Neck - 18 Flashcards
Unique Features of the Neck
- First two cervical vertebrae are specialized as atlas and axis
- Cervical segments are the only ones with a branchial-motor outflow (i.e., spinal roots of CN XI.
Similarities between trunk and neck
- Both have vertebrae.
- Both have mixed spinal nerves.
- Both have separate epaxial and hypaxial muscle masses.
Differences between trunk and neck
- Smooth muscles of trunk gut are derived from unsegmented mesoderm.
- Gut tube in neck is surrounded by striated branchial arch muscles
- Superficial striated muscles of neck form an incomplete layer
- Neck lacks a coelom
Hypaxial muscles in neck are innervated by what?
ventral rami of spinal nerves
Anterior Triangle of the Neck
Borders:
•Superior: •Mandible
•Posterior: •Sternocleidomastoid (anterior border of)
•Anterior: •Midline of the neck
Subdivisions:
•Muscular triangle
•Submandibular triangle
•Carotid triangle
Contents of Muscular Triangle
Digastric Stylohyoid Mylohyoid Geniohyoid Sternohyoid Sternothyroid Thyrohyoid Omohyoid
Stylohyoid
Origin: styloid process of temporal bone
Insertion: body of hyoid
Action: elevates and retracts hyoid
Innervation: Mylohyoid nerve (CN VII)
Mylohyoid
Origin: mylohyoid line of mandible
Insertion: raphe and body of hyoid
Action: elevates hyoid
Innervation: mylohyoid nerve (CN V3)
Geniohyoid
Origin: Inferior mental spine of mandible
Insertion: body of hyoid
Action: elevates hyoid
Innervation: C1 via hypoglossal nerve
Sternohyoid
Origin: manubrium
Insertion: body of hyoid
Action: depresses hyoid and larynx
Innervation: ansa cervicalis
Sternothyroid
Origin: manubrium
Insertion: thyroid cartilage
Action: depresses hyoid and larynx
Innervation: ansacervicali
Sternothyroid
Origin: manubrium
Insertion: thyroid cartilage
Action: depresses hyoid and larynx
Innervation: ansa cervicalis
Omohyoid
Consists of two bellies connected via an intermediate tendon which passes through a clavicular sling
Origin of superior belly: body of hyoid
Origin of inferior belly: upper border of scapula
Insertion: intermediate tendon attached to clavicle and rib 1
Action: depresses hyoid
Innervation: ansa cervicalis
Common Carotid
Does not give off any branches below the larynx; lower part of the neck gets its blood supply from branches of the subclavian artery
Blood monitors near the point of bifurcation of the common carotid
Runs from front of trachea (at root of neck) toward the dorsal body wall (scaleni and prevertebral muscles)
Travels within the carotid sheath
What does the carotid sheath contain
- Carotid artery
- Internal jugular vein
- Part of vagus nerve
Carotid sinus:
- Dilated terminal portion of common carotid
* Baroreceptor
Carotid Body
chemoreceptor
External Carotid
Has three main branches that enter the neck:
- Superior thyroid (lowest branch of external carotid) (anterior)
- Ascending pharyngeal (medial)
- Occipital (posterior)
Branches of the external carotid
- Lingual (anterior): Crossed by hypoglossal nerve at its origin
- Facial (anterior)
- Occipital (posterior)
- Posterior auricular (posterior)
- Superficial temporal (terminal)
- Maxillary (terminal)
Cervical Plexus
- From ventral rami of C1-4
- Runs partly with hypoglossal nerve (CN XII)
•Sensory branches: Great auricular (C2-3), Lesser occipital (C2(3)) [Ventral ramus of C2, Greater occipital is dorsal ramus of C2], Transverse cervical (C2-3), Supraclavicular (C3-4)
Motor Branches of Cervical Plexus
To prevertebral muscles: •Rectus capitis anterior •Rectus capitis lateralis •Longus capitis and coli
To levator scapulae muscle (C3-4)
To scalene muscles
Ansa cervicalis: •Supplies infrahyoid muscles •Except thyrohyoid
Phrenic nerve (C3,4,5)
Nerve to Geniohyoid
C1 via hypoglossal nerve
Superior and inferior limbs:
- Omohyoid
- Sternothyroid
- Sternohyoid
Sympathetic trunk
- Ascends on anterior surfaces of longus colli and longus capitis muscles
- Lies posterior to common and internal carotids and deep to carotid sheath
- Contains preganglionic sympathetic fibers from T1 and T2 and T2 and GVA fibers as well from same levels
- Sends gray rami communicantes to all cervical ventral rami
Superior, Middle, Inferior, Stellate Ganglion
Superior Cervical Ganglion
- Elongated structure on longus capitis muscle
- At level of C1 and C2
- Postganglionic sympathetic fibers from this ganglion supply all smooth muscles and glands of the head.
Stellate ganglion:
Fused inferior cervical ganglion and T1 ganglion