Equine palpation

8.7.1 Head, neck and temporomandibular joint (TMJ)

The physiotherapy history should follow on from the vet-erinary history and examination, in which a full dental examinationshould have been undertaken, along with any other diagnostic tests described above.

Special questions regarding temporomandibular joint (TMJ) dysfunction include asking the owner about the following clinical signs (Moll & May 2002):

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Head shaking

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^Quidding

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Apparent masticatory problems As well as:

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Bitting problems At the walk

In the absence of obvious lameness, the walk may bring out subtle movement dysfunction that faster gaits may mask.

This is because in the walk cycle there are stages where a limb must be able to stabilise unilaterally at a given point. Kinema-tic data reveals greater ranges of motion for the thoraco-lumbar spinal segments at the walk compared with the trot (Roethlisbergeret al. 2006), giving another reason for the subtle dysfunction of gait being more apparent to the observer at the walk. The horse may be led in hand or observed on the lunge. For the slower gaits of walk and trot it may be useful to assess both in a straight line and on the circle.

From the lateral aspect (straight line or circle)

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Timing of limb contact with the ground (audible as well as visual)

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Placement of hindlimb with respect to forelimb (degree of ‘overreach’)

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Placement of hoof (flat/toes first/toes up)

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Head carriage/head ‘bob’

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Maintenance of spinal curves

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Tail carriage

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Recruitment of abdominal musculature

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General mobility of trunk, pelvic and neck fascia From the caudal aspect (straight line)

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Timing of limb contact with the ground (audible as well as visual)

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Tracking of hindlimbs compared with forelimbs

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Specifically for hindlimb – plaiting/winging/mediolat-eral placement

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Mediolateral placement of hind hoof with ground

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Tail carriage

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Symmetry of rise of gluteal musculature

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Symmetry of lateral swing of pelvis

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Symmetry of lateral swing of ribcage/abdomen From the cranial aspect (straight line)

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Head carriage/head bob

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Tracking of forelimbs compared with hindlimbs

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Specifically for forelimb – winging/mediolateral placement

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Mediolateral placement of fore hoof with ground

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Symmetry of shoulder motion

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Symmetry of swing of ribcage/abdomen At the trot

Concussive limb lameness may be more apparent at the trot than the walk, owing to increased loading forces. In the absence of lameness the following are some useful points regarding gait analysis at the trot:

From the lateral aspect

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Head carriage/bob

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Symmetry of the diagonal limbs striking the ground

The above list is not exhaustive, and there may be more subtle clinical signs, which are associated with TMJ dys-function, such as minor deviations of the poll during work or inability of the horse to accept the bit on one rein.

Observation

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Symmetry of the visible muscles of mastication, primar-ily the masseter and temporalis muscles at rest

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Symmetry of facial bones, especially mandible

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Position of upper cervical spine regarding extension and flexion, plus symmetry of occipital and upper cervical muscles

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Mastication during eating

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^Mentation

Palpation

Careful palpation of the horse’s TMJ and comparison with the other side can detect joint effusion. The TMJ is located by following a horizontal projection from the lateral aspect of the eye directly caudal (Moll & May 2002). The distance between the condyle of the mandible and the mastoid pro-cess can be palpated and compared side to side as can the distance between the mastoid process and the atlas. Gentle movement of the mandible in a lateral direction can be used to confirm the location of the mandibular condyle, as the joint line is palpated.

Muscles of mastication should be palpated bilaterally for symmetry of bulk, quality of the muscle belly and pain response. The masseter, temporalis, medial pterygoid (jaw closure) and anterior belly of digastric (jaw opening) are the most easily palpable muscles. The anterior belly of digastric, and medial pterygoid muscle are palpated on the medial aspect of the mandible. The strap-like digastric belly can be distinguished medially and rostrally from the medial ptery-goid. The occipitomandibular part of caudal belly of digas-tric, which assists in raising the tongue and hyoid bone, can be palpated just caudal to the mandible. Other muscles assisting jaw opening are geniohyoid, inferior genioglossus, sternohyoid and omohyoid (Baker 2002). The latter two muscles can be palpated just caudal to the hyoid bone and run caudally to the scapula, crossing the larynx (Sisson 1975).

