorly.
Contents of Carotid Triangle:
A. Arteries:
1. Common carotid artery with carotid sinus and carotid body at its termination.
2. Internal carotid artery.
3. External carotid artery with its superior thyroid, lingual, facial, ascending pharyngeal and occipital branches.
B. Veins:
1. Internal jugular vein.
2. Common facial vein – draining into internal jugular vein.
3. Pharyngeal vein – open into internal jugular vein or common facial vein.
4. Lingual vein – open into internal jugular vein
C. Nerves:
1. Vagus nerve – running – vertically downwards postero medial to internal jugular vein.
2. Superior laryngeal branch of vagus nerve dividing into external and internal laryngeal nerve.
3. Spinal accessory nerve – running downwards on internal jugular vein.
4. Hypoglossal nerve – running forwards over external and internal carotid artery. Hypoglossal nerve gives off upper root of ansa cervicalis C1 fibres (Descendens Hypoglossi) and another branch to thyrohyoid.
5. Sympathetic chain – runs vertically downwards posterior to carotid sheath.
D. Carotid Sheath and Its Contents:
E. Lymph Nodes:
Deep cervical lymph nodes along internal jugular vein (jugulo digastric and jugulo omohyoid).
4. Muscular Triangle:
Lies below the hyoid bone.
Boundaries:
Anteriorly – Mid-line of the neck.
Supero – Laterally – Superior belly of omohyoid.
Infero – Laterally – Anterior border of sterno cleidomastoid muscle.
Floor – Sternohyoid and sternothyroid muscle.
Roof – Skin, superficial fascia, investing layer of deep fascia with platysma and cutaneous nerves and vessels.
Deep to it lies:
i. Thyroid gland
ii. Larynx and trachea
iii. Pharynx and oesophagus.
Action:
Infrahyoid muscles together with suprahyoid muscles – stabilize the hyoid bone to provide a base for movements of tongue.
Participate in movements of larynx in swallowing.
Thyrohyoid is supplied by C1 branch of XIIth nerve; other infrahyoid muscles are supplied by C1, C2 and C3 via branch from ansa cervicalis. They depress the hyoid bone and larynx.
Thyrohyoid – elevates the larynx.
They move the larynx and hyoid bone in speech and swallowing.
Hyoid Bone:
It is a small ‘U’ shaped bone present in the horizontal plane just superior to the larynx.
Parts:
1. Body:
It is anterior and forms the base of the ‘U’.
2. Horns:
Greater and lesser horn, project posteriorly from the lateral ends of the body.
Hyoid bone is a highly movable and strong bony anchor for a number of muscles and soft tissue structures, e.g., membranes and ligaments.
Significantly it is at the junction between three compartments:
(i) Superiorly- It is attached to the floor of the oral cavity.
(ii) Inferiorly- It is attached to the larynx.
(iii) Posteriorly- It is attached to the pharynx.
Term Paper # 7.
Relations of Sterno Mastoid:
Superficial:
1. Skin.
2. Superficial fascia with platysma.
3. Deep fascia – superficial lamina.
4. External jugular vein and superficial cervical lymph nodes.
5. Great auricular, transverse cervical and medial supraclavicular nerves.
6. Parotid gland overlaps the muscle.
Deep:
1. Bones – Mastoid process above.
2. Joints – Sternoclavicular joint below.
3. Carotid sheath with its contents.
4. Muscles:
(a) Sternohyoid
(b) Sternothyroid
(c) Omohyoid
(d) 3 Scalenus – anterior, medius and posterior
(e) Levator scapulae
(f) Splenius capitis
(g) Semi spinalis capitis
(h) Posterior belly of digastric
5. Arteries:
(a) Common carotid
(b) Internal carotid artery
(c) External carotid artery.
(d) Occipital artery
(e) Subclavian artery
(f) Supra scapular artery
(g) Transverse cervical artery.
6. Veins:
(a) Internal jugular vein
(b) Anterior jugular vein
(c) Facial and lingual veins.
7. Nerves:
(a) Vagus nerve
(b) Accessory nerve
(c) Cervical plexus
(d) Upper part of brachial plexus
(e) Phrenic and ansa-cervicalis.
8. Lymph nodes – deep cervical group.
Applied Anatomy:
1. Swelling in posterior triangle is due to enlargement of supra clavicular lymph nodes.
(a) Lipoma
(b) Cystic hygroma
(c) Lymphangioma
(d) Cervical rib
(e) Pharyngeal pouch
(f) Hodgkin’s disease
(g) Tuberculosis – cold abscess
(h) Secondaries – from CA breast, CA stomach (G.I.T.) or chest.
Left supraclavicular lymph nodes or Virchow’s or Scalene nodes also known as signal nodes enlarged in cases of CA stomach, testis and other abdominal organs – due to vast territory drained by thoracic duct.
2. Torticollis or Wry Neck is deformity caused by spasm or contracture of muscles supplied by spinal accessory nerve. Rheumatic Torticollis due to exposure to cold or draught.
(a) Reflex torticollis due to inflammed lymph nodes which irritate the spinal accessory nerve.
(b) Congenital torticollis – due to contracture of muscle since birth or due to injury at birth.
3. Cervical rib – May compress subclavian artery and brachial plexus – radial pulse decreases, tingling, numbness etc.
4. Block dissection of neck is done in malignancies.