Spinal Anatomy - Final Exam

PCC, SP26; Based on our most missed questions from the Tri

How many synovial joint surfaces are on typical cervical vertebrae? 

4: 2 superior articular facets and 2 inferior articular facets

Which ligaments attach to the C2 vertebral body?

ALL, PLL, and Tectorial membrane

Where is the median atlantoaxial joint anteriorly?

Between dens and osteoligamentous ring

Where is the median atlantoaxial joint posteriorly?

Between transverse atlantal ligament

What kind of joint is the median atlantoaxial joint?

A synovial pivot joint

What is the anterior portion of the median atlantoaxial joint?

Facet for fovea dentis

What is the posterior portion of median atlantoaxial joint?

Groove for transverse atlantal ligament

What is the neurocentral synchondrosis?

The synchondroses formed between centrum and neural arch centers of ossification on each side

What is the ponticulus posticus?

An accessory bone that may be complete, incomplete, or absent.

When complete, it forms the arcuate foramen.

What is the location of the ponticulus posticus?

Occurs along attachment sites of lateral mass and arcuate rim. Appears superior to groove/sulcus of vertebral artery (potential source of compression)

What ligament(s) form the anterior boundary of the spinal canal?

PLL: forms a fibrous (amphiarthrosis) syndesmosis joint with posterior lip and posterior groove; Attached along VB and IVD; inferior continuation of Tectorial membrane

What ligament(s) form the posterior boundary of the spinal canal?

(Posterior atlantoaxial ligament)

Ligamentum Flavum: attaches to laminae; forms para-articular process if ossified

What is a fibrous joint?

It has more than two bony surfaces connected by a thin layer of dense connective tissue. Does not have a joint cavity

What are the types of fibrous joints?

Suture

Syndesmosis

Gomphosis

Schindylesis

What is a suture?

Dense fibrous connective tissue. Only between skull bones.

What is a syndesmosis?

Fibrous connective tissue. ALL, PLL, and Ligamentum flavum are syndesmoses, along with interosseus membranes in forearms and lower legs.

What is a gomphosis?

Conical process into a socket. Articulation of roots of teeth with alveoli of the mandible and maxilla

What is a schindylesis?

Ridged-bone articulates into a groove on neighboring bone (vomer articulating with sphenoid).

Which muscles attach to the T1 Transverse process?

• Longissimus thoracis, cervicis, capitis

• Semispinalis cervicis, capitis

• Multifidus

• Rotator longus, brevis

• Intertransversarii

• Levator costorum brevis

How many synovial joint surfaces are located on T10, T11, and T12 vertebral body?

6: 4 zygapophyseal (facet) joints and 2 costocentral joints

(T10 has 2 extra costotransverse joints, but those aren’t on the body)

Which costal notches are on the manubrium?

Costal notch 1 and half of costal notch 2

Which costal notches are on the corpus sterni/body?

Half of costal notch 2 and costal notches 3-7

What makes Costal notch 1 unique?

It is separated from articular surface of 1^st rib by hyaline cartilage (cartilaginous synchondrosis joint)

It is located wholly on the manubrium

What kind of joints are costal notches 2-7?

Synovial plane joints

What is a costovertebral joint?

A joint formed when ribs articulate with thoracic vertebrae

Two types: costocentral and costotransverse joints

What is a costocentral joint?

A type of costovertebral joint

Synovial plane joint

Located on vertebral body

Has 4 joint surfaces: Left & Right Sup. & Inf. costal demifacets

What is a costotransverse joint?

A type of costovertebral joint

Synovial plane joint

Located on transverse process of vertebrae (specifically, transverse costal facet)

Has 2 joint surfaces: Left & Right costotransverse joints.

How many primary centers of ossification are in the manubrium sterni?

1-3 PCOs

How many primary centers of ossification are present in the corpus sterni?

One PCO appears in each of the first two sternabrae.

Bilateral PCOs appear in the 3^rd and 4^th sternabrae.

Does the sternum have secondary centers of ossification?

Yes. Xiphoid may have an SCO.

What direction does synostosis (separate bones ossifying together) occur in the sternebrae?

Caudal to cranial direction

What direction do centers of ossification appear in the sternebrae?

Cranial to caudal direction

Which joints are associated with the manubrium?

Manubriosternal symphysis

Sternoclavicular joint

First & Second sternochondral joint

What is the manubriosternal symphysis?

It is between manubrium and corpus sterni/body.

A cartilaginous symphysis joint.

It is level with the inferior margin of T4 body.

What is the sternoclavicular joint?

At clavicular notches and clavicles.

Includes the first rib.

Synovial saddle (diarthrosis sellar) joint.

What kind of joint is the first sternochondral joint?

Cartilaginous synchondrosis joint

What kind of joint is the second sternochondral joint?

Synovial plane joint

Where does the superior costal demifacet articulate?

Articulates with the inferior articular facet of the rib at the same level.

Rib 3 articulates with INFERIOR demifacets of T2 and SUPERIOR demifacets of T3.

Where does the inferior costal demifacet articulate?

Articulate with the superior articular facet of the rib of the level beneath it.

Rib 3 articulates with INFERIOR demifacets of T2 and SUPERIOR demifacets of T3.

What is a para-articular process?

An ossified ligamentum flavum, resulting in a spur-like bony growth or calcification located on the laminae of thoracic vertebrae.

Where does cervical nerve C5 exit?

Below vertebra C4 in the C4-C5 IVF

Where do thoracic and lumbar spinal nerves exit?

Below their corresponding vertebra

T6 spinal nerve exits below T6 in T6-T7 IVF

L3 spinal nerve exits below L3 in L3-L4 IVF

How is a lumbar’s superior articular process/facet oriented?

