Occupational Therapy Biomechanics: Thorax, Lower Extremity, Pelvic Health, and Hip

Comprehensive practice flashcards covering thoracic wall biomechanics, respiration, knee, ankle, and foot kinematics, pelvic floor rehabilitation, and hip and pelvis evaluation for occupational therapy.

Trunk (Torso)

The central area of the body excluding the extremities and the head and neck, comprising the vertebral column (most) and the thorax.

Thorax

The skeletal framework composed of the sternum, ribs, and thoracic vertebrae that encloses and protects the heart, lungs, and other essential viscera.

True Ribs

Rib pairs $1$ through $7$ ($14$ total), which articulate directly with the sternum via costal cartilage.

False Ribs

Rib pairs $8$ through $10$, which connect indirectly to the sternum through the costal cartilage of the superior rib.

Floating Ribs

Rib pairs $11$ and $12$, which lack an anterior attachment to the sternum and provide stability to the thoracic spine.

Sternocostal Joints

Planar (gliding) joints formed between the true ribs and the sternum.

Costochondral Joints

Synchondroses connecting the ribs directly to their associated costal cartilages.

Interchondral Joints

Joints situated between the costal cartilages of adjacent ribs.

Costovertebral and Costotransverse Joints

Articulations connecting the ribs to the thoracic vertebral bodies and transverse processes, permitting rib elevation, depression, and slight rotation.

Diaphragm

The primary muscle of inspiration separating the thoracic and abdominal cavities; upon contraction it displaces inferiorly to generate a partial vacuum, accounting for $80\%$ of ventilation.

External Intercostal Muscles

Primary muscles of respiration that contract to elevate the ribs during inspiration.

Internal Intercostal Muscles

Respiratory muscles that depress the ribs to assist in exhalation.

Hyperpnea

Forced inhalation occurring as a biophysiological response to increased oxygen demand (e.g., during exercise, stress, fever, high altitude, or hypoxia), requiring increased respiration rate and accessory muscle recruitment.

Accessory Muscles of Forced Inhalation

Muscles recruited during labored inhalation, specifically including the scalenes, sternocleidomastoid (SCM), pectoralis major and minor, serratus anterior, and latissimus dorsi.

Muscles of Forced Exhalation

Muscles that actively contract to expel air, consisting of the internal intercostals, transversus thoracis, and the abdominal wall musculature.

Spinal Flexion Rib Mechanics

Vertebral movement pattern that produces anterior ribcage compression and posterior ribcage expansion.

Spinal Extension Rib Mechanics

Vertebral movement pattern that produces anterior ribcage expansion and posterior ribcage compression.

Spinal Lateral Flexion Rib Mechanics

Vertebral motion causing ipsilateral ribcage compression and contralateral ribcage expansion.

Tripod Position

An anteriorly leaning seated posture with elbows braced on the lower extremities, commonly adopted during respiratory distress to optimize accessory muscle function.

Hammock Position

A slumped bed-positioning posture that decreases diaphragmatic excursion and lung capacity, weakens the diaphragm and trunk extensors, and shortens anterior neck muscles.

Chronic Obstructive Pulmonary Disease (COPD)

A chronic progressive lung disease marked by bronchial and alveolar destruction, chronic inflammation, airway narrowing, and fibrosis, leading to an inability to fully exhale and carbon dioxide retention.

Pneumonia

An infectious inflammatory condition affecting one or both lungs where the alveoli fill with fluid and pus, requiring early out-of-bed mobilization in therapy.

Tibiofemoral Joint

A modified hinge joint between the distal femoral condyles and the tibial plateau that permits knee flexion, extension, and slight rotation.

Patellofemoral Joint

The articulation between the patella and the femoral trochlear groove that acts as a pulley to enhance quadriceps mechanical efficiency during extension.

Medial Collateral Ligament (MCL)

An extracapsular knee ligament that resists and limits excessive valgus stress.

Lateral Collateral Ligament (LCL)

An extracapsular knee ligament that resists and limits excessive varus stress.

Anterior Cruciate Ligament (ACL)

An intraarticular knee ligament that prevents posterior displacement of the femur on the tibia and anterior displacement of the tibia; it is taut in extension and slack in flexion.

Posterior Cruciate Ligament (PCL)

An intraarticular knee ligament that prevents anterior displacement of the femur on the tibia and posterior displacement of the tibia; it tightens during flexion.

Q Angle

The angle formed between the longitudinal axis of the femur and the patellar tendon line of pull, normally measuring approximately $15^\circ$.

Genu Valgum (Knock-Knee)

A lower extremity malalignment where the Q angle exceeds $20^\circ$, placing tensile stress upon the medial collateral ligament.

Genu Varum (Bow-Legged)

A lower extremity malalignment where the Q angle is less than $10^\circ$, placing tensile stress upon the lateral collateral ligament.

