Lumbar and hips

osteology

Distal Femur

Condyles and Epicondyles

epicondyles

bony prominences located just above the condyles, serving as attachment points for muscles and ligaments.

condyles

articulate with the tibial plateau

Patella

patella is a sesamoid bone

posterior surface of the patella is shaped to fit into the patellar groove (or trochlear groove) of the femur

patella sliding superiorly during knee extension and inferiorly during knee flexion.

Tibia and Fibula

Tibia (Shank of the Leg):

proximal tibia has a tibial plateau, which consists of the medial and lateral condyles, where the femur articulates.

medial tibial plateau is C-shaped, and the lateral tibial plateau is O-shaped,

Fibula:

not involved in the knee joint. It serves mainly for muscle attachment and stability of the leg but does not contribute to the knee's articulation.

Knee Alignment

Valgus

knock knee, this is when the tibia turns outward relative to the femur, causing the knees to point inward.

Varus

bow leg, this is when the tibia turns inward relative to the femur, causing the knees to point outward

Q Angle (Quadriceps Angle)

formed between two lines:

from the ASIS (anterior superior iliac spine) to the center of the patella.

from the center of the patella to the center of the tibial tuberosity (where the patellar ligament attaches).

typically ranges between 10 to 15 degrees, but anything greater than 20 degrees is considered abnormal.

joints and ligaments

Knee Joint Articulations

Femorotibial Join

The articulation between the distal femur (femoral condyles) and the proximal tibia (tibial plateau).

Patellofemoral Join

The articulation between the patella (kneecap) and the femur (specifically the patellar groove of the femur).

Ligaments of the Knee:

Medial Collateral Ligament (MCL)

Limits valgus stress (prevents the knee from being pushed inward).

Lateral Collateral Ligament (LCL):

Limits varus stress (prevents the knee from being pushed outward).

Anterior Cruciate Ligament (ACL):

Limits anterior translation of the tibia relative to the femur (prevents the tibia from sliding forward).

Posterior Cruciate Ligament (PCL):

Limits posterior translation of the tibia relative to the femur (prevents the tibia from sliding backward).

Menisci:

C-shaped fibrocartilage structures

Reduce localized pressure

Improve congruency

Provide proprioception

thicker on the outside and thinner on the inside

The semimembranosus muscle attaches to the medial meniscus.

The popliteus muscle has attachments to the lateral meniscus.

muscles

Knee Extensors

Innervation

femoral nerve innervates the muscles responsible for knee extension.

Muscle

Quadriceps Femoris (Primary Knee Extensors):

Rectus Femoris: A central muscle that also assists with hip flexion.

Vastus Lateralis: Located on the outer side of the thigh.

Vastus Medialis: Located on the inner side of the thigh.

Vastus Intermedius: Situated between the vastus lateralis and vastus medialis.

These muscles work together to extend the knee joint during movements like standing, walking, and running.

Sartorius Muscle:

assists in internal rotation of the knee and flexion of the hip joint. It also contributes to stabilizing the medial aspect of the knee.

Knee Flexors:

innervention

sciatic nerve innervates the muscles responsible for knee flexion.

Muscles:

Hamstring Group (Primary Knee Flexors):

flex the knee and extend the hip

Semimembranosus

Semitendinosus

Biceps Femoris

Pes Anserine Muscles

These muscles are important for stabilizing the knee, especially on the medial side.

Sartorius

Gracilis

Semitendinosus

biomechanics

Ligamentous Laxity and Knee Flexion

As the knee extends, the ligaments become taut (tightened) due to their anatomical positioning posterior to the knee joint axis.

Rotation (internal and external) in the knee is only possible when the knee is flexed because the ligaments tighten with extension.

Menisci Functions

Reduce compressive stress on the articular cartilage.

Increase the concavity of the tibial condyles to better distribute weight.

Act as shock absorbers, although eccentric muscle contractions are more critical in absorbing shock.

Reduce friction during joint movement.

Knee Osteokinematics (Range of Motion)

Flexion: The knee can flex up to about 140 degrees in most people.

Extension: The knee can extend beyond 0 degrees, usually up to about 5-10 degrees.

Rotation: Internal and external rotation is only possible when the knee is flexed. External rotation typically has about 30 degrees, while internal rotation is about 15 degrees.

Abduction/Adduction: These motions do not occur actively at the knee but can be available passively by about 6 degrees.

