Q7-4: Forefoot Flashcards
how many bones in forefoot?
21 bones (5 MTs, 5 PPs, 4 IPs, 5 DPs, 2 sesamoids)
how many joints in the forefoot?
15 joints (5 MTPJs, 4 PIPJs, 4 DIPJs, 1 hallux interphalangeal joint, 1 distal intermetatarsal joint)
lesser metatarsophalangeal joints (MTPJs): bones and articular surfaces
MTs 2-5: convex heads (dorsal-plantar, medial-laterl); dorsal tubercles near surgical neck, plantar projections separated by a notch
Proximal phalanx bases: ovoid and concave (plantar tubercles)
lesser metatarsophalangeal joints (MTPJs): type of joint
synovial ellipsoidal joint
lesser metatarsophalangeal joints (MTPJs): mvmt of joint
biaxial movement (along 2 planes), motion is primarily in sagittal plane (dorsiflexion/plantar flexion), adduction/abduction) joint capsule attaches firmly medially and laterally, but is loose dorsally and plantarly
clinical significance of lesser MTP joint capsule
able to dorsiflex/plantarflex more than adduct and abduct
joints holding lesser MTPJ joint together?
5 capsular ligaments (plantar MTP ligaments, collateral ligaments x2, and suspensory ligaments x 2)
describe the plantar metatarsophalangeal ligament x 1 (plantar pads)
thick, fibrocartilaginous pad indicative of inc pressure/force to deal w/ the stress it encounters
has metatarsal and phalanx attachments
metatarsal attachment of plantar metatarsophalangeal ligament
loosely attached to the plantar MT neck; thin and flexible
phalanx attachment of plantar metatarsophalangeal ligament
firmly attached to plantar base; thick and strong
plantar metatarsophalangeal ligament is continuous with/reinforced by…
plantar aponeurosis, deep transverse metatarsal ligament, and distal plantar ligaments
what can result if the groove formed by plantar projections doesn’t keep the tendon in place?
if the groove doesn’t work, the toe alignment can be affected –> creating hammer toes
collateral ligaments x 2; course & involved in which joint
run obliquely from dorsal tubercles on the metatarsal heads to the plantar tubercle on the phalangeal bases;
involved in lesser MTPJ
suspensory ligaments x 2; course & involved in which joint
run from those same dorsal tubercles on the metatarsal heads to the edge of the plantar pad;
involved in lesser MTPJ
lesser MTPJs: clinical significance
*NO dorsal ligaments; metatarsal parabola (2>1=3>4>5)
dorsiflexion versus plantarflexion
plantar pads and plantar tubercles as sesamoids of the lesser MTPJs
what reinforces the ligaments and affect of the function of the MTPJ joint?
extensor expansion (sling and wing)
distal intermetatarsal joints: define and characteristics
distal connection b/w each of the metatarsals; *NOT a true joint, but there is a ligament
ligaments in the distal intermetatarsal joint?
deep transverse metatarsal ligament
deep transverse metatarsal ligament: define and characteristics
short, strong ligaments connecting plantar pad to plantar pad (does not attach to bone)
deep transverse metatarsal ligament: clinical significance
allows distal MTs to function as a unit –> prevents spreading or “splaying” of the MTs –> limits more proximal stress –> serves as surgical anatomic landmark
how many interphalangeal joints possible?
9 possible (2 Hallux IPJs, 4 digits x each with PIPJ and DIPJ)
where are synostoses most common in the foot?
particularly in the DIPJ of the 5th digit (remember: synostoses are connections b/w bones)
interphalangeal joints: bones involved
proximal head & distal base
proximal head of interphalangeal joints: characteristics
central sagittal groove rendering the structure pulley-like; roughly convex, dorsal tubercles
distal base of interphalangeal joints: characteristics
oval or triangular, convex divided into by a sagittal crest, plantar tubercles
interphalangeal joints: type of joint
synovial, ginglymus/hinge joints
interphalangeal joints: mvment
dorsiflexion/plantarflexion; joint capsule is strong medially, laterally, plantarly, and posteriorly (very little motion if at all)
interphalangeal joints: which ligaments hold this joint together?
collateral ligaments x 2
plantar ligaments x 1
desc. collateral ligaments of the interphalangeal joint
(run obliquely from the dorsal tubercles on the head to the plantar tubercles on the base)
desc. plantar ligament of the interphalangeal joint
fibrocartilagineous and similar to those at MPJ level; continuous plantar structure ( continuous w/ PIPJ and DIPJ, which extends along the whole plantar aspect to hold the flexor tendon to hold in a stable position
which ligamentous tissue is a target for hammer toes?