Algometry has been used in assessment of pain in the muscles of mastication in human TMJ dysfunction (Farella et al. 2000, Michelottiet al. 2004), and has been shown to be useful in assessment of pain response in horses (Varcoe-Cockset al. 2006). Algometry therefore may be an objective measure of TMJ dysfunction where there is muscular adaptation or spasm.

Motion tests

Lateral mandibular glide

Symmetry of lateral glide of the mandible may give an indi-cation of altered mediolateral excursion. The mandible can be moved laterally in relation to the stabilised maxilla, where the examiner should see an initial lateral displacement of

the mandible, followed by an oblique glide of the mandible relative to the maxilla which ‘gaps’ the upper and lower incisor rows (Figure 8.12).

Flexion test

This tests the rostral movement of the mandible relative to the maxilla. The front incisors are palpated by the exam-iner’s index finger while the head is flexed on the upper cer-vical spine. There should be a relative rostral movement of the lower incisors compared with the upper incisors, indicating a slight rostral movement of the mandible. If the head is moved into a relative upper cervical extension, then the lower incisors should be felt to glide caudally on the upper incisors (Figure 8.13).

8.7.2 Equine cervical spine Palpation

The muscles of the occiput, temporal and hyoid region should be palpated for symmetry, tone, thickening, tender-ness and spasm. This can be done bilaterally, taking care of your position if in front of the horse when palpating occi-pital region, as the horse can throw his head up if there is a pain response. The larger muscles of the cervical spine should also be palpated with the same parameters in mind.

Each vertebral body can be palpated from C1–C6. When palpating horses with a lot of soft tissue coverage, it is often useful to count the spaces between the vertebral bodies to enable identification of each vertebral level.

Active movements

Observation of the horse during gait, on small circles and ridden, during grazing/feeding will give an overall impres-sion of cervical range of active motion.

Baited active movements for upper cervical spine

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Extension: Guide horse’s muzzle forward and up, (with a treat) so effecting upper cervical extension.

Figure 8.12 Lateral excursion test to examine dental/temporomandibular joint movement.

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Flexion: Guide muzzle towards the upper chest; stabilise with one hand gently over C1 and apply gentle overpres-sure to the front of the muzzle. Assess end-feel and any deviation of occiput on C1.

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Rotation: Stabilise with one hand over C2 and guide horse’s muzzle toward you on an axis that is approxim-ately through the longitudinal axis of the dens. Apply gentle overpressure via the muzzle. Compare range of motion and end-feel side to side (Figure 8.14).

Caudal cervical spine

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Flexion: Passive neck flexion is difficult to assess as it requires the horse to initiate the action.

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Extension: As above.

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Lateral flexion: Motion at each cervical level between C3–C6 can be assessed by palpating the ‘opening’ of the cervical vertebra when an assistant laterally flexes the horse’s neck away from the assessor.

Or: Stabilise with one hand over the vertebral body to effectively ‘block’ motion from the chosen level caudal, and gently guide the horse’s muzzle toward you, in a lat-eral flexion direction. Apply gentle overpressure; assess range of motion and end-feel and compare side to side.

Passive accessory palpation

Lateral glide technique to caudal cervical spine

This technique is described in detail in Chapter 9, and involves assessing the relative lateral glide of the more cra-nial level on the more caudal level. Range of motion and end-feel is compared side to side.

Oblique dorsoventral translation

This technique assesses the combined ventral and lateral glide of a vertebral level relative to the segment above and below.

Translation is applied in an oblique dorsoventral direction on the body of the vertebra, while stabilising the level cranial to that from the contralateral side (Figure 8.15).

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Flexion: Guide horse’s muzzle towards upper chest to effect a nodding movement (at the poll).

For caudal cervical spine

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Flexion: For lower cervical/upper thoracic flexion, guide horse’s muzzle down between fetlocks (or observe horse grazing – check for even weight distribution between forelimbs); also guide horse’s muzzle towards sternum to check mid-cervical flexion.

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Lateral flexion: Guide muzzle around along horse’s lateral trunk towards the flank and compare range side to side.

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Lateral flexion/flexion: Guide muzzle around towards the carpal region and compare range side to side (Figure 8.2).

Passive physiological movements

Many of these manoeuvres are passive-assisted movements (not true passive physiological movement tests) as the horse is not truly relaxed in the standing position.