Arthrokinematics:

Open-Chain Movements

When the tibia moves relative to the femur (e.g., during leg extension), the roll and glide occur in the same direction.

During knee extension, the tibia glides anteriorly.

During flexion, the tibia glides posteriorly.

Closed-Chain Movements

When the femur moves relative to the tibia (e.g., during squat), the roll and glide occur in opposite directions.

During knee extension, the femur glides posteriorly.

During flexion, the femur glides anteriorly.

Role of the Cruciate Ligaments

Anterior Cruciate Ligament (ACL)

Function: Limits anterior glide of the tibia relative to the femur and posterior glide of the femur relative to the tibia.

Becomes stretched during knee extension.

Posterior Cruciate Ligament (PCL

Function: Limits posterior glide of the tibia relative to the femur and anterior glide of the femur relative to the tibia.

Becomes taut during knee flexion.

Screw-Home Mechanism

slight lateral rotation of the tibia during knee extension, allowing the knee to "lock" in place.

Contributors

Shape of the medial femoral condyle (longer and more curved than the lateral condyle).

Tension in the ACL.

Slight lateral pull of the quadriceps.

Slight external rotation of the tibia.

Patellofemoral Joint

patella acts as a pulley for the quadriceps muscle, increasing the moment arm and improving the force output during knee extension.

During extension, the patella glides superiorly (upward).

During flexion, the patella glides inferiorly (downward).

gait

Kinematics

Stance Phase (Approx. 60% of the Gait Cycle)

Initial Position

The knee starts in about 5 degrees of flexion.

Loading Response (0-15% of the gait cycle):

The knee flexes further to absorb the initial impact and body weight as the foot makes contact with the ground.

Quadriceps Activation: The quadriceps work eccentrically to control this flexion and resist the external flexion moment generated by gravity (which acts posterior to the knee joint).

Pre-Swing (40-60% of the gait cycle):

The knee flexes again slightly, preparing for the toe-off (when the foot leaves the ground).

Mid Stance (15-40% of the gait cycle)

As the body moves forward, the knee extends. This extension is largely driven by the forward momentum of the trunk and pelvis, as the foot remains fixed to the ground.

During this phase, the quadriceps show minimal activation because the extension is more passive, driven by body motion rather than active muscle contraction.

Swing Phase (Approx. 40% of the Gait Cycle):

Initial Swing (60-75% of the gait cycle):

The knee continues to flex to allow the foot to clear the ground.

Maximum knee flexion of around 60 degrees occurs during this phase.

This flexion is mainly driven by the hip flexors, which generate momentum that is transferred from the thigh to the lower leg (shank).

Terminal Swing (75-100% of the gait cycle):

The knee flexors (hamstrings) are activated eccentrically in the latter half of the swing phase to decelerate the shank and control the knee's motion as it prepares to land

Muscle Activation During Gait

Eccentric Quadriceps Activation

During loading response (heel strike to foot flat), the quadriceps control knee flexion under the force of gravity, preventing excessive knee collapse.

Later in the stance phase, when the knee extends, the quadriceps activation is minimal as it is a passive motion driven by body momentum

Hip Flexor Momentum in Swing

The primary driver for knee flexion in the swing phase is the momentum generated by the hip flexors. This momentum is transferred to the lower leg to clear the foot off the ground.

Eccentric Hamstrings Activation

Hamstrings activate eccentrically during the second half of the swing phase to decelerate the lower leg, preparing for controlled foot placement during the next gait cycle.

CNS connection

Sensory Input to the Knee

Proprioception & Dermatomes

Sensory information from the knee comes from joint proprioceptors (which provide information on knee position) and the skin around the knee.

Dermatomes

Medial knee: L3

Anterior knee: L4

Lateral knee: L5

Posterior knee: S1 & S2

Proprioception (joint position sense) typically travels via the dorsal columns.

Pain and temperature sensations travel through the spinothalamic tract.

Motor Control of the Knee

Motor Plan Creation

The brain's premotor areas initiate a motor plan, which communicates with the knee portion of the homunculus in the primary motor cortex.

the lateral corticospinal tract transmits the signal to the spinal cord, where it crosses over to the opposite side at the pyramids of the brainstem.

Myotomes for Knee Muscles:

Knee extensors (e.g., quadriceps) are controlled by spinal nerve levels L2-L4.

Knee flexors (e.g., hamstrings) are controlled by spinal nerve levels L5-S1.

