Bones & Joints of The Neck Flashcards
What are the gross features of bones, cartilage and joints of the neck?
- Skeleton of the neck can be divided into w sets if tissues which are separated by the oesophagus
- Posterior to the oesophagus is the posterior skeleton-upper part of vertebral column
- Anterior to the oesophagus- anterior skeleton which is important in ventilation (trachea) and feeding (food goes into mouth then larynx before being diverted to the oesophagus) - switching mechanism allows dual function
- Anterior skeleton of the neck consists of the: hyoid bone, thyroid cartilage (C1 and C2), cricoid cartilage (after C6), tracheal rings (C3 and C4)
○ laryngeal prominence is made by thyroid cartilage - Posterior skeleton=cervical spine
- Bones of the neck are located in the midline of the body and can be divided int 2 sets of bones
○ Anterior set=hyoid bone (n=1)
○ Posterior set= cervical spine (n=7)
What are the anatomical features of the hyoid bone?
- It is unique as it is the only bone in the body that is not attached to other bones/is a stand-alone bone and instead is stabilised by soft tissue and ligament
- Forms and attachment to the thyroid cartilage
- Laryngeal province is suspended by the lower aspects of the Hyoid bone
- Thyroid and cricoid cartilage make larynx (attached to the Hyoid)
- Has the following features: no bony articulations, stabilised by ligaments and muscles. Suspend the larynx and supports the floor of the mouth
What are the anatomical features of the hyoid bone?
• It is unique as it is the only bone in the body that is not attached to other bones/is a stand-alone bone and instead is stabilised by soft tissue and ligament
• Forms and attachment to the thyroid cartilage
• Laryngeal province is suspended by the lower aspects of the Hyoid bone
• Thyroid and cricoid cartilage make larynx (attached to the Hyoid)
• Has the following features: no bony articulations, stabilised by ligaments and muscles. Suspend the larynx and supports the floor of the mouth
What are the parts/sections of the hyoid?
• Can be divided into 3 parts: the body, lesser horn and greater horn
○ The horns are also known as cornu
• Has 4 primary ossification centres (Ossification centre is the site where the bone ossified)
• The body
○ Can be divided into 2 parts: upper half and lower half
○ Upper half
§ 2nd Branchial Arch derivative
§ 1 Primary Ossification Centre
§ Upper half of the body
○ Lower half
§ 3rd Branchial Arch derivative
§ 1 Primary Ossification Centre
§ Lower half of the body
• Lesser horn
○ 2nd Branchial Arch derivative
○ 1 Primary Ossification Centre
• Greater horn
○ 3rd Branchial Arch derivative
○ 1 Primary Ossification Centre
What are the attachments of the hyoid bone?
• Attached to ligaments of the neck-stylohyoid ligaments
• Muscles of the head and neck (anterior)
○ tongue, pharynx (in particular the larynx), suprahyoid group, infrahyoid group
• Muscles to anterior aspect of the neck
○ Suprahyoid groups
○ Infrahyoid group
• Attached to the head by the stylohyoid ligament
• Muscles also attach to Hyoid bone so when swallowing or speaking hyoid moves up and down
• Muscular attachments allow for the anterior neck to be formally divisible into various sub-regions. By acting together, there muscles stabilize the hypoid in its resting position
• Infrahyoid muscles are also known and strap muscles as they are thin (depressors of hyoid bone)
• Suprahyoid bone are known as elevate muscles as they raise the hyoid
What is the cervical spine?
• Collection of discrete vertebra forming the skeleton of the neck
• It connects the head to the rest of the body and vice-versa
• It supports all if weight of the head
• Occupies the posterior aspects of the neck
• Collection of discrete vertebra forming the skeleton of the neck odontoid process
What are the anatomic features of the cervical vertebrae?
• Vertebrae of the cervical spine are divisible into two sets: the typical vertebrae (n5 or 4) and the atypical vertebrae (n=2 or 3-C1, C2 and C7 of the cervical vertebrae)
• Ends of vertebra spine spike /fork
Distinguishing features of typical cervical vertebrae?
