All Primary Structures - Combined

Intervertebral joints

Formed by the superior and inferior surfaces of the vertebral bodies and the associated intervertebral discs

Zygapophysial joints

Formed by the right and left superior articular facets of one vertebra and the right and left inferior articular facets of an adjacent superior vertebra

Anterior longitudinal ligament

Limits extension of the spine

Reinforces the interior portion of the intervertebral discs and vertebra

Interspinous ligaments

Located between the spinous processes

Limtis flexion and rotation of the spine

Intervertebral disks

Formed by a dense layer of collagen fibers and fibrocartilage (called the annulus fibrosus) as well as a flexible inner layer (called the nucleus pulposus)

Flexion of a vertebral segment causes the anterior portion of the disk to be compressed and the posterior portion of the disk to be distracted

Nucleus pulposus

A gelatinous mass located centrally in the intervertebral disk

Annulus fibrosus

Firmly attached to the adjacent vertebrae and provides tensile strength to the intervertebral disk during spinal movement

Intervertebral foramina

Located in the posterior pillar of each vertebral segment

Spinal nerves and blood vessels exit the spinal canal via the foramina

Size increases with flexion and contralateral side bending

Size decreases with extension and ipsilateral side bending

Nerve root entrapment can result from closure or narrowing due to arthritic changes, spurring, or narrowing of the intervertebral disks

Ligamentum flavum

Connects the lamina of one vertebra to the lamina of the vertebra above it

Limits flexion and rotation of the spine

Posterior longitudinal ligament

Limits flexion of the spine

Reinforces the posterior aspect of the intervertebral disks

Anterior sacroiliac ligament

Connects the interior surface of the ilium to the anterior sacrum

Thickening of the joint capsule and is considered the weakest of the sacroiliac ligaments

Coccyx

Articulates with the sacrum and most often consists of four small fused vertebral bodies

Does not have a specific purpose and is most often considered an embryological remnant

Iliolumbar ligament

Connects the posterior portion of the ilium to the transverse process of the L5 vertebra

Limits all motions between L5 and S1

Interosseous sacroiliac ligament

Connects the sacrum and ilium

Located deep to the posterior sacroiliac ligament

Strong and resists anterior and inferior movements of the sacrum

Lumbar plexus

Formed by the nerve roots of T12 with L1-L4

It innervates the anterior and medial muscles of the thigh, as well as the dermatomes of the medial leg and foot

Largest and most important branches of the plexus are the obturator and femoral nerves

Posterior sacroiliac ligament

Connects the posterior superior iliac spine with the lateral portions of the third and fourth sacral sections

It is strong, and its fibers run in multiple directions, eventually combining with the fibers of the sacrotuberous ligament

Limit all sacral movements, especially posterior rotation

Pubic symphysis

Joint formed between the ends of each pubis bone

Ends of the bones are covered with hyaline cartilage with a fibrocartilage disk between them

Motion is very limited

Ribs 1-10

Articulate with the thoracic vertebrae through the costovertebral joints and the costotransverse joints

Ribs 1-7

Attached to the sternum through costal cartilage

Ribs 8-10

Join with the costal cartilage of ribs 1–7

Ribs 11-12

Articulate only with the vertebral bodies of T11–T12, but not the transverse process of the same vertebra

Classified as floating because they do not attach to the sternum or the costal cartilage at their distal end

Sacral plexus

Formed by:

Lumbosacral trunk

Ventral rami of S1–S3

Descending portion of S4

Supplies the muscles of the buttocks and through the sciatic nerve, innervates to muscles of the posterior thigh and lower

Sacrospinous ligaments

Connects the ischial spine to the lateral sacrum and coccyx, also has fibers that blend with the fibers of the sacrotuberous ligament

Limits anterior rotation of the sacrum on the pelvis

Sacrotuberous ligament

It has several attachment sites, including:

Posterior superior iliac spine

Lateral sacrum

Coccyx

Ischial tuberosity

Primarily functions to resist sacral anterior rotation and prevent superior translation of the sacrum

Sacrum

Broad, thick bone consisting of five fused vertebrae that fixate the spinal column to the pelvis

Provides an attachment for the iliac bones

Protects the pelvic organs

Attached to the pelvis by strong ligaments, forming the sacroiliac joint

Supraspinous ligament

Restricts flexion in the thoracic and lumbar spine

Thoracolumbar fascia

The spinous processes of the lumbar vertebrae, the posterior superior iliac spines, and the iliac crests

Consists of three layers that separate the lumbar muscles into three different compartments