Cerebellar Influence on the Knee

The cerebellum plays a crucial role in movement coordination, refining movement quality, and maintaining balance.

Spinocerebellum: This part of the cerebellum receives input about unconscious proprioception (joint and muscle position sense) via the posterior spinocerebellar tract. It helps smooth and coordinate movements like walking and ensures accurate landing of the knee during gait.

The cerebellum communicates ipsilaterally with the spine, meaning information from the lower extremity (knee) remains on the same side of the body.

Basal Ganglia's Role in Knee Movement

basal ganglia helps in the initiation, termination, and inhibition of movement, influencing voluntary movement like knee flexion and extension.

Go pathway (direct pathway): Facilitates movement by reducing inhibition. This allows you to initiate knee movement when desired.

Stop pathway (indirect pathway): Inhibits movement, helping you stop unwanted movements, such as preventing unnecessary knee flexion at rest.

Hip

Ligaments

Iliofemoral Ligament (Y-Ligament)

Attaches from the anterior inferior iliac spine (AIIS) and the adjacent ilium to the greater trochanter and intertrochanteric line.

It limits hyperextension and external rotation during extension

Pubofemoral Ligament

Located in the lower anterior part of the joint capsule.

Attaches to the body and superior ramus of the pubic bone, blending with the inferior band of the iliofemoral ligament.

It limits extension, abduction, and possibly external rotation

Ischiofemoral Ligament

Located at the posterior part of the joint capsule.

Arises from the ischial part of the acetabular rim and attaches to the posterior base of the greater trochanter.

It is the weakest of the three ligaments and limits internal rotation during hip rotation

Vascular Supply

medial circumflex femoral artery

provides the majority of the blood supply to the femoral head

Damage to this artery can lead to avascular necrosis of the femoral head

internal iliac artery

obturator, superior gluteal, and inferior gluteal arteries

contribute to the blood supply

Osteology

Pubic Bone and Pelvic Girdle

ramus connects the pubic body to the ilium

pubic bones and inferior/superior pubic rami form the anterior half of the obturator foramen

Pubic crest, pubic tubercle, and pectineal pubis are located on the superior surface of the superior pubic ramus

pubic symphysis is the fibrocartilage plate that articulates the right and left pubic bones anteriorly

Proximal Femur

Head: Rounded, with a circular indentation called the fovea capitis.

Neck: Narrower than the head, connects the head to the trochanters.

Greater Trochanter: Large projection on the lateral and posterolateral side, superior to the neck.

Lesser Trochanter: Smaller projection on the posteromedial side at the neck-shaft junction.

Intertrochanteric Crest: A bony ridge between the greater and lesser trochanters on the posterior side.

Trochanteric Fossa: Depression between the neck and the greater trochanter.

Spiral Line: Extends toward the lesser trochanter, continuous with the intertrochanteric line.

Pectineal Line: Ridge leading to the base of the lesser trochanter.

Gluteal Tuberosity: Attachment site for the gluteus maximus muscle

Osteology

femur is the only bone in the thigh

Proximal Region

Head and neck

Greater and lesser trochanters

Intertrochanteric line and crest

Shaft (Body)

Extends from the intertrochanteric line to the femoral epicondyles

Anteriorly

Smooth surface

Posteriorly

Medial lip (continuous with the spiral line).

Lateral lip (continuous with the gluteal tuberosity).

Medial and lateral supracondylar lines (continuations of the lips)

Hip Joint

acetabular notch

pening inferiorly, bridged by the transverse acetabular ligament.

round ligament of the femur

rises from the transverse acetabular ligament

inserts into the fovea capitis of the femur. It also carries blood vessels to the femoral head.

Sensory Innervation

Femoral Nerve

Innervates the anterior aspect of the hip joint

Obturator Nerve

Provides innervation to the anterior and posterior capsules

Sciatic Nerve

Through the nerve to the quadratus femoris, innervates parts of the posterior capsule.

Superior Gluteal Nerve and Inferior Gluteal Nerve

Occasionally contribute to innervation

Muscles

Gluteal Region

spans from the iliac crest (superiorly) to the gluteal fold (inferiorly), and medially to the midline of the body

Superficial Muscles

Gluteus Maximus

largest and most superficial muscle

powerful hip extensor

Gluteus Medius & Minimus

between the gluteus maximus

stabilizing the pelvis during walking/running

Tensor Fascia Lata

anterior aspect of the iliac crest

tightens the fascia lata and assists in abduction and medial rotation of the thigh

Innervation of Superficial Muscles

Superior Gluteal Nerve: Innervates gluteus medius, minimus, and TFL.