plantar ligament of the interphalangeal joints
are there dorsal ligaments in the interphalangeal joints?
nope! (just plantar and collateral)
interphalangeal joints: clinical significance
arthroplasty versus arthrodesis procedures; surgical “J” maneuver
surgical “J” maneuver
Expose head of proximal phalanx; to do so, must release collateral ligaments; –> perform a J maneuver w/ the blade to remove the dorsal aspect of the collateral ligament (flick it off the respective tubercle)
what is the ligament involved in the INTRAphalangeal “joint”
intraosseous ligament (aka “paraterminal ligament” or lateral supporting ligament”
intraphalangeal “joints”
not a true joint, rather it is w/in the phalanx (important for performing skills on toenails)
intraosseous ligament: course
runs medially and laterally from the base of the distal phalanx to the tuft of the distal phalanx
intraosseous ligament: function
“protects” neurovascular elements to the tip of the toe and provides neurovascular supply to the nail matrix
what results when the intraosseous ligament ossifies?
“owl’s sign” forms; can ossify due to trauma in the area
unique features of hallucal metatarsophalangeal joint
bigger, has sesamoids, and movement
why is the 1st MT the biggest?
More body weight passes through this MPJ versus the other MPJs –> the 1st MT is more “stout” than the others
how is the movement of the hallucal MTP joint different than at other MTP joints?
1st ray has independent range of motion
hallucal MTP joints: joints and articular surfaces
1st MT head and proximal phalanx base
1st MT head of hallucal MTP joints: describe
rounded and convex; two plantar grooves for the sesamoids separated by distinct crest (cheated laterally)
proximal phalanx base of hallucal MTP joints: describe
concave and wider medial-lateral; articular surface is smaller than the first metatarsal head
hallucal MTP joint: bones and articular surfaces
sesamoids: (medial > lateral); ovoid, dorsal surface, and plantar surface
describe dorsal surface of sesamoid found in hallucal MTP joint
convex from medial –> lateral;
concave from anterior –> posterior
describe plantar surface of sesamoid found in hallucal MTP joint
convex and embedded w/in soft tissue structures (muscle, ligament, tendon, etc)
describe the sesamoid apparatus
5 ligaments which hold the sesamoids strongly in relation to the proximal phalanx and relatively weak to first MT
what are the 5 ligaments in the sesamoid apparatus
plantar metatarsophalangeal , medial metatarsosesamoid, lateral metatarsosesamoid, intersesamoid, and phalageosesamoid
what does the deep transverse metatarsal ligament connect?
the lateral sesamoid and not the 1st MT
plantar metatarsophalangeal ligament (of hallucal MTPJ): describe
thick plate of fibrocartilage, plantar “plate” or “pad”, firmly attached to phalanx, loosely attached to the first met; sesamoids are embedded w/in this ligament
in which ligament are the sesamoids embedded?
plantar metatarsophalangeal ligament (of hallucal MTPJ)
intersesamoid ligament (of hallucal MTPJ): describe
runs b/w the two sesamoids
phalangeosesamoid ligament (of hallucal MTPJ): describe
strongly connect the sesamoids to the proximal phalanx, 1-2
medial and lateral metatarsosesamoid ligaments: course and fxn
connects the dorsal tubercles of the first metatarsal head to the respective sesamoids and plantar ligament
what is comparable to the medial and lateral metatarsosesamoid ligaments
suspensory ligaments of the lesser MPJs
collateral ligaments of hallucal metatarsophalangeal joint: course
runs obliquely from the dorsal tubercles on the head to the plantar tubercles on the base
are collateral ligaments x2 part of the sesamoid apparatus?
NOT part of the sesamoid apparatus
hallucal metatarsophalangeal joint: clinical significance
hallux abductovalgus deformity (aka bunion)
hallux abductovalgus deformity (aka bunion)
• Prominence of 1st metatarsal head; there isn’t a large bone spur typically
• Think of a bunion as a normal first MT bone in an abnormal bone
Think of the sesamoid staying in place; and they are held firmly to the 2nd MT by the deep transverse metatarsal ligament
*More structures holding it distally and laterally (rather than holding it to the 1st MT head itself)