Provides stability to the spine

Transmits forces

Resists lumbar flexion

Provides a site for muscular attachments

Atlanto-occipital joint

Condylar synovial joint that permits flexion and extension of the cranium

Allows head to nod “yes”

Atlantoaxial joints

Plane synovial joints that permit flexion, extension, lateral flexion, and rotation of the cervical spine

Majority of rotation of the skull on the spinal column occurs at these joints

Alar ligaments

Attach the dens of the axis to the occipital condyles

Function to resist flexion, contralateral side bending, and contralateral rotation

Help to limit sagittal plane translation between the atlas and the occiput

Brachial plexus

Arises from the nerve roots C5 through T1

Nerve roots combine to form trunks, then later divide to form divisions, cords, and finally the peripheral nerves

These nerves provide innervations to muscles of the entire upper quarter

Cruciform ligament

Has vertical and horizontal portions

Vertical portion connects the dens of the axis to the foramen magnum

Horizontal portion connects the Dens with the Atlas

Limits upper cervical flexion as well as translation of the Atlas on the axis

Ligamentum nuchae

Restricts flexion in the cervical spine

Unconvertible joints (Uncinate processes)

Formed between the lateral projections on the inferior surface of one vertebra and the lateral projections on the superior surface of the vertebra below it

Found between C3 and T1

Guides motion in the sagittal plane

Limits motion of the other two planes

Distal tibiofibular joint

Formed by a fibrous union between the lateral aspect of the distal tibia and the distal fibula

Talocrural joint

Formed by the articulations of the distal tibia, talus, and fibula

Offers significant stability in dorsiflexion; however, it becomes much more mobile with plantar flexion

Subtalar joint

Formed by three articulations (anterior, middle, posterior) between the talus and calcaneus

Anterior and middle articulations are formed by two convex facets on the talus and two concave facets on the calcaneus

Posterior articulation is formed by a concave facet on the inferior surface of the talus and a convex facet on the body of the calcaneus

Midtarsal Joint

Formed by the talocalcaneonavicular joint and the calcaneocuboid joint

Consider to have two axes: one longitudinal and one oblique

Motions around both axes are triplanar

Forefoot

Consists of the tarsometatarsal joints, metatarsophalangeal joints, and interphalangeal joints

Anterior talofibular ligament

Taut during plantar flexion

Resists inversion of the talus and calcaneus

Resists anterior translation of the talus and the tibia

Calcaneofibular ligament

Extracapsular ligament that resists inversion of the talus within the midrange of talocrural motion

Deltoid ligament

Formed by:

Anterior tibiotalar ligament

Tibiocalcaneal ligament

Posterior tibiotalar ligament

Tibionavicular ligament

Provides medial ligamentous support by resisting eversion of the talus

Interosseous membrane (of ankle)

Consists of a strong fibrous tissue that serves to fixate the fibula to the tibia

Distally, the structure blends into the anterior and posterior tibiofibular ligaments

Provides additional support at the distal tibiofibular syndesmosis joint

Ankle ligaments

Majority of ligaments in the ankle are areas of increased density within the joint capsule

Damage to the ankle ligament typically produces damage to the joint capsule and irritation of the synovial lining

Plantar fascia

Thick layer of fascial tissue in the plantar aspect of the foot that originates from the calcaneal tuberosity and inserts into the plantar forefoot

Plays a role in supporting the weight of the body

Helps to support the arch of the foot for improved propulsion during gait

Posterior talofibular ligament

Resists posterior displacement of the talus or the tibia

Extensor retinaculum

Lies on the interior side of the joint

Contains the tendons of the extensor musculature and prevents them from bowstringing as the ankle dorsiflexes

Retrocalcaneal bursa

Lies just anterior to the Achilles tendon, where it attaches into the superior calcaneus, and acts as a cushion between the tendon and the bone

Sinus tarsi

Space located between the inferior talus, superior calcaneus, and interior portion of the lateral malleolus

Contains ligaments that can also be injured during a common inversion ankle sprain

Radiocarpal joint

Proximal joint surface is formed by the distal radius and the radioulnar articular disc, which connects the medial aspect of the distal radius to the distal ulna

The distal joint surface is formed by the Scaphoid, Lunate, and Triquetrum

Encased in a strong capsule reinforced by numerous ligaments shared with the mid-carpal joint

Midcarpal joint

Motion of the wrist results in complex motion between the proximal and distal row of carpals, with the exception of the pisiform