Inferior Gluteal Nerve: Innervates the gluteus maximus.

Actions: All the superficial muscles (except gluteus maximus) are involved in thigh abduction and internal rotation, while the gluteus maximus is primarily involved in hip extension.

Deep Muscles

Piriformis

dividing the gluteal region into superior and inferior parts

laterally rotates the thigh.

Gemelli (Superior & Inferior)

lateral rotation of the thigh.

Obturator Internus

Works with the gemelli to rotate the thigh laterally

Quadratus Femoris

most inferior deep gluteal muscle, contributing to lateral rotation

Innervation of Deep Muscles

Piriformis: Innervated by the nerve to piriformis.

Superior Gemellus & Obturator Internus: Innervated by the nerve to obturator internus.

Inferior Gemellus & Quadratus Femoris: Innervated by the nerve to quadratus femoris.

Hip Flexors

iliacus and psoas major muscles form the iliopsoas, the main flexor of the thigh at the hip joint.

Psoas Minor

small muscle, often absent, assists the psoas major.

Biomechanics

Movement at the Hip Joint

Flexion/Extension: The hip can flex (bend forward) or extend (move backward).

Abduction/Adduction: The hip moves away from (abduction) or toward (adduction) the body's midline.

Hip abduction: Occurs when the pelvis is lifted on one side (contralateral pelvic elevation).

Hip adduction: Occurs when the pelvis drops on the opposite side (contralateral pelvic drop)

Internal/External Rotation: The hip rotates inward (internal rotation) or outward (external rotation).

Arthrokinematics:

Abduction: Accompanied by an inferior glide of the femoral head.

External rotation: Accompanied by an anterior glide.

Flexion: Accompanied by a spin of the femoral head within the acetabulum.

Reverse Actions at the Hip

If the hip abductors are activated and the femur is free to move, the result is hip abduction. If the pelvis is free to move instead, the result is contralateral pelvic elevation

If the hip flexors are activated, they will flex the hip joint. If the pelvis is fixed and the femur moves, the result is pelvic tilt.

Muscle Force

When a muscle's angle of application is closer to 90 degrees relative to the lever (the femur), it generates large torques and small translations (movements along the joint).

When the angle is closer to 0 degrees, the muscle generates small torques but large translational forces, potentially leading to joint instability or pain.

Gait

Hip Joint Kinematics in the Gait Cycle

Sagittal Plane

At the start of the gait cycle, the hip is in approximately 30 degrees of flexion.

During the stance phase, the hip gradually extends from about 10% to 50% of the cycle, reaching a maximum of about 10 degrees of extension.

In the swing phase, the hip flexes again from 50% to 80% of the cycle and remains in flexion until the cycle begins again.

Frontal Plane

The hip adducts from 0% to 20% of the cycle (the leg moves toward the midline).

From 20% to 65%, the hip abducts (moves away from the midline).

Then, the hip adducts again from 65% to 100% of the cycle.

Transverse Plane

The hip undergoes internal rotation from 0% to 30% of the gait cycle, followed by external rotation from 30% to 60%.

It then undergoes another round of internal rotation from **60% to the end of the cycle.

Reverse Actions

Hip adduction is seen as contralateral pelvic depression (the opposite side of the pelvis drops).

Hip abduction is seen as contralateral pelvic elevation (the opposite side of the pelvis lifts).

Internal rotation of the hip is observed as contralateral forward pelvic rotation.

External rotation of the hip is observed as contralateral backward pelvic rotation.

Kinetics of the Hip Joint During Gait

Hip Extensors (Gluteus Maximus):

activated concentrically in the early stance phase (about 10% of the gait cycle) to extend the hip.

Hip Flexors

Eccentric activation around 45% of the gait cycle to limit excessive hip extension.

Concentric activation around 70% of the gait cycle, assisting in lifting the femur upward and forward to prepare for the next step.

Hip Abductors

work eccentrically to control the amount of pelvic drop (or contralateral pelvic depression) during the stance phase, especially between 0% and 10% of the cycle when the opposite leg leaves the ground.

Peak activation occurs around 10% of the gait cycle

Hip Adductors

Activation at 10% of the gait cycle to assist the hip extensors.