Upper cervical spine

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Extension: Guide muzzle as described above (with or without treat); stabilise with one hand gently over C1 and apply gentle overpressure from underneath the muzzle. Assess end-feel and any asymmetrical deviation (laterally or rotatory) of the occiput on C1.

Figure 8.13 Flexion test to examine jaw movement relative to head position.

Figure 8.14 Passive physiological assessment of equine atlantoaxial (C1–2) joint.

Oblique ventrodorsal translation

Translation is applied in an oblique ventrodorsal direction on the body of the vertebra, while stabilising the level caudal to that from the contralateral side.

8.7.3 Thoracic and thoracolumbar spine Palpation

The musculature of the trunk, including the epaxial muscles, abdominal muscles, and wither region should be palpated for symmetry, tone, thickening, swelling, tender-ness and spasm. The spinous processes of T4 –T18 should be identified and the corresponding rib angles. Often it is helpful to identify the last thoracic vertebrae via the 18th rib and palpate cranially. The sternum and manubrium and costal cartilages should be palpated ventrally.

The lumbar spinous process should be identified from L1–L6 – often it is easier to count back cranially from the lumbosacral junction. The transverse processes can be pal-pated, depending on the depth of soft tissue coverage. Note, some horses may only have five lumbar vertebrae and/or transitional thoracolumbar and sacral vertebrae (Chapter 4).

Active movements

Active movements are assisted with either baited stretching or using reflexes inherent in the horse.

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Lateral flexion: Observation of the relative contribution of the cranial thoracic spine to a baited lateral flexion test of the cervical spine, or making the horse perform a tight circle, can be compared side to side.

The lateral flexion reflex can be initiated by stimulating the contralateral gluteal region of the horse with a firm object such as fingernail, pen cap or blunt hoof pick. The horse will tend to shift the pelvis away from the irritant, and as there is minimal lateral flexion in the lumbar ver-tebral column, much of the movement occurs at the thor-acic spine (this is often combined with some flexion of the thoracolumbar region).

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Flexion: A ventrodorsal ‘lift’ reflex can be performed via the manubrium/sternum or more caudally at the level of the girth. A firm pressure with fingernails, pen cap or blunt hoof pick applied to the midline of the above-mentioned regions can cause the horse to ‘lift’ the cranial thoracic region. Observation of the motion at the thor-acic spinous processes is carried out.

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Extension: Dorsoventral extension or ‘hollowing’ of the thoracic spine can be induced by stimulating as men-tioned above along the epaxial muscles. This can be performed bilaterally for extension or unilaterally for a combined extension/lateral flexion movement. Differ-ences side to side can be noted.

Passive physiological movements

As for the cervical spine, these manoeuvres are passive-assisted movements (not true passive physiological move-ment tests) as the horse is not truly relaxed in the standing position.

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For lateral flexion: Use of the lateral flexion reflex can be localised to a given level of the thoracic spine by stabilising with one hand over the lateral aspect of the spinous process, and causing the horse to flex laterally.

The amount of intervertebral lateral flexion can be com-pared between levels and then side to side. Depending on the size of horse and examiner, the horse’s pelvis may also be pulled towards the examiner to create a lateral flexion movement as an alternative to using the reflex.

(Figure 8.16). Motion can also be assessed between ribs and rib angles with this technique.

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For flexion: Using reflexes described above, the horse can be encouraged to perform a ventrodorsal ‘lift’. The physiotherapist can palpate the relative ‘opening’ move-ments between the spinous processes and compare between levels.

Passive accessory palpation

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For extension: A dorsoventral translation can be applied in a direction perpendicular to the spinous process, to effect an extension movement between vertebral seg-ments (or groups of vertebral levels). Care should be taken to be aware of the angles of the individual spinous processes, as cranial thoracic processes tend to override the body of the next caudal vertebra. T1–T15 spinous processes are angled dorsocaudally, change at the anti-clinal vertebra T16 to an upright position, and are angled dorsocranially from T16–T17.

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For lateral flexion/rotation: A relative latero-rotatory translation of one vertebra relative to the next can be applied in variety of ways, and it is to be noted that lateral flexion is coupled with rotation in the thoracic spine (see Chapter 4 for definition).