Joint surfaces are reciprocally convex and concave

Anatomical snuffbox

Depression found in the dorsal surface of the wrist near the distal radius

It is bordered by the tendons of the adductor pollicis longus, extensor pollicis brevis, and the extensor pollicis longus

Often used for palpation of the scaphoid when there is concern for a fracture

Carpal tunnel

Located close to the deep surface of the flexor retinaculum

Provides passage for the median nerve to the palm

Dorsal radiocarpal ligament

Only major ligament on the dorsal surface of the wrist

Originates from the posterior surface of the distal radius and styloid process of the radius, and attaches to the lunate and triquetrum

Limits wrist flexion

Extensor retinaculum

Ligamentous structure that crosses the dorsal aspect of the wrist, covering the tendons of the extensor musculature

Prevents the tendons from "bowstringing" as the wrist is extended

Flexor retinaculum

Ligamentous structure that crosses the palmar aspect of the wrist, forming the most anterior aspect of the carpal tunnel

Prevents the tendons of the flexor muscle from rotation and bowstringing as the wrist is flexed

Serves as an attachment site for the thenar and hypothenar muscles

Interosseous membrane

Consists of a dense band of fibrous connective tissue that runs obliquely from the radius to the ulna

Spans from the proximal radioulnar joint to the distal radioulnar joint and serves as a stabilizer against axial forces applied to the wrist

Palmer radiocarpal ligament

Maintains the alignment of the associated joint structures and limits hyperextension of the wrist

It originates from the interior surface of the distal radius and attaches to the capitate, triquetrum, and scaphoid

Radial collateral ligament

Serves to limit ulnar deviation and becomes taut when the wrist is in extremes of extension and flexion

It originates in the styloid process of the radius and inserts on the scaphoid and the trapezium

Triangular fibrocartilage complex

Fibrocartilaginous disc that sits between the ulnar, lunate, and triquetrum

Provides stability to the wrist joint

Connects the radius and ulna together

Allows for better distribution of forces through the wrist

Tunnel of Guyon

Located between the hook of the hamate, the pisiform, the palmar carpal ligament, and the flexor retinaculum

Provides passage for the ulnar nerve and artery as they enter the hand

Compression of the nerve in this location may result in Ulnar Tunnel Syndrome

Iliofemoral joint

Proximal joint surface consists of the acetabulum, which is oriented laterally, inferiorly, and anteriorly

Distal joint surface consists of the convex head of the femur

Acetabular labrum

Fibrocartilaginous rim attached to the margin of the acetabulum

Enhances the depth of the acetabulum

Articular capsule

Extends from the rim of the acetabulum to the neck of the femur

Reinforced by the iliofemoral, pubofemoral, and ischiofemoral ligaments

Iliopsoas bursa

Located between the anterior joint capsule and iliopsoas tendon

Trochanteric bursa

Multiple exist, all of which lie between the greater trochanter and the different gluteal muscles

Ischiogluteal bursa

Located between Ischium and Gluteus Maximus

Femoral triangle

Space located in the anterior hip is bordered by the inguinal ligament, sartorius, and adductor longus

Femoral artery and lymph glands can be palpated within this space

The femoral nerve and vein also pass through this space

Iliofemoral ligament

Consists of a thickened portion of the articular capsule that extends from the anterior-inferior iliac spine of the pelvis to the intertrochanteric line of the femur

Considered to be the strongest ligament in the body

Prevents excessive hip extension

Assists to maintain upright posture

Ischiofemoral ligament

Consists of a thickened portion of the articular capsule that extends from the ischial wall of the acetabulum to the neck of the femur

Weakest of the three hip ligaments

Reinforces the articular capsule

Ligamentum teres

Provides a physical attachment between the head of the femur and the inferior rim of the acetabulum

Blood vessels and nerves travel with this ligament in a sheath to the head of the femur

Provides minimal stability to the hip

Pubofemoral ligament

Consists of a thickened portion of the articular capsule that extends from the pubic portion of the rim of the acetabulum to the neck of the femur

Prevents excessive abduction of the femur

Limits hip extension

Tibiofemoral joint

Proximal joint surface is formed by the convex medial and lateral condyles of the distal femur

The distal joint surface is formed by the concave medial and lateral condyles of the proximal tibia

Patellofemoral joint

Formed by the convex patella and the concave trochlear groove of the femur

Patella slides superiorly in the extension and inferiorly in the flexion

Patellar rotation and tilting also occur during knee extension and flexion

Anterior cruciate ligament

Runs from the anterior intercondylar area of the tibia to the medial aspect of the lateral femoral condyle in the intercondylar notch