Activation around 65-70% of the cycle to assist the hip flexors during the swing phase.

Sensory Control of the Hip

Primary Sensory Cortex

primary sensory cortex, which is located on the medial surface of the brain.

The sensory information from the hip is processed here, specifically related to touch sensations like shape, size, and texture.

The anterior cerebral artery supplies the sensory cortex, ensuring the hip’s sensory input is effectively processed.

Secondary Somatosensory Cortex

information is further processed and stored in the secondary somatosensory cortex.

This part of the brain helps with spatial memory and tactile memory related to the hip,

Sensory Pathways

Anterolateral Tract: This pathway carries pain and temperature sensations from the hip.

Fasciculus Gracilis: This tract carries fine touch and proprioception signals from the hip, giving the brain information about its position in space.

thigh

Thigh Region

Inguinal ligament

anterior

Inferior pubic ramus

medial

Hip joint

lateral

Gluteal fold

posterior

Compartments

Anterior compartment

Key Muscles

Iliopsoas

Composed of the iliacus and psoas major

powerful hip flexor.

Sartorius

The longest muscle in the body, running across the thigh

flexes, abducts, and externally rotates the hip, and also flexes the knee.

Quadriceps Femoris

Rectus femoris

Flexes the hip and extends the knee

Vastus lateralis, vastus medialis, vastus intermedius

Primarily responsible for extending the knee.

Innervation and Blood Supply

Femoral Nerve (L2-L4)

Provides motor innervation to the muscles of the anterior compartment

Supplies blood to the anterior thigh.

Femoral Artery

Femoral Triangle

Bound by the inguinal ligament, sartorius, and adductor longus

Contains the femoral nerve, artery, and vein.

Medial compartment

Key Muscles

Gracilis: Adducts the hip and flexes the knee.

Adductor Longus: A flat muscle that forms the medial border of the femoral triangle.

Adductor Brevis: A short muscle beneath the adductor longus.

Adductor Magnus: The largest muscle in the medial compartment, with dual innervation (adductor part by obturator nerve, hamstring part by sciatic nerve).

Obturator Externus: Laterally rotates the thigh.

Innervation and Blood Supply:

Obturator Nerve: Innervates the medial thigh muscles.

Obturator Artery: Supplies blood to the medial compartment.

Posterior compartment

Key Muscles

Biceps Femoris: Consists of two heads (long head from the ischial tuberosity, short head from the femur). It is located laterally and flexes the knee.

Semitendinosus: A tendinous muscle located medially to the biceps femoris.

Semimembranosus: A broad, flattened muscle located deep to the semitendinosus.

Innervation and Blood Supply

Sciatic Nerve (L4-S3)

Popliteal Fossa

behind the knee where the tendons of the hamstring muscles converge.

Sensory Control

Primary Sensory Cortex

located on the medial surface of the brain.

The sensory information from the thigh, including touch, proprioception (awareness of position), and pain, is processed in this area of the brain.

Secondary Somatosensory Cortex

After the sensory data from the thigh is processed in the primary sensory cortex, it is sent to the secondary somatosensory cortex.

This cortex is involved in more complex processing of the sensory information, specifically for storing and processing spatial and tactile memories related to the thigh.

inferior MCA branch also supplies blood to this part of the brain

Sensory Pathways

Anterolateral Tract: This pathway carries pain and temperature information from the thigh, allowing the brain to interpret sensations like discomfort or heat.

Fasciculus Gracilis: This tract is responsible for carrying fine touch and proprioception signals from the thigh, helping the brain recognize the thigh's position in space and its movement relative to other body parts.

osteology, joints, ligaments

osteology

illium

Largest of 3 hip bones

Iliac Crest

Superior border

ends at PSIS

Iliac Fossa

Attachment for iliacus muscle

Auricular Surface

Articulates with the sacrum (SI joint)

ASIS

Anterior Superior Iliac Spine

Muscle and ligament attachments

AIIS

Anterior Inferior Iliac Spine

Muscle and ligament attachments

Supports upper body weight

Provides attachment for muscles

Connects to sacrum for weight transfer

ischium

forms the lower and back region of the hip bone

Body

Contributes to acetabulum

Ramus

Forms part of obturator foramen

Ischial Tuberosity

Large protuberance, supports weight while sitting

Ischial Spine

Small pointed projection

Greater Sciatic Notch

Superior to ischial spine

Lesser Sciatic Notch

Between ischial spine and tuberosity

Provides support for sitting posture

Facilitates muscle attachment

Protects pelvic viscera

pubis

forms the lower and anterior part of each side of the hip bone

Superior Ramus

Forms part of acetabulum

Inferior Ramus

Contributes to obturator foramen

Pubic Crest

Thickening at the anterior part of the pubis

Pubic Tubercle

Prominent swelling at lateral end

Pecten Pubis (Pectineal Line)

