D’YOUVILLE COLLEGE
BIOLOGY 339/639 GROSS HUMAN ANATOMY
LECTURE #5
POSTERIOR CERVICAL TRIANGLE
Regional Anatomy of the Neck (chapter 8)
1.
General Relationships:
a. Contents of the Neck (fig. 8 – 4 & ppt. 1):
• cervical vertebral column (+ spinal cord); some spinal & cranial nn.
• arteries (aa.) and veins (vv.) serving the head
• parts of digestive, respiratory and endocrine systems (cervical viscera)
b. Palpable Skeletal Features (ppt. 2):
• hyoid bone
• transverse processes of the atlas
• inferior border of the mandible
• vertebra prominens (spinous process of C7)
• laryngeal prominence (level of C4)
• cricoid cartilage (level of C6)
c. Fascial Compartments (fig. 8 – 4 & ppt. 1):
Superficial Fascia: contains platysma muscle (figs. 8 – 5, 8 – 7A & ppt. 3),
muscle of facial expression attached to deep fascia superomedial to inferior border
of mandible and to the skin inferior to the clavicle; supplied by cervical branch of
the facial nerve (cranial n. VII); tenses skin of anterior neck and draws down
corners of the mouth
Investing Layer of Deep Fascia: encircles neck like a collar; envelops
superficial mm. (trapezius and sternomastoid)
Prevertebral Fascia: encloses vertebral column and associated mm.
Pretracheal Fascia: encloses cervical viscera (trachea, larynx, esophagus,
thyroid gland) and infrahyoid mm. (anterior strap mm.)
Carotid Sheath: encloses common carotid a., internal jugular v. and vagus
n. (cranial n. X)
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d. Triangles (fig. 8 – 6, table 8 – 1 & ppt. 4):
• Posterior Cervical Triangle (described below)
• Anterior Cervical Triangle (described in later lecture)
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Posterior Triangle of the Neck (chapter 8)
1.
Sternomastoid m. (Sternocleidomastoid) (fig. 8 – 7, table 8 – 2 & ppt. 5):
• important landmark, easily palpable, separating anterior and posterior
triangles; intervenes between external and internal jugular vv.; protects contents of
carotid sheath
• attachments: superiorly, from mastoid process and adjacent superior nuchal
line, inferiorly, to sternum and medial end of clavicle
• innervation: spinal accessory n. (cranial n. XI) + branches of C2
• actions: flexion of cervical spine, ipsilateral flexion (ppt. 6), contralateral
rotation, and extension of head at atlantooccipital joint
• Note: congenital fibrosis of sternomastoid on one side causes a condition
called torticollis (= wry neck)
2.
Basic Posterior Cervical Triangle Features (fig. 8 – 6 & ppts. 4 & 5):
• Boundaries: sternomastoid and trapezius mm. and the clavicle outline the
triangle (known as “the gateway to the upper limb”)
• Roof: investing layer of deep fascia
• Floor: fascial carpet (lateral extension of prevertebral fascia)
• Subdivisions: upper “carefree” and lower “careful” zones defined by the
course of the spinal accessory n.
• omohyoid m. (in deeper layer) defines an inferiorly located subclavian
triangle (omoclavicular triangle) where subclavian a. and v. are found
3. Superficial Nerves (fig. 8 – 8 & ppt. 7): (cutaneous branches of cervical plexus
(fig. 8 – 13 & ppt. 8); all are from anterior primary rami):
a. Three Go Up:
• Lesser Occipital (C2): follows posterior border of sternomastoid m. to supply
skin behind ear
• Great Auricular (C2 & C3): extends vertically across sternomastoid m. to
supply skin around external ear
• Transverse Cervical (C2 & C3): extends horizontally across sternomastoid m.
to supply skin of anterior neck
b. Three Go Down:
• three Supraclaviculars (C3 & C4): medial, intermediate & lateral; pierce
platysma to supply skin inferior to clavicle
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4.
Contents of the Posterior Cervical Triangle (figs. 8 – 8, 8 – 9 & ppt. 9):
a. External Jugular v. (fig. 8 – 12 & ppt. 7): traverses sternomastoid m., parallel
to great auricular n., carrying superficial head drainage to subclavian v.
b. Omohyoid m. (to be described with anterior triangle): inferior belly crosses
lower portion of posterior triangle
c. Spinal Accessory n. (cranial n. XI):
• major landmark of posterior triangle, supplies trapezius and sternomastoid
mm.
d. Important Vessels (figs. 8 – 10, 8 – 11 & ppt. 10):
• Suprascapular a.: passes deep to clavicle from thyrocervical trunk
posteriorly to supply dorsal scapular mm.
• Transverse Cervical a.: also from thyrocervical trunk, passes superior to
clavicle (& deep to omohyoid) posteriorly; important branch, dorsal scapular a.
supplies trapezius, rhomboids and levator scapulae mm.; often, the dorsal scapular
a. arises separately from the subclavian a.
5. Structures Deep to or Peripheral to the Posterior Cervical Triangle (fig. 8 – 10 &
ppt. 11):
a. Scalenus Anterior, Medius & Posterior mm.: lying deep to floor of posterior
triangle, extend from transverse processes of C4 - C6 to first rib (anterior & medius)
and second rib (posterior)
• supplied by anterior primary rami of cervical nn. 4 - 6 (anterior & medius)
and cervical nn. 7 - 8 (posterior); serve as accessory respiratory mm., flexors &
contralateral rotators of neck
b. Subclavius m.: (to be described with pectoral region)
c. Phrenic n. (C3, C4, C5 – from cervical plexus): lies on front of scalenus
anterior m.; only motor nerve to diaphragm
d. Brachial Plexus (C5 - C8, T1): upper part (roots, trunks) emerges from
between scalenus anterior and scalenus medius mm. (fig. 8 – 11 & ppt. 12)
e. Important Vessels:
• Subclavian a. (fig. 8 – 11 & ppt. 12): passes deep to scalenus anterior m. to
lateral border of rib 1, grooving the rib surface (becomes the axillary a.); found in
subclavian triangle, deep to clavicle; important branch in this region: thyrocervical
trunk
• Subclavian v.: passes superficial to scalenus anterior m., grooving surface
of rib 1
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