Screw Home Mechanism

An involuntary biomechanical phenomenon occurring in the final $5^\circ$ of knee extension where the tibia externally rotates to lock the knee into a close-packed position.

Patellar Tracking

The smooth excursion of the patella along the femoral sulcus without osseous impingement, displacing distally during knee flexion and proximally during extension.

Knee Flexion Required for Gait

The average active knee range of motion necessary for level walking, which is $60^\circ$.

Knee Flexion Required for Chair Transfers

The average active knee range of motion necessary to sit and transfer from a standard chair, which is $90^\circ$.

Knee Flexion Required for Bathtub Transfers

The active knee range of motion required to safely transfer in and out of a bathtub, which is $135^\circ$.

Ankle and Foot Complex Anatomy

A functional anatomical unit comprising $28$ bones, $33$ joints, $112$ ligaments, $13$ extrinsic muscles, and $21$ intrinsic muscles.

Talocrural Joint

A uniaxial hinge joint formed by the distal tibia, fibula, and talus that produces plantar flexion and dorsiflexion.

Subtalar Joint

The joint formed between the talus and calcaneus that allows triplanar rotational motions, primarily inversion and eversion.

Plantar Aponeurosis

A dense fibrous aponeurotic band supporting the longitudinal and transverse arches of the foot and facilitating weightbearing; prone to inflammation known as plantar fasciitis.

Foot Drop

The inability to actively dorsiflex the ankle, resulting in toe drag during gait and heightened fall risk; managed with an ankle-foot orthosis (AFO) to maintain neutral position.

Normal Ankle Plantar Flexion ROM

The normative active range of motion for plantar flexion, which is $50^\circ$, primarily actuated by the gastrocnemius and soleus.

Normal Ankle Dorsiflexion ROM

The normative active range of motion for dorsiflexion, which is $20^\circ$, primarily actuated by the tibialis anterior.

Normal Ankle Inversion ROM

The normative active range of motion for ankle inversion, which is $35^\circ$, driven primarily by the tibialis posterior and tibialis anterior.

Normal Ankle Eversion ROM

The normative active range of motion for ankle eversion, which is $15^\circ$, driven primarily by the fibularis longus and fibularis brevis.

Pelvic Rehabilitation

The specialized rehabilitation of pelvic dysfunctions contributing to bowel, bladder, sexual dysfunction, and pelvic pain complaints across the lifespan.

Normal Urinary Voiding Frequency

A standard physiological pattern of voiding $5-8$ times per $24\text{ hours}$, $0-1$ times overnight, and every $2-4\text{ hours}$ during waking hours.

Normal Urinary Stream Duration

The physiological duration of an unobstructed urine stream during bladder emptying, which is approximately $8\text{ seconds}$.

Normal Bowel Movement Frequency

Defecation frequency ranging between $1-3\text{ times per day}$ and $3\text{ times per week}$, characterized by complete evacuation and Type $3-4$ stool consistency on the Bristol Stool Scale.

Six Goals of Pelvic Rehabilitation

Primary clinical aims: 1) Achieve urinary continence, 2) Achieve urinary completion, 3) Improve quality of life, 4) Reduce/prevent UTIs, 5) Improve independence, and 6) Promote sexual activity.

Patient-Specific Functional Scale (PSFS)

A validated functional outcome assessment utilized in pelvic floor rehabilitation primarily to establish patient-centered goals.

Extended PLISSIT Model

A tiered clinical model addressing sexual wellbeing consisting of Permission (P), Limited Information (LI), Specific Suggestions (SS), Intensive Therapy (IT), and Reflection and Review.

Pelvic Floor Support Function

The anatomical role of the pelvic floor musculature serving as an inferior muscular hammock or shelf supporting internal pelvic organs.

Pelvic Floor Sphincter Function

The muscular action of the pelvic floor that constricts around orifices to maintain continence during physical stress and relaxes to allow voiding and defecation.

Pelvic Floor Stability Function

The dynamic stabilization provided by the pelvic floor through its myofascial connection to the deep abdominal core.

Pelvic Floor Sump-Pump Function

The respiratory-linked lymphatic and venous pumping action generated by coordinated piston movements between the diaphragm and the pelvic floor.

Levator Ani

A major pelvic floor muscle group composed of the pubococcygeus, puborectalis, and iliococcygeus that provides visceral support and continence.

Coccygeus

A posterior pelvic muscle that, together with the levator ani, forms the pelvic diaphragm to support the pelvic floor and elevate it during defecation.

Superficial Transverse Perineal Muscle

A bilateral superficial perineal muscle that anchors and stabilizes the central tendon of the perineum.