Oblique ridge on the superior pubic ramus

Forms front part of the pelvic girdle

Supports lower body

Protects internal organs

joints

Sacroiliac joint

connection between the spine and pelvis

Pubic symphysis

connects the left and right pelvic bones

Sacrococcygeal joint

where the sacrum and coccyx meet

ligaments

Iliolumbar ligament

stability to the lumbosacral junction

Sacrotuberous ligament

Attaches the sacrum to the ischial tuberosity, helping to stabilize the pelvis and limit movement

Sacrospinous ligament

Connects the sacrum to the ischial spine, also contributing to pelvic stability

pelvic girdle

Basin-shaped ring of bones

connects vertebral column to femurs

Composed of sacrum and innominate bones (ilium, ischium, pubis)

Sacrum articulates with ilium at SI joints

functions

Weight-bearing: Supports body weight during standing and sitting

Weight transfer: Transfers weight to lower limbs via sacroiliac joints

Muscle attachment: Provides attachment for muscles of locomotion and posture

Protects pelvic organs: Includes bladder, reproductive organs, intestines

Supports pelvic viscera: Assists with abdominal functions and stability

neurovascular

arteries

Gonadal

Testicular

Traverses inguinal canal and enters scrotum

Ovarian

Crosses pelvic brim

Superior rectal

Crosses left common iliac vessels and descends into pelvis

Median sacral

Descends close to midline over L4 and L5 vertebrae, sacrum, and coccyx

Internal iliac

Passes medially over pelvic brim and descends into pelvic cavity; often forms anterior and posterior divisions

Anterior division of internal iliac

Passes anteriorly along lateral wall of pelvis

Umbilical

superior aspect of urinary bladder

Superior vesical

pass to superior aspect of bladder

Obturator

runs antero-inferiorly on obturator fascia

Inferior vesical

gives rise to prostatic artery

Artery to ductus deferens

runs to ductus deferens

Prostatic branches

Descends to prostate

Uterine

crosses ureter superiorly to reach cervix

Middle Rectal

descends in pelvis to inferior part of rectum

Inferior gluteal

exits pelvis vis greater sciatic foramen

Superior gluteal

passes between lumbosacral trunk

veins

internal iliac veins

drain via the superior rectal vein

Parietal median sacral vein

provides small branches that supply the pelvis

Ovarian veins (in females)

drain deoxygenated blood from the ovaries and return it to the heart

Internal iliac veins

drains the blood from the pelvic organs and pelvic wall

nerves

Pelvic Floor

Functions

Support for Internal Organs

Supports the pelvic and abdominal viscera

Sphincter Control

Controls the urethra, vagina, and anus

Sexual Function

Allows relaxation for penetration and contraction for orgasm

Stability

Fixes the trunk for extremity movement

Pump for Circulation

Aids in lymphatic fluid circulation from the legs back to the heart

Structure

Greater Pelvis

Surrounded by the superior pelvic girdle

Contains inferior abdominal viscera, providing protection

Lesser Pelvis

Surrounded by the inferior pelvic girdle, supporting the pelvic cavity and perineum

Separated by the musculofascial pelvic diaphragm

Anatomy

Muscles

Coccygeus (Ischiococcygeus)

Forms part of the pelvic floor

Levator Ani Muscles

Puborectalis

U-shaped loop around the anorectum

helps maintain fecal continence and plays a role in bowel movements

Pubococcygeus

Supports pelvic viscera

Iliococcygeus

Elevates pelvic floor

Fascia

Covers superior and inferior aspects of the pelvic diaphragm muscles

Forms a supportive layer around pelvic structures

biomechanics

Pelvic Osteokinematic Movements

distal segment relative to the proximal segment

Sacroiliac (SI) Joint Movements:

Nutation

Anterior rotation of the sacrum on the iliac bone, or posterior rotation of the iliac bone on the sacrum, or both.