• They are the smallest of the discrete vertebrae from skeleton of the neck
• Two distinguishing features: Bifid spinous process and Oval transverse foramen in the transverse processes
• Bifid spinous process (forking at the spine of the vertebrae-not in C7)
• Oval transverse foramen also called the foramina transversaria- vertebral artery passes though the Oval transverse foramen except from C7 and the C7 foramen passes the smaller accessory vertebral veins (looks like the eyes of the smiley face)
• Large vertebral (or neural) foramen (looks like the mouth of a smiley face)
• Broken neck may be sub-clinical because
○ Main feature is the odontoid peg
○ Spinous process is bifid
• Both structurally and functionally atypical vertebrae
• C7 is called the vertebrae prominence
○ Prominent spinous process: not bifid (easily palpable)
○ Large transverse process
• General rule = 3 ossification centres unless told otherwise
The atlas
• Articulates as follows: skull above and axis below
○ Skull above -(atlanto-occipital joint for nodding Yes)
○ Axis below-(atlanto-axial joint for side-to-side rotation when we say “No”)
• Lacks a body
• Lacks spinous process
• Widest cervical vertebra
• Has 2 primary ossification centres
• its body is fused with that of the axis to form the Dens or Odontoid Process
• Each Neural Arch is thick and strong to form a powerful lateral mass
The axis
• Strongest cervical vertebra
• Characterised by 3 main features:
○ The Odontoid Process or Dens
○ Rugged lateral mass
○ Large Spinous Process
○ 4 Primary Ossification Centres
• Dens prevents horizontal displacement of atlas
• Fractures & dislocates in hanging to give hangman’s fracture The Axis
• Fractures & dislocates in hanging to give hangman’s fracture
• 4 primary ossification centre is distinguishing features
• Large rugged lateral masses to carry weight of the head
• Dens prevents displacing of the axis and atlas
• Hanging causes Fracture to laminar and dens to break off and shoot off into the brain
•
What are the Joints of the cervical spine?
• Intervertebral joints has 2 parts: the nucleus pulposus and annulus fibrosis
○ Absent between C1 and C2
○ Present for all vertebrae below C2 onwards
○ Look at NMS notes for their anatomical feature
• Facet joints
○ Facet Joints can be divided into:
§ Upper Neck Apophyseal Joints
□ Atlanto-occipital joint
□ Atlanto-axial joint
§ Lower Neck Apophyseal Joints
□ Joints between superior and inferior articular processes of the rest of the cervical spine (c3-c7)
○ Also known as Apophyseal joints
○ Look at NMS notes for their anatomical locations
What is the Atlanto-occipital joint?
• uniquely connects the cervical spine to the base of the occiput
• Atlas (C1) articulates with the base of occiput
• Atlanto-occipital joints lack corresponding cervical discs and uncinate processes.
• Atlanto-occipital joints lie anterolateral to the spinal cord (rather than posterolateral), and they align with the uncinate processes of the lower cervical bodies
• AO joints are condyloid joints
• Classified as synovial joints with capsules
• The AO joints are very mobile joints with primarily ligamentous stabilization
• The joints facilitate occipital flexion and extension on the atlas (C1).
What is the Atlanto-axial joint?
• Joint between C1 and C2 vertebrae
• i.e. between the atlas and axis
• It is a pivot joint.
• It is a complicated joint
• It consists of no fewer than four distinct joints
• There is a pivot articulation between the odontoid process of the axis and the ring formed by the anterior arch and the transverse ligament of the atlas
• There are three atlantoaxial joints: median, lateral and posterior
• The median atlantoaxial joint is sometimes considered a triple joint
• one between the posterior surface of the anterior arch of atlas and the front of the odontoid process
• one between the anterior surface of the ligament and the back of the odontoid process
• The lateral atlantoaxial joint involves the lateral masses of atlas and axis.
• Between the articular processes of the two bones there is on either side an arthrodial or gliding joint