Bulbospongiosus and Ischiocavernosus

Superficial perineal muscles responsible for maintaining penile or clitoral erection during sexual activity.

Pudendal Nerve

The primary peripheral nerve arising from the sacral plexus that innervates the external genitalia, perineum, and external urethral and anal sphincters.

S4-S5 Dermatomes

Perianal sacral dermatomes whose sensory and motor integrity is critically assessed to determine lower bowel function.

Functional Pressure Canister

The intra-abdominal pressure management system enclosed by the diaphragm (regulator), pelvic floor, deep psoas, deep quadratus lumborum, multifidus, transverse abdominis, internal obliques, and glottis.

Pelvic Mechanics during Inhalation

A respiratory phase wherein the diaphragm descends, the abdomen moves outward, and the pelvic floor relaxes and elongates inferiorly.

Pelvic Mechanics during Exhalation

A respiratory phase wherein the diaphragm ascends, the abdomen moves inward, and the pelvic floor contracts and lifts superiorly.

Stress Urinary Incontinence

Involuntary loss of urine resulting from increased intra-abdominal pressure during physical exertion such as coughing, sneezing, laughing, or exercising.

Urge Urinary Incontinence

Involuntary urine leakage preceded immediately by an intense, uncontrollable sensation of urgency due to involuntary bladder detrusor contractions or dyscoordination.

Lumbo-Pelvic-Hip Complex

The functional kinematic region encompassing the spine, pelvis, hip, and lower extremity that serves as the foundation for postural stability.

Acetabular Labrum

A fibrocartilaginous rim encircling the acetabulum that deepens the socket and absorbs joint reaction forces from the femoral head.

Hip Joint Stability Factors

Anatomical features preventing hip dislocation despite high mobility, including a deep bony socket, acetabular labrum, robust capsule, and strong surrounding musculature.

Pelvic Bones

The three fused bones of the pelvis: the ilium (housing the iliac crest, ASIS, and PSIS), the ischium, and the pubis.

Female Pelvic Kinematics

Anatomical morphology featuring a wider and shorter iliac crest, resulting in an increased Q angle and a more adducted resting femoral alignment.

Male Pelvic Kinematics

Anatomical morphology featuring a narrower and taller iliac crest, resulting in a lower Q angle and a more abducted resting femoral alignment.

Iliopsoas

The primary flexor of the hip joint situated in the anterior compartment, composed of the iliacus and psoas major muscles.

Gluteus Maximus

The largest posterior hip muscle responsible for powerful hip extension and external rotation.

Gluteus Medius and Minimus

Lateral hip musculature that functions primarily in hip abduction and hip internal rotation.

Hip Adductor Group

Musculature occupying the medial compartment of the thigh, comprising the adductor magnus, longus, brevis, pectineus, and gracilis.

Deep 6 External Rotators

A group of six deep hip lateral rotators situated between the sacrum and greater trochanter, with the piriformis serving as the primary muscle.

Anterior Pelvic Tilt

A sagittal plane rotation of the pelvis forward that increases lumbar lordosis and upper thoracic extension, associated with tight hip flexors and weak abdominals.

Posterior Pelvic Tilt

A sagittal plane rotation of the pelvis backward that flattens the lumbar lordosis and increases thoracic kyphosis, associated with tight hamstrings.

Pelvic Obliquity

A frontal plane deviation in which one hemipelvis rests higher than the other (upslip), often secondary to a shortened quadratus lumborum.

Hip Capsular Pattern

A proportional limitation of joint range of motion characteristic of hip osteoarthritis, presenting with restriction in internal rotation, flexion, and abduction.

Posterior Approach Hip Precautions

Postoperative precautions following total hip arthroplasty to prevent dislocation, requiring avoidance of hip internal rotation, adduction past midline, and flexion beyond $90^\circ$.

Anterior Approach Hip Precautions

Surgical approach guidelines after total hip replacement where surgeons typically order no formal restrictions, though advising against extreme hip extension, external rotation, and abduction.

Toe-Touch Weightbearing (TTWB)

A weightbearing restriction allowing only the toe of the affected lower extremity to contact the floor solely for balance, bearing minimal to no weight.

Hip ORIF Precautions

Post-surgical protocol following open reduction internal fixation of a hip fracture that typically mandates strict non-weightbearing ($\text{NWB}$) while having no range-of-motion limitations.

Normal Hip Flexion ROM

The normative active range of motion for hip flexion, which is $120^\circ$, primarily produced by the iliopsoas and rectus femoris.

Normal Hip Extension ROM

The normative active range of motion for hip extension, which is $30^\circ$, primarily produced by the gluteus maximus and hamstrings.

Manual Muscle Testing (MMT) Grade 3 (Fair)

A manual muscle testing grade indicating that the muscle completes full active range of motion against gravity but is unable to hold any manual resistance.