Counternutation

Posterior rotation of the sacrum on the iliac bone, or anterior rotation of the iliac bone on the sacrum, or both.

Lumbopelvic Rhythm:

Contra-directional rhythm

pelvis and lumbar spine rotate in opposite directions

Ipsidirectional rhythm

pelvis and lumbar spine rotate in the same direction

Pelvic Force Couples:

Anterior pelvic tilt

hip flexors and lumbar extensors.

Posterior pelvic tilt

hip extensors and lumbar flexors.

Hip hiking

Contralateral elevation of the pelvis

etc: right gluteus medius and left quadratus lumborum

reproductive organs

Male Reproductive Organs

Testes and Epididymis

testes are responsible for producing sperm and hormones, primarily testosterone. The epididymis stores and matures sperm cells.

Ductus Deferens (Vas Deferens)

connects the epididymis to the urethra

passes through the inguinal canal

Ejaculatory Ducts

deliver sperm and seminal fluid into the urethra.

Prostate Gland

role in sperm motility and protects sperm

Female Reproductive Organs

Ovaries

Uterine Tubes (Fallopian Tubes)

carry oocytes from the ovaries to the uterus and are typically the site of fertilization

Uterus

muscular organ where the fertilized egg implants and develops during pregnancy

terine artery supplies the uterus, while the uterine veins drain into the internal iliac veins

Vagina

serves as the passage for menstruation, childbirth

Ligaments

broad ligament

connects the sides of the uterus to the pelvic walls and supports the uterus, ovaries, and uterine tubes.

round ligament and ovarian ligaments

secure the uterus and ovaries.

gait and posture

Pelvic Movements in Gait

Pelvic Rotation in the Horizontal Plane

Internal rotation (counterclockwise)

external rotation (clockwise)

Pelvic Tilting in the Sagittal Plane

anterior pelvic tilt (forward tilt of the iliac crests)

Posterior pelvic tilt (backward tilt)

Pelvic Movements in the Frontal Plane (Adduction and Abduction):

pelvic on femoral adduction and abduction during weight-bearing and swing phases.

At weight acceptance (initial stance phase), the left iliac crest drops below the right, reflecting pelvic adduction of the right hip.

Muscle Activation During Gait:

Hip Muscles and Pelvic Movements:

Hip flexors and extensors play a key role in controlling pelvic tilt and rotation

stance phase, the hip flexors (like the iliopsoas) are active to prevent excessive posterior pelvic tilt, while the hip extensors (like the gluteus maximus) control anterior pelvic tilt and stabilize the pelvis.

Hip abductors, such as the gluteus medius, are crucial for frontal plane stability, helping prevent excessive pelvic drop on the opposite side

Pelvic Rotation and Muscular Control:

pelvic rotators (obliques, internal and external rotators) help coordinate pelvic rotation in the horizontal plane

Internal rotation of the pelvis occurs as the stance leg's hip internally rotates, especially during the early stance phase when the foot is pronating.

internal rotation of the tibia causes internal rotation of the femur

Foot and Tibial Movements in Relation to Pelvic Control

pronation of the foot during the early stance phase of walking leads to internal rotation of the tibia

CNS connection

Sensory Input to the Pelvis

relayed through the dorsal portion of the spinal cord

L1 to L3

Pathways

light touch and proprioception follows the dorsal column-medial lemniscal pathway.

pain and temperature travels via the spinothalamic tract.

Motor Output

Pathways

anterior corticospinal tract

reticulospinal tract also plays a role in postural control and helps with gross limb movements.

exit the spinal cord at the level of the pelvis (anterior spinal cord) and control muscles involved in pelvic and lower limb movements

Blood Supply to the Pelvis and Lower Extremities

anterior cerebral artery

supplies the blood flow to the medial portion of the brain, including the pelvic region of the motor and sensory homunculi

Middle cerebral artery

supplies the more lateral brain regions, including those associated with the upper extremities.

Cerebellar Influence

smooth and coordinated control of trunk and pelvic movements, essential for balance and gait.

vermis and the flocculonodular lobe of the cerebellum are the primary regions responsible for these functions, known as the spinocerebellum (for trunk control) and vestibulocerebellum (for balance control).

Basal Ganglia Influence

movement initiation, modulation, and coordination, contributing to the overall goal-directed movement of the pelvis and lower limbs.

influence behavioral control and movement planning, indirectly affecting movement efficiency and precision.