Digital pressure may be used to ‘pull’ a spinous pro-cess towards you from the contralateral side, effecting a lateral flexion at that given level combined with an

Figure 8.15 Oblique dorsoventral translation at C3–4. Near hand is applying translation to C4 vertebral body while far hand is stabilising C3 contralaterally.

brae, pelvic symphysis and greater trochanter should be identified – in particular, symmetry of the tubera coxae and sacrale, sacral spines and pelvic symphysis. The dorsal sacroiliac ligament is palpable running from tuber sacrale to abaxial surface of sacral spine. The sacrotuberous ligament is palpable medial and cranially to the ischial tuberosity.

Active movements

Active movements of the lumbopelvic and sacroiliac region can be observed during straight line gait (look for symmetry at walk and trot), tight circles, canter transitions, rein-back, walking up and down hills, and unilateral hind limb stance.

Rounding reflex via the gluteal musculature can indicate ability to rotate the pelvis caudally and extension reflex can indicate ability to rotate the pelvis cranially.

Passive movements

The tail can be extended and moved laterally to ascertain tail head muscle tone, as well as comparison of motion side to side, as far cranial as the sacrum (one hand moves the tail, while the other palpates over the relevant vertebral level).

The hindlimb can be moved into protraction to assess relative caudal rotation of the pelvis on that side, and retraction to assess relative cranial rotation (Figure 8.17).

It is difficult to differentiate between coxofemoral joint and pelvic motion when using the hindlimb to cause physio-logical movement, so these joints could be considered a functional unit. The limb can be adducted and abducted to assess relative motion of the hip in these ranges. Compare range and quality of motion side to side.

Passive physiological and passive accessory

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Ilium on sacrum: Cranial, caudal, and oblique rotations can be applied to the ilium around the sacrum as well as dorsoventral translations via the tuber coxae and tuber sacrale. The latter may be angulated laterally to follow the plane of the ilial wing. Compare range and quality of motion, and end-feel side to side (Figure 8.18).

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Sacrum on ilium – The sacrum can be translated laterally by stabilising the ipsilateral tuber sacrale and gripping the sacral spines and gliding towards the operator.

Compare range and quality of motion, and end-feel side to side (Figure 8.19).

A dorsoventral translation can be applied to the sacrum, centrally, and a relative longitudinal distraction translation can be applied by ‘cupping’ the most anterior sacral spinous process and gliding the sacrum caudally.

8.7.5 Scapulothoracic articulation Palpation

The borders and surfaces of the scapula including the sup-raglenoid tubercle, the dorsal scapular cartilage as well as the superficial muscles such as deltoid, supraspinatus, infraspinatus, tricep group, serratus ventralis, subclavius ipsilateral rotation. Comparison between levels and side

to side, regarding range and quality of motion should be performed.

Translation of the vertebral body via the spinous process from the ipsilateral side may achieve a relative movement between adjacent vertebrae – it is useful to provide a ‘counter’ stabilisation at the spinous process cranial or caudal.

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For rotation/lateral flexion: An obliquely, medially and ventrally directed glide applied over the costotransverse joint (between transverse process and tubercle on rib) may effect a relative rotation and lateral translation between vertebral levels in the thoracic spine. The quality of movement and end-feel should be compared between levels and side to side.

8.7.4 Lumbo-pelvic and sacroiliac/hip region Palpation

The gluteal musculature in particular (note middle gluteal;

extends as far cranial as the lumbar spine) should be pal-pated for symmetry, tone, thickening, swelling, tenderness and spasm, along with biceps femoris, hamstring group, tail head muscles, adductor and medial and lateral thigh mus-cles. The lumbosacral junction, tuber coxae, tuber sacrale, ischial tuberosity, sacral spinous processes, caudal

verte-Figure 8.16 Use of reflex to induce left lateral flexion at thoracolumbar spine.

Physiotherapist localises the lateral flexion at desired level with hand.

Figure 8.17 Palpating relative iliosacral motion at tuber sacrale and sacrum via movement of hindlimb.

(a) Neutral; (b) in protraction; (c) in retraction.

(a) (b)

(c)

Passive movements

Gliding or translatory movements of the scapula can be performed in craniocaudal, dorsoventral and abduction directions. The forelimb is elevated and flexed at the carpus, elbow and shoulder and the physiotherapist faces the scapula, holding the flexed forelimb and supporting under-neath the elbow. The scapula is then translated as described above, in its plane against the thorax. Range and quality of movement is noted and compared side to side.