Concave; backward, upward, medial (BUM)

How is a lumbar’s inferior articular process/facet oriented?

Convex; forward, lateral, downward (FoLD)

How do lumbar articular processes’ width differ?

Superior articular process width greater than inferior processes, “cradles” segment above

What occurs in cervicalization of T1?

T1 appears cervical-like

T1 rib small or absent

Transverse foramen (fusion of short rib 1 to transverse process)

T1 superior articular facet orientation is BUM

Uncinate processes on T1 and a true joint of Luschka between C7 and T1

Describe normal facet orientation of C7 and T1 articular processes/facets

C7 → BUM; ForMeD

T1 → BUL; ForMeD

Describe facet orientation of C7 and T1 articular processes/facets when there is cervicalization of T1

C7 → BUM; FoLD

T1 → BUM; ForMeD

What is the subdental synchondrosis?

Cartilaginous synchondrosis formed from the ossification downward from dens and upward from centrum.

Associated with Primary centers of ossification.

Failure to fuse past age 7 results in Os odontoideum.

What is the tip of the dens synchondrosis?

Cartilaginous synchondrosis formed between the tip of dens and odontoid process centers of ossification.

Associated with Secondary centers of ossification.

Failure to fuse beyond age 12 results in terminal ossicle.

What forms the sacral hiatus?

The lack of fusion between the laminae/spinous tubercle at S4/S5.

Sacral cornu (S5 inferior articular facet) form the left and right inferior boundaries.

What is the function of the sacral hiatus?

Acts as the inferior opening of sacral spinal canal.

Contains Cauda equina, spinal meninges, Co1 spinal nerves, S5 (sometimes S4) sacral spinal nerve exits.

What is Assimilation of the Atlas?

A congenital issue resulting in the partial or complete fusion of Atlas with Occiput

In Assimilation of the Atlas, what does the arcuate rim fuse with?

Posterior aspect of foramen magnum

In Assimilation of the Atlas, what does the Occipital condyle fuse with?

Superior articular facet and lateral mass of C1

In Assimilation of the Atlas, what does the Anterior arch fuse with?

Anterior aspect of foramen magnum

What are cervical and lumbar ribs?

Elongated transverse processes.

Cervical ribs occur due to dorsalization of C7. Can go up to C4.

Lumbar ribs occur due to dorsalization of L1. 7% of population.

What is the morphological appearance of lumbar laminae?

Broad and thick. Asymmetric in superior-inferior length.

Overlapping laminae, “shingling”, diminishes in lumbar region when compared to thoracic. 

Spinal tap is done at L3-L4 because spinal cord terminates at L1.

What connects to the superior-inferior margins of lumbar laminae?

Ligamentum flavum

Describe the superior and inferior margins of lumbar laminae

Superior margin has a curved and smooth inner surface.

Inferior margin has a rough inner surface for LF attachment while supporting inferior articular processes.

Where are ciliary bodies located?

In the chambers of the eye.

Posterior chamber receives aqueous humor produced by ciliary body.

Passes into anterior chamber where it is reabsorbed into scleral venous plexus.

Where are ciliary glands located?

At the base of the eyelashes.

Produces aqueous humor which nourishes cornea and lens.

Where are meibomian (tarsal) glands located?

Within the tarsus.

They secrete meibum, which prevents evaporation of tear film. 

Tell me about the Supraorbital artery

Comes from Ophthalmic artery, a branch of the Internal carotid artery

Tell me about the Infraorbital artery

Comes from Internal maxillary artery, a branch of the External carotid artery

What is the parasympathetic innervation of the parotid gland?

Glossopharyngeal nerve (CN IX)

Describe the preganglionic fibers associated with the parotid gland

Preganglionic fibers from foramen ovale (lesser petrosal n.) synapse in Otic ganglion

Describe the postganglionic fibers associated with the parotid gland

Postganglionic fibers “hitch a ride” on Auriculotemporal n. (V3)

What is the tectorial membrane?

Superior continuation of the PLL. Resists excessive cervical flexion.

Where does the Ligamentum nuchae attach?

Runs from Occiput-C7 spinous process.

1)        Funicular/superficial/posterior layer: Runs from EOP and external occipital crest to C7 SP

2)        Lamellar/deep/anterior layer: Runs from posterior tubercle on posterior arch of C1 to C2-C6 SP

What is the ligamentum nuchae?

It is the superior continuation of the supraspinous ligament.

It limits flexion within cervical region.

What does the ligamentum flavum do?

Connects laminae of adjacent vertebrae (C2 → S1)

Supports anterior portion of Z-joint capsule

Limits flexion of spine

What are the characteristics of the ligamentum flavum?

Homologue of Posterior atlanto-occipital membrane

Thinnest in cervical spine, thickest in lumbar spine

Blends with the interspinous ligament

May undergo degeneration with aging or trauma.

Ossification is most common in thoracic or thoracolumbar region, due to mechanical stress.

What are the muscles of mastication?

Temporalis, masseter, medial pterygoid, and lateral pterygoid.

What is the innervation of the muscles of mastication?

All are innervated by mandibular division of CN V (V3) (Trigeminal N.)

What are the muscles of mastication derived from?

All are derived from 1^st pharyngeal arch

What are the actions of the muscles of mastication? (Don’t say mastication…)

Elevation (close mouth): Temporalis, masseter, medial pterygoid

Depression (open mouth): Lateral pterygoid

Protrusion (protrude chin): Lateral pterygoid, masseter, medial pterygoid

Retrusion (retrude chin): Temporalis, masseter

Lateral movements (grinding & chewing): Temporalis of same side, pterygoids of opposing side, masseter