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Anatomy
Published in Peter Houpt, Hand Injuries in the Emergency Department, 2023
Intrinsic muscles are those whose origin and insertion are located within the hand. Located in the thenar eminence are three muscles that together provide opposition (m. opponens pollicis), abduction (m. abductor pollicis brevis) and flexion of the first MCP joint (m. flexor pollicis brevis). The muscles of the hypothenar consist of the m. opponens digiti minimi, m. abductor digiti minimi and the flexor digiti minimi. The thumb is adducted towards the palm by the adductor pollicis, palpated best on the dorsal side of the hand. Located between the metacarpal bones are the mm. interossei. The palmar interossei, three in total, adduct the fingers in the direction of the middle finger. The dorsal interossei, four in total, abduct the fingers away from the middle finger (Figure 2.5). Last but not least the hand contains the mm. lumbricales, which originate from the FDP tendons and insert onto the extensor aponeurosis at the proximal phalangeal level. These lumbrical muscles tighten the extensors such that the fingers can remain extended during the flexion of the MCP joints.
Assessment – Nutrition-Focused Physical Exam to Detect Macronutrient Deficiencies
Published in Jennifer Doley, Mary J. Marian, Adult Malnutrition, 2023
The palmar thenar muscles are a group of muscles at the base of the thumb and are used for thumb movement. Inspect the base of the thumb for muscle bulk. A well-defined thenar eminence will appear as a mound at the base of the thumb. The thenar muscles can be palpated using the same technique described above for muscle engagement. While the patient is holding their thumb pressed against the other four fingerpads, palpate the base of the thumb on the palmar side to assess the musculature. Well-nourished patients will have adequate muscle bulk between the metacarpal bones and thumb base with no apparent depressions. In severely malnourished patients, an apparent depression will be seen between the metacarpal bones and the base of the thumb. Lack of muscle bulk can also be felt on palpation. See Figures 6.14–6.16.
Compression Neuropathies
Published in J. Terrence Jose Jerome, Clinical Examination of the Hand, 2022
The examination should assess light touch or threshold testing and involve both palms. The bulk of the thenar muscles should be palpated and any wasting of the abductor pollicis brevis (APB) should be documented (Figure 11A.8). The thumb is opposed to the little finger and strength is assessed (Video 11A.3). With loss of the thenar function, the patient may be able to oppose with the ulnar innervated deep head of the flexor pollicis brevis and flex the thumb across the palm to the little finger using the FPL tendon [8].
Facing symptoms and limitations: A qualitative study of women with carpal tunnel syndrome
Published in Scandinavian Journal of Occupational Therapy, 2023
Paloma Moro-López-Menchero, Margarita Inés Cigarán-Méndez, Lidiane L. Florencio, Javier Güeita-Rodríguez, César Fernández-de-las-Peñas, Domingo Palacios-Ceña
Carpal tunnel syndrome (CTS) is a neuropathic pain condition characterised by signs and symptoms associated to compression of the median nerve. The clinical presentation consists of pain and/or paresthesia within the area innervated by the median nerve that worsens at night, loss of strength and, in severe cases, atrophy of the thenar eminence musculature. It is estimated that between 4 and 5% of the world population suffers from CTS, with incidence rates of 9.2% in women and 6% in men. The most affected age group is between 40 and 60 years old [1]. In Spain, the incidence of CTS is 4.2 cases per 100,000 workers, of which 62.8% are women [2]. Potential risk factors for CTS include obesity, pregnancy, autoimmune diseases (rheumatoid arthritis), diabetes, hypothyroidism, and renal and cardiac insufficiency, together with mechanical factors such as constant wrist activity with wrist flexion or extension positions, or exposure to vibration [1,3].
Development and testing of a wearable wrist-to-forearm posture measurement system for hand-tool design evaluation
Published in International Journal of Occupational Safety and Ergonomics, 2021
Michail Karakikes, Dimitris Nathanael
The presented findings combined with direct observation can be used to directly inform tool design with the following recommendations: Longer and narrower handles tend be held so that they lie diagonally across the entire palm; the thenar eminence forcing a diversion from the axis of the forearm. This causes postural compensation by ulnar deviation of the wrist, leading to higher discomfort.Shorter and wider handles tend to be held so that the head of the handle rests inside the palm, with less deviation from the axis of the forearm. However, this resting causes constant wrist extension in order to apply the required force for screwdriving.The aforementioned hold true both for the horizontal and for the vertical screwing task, signifying that there is no benefit in differentiating handle design for these two typical screwing directions.Based on SD values of P/S, it is evident that the forearm rotational displacement which is employed by the participants is independent of the screwdriver design. Hence, handle width, while desirable for minimizing tissue pressure, was not found to affect the rotational amplitude per turn.
Multimodal Spinal Cord Mapping during Spinal Cord Stimulator Placement: Technical Note
Published in The Neurodiagnostic Journal, 2021
Geoffrey Allott, Satish Krishnamurthy
Standard neuromonitoring consisted of SSEPs recorded using scalp electrodes at Cp3, Cp4, Fpz, Cz, Cs5 as outlined in the International 10–20 System, as well as the bilateral popliteal fossae (PF). Responses were recorded using a standard neuromonitoring suite (Cadwell Elite/Cadwell Pro/ Cadwell Cascade, Cadwell Labs, Kennewick, WA) and a bandpass of 50–500 Hz. Subdermal needles (paired needle electrodes, Medtronic Dual Electrode, 2.0 m Memphis, TN) were placed bilaterally at the PF, as well as the ulnar, median, and tibial nerves. Standard peripheral stimulation consisted of stimulation at the medial malleolus (posterior tibial nerve) or the wrist (median nerve) at a frequency of 4.44 or 4.55 Hz. Free run electromyography (EMG) was monitored from thenar, hypothenar, vastus lateralis, tibialis anterior, gastrocnemius, and abductor hallucis brevis muscles for thoracic placement. Thenar, hypothenar, deltoid, biceps extensor carpi radialis, and abductor hallucis brevis muscles were recorded during cervical implantation. Also, during cervical implantation, ulnar nerve (UN) recordings at the wrist were recorded. The bandpass for EMG channels was 100–1000 Hz with a notch filter. Transcranial motor evoked potentials were monitored from the muscle groups previously defined utilizing either C3-C4 or C1-C2 stimulation sites utilizing constant voltage stimulation.