Relative flexion/extension excursion of the scapula can also be observed and/or palpated with full retraction and protraction of the forelimb. Relative abduction and adduc-tion of the forelimb can provide an observable assessment for abduction/adduction excursion of the scapula.

8.7.6 Glenohumeral joint Palpation

The greater and lesser tubercles of the humerus are readily palpated, and the joint line can be identified with the shoul-der in flexion, applying a slight cranial force along the axis of the humerus. The biceps tendon, from supraglenoid tubercle via the intertubercular groove can be palpated.

Active movements

Active movements of flexion and extension can be observed during various gaits.

and trapezius, should be palpated and compared side to side.

The muscles on the ventral thorax, that is the pectoral groups (ascending, transverse and descending), sternocephalicus and brachiocephalicus should also be palpated.

Active movements

The movement of the scapula on the thorax can be observed during varieties of gait, including changes of direction that involve adduction and abduction of the forelimb.

Figure 8.18Assessing movement of ilium on sacrum (a) cranial rotation; (b) oblique rotation.

Figure 8.19 Lateral translation of sacrum relative to the ilia – physiother-apist’s right hand stabilises against right tuber sacrale and left hand glides sacrum laterally towards the right.

(a)

(b)

Passive movements Passive physiological

The humerus lies at right angles to the scapula and may be further flexed, with the rest of the forelimb also flexed for ease of handling. The physiotherapist faces the trunk of the horse and applies flexion to the shoulder via the distal humerus. The integrity of the muscular support of the joint can be assessed by applying medial and lateral rotations to the humerus, via its distal end, and comparing end-feel and range of motion side to side. Extension of the glenohumeral joint is most easily assessed when combined with a caudal translation of the scapulothoracic articulation (see above).

Passive accessory

The forelimb is flexed for ease of handling with physiother-apist facing slightly cranially, palpating the glenohumeral joint line. Cranial and caudal translation of the humerus can be performed to assess joint range of motion (Figure 8.20).

Medial and lateral rotations can be applied via the humerus (as above) and assessed via palpation of the joint line.

8.7.7 Elbow joint Palpation

Medial and lateral epicondyles of the humerus, olecranon, lacertus fibrosus (crossing the flexor aspect of the elbow),

brachialis and triceps may be palpated and compared side to side. Musculature distal to the elbow (muscles of the forearm) includes the extensor and flexor groups.

Active movements

Active movements of the elbow may be observed during various gaits.

Passive movements Passive physiological

The elbow may be flexed passively and extended via the radius/ulna (with the carpus in flexion for ease of handling), using counter-pressure on the distal humerus. Medial and lateral movements may be applied to the joint at various angles of flexion and extension to test joint integrity. For all passive physiological movements, joint end-feel, quality and range of motion are compared side to side.

Passive accessory

With the elbow in a neutral flexed/extended position, a lon-gitudinal force can be applied along the radius/ulna, and the relative translation palpated via the heel of the hand at the olecranon (humerus is stabilised distally). Medial and lateral translation can be applied, and joint end-feel, quality and range of motion are compared side to side.

8.7.8 Carpal joint

Palpation (including metacarpal region)

In extension (standing), the styloid processes of distal radius, extensor tendons and accessory carpal bone are readily palpable. In flexion, the radiocarpal joint space (which has greatest mobility) and mid-carpal joint space are able to be palpated on the extensor aspect, for relative range of motion and the presence of any joint distension. The joint line of the carpometacarpal joint may also be palpated on the extensor aspect. The palmar carpal ligament can be pal-pated on the flexor aspect, and just distally, the accessory (check) ligament of the deep digital flexor tendon. Distal to these structures, the superficial and deep digital flexor tendons should be distinguishable from each other. The 3rd metacarpal should be palpated for irregularities, as should the 2nd and 4th metacarpals (medial and lateral splint bones).

Active movements

Active movements of the carpal joint may be observed during various gaits.

Passive movements Passive physiological

The carpus as a whole may be fully flexed, and mediolateral movements and medial and lateral rotations applied to the fully flexed position, via the metacarpal, to test joint integrity and range of motion. The carpus is in extension in standing, but overpressure may be applied with the

Figure 8.20 Assessing cranial translation of the humerus at glenohumeral joint – left hand is palpating the joint line, while cranial translation of humerus is applied along the humeral longitudinal axis via the physiotherapist’s forearm.

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