Prevents anterior displacement of the tibia on the femur

Arcuate ligament complex

Consists of:

Arcuate ligament

Oblique popliteal ligament

Lateral collateral ligament

Popliteus tendon

Lateral head of the gastrocnemius

Arcuate ligament complex:

Assists the cruciate ligaments in controlling posterolateral rotary instability of the knee and provides support to the posterolateral joint capsule

Prepatellar bursa

Lies over the patella and allows for greater freedom of movement of the skin covering the interior aspect of the patella

Superficial infrapatellar bursa

Lies between the patellar tendon and skin

Deep infrapatellar bursa

Lies between the patellar tendon and the tibia

Fat pads

There are three fat pads of the knee:

Quadriceps

Prefemoral

Infrapatellar

The infrapatellar fat pad is the one most commonly affected. It can be a source of anterior knee pain when it becomes impinged (e.g. Hoffa’s syndrome)

Lateral collateral ligament

Runs from the lateral femoral epicondyle to the fibular head

Prevents excessive varus displacement of the tibia relative to the femur

Medial collateral ligament

Runs from slightly above the medial femoral epicondyle to the medial aspect of the shaft of the tibia

Deep capsular fibers are attached to the medial meniscus

Prevents excessive valvular displacement of the tibia relative to the femur

Menisci

Firmly attached to the proximal surface of the tibia

Thick at the periphery and thinner at their internal unattached edges

Function to deepen the articular surfaces of the tibia where they articulate with the femoral condyles

Absorbs shock

Contribute to lubrication and nutrition of the joint

Pes anserine

Common insertion point for the gracilis, semitendinosus, and sartorius muscles

Located medial and distal to the tibial tuberosity

Pain and/or swelling in this region may indicate the presence of bursitis

Plicae

Extensions of the synovial membrane that are sometimes found in the anterior knee, most commonly medial to the patella

Do not serve a specific function, though can be a source of anterior knee pain

Posterior cruciate ligament

Runs from the posterior intercondylar area of the tibia to the lateral aspect of the medial femoral condyle in the intercondylar notch

Prevents posterior displacement of the tibia on the femur

Retinacula

Ligamentous structures that attach the patella to the femur, tibia, and menisci

Lateral retinaculum is stronger than the medial retinaculum and plays a larger role in patellar positioning

Radiohumeral joint

Proximal joint surface is the ball-shaped capitulum of the distal humerus

The distal joint surface is the concave head of the radius

Ulnohumeral Joint

Formed by the hourglass-shaped trochlea of the humerus and the trochlear notch of the ulna

Proximal radioulnar joint

Consists of the concave radial notch of the ulna and the convex rim of the radial head

Annular ligament

Consists of a band of fibers that surrounds the head of the radius

Allows the head of the radius to rotate and retain contact with the radial notch of the ulna

Anterior ligament

Capsular in nature and function

Stretches from the radial collateral ligament and attaches above the upper edge of the coronoid fossa, extending to just below the coronoid process

Cubital fossa

Triangular space located at the anterior elbow that is bordered by the brachioradialis, pronator teres, brachialis, and a horizontal line passing through the humeral epicondyles

It contains several structures, including:

Biceps brachii tendon

Median nerve

Radial nerve

Brachial artery

Median cubital vein

Cubital tunnel

This is the space formed by the ulnar collateral ligament, flexor carpi ulnaris, medial head of the triceps, and the medial epicondyle

Is a passageway for the ulnar nerve

Becomes smallest with the elbow held in full flexion

Olecranon bursa

Lies posterior to the olecranon process and is considered the main bursa in the elbow

Commonly becomes inflamed with direct trauma to the elbow due to its superficial position

Posterior ligament

Blends on each side with the collateral ligaments and is attached to the upper portion of the olecranon fossa, and to just below the olecranon process

Radial collateral ligament

Extends from the lateral epicondyle of the humerus to the lateral border of the olecranon process of the ulna and to the annular ligament

Fan-shaped ligament that prevents adduction of the elbow and provides reinforcement for the radial humeral articulation

Ulnar collateral ligament

Runs from the medial epicondyle of the humerus to the proximal portion of the ulna

Prevents excessive abduction of the elbow joint

Glenohumeral joint

Formed by the convex head of the humerus and the concave glenoid fossa of the scapula

Inherently unstable

Sternoclavicular joint

Formed by the medial end of the clavicle and the manubrium of the sternum

Stability enhanced by fibrocartilaginous disc between the mandible and clavicle

Acts as a shock absorber and serves as the axis for clavicular rotation